Follow-Up on the Recovery of Cardiorespiratory Parameters and Quality of Life in Post-COVID-19 with Hypertension

Abstract

Background: This study aims to investigate and monitor cardiorespiratory fitness levels, measured by the 6-minute walk test (6MWT) and quality of life (QoL), assessed using the Short form-36 (SF-36), in patients with hypertension, both with and without coronavirus disease 2019 (COVID-19), at a 3-month follow-up. Methods: Sixty participants were recruited, comprising two groups: hypertensive patients with COVID-19 and hypertensive patients without COVID-19, with 30 individuals in each group. Cardiorespiratory response parameters were assessed before and after performing the 6MWT. QoL was evaluated using the SF-36 at baseline and again at 3 months. Results: Hypertensive patients who recovered from COVID-19 showed significant improvements, including reduced post-exercise HR, SBP, SpO₂, RPE, and leg fatigue, as well as increased 6MWT distance and enhanced QoL compared to baseline (p < 0.05). These parameters improved and returned to levels similar to those of hypertensive patients without COVID-19 by the 3-month follow-up. Conclusions: Hypertensive patients who have recovered from COVID-19 can achieve cardiorespiratory fitness and QoL levels comparable to those of hypertensive individuals who did not contract COVID-19 by the 3-month follow-up.

1. Introduction

Individuals with hypertension are at high-risk factor for coronavirus disease 2019 (COVID-19) infection as well as the progression of severity of disease and even death [1]. A previous study reported that COVID-19 patients with hypertension had high systolic blood pressure (SBP) due to the decreased enzymatic activity of angiotensin-converting enzyme-2 (ACE2), which is caused by a higher load of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [2]. This study suggested that the role of basal and achieved blood pressure control rather than hypertension per se could be considered as a prognostic factor in COVID-19 [2]. In addition, untreated or uncontrolled blood pressure levels can lead to vascular dysfunction in COVID-19 patients, resulting in mortality in these populations [3,4]. It is known that hypertension induces endothelial dysfunction and atherosclerosis, which negatively impacts cardiovascular outcomes in COVID-19 patients [5].

Hypertension is associated with dysfunction of various organs, including the heart, brain, kidney, and endocrine system [6]. Moreover, the dysfunction of these organs in individuals with hypertension is exacerbated by SARS-CoV-2 infection [7]. A previous study found that increased diastolic blood pressure (DBP) in post-COVID-19 patients was due to vascular inflammation involving innate and adaptive immunity. This results in vascular constriction of resistance vessels, decreased vasodilation, and increased vasoconstriction in these populations [8,9]. Several studies have reported that hypertensive patients exhibit increased cytokine release due to sympathovagal imbalance, which triggers the inflammatory process during COVID-19 infection [10,11]. Furthermore, SARS-CoV-2 infection decreases functional capacity and quality of life (QoL) in post-COVID-19 patients. Symptoms of these impairments include dyspnea, fatigue, chest pain, arrhythmias, and exercise intolerance [12,13,14]. Typically, hypertensive patients show a reduced functional capacity and exercise intolerance, which leads to a decreased QoL [14]. These responses may be due to a reduced ability to perform daily activities [14]. Therefore, SARS-CoV-2 infection in hypertensive patients may have a more significant impact on functional capacity and QoL compared to those without SARS-CoV-2 infection. A previous study found that individuals with systemic arterial hypertension (SAH) who had a COVID-19 infection had reduced functional capacity compared to those with SAH without COVID-19 infection [15]. Moreover, SAH without COVID-19 infection showed a positive correlation between physical capacity and parasympathetic modulation at rest [15]. Additionally, another study found a positive correlation between physical activity and vagal modulation in SAH patients without COVID-19 infection [16]. However, the recovery of cardiorespiratory parameters and QoL in post-COVID-19 with hypertension has not been reported. Additionally, the follow-up cardiorespiratory fitness levels and QoL at 3 months in these populations have not been investigated. A three-month follow-up period provides a critical window to assess the recovery trajectory of cardiorespiratory parameters and QoL in post-COVID-19 with hypertension. This period allows for the evaluation of both immediate and residual effects of the virus on heart and lung function, as well as the impact on daily living and overall well-being. Understanding these outcomes is essential for developing targeted post-COVID-19 care strategies and improving the management of hypertensive patients who have recovered from the infection. Therefore, this study aims to investigate and monitor the cardiorespiratory fitness levels using the 6-minute walk teat (6MWT) and QoL using the Short-Form-36 (SF-36) in patients with hypertension, with and without COVID-19, at a 3-month follow-up.

