New-Onset Left Bundle Branch Block and Other Conduction Disturbances After TAVR: Incidence, Predictors, and Clinical Implications

Abstract

Transcatheter aortic valve replacement (TAVR) is now established as a safe and effective treatment for severe aortic stenosis across all surgical risk categories. Nevertheless, periprocedural conduction disturbances—including new-onset left bundle branch block (LBBB), right bundle branch block (RBBB), and other intraventricular blocks—remain among the most frequent complications, often resulting in permanent pacemaker (PPM) implantation and impacting left ventricular remodeling. A review was conducted using the PubMed/MEDLINE database. Relevant clinical trials, observational studies, and meta-analyses addressing post-TAVR LBBB were included and analysed with a focus on frequency, risk factors, and association with adverse outcomes. We describe the incidence of post-TAVR conduction disturbances and identify key predictors: pre-existing RBBB, membranous septum length, valve oversizing, implantation depth, infra-annular leaflet extension, compression ratio, and valve type/generation. New-onset LBBB is a frequent complication after TAVR and may negatively affect patient outcomes. Accurate risk stratification and standardised post-procedural monitoring protocols are essential. Further prospective studies are needed to better define management strategies for patients developing LBBB after TAVR.

1. Introduction

One of the most common valvular heart diseases is aortic stenosis, which is a fatal condition if left untreated [1]. TAVR is now recognised as a safe and effective treatment for patients with severe aortic stenosis, regardless of age [2]. TAVR, or transcatheter aortic valve implantation, involves the minimally invasive insertion of a new heart valve, usually through a femoral access, without the need to open the chest. Thanks to technological advances, this procedure can be performed under local anaesthesia, often without the need for general anaesthesia or routine use of transesophageal echocardiography (TEE), particularly in patients undergoing transfemoral access. However, TEE remains a valuable tool in selected cases, depending on anatomical complexity or intraoperative needs [3,4]. TAVR has a shorter hospitalisation time with a comparable safety profile [5]. TAVR has become particularly attractive in high-risk surgical patients who are ineligible for surgical aortic valve replacement (SAVR), although it is now recommended for patients of all risk levels [6,7,8]. Transcatheter aortic valve replacement (TAVR) is indicated in patients with symptomatic severe aortic stenosis who are either ≥75 years old (as per ESC guidelines) or ≥65 years old (according to ACC/AHA guidelines), or in younger patients when surgical risk is high. It is the preferred treatment in patients with frailty, prior cardiac surgery, or significant comorbidities such as chronic kidney or pulmonary disease. TAVR is especially suited for transfemoral access and favorable anatomical conditions. The choice between TAVR and SAVR should always involve a multidisciplinary Heart Team assessment [9,10]. In this article, we briefly compare TAVR with other treatments and focus on complications and their consequences, in particular conduction disturbances (including LBBB) and permanent pacemaker implantation (PPM).

2. Materials and Methods

This article is a literature review. Searches were conducted in the PubMed/MEDLINE database using the following keyword combinations: “transcatheter aortic valve replacement AND LBBB”, “transcatheter aortic valve replacement AND left bundle branch block”, “TAVR AND left bundle branch block”, “TAVR AND LBBB”. A total of 1132 results were obtained, which were reduced to 569 items after removal of duplicates. A total of 154 articles were qualified for further analysis. Inclusion criteria were English language; publications mainly from the last 5 years; original clinical data; and prospective, retrospective studies and meta-analyses. Classic literature reviews, preclinical papers and articles not directly related to the topic of TAVR and conduction disorders were excluded. Many of the initially retrieved articles, although identified through LBBB-related keywords, also included data on other conduction disturbances such as right bundle branch block (RBBB), atrioventricular block (AVB) or pacemaker implantation. This overlap reflects the nature of clinical studies, which frequently address multiple types of conduction disorders following TAVR. Therefore, despite the initial search focus, our analysis included a broad range of conduction-related outcomes. To further enhance coverage and ensure thematic completeness, a second-stage search was performed using broader terms: “TAVR AND RBBB”, “TAVR AND conduction disturbances”, “TAVR AND pacemaker implantation”. The result of this expanded search were screened and incorporated following the same inclusion criteria. This second-stage search yielded 925 additional unique results, of which 14 articles met the inclusion criteria and were included in the final analysis. A total of 167 relevant articles were identified and reviewed.

3. Comparison of TAVR and SAVR

Although both surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) effectively treat severe aortic stenosis, each method has a different complication profile. Lodo et al. reported a 4-year survival rate of 89.8% for SAVR and 75.6% for TAVR, highlighting potential differences in patient selection and long-term risk. However, several large randomised controlled trials conducted in the past decade have demonstrated comparable survival and clinical outcomes between TAVR and SAVR across various risk groups [11]. In the PARTNER 3 trial, conducted in low-risk patients, both approaches demonstrated similar valve hemodynamics at 5 years. TAVR showed a higher rate of mild aortic regurgitation (24.5% vs. 6.3%) but improved right ventricular function and reduced valvulo-arterial impedance compared to SAVR [12]. The SURTAVI trial, focusing on intermediate-risk patients, found that at 5 years, the composite rate of death or disabling stroke was similar between TAVR and SAVR (31.3% vs. 30.8%). TAVR yielded lower transprosthetic gradients and larger aortic valve areas, but was associated with more frequent pacemaker implantation (39.1% vs. 15.1%) and paravalvular leak (3.0% vs. 0.7%) [13]. In the Evolut Low Risk trial, the 5-year incidence of all-cause mortality or disabling stroke was virtually identical for TAVR and SAVR (15.5% vs. 16.4%). Both groups experienced sustained improvements in quality of life, and valve reintervention rates remained low [14]. Lastly, the NOTION trial, which provided 10-year follow-up data, demonstrated no difference in the combined risk of all-cause mortality, stroke, or myocardial infarction between TAVR and SAVR (65.5% in both arms). Notably, severe structural valve deterioration occurred significantly less frequently after TAVR (1.5%) than after SAVR (10%) [15]. These findings underscore that TAVR, while associated with a higher risk of conduction disturbances and pacemaker implantation, provides comparable or even favorable long-term outcomes in selected patients, including those at low or intermediate surgical risk. Surgical aortic valve replacement has a significantly lower incidence of conductive complications and paravalvular leaks, but carries a higher risk of renal failure and a longer operative time [11,16]. The choice of treatment should take into account both the haemodynamic benefits and the risk of conduction complications. The adverse effects of left bundle branch block (LBBB) and other conduction abnormalities should be taken into account when selecting a treatment modality for an individual patient [16].

