Effects of Pilates Breathing Versus Diaphragmatic Breathing on Oxygen Saturation and Heart-Rate Variability in Post-Percutaneous Coronary Intervention Patients

Percutaneous Coronary Intervention (PCI) is a commonly performed procedure for restoring coronary blood flow in patients with coronary artery disease. Following PCI, patients may experience altered breathing patterns, reduced exercise tolerance, and changes in autonomic cardiovascular regulation, which may influence oxygen saturation and heart-rate variability (HRV) during the early recovery period. Breathing exercises are simple, safe, and non-pharmacological interventions that can be incorporated into early cardiac rehabilitation. This study aims to compare the effects of Pilates breathing and diaphragmatic breathing on oxygen saturation and heart-rate variability in hemodynamically stable patients following PCI. The study will be conducted as a parallel-arm randomized controlled trial at Fauji Foundation Hospital, Rawalpindi. A total of 36 participants will be recruited through non-probability purposive sampling and randomly allocated into two groups using sealed opaque envelopes. The Pilates breathing group will receive supervised Pilates breathing exercises, while the diaphragmatic breathing group will receive supervised diaphragmatic breathing exercises. Both groups will undergo the intervention for two consecutive days, with three sessions per day. On Day 0, each session will last 15 minutes and include 10 repetitions, while on Day 1, each session will last 20 minutes and include 15 repetitions. Routine care will continue alongside the breathing interventions. Oxygen saturation (SpO2) will be assessed using a pulse oximeter, while heart-rate variability will be measured using a Polar H10 chest belt/ECG-based HRV assessment. Heart rate, blood pressure, respiratory rate, and oxygen saturation will be monitored before and after each session. Participants will be kept blinded to group allocation. The study will include hemodynamically stable post-PCI patients aged 44-75 years who meet the predefined eligibility criteria, including SpO2 ≥92% on room air and ejection fraction greater than 35%. Patients with ongoing myocardial ischemia, unstable angina, significant arrhythmias, cardiogenic shock, severe heart failure, severe cognitive impairment, uncontrolled hypertension, severe anemia, or other specified exclusion criteria will not be included. The primary outcome will be oxygen saturation, while heart-rate variability will be assessed as a secondary outcome. The study findings will help determine the effects of Pilates breathing and diaphragmatic breathing on oxygen saturation and autonomic cardiovascular regulation during early post-PCI recovery.