2. Materials and Methods

2.1. Study Design

A prospective cohort study design was conducted to compare the cardiorespiratory response parameters measured by the 6MWT and QoL assessed using the SF-36 at 3 months. The study also aimed to evaluate the correlation between the 6MWT distance and QoL in individuals with hypertension, both with and without a history of COVID-19.

2.2. Participants

Sixty participants were recruited, including those with hypertension and COVID-19, and those with hypertension without COVID-19, and were divided into two groups (n = 30/group). The sample size was determined using the GPower 3.1 software, with a desired power of 0.95, an alpha level of 0.05, and an effect size f of 0.25 [11]. Participants were aged between 31 and 80 years old, with or without a history of COVID-19 infection, and had confirmed SARS-CoV-2 infection via polymerase chain reaction (PCR) or antigen test kit (ATK) within 3 months or less prior to participation in the study. They also had normal body mass index (BMI) values (18.5–24.9 kg/m²) [17], a resting respiratory rate of fewer than 22 beats per minute, and a resting pulse oximetry of more than 94%. Participants with a history of acute myocardial infarction, asthma, musculoskeletal diseases, or neurological disorders that could affect their test performance were excluded. All participants provided written informed consent. This study was approved by the Clinical Research Ethics Committee of the University of Phayao, Phayao, Thailand (HREC-UP-HSST 1.3/004/67).

2.3. Procedure

All participants were assessed for age, weight, height, BMI, history of COVID-19 infection, duration of hypertension, and other comorbidities. Cardiorespiratory response parameters were measured using 6MWT, and QoL was assessed using the SF-36 both at baseline and at 3 months.

Before performing 6MWT, participants were assessed for cardiorespiratory parameters, including heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse oxygen saturation (O₂sat), rate of perceived exertion (RPE), and leg fatigue. Participants were then instructed to walk as far as possible for 6 min without running, within a 30 m corridor. The distance covered during the 6MWT was recorded [18], and cardiorespiratory response parameters were assessed and recorded upon test completion.

2.4. Measures

2.4.1. 6-Minute Walk Test (6MWT)

6MWT is a widely used functional test that measures the distance an individual can walk in six minutes as a submaximal assessment of aerobic capacity and endurance [18]. It has been validated in various populations, including patients with cardiorespiratory diseases, and demonstrates good reliability and sensitivity to changes in functional status [19].

2.4.2. SF-36 Questionnaire

SF-36 is a standardized questionnaire assessing quality of life across eight dimensions: physical functioning, physical role limitations, bodily pain, general health perceptions, vitality, social functioning, emotional role limitations, and mental health [20]. SF-36 has been extensively validated and shown to have high reliability and validity in both healthy populations and patients with chronic diseases, including cardiovascular conditions [21].

2.5. Statistical Analysis

The Shapiro−Wilk test was used to assess the normality of the data distribution. Continuous variables are reported as means and standard deviations (SD). A paired t-test was conducted to compare cardiorespiratory response parameters within the group. An independent sample t-test was performed to compare these parameters between groups. Statistical analysis was carried out using IBM SPSS Statistics software, version 26.0, with a p-value of less than 0.05 considered statistically significant.