In addition to the traditional sutured bioprosthesis (SB), there are also sutureless bioprostheses, such as the Perceval SU-AVR, whose use significantly reduces operative time and is equally effective compared to SB. However, Perceval SU-AVR is associated with a higher rate of peri-valvular leaks, a higher risk of LBBB and a greater need for pacemaker implantation (PPM), and is therefore recommended mainly for minimally invasive procedures in older patients [17,18]. As with TAVR, a pre-existing RBBB or newly formed LBBB increases the risk of PPM implantation after the procedure [19,20]. Overall, although SAVR alone is associated with a lower risk of conduction disturbances than TAVR, the use of an appropriate surgical suture technique may further reduce this risk [21,22,23].

4. New Conduction Disturbances After TAVR

4.1. Left Bundle Branch Block (LBBB)

The most common complication of TAVR is the appearance of left bundle branch block (LBBB) [15]. After TAVR, new left bundle branch block occurs in between 4 and 66% of patients [24,25,26]. This wide range is due to a number of factors, such as the type of valve used (balloon vs. self-expandable), implantation technique, depth of implantation, differences in LBBB definitions, previous conduction disturbances and the method and duration of postoperative monitoring. The definition of persistent LBBB includes the persistence of conduction changes for at least 3 days after surgery—only about 10% of patients meet this definition [27,28,29,30].

LBBB after TAVR may be a reversible conduction disturbance caused, for example, by valve compression of the conduction system or tissue oedema. Such LBBB is usually characterised by a characteristic notching in the QRS complex (notching) or haziness (slurring) of the waves in the lateral leads (I, aVL, V5, V6) and can be corrected using conduction system pacing (CSP) methods [27]. Intermittent conduction in the diseased leg can manifest as alternating wide and narrow QRS complexes. Three physiological mechanisms that explain this are (1) supernormal conduction—the existence of a ‘conduction window’ after premature beats that transmits the impulse in a normal, physiological manner; (2) concealed retrograde penetration—the appearance of a pulse that modifies the refractoriness of the diseased leg; and (3) concealed Wenckebach—gradual conduction delay, similar to AV block [28]. To differentiate true LBBB from left ventricular conduction delay, Alqarawi et al. proposed two criteria: the presence of an R-wave indentation/blur in ≥1 lateral lead and an R-wave duration ≤20 ms in V1 [29]. In addition to a change in the morphology of the QRS complexes, there may also be a change in the QRS axis. A new LBBB after TAVR is usually associated with a leftward shift of the QRS axis, but this change does not occur in approximately 27% of patients—these are patients at increased risk of developing atrioventricular (AV) block, requiring pacemaker implantation [23].

Conduction abnormalities after TAVR negatively affect left ventricular (LV) remodelling and regeneration, affecting features such as LV systolic function (LVEF), reduced end-systolic volume (LVESV) and end-diastolic volume (LVEDV), or LV mass regression [30,31]. This may influence myocardial dysfunction. It has been shown that although ECG criteria may indicate LBBB after TAVR, only a few actually have impaired mechanical synchrony, i.e., uncoordinated ventricular contractions, identified as ‘septal flash’ on echocardiography, and delayed contraction of the lateral wall compared to the right ventricle (IVMD). In contrast, the classic pattern of dyssynchrony on speckle tracking only occurs in about 5% of patients with LBBB after TAVR, with the septal flash proving to be the most important indicator, being the only one that appears fast enough [32,33]. ECG changes may better reflect cardiac status and synchrony, and ejection fraction (LVEF) may remain normal [34]. LBBB in the vast majority of patients after TAVR is likely to be of a different nature than in classic heart failure, with less impact on contractility and less impact on survival [32]. Although a full ‘classical’ LBBB pattern does not always develop after TAVR, left ventricular systolic dyssynchrony partially occurs immediately after the procedure [35]. The newly developed LBBB increases mechanical dispersion (MD), a measure of the heterogeneity of ventricular contraction. High MD after TAVR is associated with a worse prognosis and higher mortality, proving to be a more accurate prognostic marker than, for example, GLS [36,37].

The anatomical proximity of the cardiac conduction system (CCS) to the aortic ring explains the frequent conduction complications after TAVR (Figure 1). Atkinson et al. created a three-dimensional model of the heart in which the bundle of His and its left branch, located in the membranous part of the interventricular septum, are particularly vulnerable structures [38,39].

Although LBBB after TAVR does not always take the ‘classic’ form known for heart failure, it can lead to significant, though often mild, left ventricular systolic dyssynchrony. In some patients, this results in reduced cardiac performance in the first few days after the procedure and, in the long term, can lead to cardiomyopathy [40,41].

