Not Yet RecruitingNot Applicable

Effects of Slow-paced Breathing on Heart Rate Variability in Patients With Heart Failure

27 participantsStarted 2026-08-15

Plain-language summary

Background: Heart failure (HF) is a major global public health concern characterized by impaired cardiac function, high mortality, frequent hospital readmissions, and substantial healthcare burden. Autonomic nervous system (ANS) dysfunction plays a critical role in the pathophysiology of HF, typically presenting as increased sympathetic activity and reduced parasympathetic activity. Heart rate variability (HRV), a non-invasive marker of cardiac autonomic regulation, has been widely used to evaluate autonomic function and predict clinical outcomes in patients with HF. Reduced HRV is associated with increased risks of sudden cardiac death, cardiovascular events, and hospital readmission. Although cardiac rehabilitation (CR) has been demonstrated to improve exercise capacity, quality of life, and clinical outcomes in HF patients, its effects on autonomic modulation, particularly during Phase I cardiac rehabilitation, remain insufficiently investigated. Slow-paced breathing (SPB) has emerged as a potential non-pharmacological intervention for enhancing autonomic regulation. By synchronizing respiratory rhythm with cardiovascular oscillations, SPB may enhance baroreflex sensitivity, increase vagal activity, and improve HRV. Previous studies have suggested beneficial effects of SPB on autonomic function; however, the findings remain inconsistent, and evidence regarding its short-term effects on HRV among hospitalized HF patients undergoing early cardiac rehabilitation is limited. Therefore, further investigation is warranted to determine whether SPB can provide additional autonomic benefits when incorporated into Phase I cardiac rehabilitation. Objective: This study aims to investigate the effects of slow-paced breathing combined with Phase I cardiac rehabilitation on autonomic nervous system function in patients with heart failure, using HRV as the primary outcome measure. Methods: This study will employ a parallel randomized controlled trial design. Hospitalized patients diagnosed with heart failure will be randomly allocated into either the SPB intervention group or the control group. Both groups will receive standard Phase I cardiac rehabilitation, while the intervention group will additionally receive slow-paced breathing training. The primary outcomes will include changes in HRV parameters, including time-domain indices (standard deviation of NN intervals \[SDNN\] and root mean square of successive differences \[RMSSD\]) and frequency-domain indices (low-frequency power \[LF\], high-frequency power \[HF\], and LF/HF ratio), to evaluate changes in cardiac autonomic regulation before and after intervention.

Who can participate

Age range

20 Years – 80 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: * Patients diagnosed with heart failure during hospitalization and who are clinically stable. Exclusion Criteria: Respiratory distress at rest with the utilization of accessory neck muscles (neck breathing pattern). Presence of an implanted cardiac pacemaker. Chronic pulmonary diseases, such as chronic obstructive pulmonary disease (COPD), pulmonary hypertension, pulmonary fibrosis, or exercise-induced asthma. Current use of mechanical ventilation. Severe aortic stenosis. Aortic dissection. Acute myocarditis, pericarditis, or infective endocarditis. Inability to walk independently due to orthopedic, neurological, or other medical conditions. Inability to understand the study protocols or cooperate, such as individuals with psychiatric disorders, dementia, or a history of stroke.

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Heart Rate Variability

Timeframe: 20 mins/session, 2 sessions/day, for 8 weeks

Trial details

NCT IDNCT07763353

SponsorChung Shan Medical University

Sponsor typeOTHER

Study typeINTERVENTIONAL

Primary completion2027-08-14

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