3. Results

The variables of age, weight, height, and BMI did not show significant differences between non-COVID-19 and post-COVID-19 patients. The duration of recovery from COVID-19 was on average about 1.07 months. The results are detailed in

Table 1. Characteristics of the hypertensive patients with and without post-COVID-19.

Variables	Non-COVID-19 (n = 30; F = 23; M = 7)	Post-COVID-19 (n = 30; F = 24; M = 6)	p-Value
Age (years)	58.77 ± 6.35	58.07 ± 7.91	0.707
Weight (kg)	52.27 ± 4.93	50.43 ± 6.33	0.216
Height (m)	1.55 ± 0.07	1.55 ± 0.08	0.932
BMI (kg/m2)	21.77 ± 1.41	21.00 ± 1.50	0.616
Duration of recovery from COVID-19 (months)	-	1.07	-

Denote: n = number; F = female; M = male; kg = kilograms; m = meters; BMI = body mass index.

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The results of cardiorespiratory response parameters were assessed using 6MWT. The results showed that the post-COVID-19 group had significantly reduced post-HR, post-SBP, post-RPE, post-leg fatigue, and increased post-SpO₂, 6MWT distance at the 3-months follow-up compared to baseline (p < 0.05). In contrast, these cardiorespiratory response parameters did not show significant differences between baseline and the 3-months follow-up in the non-COVID-19 group (p > 0.05). The results are detailed in

Table 2. Comparison of cardiorespiratory parameters using the 6MWT in hypertensive patients with and without post-COVID-19 at baseline and 3 months.

Variables	Baseline	3 Months	p-Value Within Group
	Mean ± SD	Mean ± SD
Post-HR (bpm)
Non-COVID-19	103.30 ± 7.96	102.20 ± 5.46	0.549
Post-COVID-19	113.23 ± 7.93	104.33 ± 6.24	<0.001
p-value between groups	<0.001	0.164
Post-SBP (mmHg)
Non-COVID-19	135.60 ± 5.61	136.53 ± 7.89	0.584
Post-COVID-19	143.50 ± 10.70	137.17 ± 9.33	0.041
p-value between groups	0.001	0.777
Post-DBP (mmHg)
Non-COVID-19	78.57 ± 7.96	78.36 ± 5.01	0.898
Post-COVID-19	79.03 ± 7.82	78.77 ± 6.46	0.863
p-value between groups	0.820	0.790
Post-SpO2 (%)
Non-COVID-19	97.37 ± 0.49	97.53 ± 0.51	0.169
Post-COVID-19	96.63 ± 0.76	97.23 ± 0.58	0.008
p-value between groups	<0.001	0.093
Post-RPE
Non-COVID-19	10.70 ± 0.99	10.43 ± 1.48	0.842
Post-COVID-19	12.27 ± 1.57	10.90 ± 1.27	<0.001
p-value between groups	<0.001	0.195
Post-leg fatigue
Non-COVID-19	1.77 ± 0.76	1.78 ± 0.78	0.940
Post-COVID-19	3.23 ± 1.04	1.80 ± 0.75	<0.001
p-value between groups	<0.001	0.933
Distance (m)
Non-COVID-19	401.57 ± 12.27	403.27 ± 11.27	0.615
Post-COVID-19	387.23 ± 20.75	400.20 ± 20.75	0.010
p-value between groups	0.002	0.338

Denote: HR = heart rate; SBP = systolic blood pressure; DBP = diastolic blood pressure; SpO₂ = pulse oxygen saturation; RPE = rate of perceived exertion; m = meter.

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Comparison of cardiorespiratory response parameters between the non-COVID-19 and post-COVID-19 groups revealed that the post-COVID-19 group had significantly higher post-HR, post-SBP, post-RPE, and post-leg fatigue, along with lower post-SpO₂ and 6MWT distance at baseline compared to the non-COVID-19 group (p < 0.05). However, no significant differences were observed between the groups at the 3-months follow-up (p > 0.05). The results are detailed in Table 2.