4.2. Other Conduction Disturbances After TAVR

In addition to the most common left bundle branch block (LBBB), other conduction disturbances may occur after TAVR. Right bundle branch block (RBBB) may be a rare complication, but its new occurrence after the procedure is associated with a more than eightfold increased risk of pacemaker implantation (PPM) [42,43]. This may be due to the anatomical location of the right bundle branch, which in some patients runs closer to the left side and is more fragile, and thus more easily damaged [44]. Other conduction abnormalities that are early or late complications of TAVR can also be found in the literature. Among others, Left Septal Fascicular Block (LSFB) combined with RBBB has been described [45], or alternating BBB, in which conduction in both branches is alternatively delayed [46,47]. One late complication of TAVR may be bundle branch reentry ventricular tachycardia (BBR-VT), a ventricular tachycardia with LBBB morphology resulting from reentry within the His bundle. It occurs despite preserved ejection fraction and a properly functioning valve, leading to syncope and haemodynamic instability. The occurrence of LBBB itself may be a risk factor for the subsequent development of BBR-VT [48,49,50,51]. In addition, patients may experience asymptomatic tachy- and bradyarrhythmias, such as atrial fibrillation or flutter, ventricular tachycardias or atrioventricular blocks (HAVBs) [52].

4.3. Consequences of Conduction Disturbances After TAVR

Both LBBB and RBBB after TAVR can lead to transient or permanent atrioventricular block, which, in turn, can cause syncope and require PPM implantation. The association of LBBB with increased risk of death is uncertain, while RBBB clearly increases this risk. In both cases, the pacemaker does not improve the risk of death [53]. Approximately 10 percent of patients develop high-grade block in the immediate postoperative period, but in nearly half, the disorders resolve by the time of discharge. Implantation of a PPM does not always confer a survival benefit—only about 50% of patients who receive a PPM after TAVR are actually dependent on it [53,54]. RBBB is associated with an increased risk of death, in contrast to LBBB, whose association with survival is less clear. If LBBB persists, it increases the risk of hospitalisation for heart failure and death, especially in patients with previously implanted PPM, atrial fibrillation, reduced ejection fraction and trans-thoracic access. On the other hand, the risk of sudden cardiac death increases significantly with the coexistence of diabetes, chronic kidney disease, the use of the valve-in-valve technique, atypical vascular accesses and, especially, the occurrence of ventricular arrhythmias during the procedure (more than sevenfold increase in risk) [55]. The prognosis of patients in whom LBBB resolves is good—even without pacemaker implantation [56]. Some more recent studies suggest that persistent LBBB alone is not necessarily associated with worsened survival [57,58,59,60], but other sources indicate its association with heart failure progression and reduced left ventricular ejection fraction [61,62]. The inconclusiveness of the findings may be due to individual differences: previous cardiac function, type of valve implanted, implantation technique, or the presence of dyssynchrony or myocardial fibrosis.

5. Pacemaker After TAVR

5.1. Predictors of Implantation PPM

New conduction disturbances after TAVR—including LBBB, RBBB or rare intraventricular blocks—significantly increase the risk of progression to advanced blocks requiring pacemaker implantation (PPM). There is a lack of clear guidance on whether every patient with new conduction block after TAVR should have a PPM implanted at hospital discharge [53]. It is known that the presence of a PPM, whether implanted before or after the procedure, is associated with higher annual mortality, especially in patients with an EF < 40% [63,64]. Sometimes, however, the use of PPM proves necessary. Even before valve implantation, several important predictors of PPM implantation can be identified. These include the following: (1) male sex; (2) older age; (3) ECG conduction abnormalities including (4) the presence of RBBB, left-anterior fascicular block or atrioventricular block and its duration; (4) small LVOT diameter and large prosthesis size relative to the left ventricular outflow tract (LVOT), or narrow conical LVOT shape; (5) large left ventricular end-diastolic dimension; (6) small interventricular membranous septal (MS) height; (7) aortic leaflet calcification on echocardiography; and (8) chronic conditions and diseases including type II diabetes mellitus (DM II), chronic kidney disease (CKD), atrial fibrillation and others [53,65,66,67,68,69,70,71,72,73].

It is worth noting that the classic risk indicators are not universal, however. In patients with atrial fibrillation, they have limited predictive value (Table 1). In such cases, a simple HRratio—i.e., the ratio of heart rate before and after the procedure—may be helpful [74].

Certain procedural parameters and changes observed immediately after valve implantation also correlate with a higher risk of needing PPM. These include the following: (1) larger prosthesis size (29 mm); (2) type of prosthesis, such as the use of a self-expandable valve (versus balloon-expandable valves) (there is no significant difference between generations I and II of either type of valve); (3) the depth of implantation, which can be better controlled by, among other things, using the COP (Cusp Overlap Projection) technique instead of TCV (Tall Cusp View) during implantation; (4) transient total atrioventricular block (AVB) during the procedure; (5) distance of the aortic ring from the left coronary artery and others [24,65,75,76,77,78]. The latter appears to be the most important risk factor for permanent pacemaker implantation after TAVR [79].

Table 1. Summary of predictors for permanent pacemaker implantation (PPM) and conduction disturbances (CDs) After TAVR [24,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98].

