The Use of Digital Devices in the Management of Athletes with Paroxysmal Arrhythmias During Exercise—A Case Series

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This case series is highly interesting and informative, offering valuable clinical insights into importance of valuable new diagnostic tools.

The authors are to be congratulated for the clarity and quality of the presentation, as well as for their contribution to the field.

My sugestion regarding improvement of this paper are: 

Abstract and Introduction section:

"Athletes may experience paroxysmal arrhythmias that occur exclusively 
during exercise.." 

This statement regarding AF is not accurate, as AF in this context typically occurs under conditions of pronounced vagal predominance, most commonly during nighttime. Given that the presented patients are master athletes with documented AF, the proposed mechanism is questionble.

This statement must be revised in both the Abstract and the Introduction to ensure physiological accuracy and consistency with the established pathophysiological understanding.

Also in the Discussion section, it should be specifically explained point 5 of the conclusions, particularly the statement regarding “termination with cessation of exercise” in athletes with diagnosed AF.

In master athletes with established AF, arrhythmia episodes are frequently vagally mediated and may occur during recovery or at rest rather than during peak exertion. Therefore, the concept of termination simply with cessation of exercise may be an oversimplification and requires a extensive physiological explanation.

The authors need to clarify the underlying mechanisms, differentiate between adrenergic and vagal AF patterns, and suport this statement within the specific population studied.

Author Response

Abstract and Introduction section: "Athletes may experience paroxysmal arrhythmias that occur exclusively during exercise." 

            Thank you for that comment. We have modified this sentence as suggested by removing the world "exclusively".

This statement regarding AF is not accurate, as AF in this context typically occurs under conditions of pronounced vagal predominance, most commonly during nighttime. Given that the presented patients are master athletes with documented AF, the proposed mechanism is questionable. This statement must be revised in both the Abstract and the Introduction to ensure physiological accuracy and consistency with the established pathophysiological understanding.

            Thank you for this comment. Atrial fibrillation (AF) in athletes is not only vagally mediated. While vagal AF is common in endurance athletes, AF can also be adrenergic (exercise-induced) and may indeed start during exercise and terminate shortly after cessation. However, following your suggestion we have added the following statement to the text: "Importantly, atrial fibrillation (AF) in athletes is often vagally mediated. In these circumstances AF typically occurs under conditions of pronounced vagal predominance, most commonly during nighttime or rest. Nevertheless, AF can also be adrenergic (exercise-induced) and may start during exercise and terminate shortly after cessation."

Also in the Discussion section, it should be specifically explained point 5 of the conclusions, particularly the statement regarding “termination with cessation of exercise” in athletes with diagnosed AF. In master athletes with established AF, arrhythmia episodes are frequently vagally mediated and may occur during recovery or at rest rather than during peak exertion. Therefore, the concept of termination simply with cessation of exercise may be an oversimplification and requires a extensive physiological explanation. The authors need to clarify the underlying mechanisms, differentiate between adrenergic and vagal AF patterns, and support this statement within the specific population studied.

            Thank you for this comment. We have added the statement regarding a vagally mediated and adrenergic ally mediated AF to the discussion section as reported above.

Reviewer 2 Report

Comments and Suggestions for Authors

his Communication presents a case series of ten athletes with exercise-induced paroxysmal arrhythmias initially identified using wearable digital devices, primarily chest-strap heart rate monitors and smartwatches. In most cases, conventional monitoring failed to capture the arrhythmia, and electrophysiological study confirmed supraventricular tachyarrhythmias amenable to ablation.

The topic is relevant to sports cardiology and digital health. However, the novelty and incremental contribution of this case series require further clarification.

Comments:
1. The ability of wearable devices to detect arrhythmias is already well established and acknowledged in current guidelines and prior publications. The manuscript does not clearly articulate what is substantially new beyond existing knowledge. The authors should more clearly define what gap in the literature this series fills and  how this case series changes clinical decision-making.

2. Given the small sample size and lack of a control group, conclusions should be moderated and framed as illustrative rather than practice-changing.

3. Clarify the decision-making process leading to EPS referral.

Author Response

1. The ability of wearable devices to detect arrhythmias is already well established and acknowledged in current guidelines and prior publications. The manuscript does not clearly articulate what is substantially new beyond existing knowledge. The authors should more clearly define what gap in the literature this series fills and how this case series changes clinical decision-making.