Quality of life was assessed using SF-36. The results indicated that the scores for eight dimensions, including physical functioning, physical role limitations, bodily pain, general health perceptions, vitality, social functioning, emotional role limitations, and mental health, were significantly lower in the post-COVID-19 group when comparing baseline to the 3-months follow = up (p < 0.05). In contrast, no significant differences were observed in the non-COVID-19 group (p > 0.05). The results are detailed in

Table 3. Comparison of quality of life using the Short Form-36 in hypertensive patients with and without post-COVID-19 at baseline and 3 months.

Variables	Baseline	3 Months	p-Value Within Group
	Mean ± SD	Mean ± SD
Physical function
Non-COVID-19	73.33 ± 11.24	74.67 ± 10.08	0.161
Post-COVID-19	62.00 ± 6.10	72.00 ± 7.14	<0.001
p-value between groups	<0.001	0.242
Physical role limitations
Non-COVID-19	74.83 ± 7.70	75.10 ± 9.25	0.712
Post-COVID-19	62.93 ± 5.61	73.13 ± 95.38	< 0.001
p-value between groups	<0.001	0.326
Bodily pain
Non-COVID-19	60.80 ± 13.13	61.47 ± 12.53	0.326
Post-COVID-19	53.33 ± 13.73	59.33 ± 13.63	0.004
p-value between groups	0.035	0.530
General health perceptions
Non-COVID-19	69.67 ± 10.66	70.33 ± 10.33	0.169
Post-COVID-19	56.67 ± 8.84	68.33 ± 8.74	0.008
p-value between groups	<0.001	0.422
Vitality
Non-COVID-19	69.67 ± 9.99	70.33 ± 10.33	0.161
Post-COVID-19	58.33 ± 9.13	68.67 ± 7.30	<0.001
p-value between groups	<0.001	0.195
Social functioning
Non-COVID-19	68.57 ± 6.27	70.50 ± 9.36	0.169
Post-COVID-19	59.30 ± 7.41	69.83 ± 10.68	<0.001
p-value between groups	<0.001	0.351
Emotional role limitation
Non-COVID-19	87.67 ± 7.74	88.33 ± 6.99	0.423
Post-COVID-19	70.67 ± 9.44	86.67 ± 9.59	< 0.001
p-value between groups	<0.001	0.445
Mental health
Non-COVID-19	84.33 ± 6.26	85.00 ± 5.09	0.662
Post-COVID-19	71.50 ± 10.43	84.00 ± 6.21	<0.001
p-value between groups	<0.001	0.498

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Comparison of quality of life between the non-COVID-19 and post-COVID-19 groups revealed that the post-COVID-19 group had significantly lower scores in physical functioning, physical role limitations, bodily pain, general health perceptions, vitality, social functioning, emotional role limitations, and mental health at baseline compared to the non-COVID-19 group (p < 0.05). However, at the 3-months follow-up, no statically significant differences were found between the groups (p > 0.05). The results are detailed in Table 3.