Category	Predictors
Clinical	- Male sex - Older age - Atrial fibrillation - Diabetes mellitus type II - Chronic kidney disease
Preprocedural ECG	- Pre-existing RBBB - Pre-existing LBBB - Left anterior fascicular block - Atrioventricular block - PR interval > 180 ms
Echocardiographic/CT	- Small membranous septum - Small LVOT diameter - Narrow LVOT shape - Aortic leaflet calcification
Valve Characteristics	- Self-expandable valve (e.g., CoreValve, Evolut R/PRO) - Valve oversizing (esp. balloon-expandable) - Predilatation before implantation
Implantation Technique	- Deep valve implantation - High ∆MSID (implantation depth > MS length) - No use of Cusp Overlap Projection (COP) technique
Procedural Events	- Transient AV block during procedure - Larger prosthesis size (e.g., 29 mm) - High compression ratio - RCC/NCC infra-annular leaflet descent
Postprocedural ECG	- New-onset LBBB - Widened QRS - Change in PR interval - Hear rate drop (HRratio)

Table 1. Summary of predictors for permanent pacemaker implantation (PPM) and conduction disturbances (CDs) After TAVR [24,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98].

Category	Predictors
Clinical	- Male sex - Older age - Atrial fibrillation - Diabetes mellitus type II - Chronic kidney disease
Preprocedural ECG	- Pre-existing RBBB - Pre-existing LBBB - Left anterior fascicular block - Atrioventricular block - PR interval > 180 ms
Echocardiographic/CT	- Small membranous septum - Small LVOT diameter - Narrow LVOT shape - Aortic leaflet calcification
Valve Characteristics	- Self-expandable valve (e.g., CoreValve, Evolut R/PRO) - Valve oversizing (esp. balloon-expandable) - Predilatation before implantation
Implantation Technique	- Deep valve implantation - High ∆MSID (implantation depth > MS length) - No use of Cusp Overlap Projection (COP) technique
Procedural Events	- Transient AV block during procedure - Larger prosthesis size (e.g., 29 mm) - High compression ratio - RCC/NCC infra-annular leaflet descent
Postprocedural ECG	- New-onset LBBB - Widened QRS - Change in PR interval - Hear rate drop (HRratio)

The following section outlines the most important risk factors for the development of conduction abnormalities and the need for PPM implantation.

5.1.1. Type of Valve Used

The type and generation of valve used during TAVR significantly affect the incidence of left bundle branch block (LBBB). Self-expandable valves, such as CoreValve or Evolut R, are associated with the occurrence of LBBB in 18–65% of patients, compared with 4–30% for balloon valves (e.g., SAPIEN XT, SAPIEN 3) [24]. Differences also exist within the different generations of the same valve type. For example, the Evolut PRO valve is associated with the occurrence of LBBB in approximately 20% of patients, whereas the modern ACURATE neo2 valve is associated with only 9%, with a lower overall risk of conduction disturbances [99]. Almost half of the conduction disturbances in balloon-expandable valves already occur at the time of balloon dilation prior to implantation, suggesting that the predilatation itself is already the moment of usually transient damage to the conduction system [100]. This was also noted in the electrophysiological study performed during TAVR [101]. Despite similar clinical results, skipping the predilatation step was associated with a lower rate of new permanent left bundle branch block [102,103]. Balloon oversizing in balloon-expandable valves can lead to the development of conduction abnormalities after the procedure [104]. The MARE study reported that persistent LBBB after 30 days occurred in 68% of patients after balloon valve implantation and in 59% after the use of a self-expandable valve [52]. Although valve type influences the incidence of LBBB and the eventual need for pacemaker implantation, it does not appear to have a significant impact on overall mortality [105]. Nevertheless, the selection of the appropriate valve type and consideration of omitting predilatation may help to minimise the risk of conduction disturbances.

5.1.2. Conduction Disturbances Before TAVR

Conduction disturbances already present before TAVR are of significant prognostic importance. The multicentre study by Muntané-Carol et al. and the study by Egger et al. showed that, compared with patients without conduction disturbances before and shortly after the procedure, patients with a pre-existing RBBB or newly developed conduction disturbance are at higher risk of dangerous HAVB/CHB episodes [80,81]. The presence of LBBB even before surgery is associated with a higher mortality rate than newly formed LBBB after TAVR. It is unclear whether LBBB by itself worsens prognosis or is merely an indicator of advanced cardiomyopathy. However, its presence may be indicative of deeper myocardial damage [106]. Conduction abnormalities present prior to TAVR should be taken into account when planning the patient’s monitoring strategy after the procedure. Particular vigilance should be exercised in patients with RBBB and those with LBBB as a potential marker of underlying myocardial disease.

5.1.3. Other ECG Changes

ECG parameters can provide valuable prognostic information after TAVR. Faroux et al. noted that in 33% of patients studied after one year, LBBB resolved; however, no clinical or electrocardiographic parameters could be identified that would predict this effect. In the same study, 9% of patients required pacemaker implantation, and a significant risk factor was a large change in PR segment length [107]. A PR ≤ 180 ms after TAVR is known to be associated with a negligible risk of HAVB compared to a longer PR episode [82]. An additional parameter of poor success has been shown to be the occurrence of atrial fibrillation [107]. Another negative factor affecting cardiac function and prognosis is QRS length. A very wide QRS (≥150 ms) was correlated with deterioration of left ventricular function (decrease in LVEF) [108]. Pre- and post-procedure ECG assessment—with particular attention to PR length, presence of AF and QRS width—can help identify patients requiring more intensive monitoring or earlier consideration of PPM implantation.