            In our opinion strength of the work is the clear clinical pathway described, in which wearable-detected abrupt heart rate increases prompted referral for electrophysiological study, leading to successful ablation and return to sport. The focus on chest-strap monitors is particularly valuable, as these devices are less frequently discussed than smartwatch-based systems. The procedural success and favourable mid-term follow-up reinforce the clinical relevance of the observations.

2. Given the small sample size and lack of a control group, conclusions should be moderated and framed as illustrative rather than practice-changing.

            Thank you for that comment. Following your suggestion, we have modified the conclusions section as follows: "When characteristic features are present, data obtained from these devices may support referral for an invasive electrophysiological evaluation, even in the absence of arrhythmia documentation using standard methods."

3. Clarify the decision-making process leading to EPS referral.

           Thank you for the comment. We have added the following sentence to the text: "In our group all athletes with justified presence of the symptomatic isolated supraventricular arrythmia based on arrythmia analysis from a wearable device and willing to undergo ablation to eliminate the arrhythmia background were referred for EPS."

Reviewer 3 Report

Comments and Suggestions for Authors

The authors present a clinically relevant case series of ten athletes with exercise-induced paroxysmal arrhythmias initially detected using wearable digital devices, predominantly chest-strap heart rate monitors . The manuscript addresses a frequent and challenging scenario in sports cardiology: symptomatic arrhythmias occurring exclusively during high-intensity exercise and remaining undocumented despite repeated conventional testing. The topic is timely and well aligned with current recommendations supporting the integration of digital tools into arrhythmia evaluation.

A major strength of the work is the clear clinical pathway described, in which wearable-detected abrupt heart rate increases prompted referral for electrophysiological study, leading to successful ablation and return to sport. The focus on chest-strap monitors is particularly valuable, as these devices are less frequently discussed than smartwatch-based systems. The procedural success and favourable mid-term follow-up reinforce the clinical relevance of the observations.

The manuscript would, however, benefit from some additional clarification:

-It would be helpful to specify whether the cases were consecutive and to outline the general criteria used to refer patients for invasive evaluation based primarily on wearable data.

-Given that EPS was performed in several cases without prior ECG documentation, a more explicit description of the features considered highly suggestive of supraventricular arrhythmia would strengthen the clinical message and avoid overgeneralization.

-Further discussion of the limitations of heart rate–only tracings, including potential artifacts and the absence of systematic ECG validation during exercise, would provide a better balance.

-Additional detail on structural heart disease screening and on follow-up methodology, particularly in athletes with atrial fibrillation, would also enhance transparency and robustness.

-The description of Figure 3 could be more precise regarding rhythm interpretation.

-The table would benefit from inclusion of: Symptom type, episode duration, time to diagnosis, time from wearable detection to EPS

-The statement that wearable data may constitute “sufficient evidence” to justify EPS should be slightly moderated to avoid overgeneralization.

Author Response

-It would be helpful to specify whether the cases were consecutive and to outline the general criteria used to refer patients for invasive evaluation based primarily on wearable data.

            Thank you for that comment. Our cases were consecutive. We have added a statement on the to the case report. We have also included the following sentence regarding the referral for EPS process: "In our group all athletes with justified presence of the symptomatic isolated supraventricular arrythmia based on arrythmia analysis from a wearable device and willing to undergo ablation to eliminate the arrhythmia background were referred for EPS."

-Given that EPS was performed in several cases without prior ECG documentation, a more explicit description of the features considered highly suggestive of supraventricular arrhythmia would strengthen the clinical message and avoid overgeneralization.

            Thank you for this important comment. We have modified the information in the discussion section as follows:

"Characteristic features of paroxysmal arrhythmias detected using heart rate monitoring, which may help in decision-making towards EPS referral included:

1. sudden and atypical heart rate increase exceeding expected maximal values,
2. concomitant symptoms such as palpitations, loss of power, dizziness, or presyncope,
3. reproducibility across different training sessions,
4. various duration ranging from seconds to over an hour, and
5. termination with cessation of exercise."

- Further discussion of the limitations of heart rate–only tracings, including potential artifacts and the absence of systematic ECG validation during exercise, would provide a better balance.