4. Discussion

This study investigated cardiorespiratory response parameters and quality of life (QoL) in hypertensive patients who had recovered from mild COVID-19 compared to hypertensive patients who had not been infected. At baseline, post-COVID-19 patients demonstrated slightly lower 6MWT distances and QoL scores than non-COVID-19 patients, indicating a transient negative impact of COVID-19 on functional capacity and well-being. The cardiorespiratory response parameters, including heart rate, blood pressure, SpO₂, RPE, and leg fatigue, improved in the hypertensive patients with post-COVID-19 at the 3-month follow-up. These results demonstrate changes in physiological responses and functional capacity during the recovery period. The improvement in heart rate and blood pressure control may be related to reduced systemic inflammation and oxidative stress following recovery, which can improve endothelial function and vascular health [22]. In addition, improvements in RPE and leg fatigue can be attributed to enhanced autonomic regulation. During post-COVID-19 recovery, the autonomic nervous system may normalize, reducing sympathetic over-activity and improving parasympathetic tone. This normalization can lead to better exercise tolerance and lower perceived exertion [12]. Furthermore, the enhanced SpO₂ levels post-COVID-19 recovery can indicate improved lung function and oxygen exchange efficiency. Pulmonary rehabilitation and recovery from COVID-19-related pneumonia or lung injury contribute to better respiratory outcomes [23,24]. 6MWT has been widely used to assess exercise capacity in individuals with various conditions, including cardiorespiratory diseases, metabolic diseases, and post-COVID-19 recovery [25,26]. A previous study has shown that the distance covered in 6MWT correlates with the severity of COVID-19, with individuals experiencing mild COVID-19 symptoms covering greater distances than those with moderate to severe symptoms [27]. Our results indicate that hypertensive patients who have recovered from COVID-19 covered shorter distances in 6MWT compared to hypertensive patients who had not contracted COVID-19 at baseline. This finding aligns with earlier research showing that individuals with systemic arterial hypertension (SAH) who had post-COVID-19 had significantly reduced 6MWT distances compared to those without post-COVID-19 [15]. Therefore, SAH may negatively influence exercise capacity in post-COVID-19 patients. However, our study found that the 6MWT distances in hypertensive patients who recovered from COVID-19 returned to the levels of hypertensive patients without COVID-19 infection at the 3-month follow-up. This recovery may be attributed to the fact that none of the post-COVID-19 participants were hospitalized and all experienced only mild COVID-19 symptoms.

The quality of life (QoL) improved in hypertensive patients with post-COVID-19 at the 3-month follow-up compared to those without COVID-19 infection. Previous studies have reported that post-COVID-19 patients experienced lower scores across all eight dimensions of SF-36, including physical functioning, physical role limitations, bodily pain, general health perceptions, vitality, social functioning, emotional role limitations, and mental health, when compared to healthy individuals, indicating a decrease in QoL [28,29]. Additionally, a study found that post-acute COVID-19 patients had significantly lower scores in the domains of physical functioning, physical role limitations, bodily pain, general health perceptions, and mental health compared to healthy individuals [30]. These reduced QoL scores may be attributed to symptoms such as impaired mental health, dyspnea, and neuropsychological disorders associated with prolonged COVID-19 infection [31,32]. Therefore, the observed improvement in QoL at the 3-month follow-up in hypertensive patients with post-COVID-19 may be attributed to increased cardiorespiratory fitness levels, which could enhance overall health and well-being.

Overall, these findings suggest that mild COVID-19 may temporarily impair cardiorespiratory function and QoL in hypertensive patients, but structured monitoring and recovery allow patients to regain their previous health status within 3 months.

5. Limitations of This Study

This study has several limitations. First, only key cardiorespiratory response parameters and quality of life were assessed, while other relevant clinical indicators such as echocardiography, cardiac biomarkers, and imaging for lung injury were not included. Second, all post-COVID-19 participants experienced mild symptoms and were not hospitalized, which limits the generalizability of the results to patients with more severe disease. Third, the follow-up period was limited to 3 months, and long-term effects on cardiorespiratory function and quality of life remain unknown. Fourth, some explanations, such as improvements in heart rate or vascular function, are speculative and based on previous literature, as myocarditis and autonomic function were not directly assessed. Finally, the small sample size (n = 60) and strict inclusion criteria may limit the external validity of the findings.

6. Conclusions

This study reveals that hypertensive patients who have recovered from mild COVID-19 may experience temporary impairments in cardiorespiratory function and QoL; however, structured monitoring and recovery enable them to regain their previous health status within 3 months. Compared with hypertensive patients who did not contract COVID-19, those recovering from COVID-19 showed improvements in both cardiorespiratory response parameters and QoL, indicating beneficial effects of recovery over time.