5.1.4. Length of Membranous Septum

Membranous septal (MS) length alone may be an independent risk factor for the development of conduction abnormalities and the need for PPM implantation after TAVR [83]. Boonyakiatwattana et al. described an MS membranous septal length ≤ 6.43 mm as high risk. Furthermore, the parameter ∆MSID (difference between MS length and implantation depth) < 0 mm was found to be the strongest and only modifiable predictor of conduction disturbances. When the implantation depth is less than the MS length, such a patient is at high risk of conduction disturbances [109]. In the case described by Miyamoto et al., the physicians used ICE (transvenous echocardiography), which allowed the membranous septum (MS) to be seen directly in real time, so that the implanted valve could be precisely positioned so that its lower edge did not exceed the length of the MS. Using the MS-guided TAVR strategy avoided the need for pacemaker implantation. This approach may be particularly beneficial in patients with pre-existing RBBB [110]. Accurate assessment of the length of the membranous septum and control of the depth of valve implantation are crucial for reducing the risk of conduction system damage. The MS-guided TAVR strategy could be an important step towards personalised and safer treatment.

5.1.5. Position of the New Valve in Heart

The use of new-generation valves (such as the Evolut R) allows them to be precisely positioned shallower, i.e., higher in the heart, and to be repositioned during the procedure. This possibility reduces the risk of the need for pacemaker implantation by almost half compared to older models such as the CoreValve [84,85]. Adequate valve repositioning can be achieved with a line of lucency visible on X-ray and a marker on the balloon showing the centre of the valve [111]. Increasingly, the MIDAS (Minimizing Implantation Depth According to the membranous Septum) strategy, an anatomically adapted implantation depth based on the length of the membranous septum, is being used. Its aim is to reduce the risk of damage to the conduction system [112]. Importantly, if valves need to be implanted deeper, modern self-expanding valves should be chosen, which, regardless of the depth of implantation, still reduce the risk of conduction disturbances [113]. At the same time, it should be borne in mind that even with high valve implantation, factors such as calcification of the valve leaflets or valve annulus or oversizing of the valve are still important predictors of conduction disturbances and the need for PPI [86]. It has been investigated that a greater depth of TAVR valve implantation, and thus a greater angle between the aortic annulus, also known as the virtual basal ring (VBR), and the sinotubular junction (STJ), which is where the aortic sinus ends and the ascending aorta begins, increases the risk of conduction abnormalities, including LBBB. Patients who developed LBBB after TAVR had a larger angle (and therefore deeper implantation), and the risk of LBBB increased by 8% for each additional degree of VBR-STJ angle. Accurate anatomical assessment, including measurement of the VBR-STJ angle and length of the membranous septum, as well as individual adjustment of the implantation technique, can significantly reduce the risk of conduction abnormalities [114].

5.1.6. Implantation Technique

Striving for the highest possible but safe valve implantation is a key element in reducing the risk of conduction complications. The use of standardised protocols and modern imaging techniques contributes to improving clinical outcomes. One of the most effective methods is the Cusp Overlap Projection (COP) technique, which allows precise visualisation of the relevant landmarks and accurate valve placement. The use of COP significantly reduces the risk of LBBB and the need for PPM implantation, as well as improving valve integrity and reducing hospitalisation time [87,88,89,90,91]. Although the use of the Cusp Overlap Projection (COP) technique is certainly associated with a lower incidence of new total heart block and PPM implantation, some studies have questioned whether it is related to the incidence of LBBB [115]. The use of modern implantation techniques, such as COP, should be part of routine practice in centres performing TAVR, especially in patients at high risk of conduction abnormalities.

5.1.7. Compression Ratio

The so-called compression ratio, i.e., the degree of compression of the aortic valve by the surrounding structures, mainly the aortic annulus, may also be important. This ratio is calculated from the ratio of the diameter of the valve after implantation to its diameter before implantation. The higher the compression ratio, the greater the mechanical pressure exerted on the cardiac conduction system and, thus, the greater the risk of needing PPM implantation [92]. Therefore, patients with so-called BAM (borderline aortic annulus measurement) were studied, i.e., those whose aortic annulus dimensions fall on the borderline between two valve sizes, according to the manufacturer’s table. Implanting a larger balloon-expandable valve increases the risk of conduction and pacemaker abnormalities and does not offer the benefits of better haemodynamics or less regurgitation. Thus, a smaller valve seems to be a safer choice in BAM [116]. In the situation of ambiguous ring size (BAM), choosing a smaller valve may help to minimise the risk of PPM without compromising valve performance.

5.1.8. Infra-Annular Extension

Unlike surgical valve replacement, in TAVR, the native aortic leaflets are left in place. A new predictor of conduction disturbances is the so-called infra-annular extension, i.e., the descent of the leaflets below the valve ring after valve implantation. In particular, the right coronary (RCC) and noncoronary (NCC) leaflets can move towards the cardiac conduction system and interfere with its function. The deeper the native valve leaflet descends, the greater the likelihood of arrhythmia and the need for PPM. Analysis of angiography after TAVR, taking into account the degree of infra-annular extension, can help predict the need for pacemaker implantation and provide a valuable diagnostic tool [117].

5.1.9. Other Risk Factors

Although it has been suspected that the inflammatory process may play an important role in the development of conduction abnormalities after TAVR, studies have not confirmed the efficacy of prednisone in preventing them [118]. Chronic use of systemic corticosteroids does not affect the risk of death, either total or from cardiac causes, nor is it associated with an increased incidence of pacemaker implantation (PPM), left bundle branch block (LBBB), stroke or myocardial infarction. On the contrary, it may even be associated with a reduced incidence of PPM requirement. On the other hand, this therapy increases the risk of serious vascular complications not directly related to the heart and may also lead to the development of cardiac tamponade [119,120]. The use of steroids should not be routinely used as a form of prophylaxis for conduction disturbances after TAVR. Their use requires a careful assessment of the benefit–risk balance in the individual patient.