            Thank you for this comment. We agree that reliance on heart rate–only tracings represent an important limitation. Heart rate–based recordings do not provide access to raw ECG waveforms and therefore do not allow definitive rhythm adjudication, including confirmation of P-wave absence or precise RR interval analysis. In addition, recordings obtained during exercise are particularly prone to motion artifacts, signal noise, and algorithm misclassification, especially in the setting of rapid sinus tachycardia. Importantly, no systematic multi-lead ECG validation was performed during peak exercise, which limits certainty regarding the exact rhythm mechanism at that time. We have added the following section to the discussion: "Recordings obtained during exercise are particularly prone to motion artifacts, signal noise, and algorithm misclassification, especially in the setting of rapid sinus tachycardia. Therefore, rhythm assessment based on heart rate–only tracings without systematic ECG validation during exercise should be interpreted with caution."

-Additional detail on structural heart disease screening and on follow-up methodology, particularly in athletes with atrial fibrillation, would also enhance transparency and robustness.

            Screening for the presence of structural heart disease was based on routinely performed test as described in the text: "All patients underwent resting 12-lead ECG, transthoracic echocardiography, maximal exercise testing, and between one and several 24- to 72-hour ambulatory ECG recordings. At baseline, all athletes were free of known heart disease, otherwise asymptomatic, and in excellent physical condition." However, we have added the following information to the cases description regarding follow-up: "Additionally, 24h ambulatory ECG recordings with exercise after 3-6 months from ablation did not disclose the presence of arrythmia."

- The description of Figure 3 could be more precise regarding rhythm interpretation.

            Thank you. We have clarified the rhythm interpretation in the description on Figure 3C as "diagnosed during EPS as atrio-ventricular nodal re-entrant tachycardia (AVNRT)". A and B are atrial fibrillation.

- The table would benefit from inclusion of: Symptom type, episode duration, time to diagnosis, time from wearable detection to EPS

            Thank you for that comment. Due to space constraints and to preserve table readability, we have decided not to include the information in the table, but instead to support case presentation with more details in the text: "Each athlete sought consultation because of palpitations occurring during exercise characterized by abrupt increase in heart rate disproportionate to exercise intensity and loss of power, dizziness or presyncope. During these episodes, most athletes were forced to interrupt training or continue at markedly reduced intensity. In all cases, the arrhythmia terminated spontaneously either during or shortly after exercise. The frequency of episodes ranged from weekly to once every several months, and onset was consistently unpredictable. Arrythmia was present for months to up to 2 years with some athletes already seeking medical advice without success. ... Time from wearable detection to EPS was between 6 months and 2.5 years."

- The statement that wearable data may constitute “sufficient evidence” to justify EPS should be slightly moderated to avoid overgeneralization.

            Thank you for that comment. We have softened the conclusions to sound: "When characteristic features are present, data obtained from these devices may support referral for an invasive electrophysiological evaluation, even in the absence of arrhythmia documentation using standard methods."

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for your revisions and clarifications. The manuscript has improved, particularly with respect to moderating the conclusions and clarifying the clinical decision-making process leading to EPS referral.

The revised conclusion is appropriately cautious and better reflects the illustrative nature of this case series. The clarification regarding referral criteria also improves transparency.

That said, while the manuscript clearly describes a structured clinical pathway, the incremental novelty remains modest, as the role of wearable devices in arrhythmia detection is already recognized in current guidelines and prior publications. The primary value of the manuscript lies in illustrating real-world application rather than introducing a new diagnostic concept.

Overall, the manuscript is coherent and clinically relevant within the Communication format, provided its conclusions remain appropriately restrained and framed as illustrative.

Author Response

Thank you for that comment. However, in current clinical practice and guideline-driven arrhythmia management, including for paroxysmal exercise-induced supraventricular arrhythmias in athletes, data from consumer digital wearable devices alone (like chest straps, smartwatches, and wrist wearables) do not by themselves constitute a standard sole basis for referral for invasive electrophysiology study (EPS) or catheter ablation unless supported by corroborating clinical evidence. Although there are small case series advocating for such approach published in recent years for (10.1111/pace.14388) current guidelines do not recommend wearable data alone as definitive for therapeutic referral. Therefore, our manuscript can indeed be found as illustrative but also as a small step towards acknowledging the presented pathway in arrhythmia management of athletes as stated in the conclusion section. So far, wearable sensor or smartwatch data can alert clinicians to possible arrhythmias and support decision-making, especially when the standard ECG fails to capture events. However, such data alone do not constitute a guideline-endorsed threshold for invasive EPS or ablation referral—guidelines and expert consensus emphasize validated clinical evidence before proceeding to invasive studies or definitive therapy.