5.2. Stratification of Risks

In a more recent study, Klambauer et al. examined nine risk factors and demonstrated that ECG and clinical factors were stronger predictors of PPM relative to computed tomography (CT) data. The strongest risk factor was again found to be RBBB [93].

Table 2. Risk factors, OR and estimated increase in risk (%) of pacemaker implantation (PPM) after TAVR. Note: estimated risk increases are approximate counts that do not convert statistical analysis, but help to interpret the data clinically [93].

Risk Factor	OR	Estimated Increase in Risk (%)
Right bundle branch block (RBBB)	2.739	+174%
AV block I°	2.091	+109%
Valve diameter	1.351	+35%
Atrial fibrillation (AF)	1.255	+26%
Hypertension (HT)	1.215	+21%
Coronary artery disease (CAD)	1.070	+7%
Angle of axis of the ventricle and aortic root—CT	1.030	+3%
Height of the sinus–cephalic junction—CT	1.014	+1.4%
Calcification of the left coronary valve—CT	1.007	+0.7%

summarises the risk factors analysed, with their corresponding odds ratios (OR) and estimated percentage increase in risk of PPM implantation. These values represent approximate conversions, which, although not a substitute for formal statistical analysis, may be helpful in the clinical interpretation of the results.

The identification of risk factors for new conduction disturbances after TAVR has led to the development of risk stratification tools. These are designed to support clinical decisions regarding patient follow-up, the need for extended diagnostics and possible pacemaker implantation (PPM). One such tool is the D-PACE scale, developed by an Italian expert group. It is a three-step algorithm that assesses the risk of conduction complications in patients after TAVR who have not developed high-grade atrioventricular block (AVB) within the first 24 h after the procedure [121]. Details of this assessment are included in

Table 3. D-PACE Score—risk model after TAVR. The algorithm for risk stratification can be used in patients after TAVR without high-grade AVB within 24 h after surgery [121].

Risk Factor	Points Scored
Self-expanding valve	Yes	1
	No	0
Preprocedural RBBB	Yes	2
	No	0
New-onset persistent LBBB	Yes	3
	No	0
New-onset persistent RBBB	Yes	4
	No	0
Implantation depth	<3.0 mm	0
	3.0–4.9 mm	1
	5.0–6.9 mm	2
	≥7.0 mm	4
Preprocedural PR duration	<150 ms	0
	150–199 ms	1
	200–249 ms	2
	≥250 ms	3
Next-day PR interval increase	<1 ms	0
	1–19 ms	1
	≥20 ms	3

Interpretation: scores 0–3—low risk, discharge within 24 h strongly recommended; 4–5—intermediate risk, discharge within 24 h may be considered; ≥6—high risk, discharge within 24 h contraindicated.

.

Another tool to help assess the risk of PPM after TAVR is the PRIME Score, which is based on preoperative clinical and electrocardiographic factors. This algorithm can be useful for decision-making even before TAVR is performed [122]. Its calculation and interpretation are shown in

Table 4. PRIME Score—risk assessment of PPM implantation based on preoperative data [122].

Acronym	Risk Factor	Points Scored
P	PR interval > 200 ms	1
R	Right bundle branch block	3
I	Valve In Valve procedurę	−3
M	Myocardial infarction	−1
E	Self-Expanding valve	1

Interpretation: a score equal to or above 2 should prompt the physician to collaborate interdisciplinarily with the medical team and the patient, intervene appropriately and perform an electrophysiological study (EP).

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An alternative approach to risk assessment is a modified electrophysiological study (EPS), already performed after TAVR (EP study). The key parameter here is the HV interval, i.e., the conduction time of the impulse from the His bundle to the ventricular muscle. Researchers in a retrospective study concluded that an HV interval <55 ms can be considered a safe threshold, which suggests a low level of risk and, therefore, the patient can be discharged with monitoring, while for an HV interval >70 ms, it is worth considering PPM [123]. Another prospective study already suggests an HV interval >55 ms as a cut-off point for considering PPM implantation, while more recent data suggest that the current ESC threshold of ≥70 ms may not be optimal, as some patients with this outcome hardly need pacing [124,125]. Moreover, if a patient develops a new LBBB but no prolonged HV interval is found during EPS, the risk of further conduction blocks is low [126]. Artificial intelligence (AI) is becoming increasingly important in modern approaches to diagnosis. Jia et al. created a model based on a convolutional neural network (CNN)—an algorithm commonly used for image analysis—that allows the risk of conduction complications to be assessed even before TAVR surgery, based solely on a simple ECG. When simple clinical data (e.g., age, hypertension) were added, the model showed greater accuracy in predicting risk than classic interpretation-based assessments [127].

Although pacemaker implantation after TAVR is often necessary, it is not without potential complications. These include infection (e.g., device-related endocarditis), lead dislodgement, bleeding or venous thrombosis. The risk of device-related endocarditis, although low, may be significant in elderly and immunocompromised patients. This aspect should be considered especially when planning TAVR in patients with a history of repeated infections or poor vascular access [128,129]. Further research is needed to determine the optimal management strategy for such cases.

6. Management of Conduction Disturbances

Conduction disturbances after TAVR may be asymptomatic, so early detection and monitoring is crucial. Continuous ECG monitoring for at least 24 h prior to surgery is recommended, which may help to identify latent arrhythmias and allow faster implementation of appropriate management [130].

The risk of persistent LBBB itself can be predicted before the procedure by measuring the EDACS (Effective Distance Between Aortic Valve and Conduction System), which is the distance in mm between the aortic valve and the origin of the cardiac conduction system, i.e., the area of the interventricular septum where the left bundle branch runs. The smaller this distance is, the easier it is to damage the conduction system during valve deployment and the higher the risk of LBBB. EDACS can be measured with CT scans and can help the physician to assess the risk of complications or to consider a different technique (e.g., SAVR) or type of valve [131].

In addition—using pre-procedural computed tomography angiography (CTA) data, a 3D anatomical model of the patient’s heart can be created to simulate the TAVR procedure even before it is performed. This allows the operator to select the best implantation technique and reduce the risk of damage to the cardiac conduction system [132,133]. For example, in the case of calcification, detected, for example, by CT scan, more aortic deployment of the prosthesis should be considered [134]. A more accurate anatomical view of the aortic root and surrounding cardiac structures and an understanding of the causes of conduction abnormalities in the patient after TAVR can also be provided by a modern tool, CTA synchronised with ECG [132]. On the other hand, with cardiac magnetic resonance (CMR) before TAVR, scar foci and the amount of diffuse myocardial fibrosis (ECV) can be assessed. It is the diffuse myocardial fibrosis measured by ECV that can help predict in advance who may have heart rhythm problems after TAVR [135]. The use of ICE transvenous echocardiography, a state-of-the-art transjugular intracaardiac echocardiography (TJ-ICE) technique, during TAVR is safe and very precise. It allows the membranous septum to be measured accurately, which helps to select the valve seating depth in such a way as to minimise the risk of damage to the conduction system. If the valve does not reach too deep—the risk of pacemaker implantation is significantly reduced [136]. An additional support for TAVR operators is the possibility to perform a computer simulation of the valve’s contact with the conduction system (CCA—Conduction Contact Analysis). This allows the risk of conduction disturbances to be predicted and the location of the implantation to be optimised according to the individual anatomy [137].

Follow-Up and Management Strategies After TAVR

Low-risk patients do not need to be admitted to the intensive care unit after the procedure [138]. A 7-day follow-up after TAVR to avoid hasty pacemaker implantation is recommended, but not very practical, due to cost and hospitalisation time [139]. Sandhu et al. noted that delayed high-grade atrioventricular block occurred among a significant proportion of patients after TAVR. For this reason, they use a thorough 30-day ambulatory ECG monitoring and, if necessary and AVB occurs, the use of permanent pacemaker implantation [65].

In practice, there is a lack of standardisation in the management of patients with LBBB after TAVR. European centres most commonly use telemetric 48 h follow-up after TAVR for newly formed LBBB or pre-existing LBBB. However, almost half of the centres monitor patients for at least 72 h. When an electrophysiological study is performed, the HV interval threshold resulting in PPM implantation is also lacking, although >75 ms is the most commonly chosen threshold. Pacing of the conduction system is still rarely chosen [140].

A promising strategy is the introduction of remote ambulatory cardiac monitoring (rACM), both before and after TAVR (Figure 2). It can greatly facilitate rhythm control and support the decision on the need for PPM implantation [141].

The mere occurrence of LBBB after TAVR is not always an indicator of the need for PPM. Among 70 patients with new LBBB after TAVR, 21 required pacemaker implantation in the study by Bar-Moshe et al. [94]. The researchers suggest implanting a PPM if LBBB progresses or if the duration of QRS complexes is above 160 ms in persistent LBBB (>48 h) [79,94]. Other researchers suggest that early PPM implantation for LBBB after TAVR is only indicated when high-grade atrioventricular block or complete heart block is present [142].

Rodes-Cabau et al. propose to divide patients based on their risk of conduction disturbances after TAVR into five groups with corresponding recommendations for patient follow-up after TAVR. Details of patient characteristics and expert group recommendations are provided in

Table 5. Risk groups among patients undergoing TAVR with expert group recommendations [79].

Group Number	Patient Characteristics	Recommendations
Group 1.	No significant changes in ECG before and after surgery.	Exclusive telemetry monitoring for 24 h after the procedure. Removal of temporary pacemaker (if used during TAVR) immediately after the procedure.
Group 2.	RBBB existing before the procedure.	Highest risk group for high atrioventricular block (HAVB) or complete heart block (CHB). Follow-up for a minimum of 48 h after the procedure along with a temporary pacemaker for at least the first 24 h.
Group 3.	QRS complex duration >120 ms before the procedure or 1st degree atrioventricular block before the procedure with prolongation of the QRS complex or PR interval by ≥20 ms after the procedure.	Telemetry follow-up for 24–48 h after the procedure. Retention of temporary pacemaker until regression of QRS or PR length. If no improvement, perform invasive electrophysiology study (EPS).
Group 4.	Appearance of LBBB after TAVR.	Telemetry follow-up for 24 h after the procedure with the use of a temporary pacemaker. Removal of pacemaker if no progression of LBBB, QRS complexes or intervals of PR. If deterioration, conduct EPS, ambulatory monitoring or implantation of a permanent pacemaker (PPM).
Group 5.	Appearance of transient high-grade atrioventricular block or complete heart block during the procedure.	Telemetric monitoring for 24 h after the procedure with the use of a temporary pacemaker. If no improvement, use of permanent pacemaker.

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Instead of implanting a PPM, the use of a temporary permanent pacemaker (TPPM) also seems promising. This is a safe and effective method that can serve as a ‘bridge’ in waiting for the decision to implant a permanent pacemaker in patients after TAVR. It can avoid unnecessary PPM in patients whose heart rhythm stabilises [143]. A 1-month period seems an appropriate time to assess whether the conduction disturbance is permanent or reversible [144]. In patients with RBBB before TAVR, it may be worthwhile to plan TPPM earlier, which may improve logistics and comfort for a shorter period of time in the ICU [145]. More research in this direction is worthwhile. On the other side, we find physicians who prophylactically place PPMs on patients who have pre-existing conduction disturbances. With the increase in known risk factors, physicians are increasingly making this decision, especially when there is a need to insert a valve associated with a higher risk of a potential pacemaker [146]. Researchers have confirmed that prophylactic PPM implantation in patients with pre-existing RBBB is safe, reduces procedure time and patient hospital stay, and prevents subsequent electrophysiological complications requiring re-hospitalisation [147,148,149]. In general, physicians are much quicker and more likely to make the decision to implant a pacemaker after TAVR than after SAVR surgery [150]. Mazzella et al. point out that when thinking about risk factors for PPM implantation, early and late PPM factors should be analysed separately. The former include bifascicular block, pacing of the heart just after TAVR, or the oversized valve mentioned earlier. Risk factors for late PPM include RBBB and a history of atrial fibrillation or flutter [151].

Severe atrioventricular block (HAVB) usually occurs in the first months after the procedure, which, in turn, does not support the idea of prophylactic pacemaker implantation in all patients with LBBB after TAVR, while the MARE study in a 2-year follow-up of patients showed that new cases of atrial fibrillation (AF/AGL) are frequent (about one-third of patients) and occur evenly over the 2 years studied. This may suggest that anticoagulant treatment may be needed [152].

Among the various pacemakers, we can distinguish between the standard right ventricular pacing (RVP) and newer methods, namely conduction system pacing (CSP), which attempts to mimic the natural conduction of the heart’s impulses, i.e., stimulating the His bundle, known as His bundle pacing (HBP), or its left bundle branch, known as left bundle brach pacing (LBBP). It appears that CSP is possible after TAVR, but due to the low implantation efficiency of HBP, it is LBBP that is easier to implant and has better technical performance. The use of LBBP is also associated with lower pacing thresholds compared to HBP. The use of CSP LBBP is associated with narrower QRS associated with more physiological ventricular beats, higher ejection fraction (LVEF), smaller left ventricular size (LVEDD) and overall lower mortality [153,154,155]. LBBP is possible and safe in the majority of patients with prosthetic heart valves who have conduction abnormalities. The prosthesis may even assist in precise electrode positioning [156]. The use of the electrodeless Micra AV pacemaker in patients after TAVR has also been investigated. It is a safe and effective option in these patients as well [157].

7. Future Prospects and Scope of Research

Over the years, the perioperative management of patients undergoing transcatheter aortic valve implantation (TAVR) has improved significantly, with shorter hospitalisation times, lower costs and lower complication rates [158]. Patient selection for long-term ambulatory cardiac rhythm control after TAVR should be further investigated Despite progress, still not all centres have standardised protocols for the management of advanced conduction disturbances—currently only about 60% have implemented such procedures. There is considerable variation in approach, indicating the need for further standardised management strategies [140]. It is important to assess what contributes to the higher risk of major arrhythmic events in patients with LBBB after TAVR and to consider the administration of anticoagulant treatment because of the high risk of atrial fibrillation [52,152]. An interesting option for monitoring patients after transcatheter aortic valve replacement also seems to be the use of an ECG monitoring smartwatch, which seems to be a better alternative due to its ease of use, mobility, and remote and real-time monitoring [159,160,161].

Data are also still lacking on transcatheter aortic valve replacement (TAVR) in specific patient groups, including those with bicuspid aortic valve (BAV) disease, where surgical aortic valve replacement is the method of choice [162]. The rudiments associated with BAV include, but are not limited to, irregular anatomy (e.g., type 0—no comb connecting the leaflets), difficulty in accurately sizing the valve, limited effectiveness of existing imaging and surgical planning strategies such as BAVARD, LIRA, CASPER, Circle Method or Down Sizing Strategy [163]. From recent studies, it appears that, in addition to RBBB and short ventricular septum, type 1 L-R valve leaflet fusion is an additional risk factor in patients with BAV, and overall patients with BAV have a higher risk of new-onset persistent LBBB [164,165,166]. Paediatric patients have also been excluded from major randomised clinical trials of TAVR. Few studies show that TAVR may be a good alternative to surgery in children with aortic valve disease [167]. Further development of transcatheter aortic valve replacement requires the following: standardised management of conduction abnormalities, development of precise criteria for monitoring and treatment of arrhythmias, implementation of modern remote monitoring technologies, and adaptation of TAVR to special populations (e.g., BAV, children). The development of these areas may significantly improve the safety, efficacy and availability of this method in the coming years.

8. Conclusions

Transcatheter aortic valve replacement (TAVR) has emerged as a safe and effective alternative to surgical replacement (SAVR) in patients with aortic stenosis, regardless of risk. One of the most common and significant complications after TAVR is conduction abnormalities, in particular newly developed left bundle branch block (LBBB), which, together with other forms of abnormalities (RBBB, intraventricular blocks), significantly increase the risk of permanent pacemaker (PPM) implantation and may affect left ventricular systolic mechanics. Key predictors of these complications include the depth and position of valve implantation, length of the membranous septum, oversizing and conduction abnormalities present before the procedure. The implementation of personalised strategies (MS-guided TAVR, Cusp Overlap Projection, EDACS, CCA), advanced imaging techniques (ICE, CTA-EKG, CMR) and risk stratification tools (D-PACE, PRIME, EPS/HV interval, AI models) enables procedure optimisation and targeted patient monitoring. Despite the progress, standardised management protocols, large prospective studies and further improvements in technology are still needed to further minimise conduction complications and improve long-term patient outcomes after TAVR.