Supervised Phase-II Cardiac Rehabilitation vs Home Walking Advice After CABG: Effect on Six-Minute Walk Distance

Coronary artery bypass grafting (CABG) is performed in large numbers in Indian cardiac centres, and patients are usually discharged within a week with a printed sheet that says "walk daily". Formal outpatient phase-II cardiac rehabilitation — supervised, individually prescribed, monitored exercise with education — is well supported by international guidelines but is available in few Indian hospitals, and uptake is low because patients live far away and cost matters. Hospitals need local evidence that a structured programme produces gains large enough to justify the space, staff and patient time.

This MPT dissertation compares 8 weeks of supervised phase-II cardiac rehabilitation (aerobic training at 40–70% heart-rate reserve by the Karvonen method, progressed by Borg RPE, plus resistance and flexibility work, three sessions per week) with structured home walking advice in patients 3–6 weeks after elective CABG. The primary outcome is six-minute walk distance (6MWD) measured strictly according to the ATS 2002 guideline; secondary outcomes are modified Borg dyspnoea, Borg RPE, SpO₂, heart rate at rest, peak and one-minute recovery, and predicted-6MWD percentage.

The sample size is computed in G*Power from an expected effect size, the trial is registered on CTRI, approved by the Institutional Ethics Committee and conducted with written informed consent. It follows the MPT synopsis → ethics approval → dissertation → viva route used by RGUHS, KUHS and MUHS.

Abstract

Background: Functional capacity after CABG often remains reduced for months. Supervised phase-II cardiac rehabilitation improves exercise capacity, but Indian data comparing it with the common practice of home walking advice are limited. Aim: To compare the effect of supervised phase-II cardiac rehabilitation and home walking advice on 6MWD in post-CABG patients. Methods: Two-group randomised comparative study; 44 patients 3–6 weeks post-CABG; 8 weeks of intervention; 6MWT per ATS 2002 at baseline, week 4 and week 8; analysis by repeated-measures ANOVA.

Introduction

After CABG, deconditioning, sternotomy pain, anaemia, fear of exertion and beta-blockade all limit activity. The 6MWT is a submaximal, self-paced test that reflects functional capacity for daily activities, needs only a 30-metre corridor, and predicts outcomes in cardiac patients. It is therefore practical for Indian hospitals that lack cardiopulmonary exercise-testing equipment.

Review of literature and gap

Meta-analyses show that exercise-based cardiac rehabilitation improves exercise capacity and quality of life and reduces readmissions in coronary heart disease. Studies from India are few, often single-group, and frequently do not follow the ATS protocol for the 6MWT (practice walk, standard encouragement, fixed track length), which makes results hard to compare. There is also little local evidence on how early after surgery gains appear, which is why this study adds an intermediate week-4 measurement rather than testing only before and after the programme.

Hypotheses

• H0: there is no significant difference in 6MWD change between supervised rehabilitation and home walking advice.
• H1: supervised phase-II rehabilitation produces a significantly greater increase in 6MWD.

Feasibility

• Setting: cardiac rehabilitation unit of a tertiary cardiac hospital with a 30 m corridor, telemetry, crash cart and physician cover.
• Equipment: treadmill/cycle ergometer, pulse oximeters, Borg charts, cones, stopwatch.
• Time: 6 months for recruitment, 8-week intervention and follow-up.
• Ethics: IEC approval, CTRI registration, written consent, physician clearance and predefined stopping criteria.

Patients discharged after CABG in India frequently receive only verbal or printed advice to walk at home, and structured, supervised phase-II cardiac rehabilitation is offered in few centres and taken up by fewer patients. Without local evidence of meaningful improvement in functional capacity, hospitals have little reason to invest in rehabilitation units and patients have little reason to attend. Where local studies exist, the six-minute walk test is often performed without adherence to the ATS standard, which undermines comparison.

This dissertation therefore asks: in patients 3–6 weeks after elective CABG, does 8 weeks of supervised phase-II cardiac rehabilitation produce a greater improvement in six-minute walk distance, measured to the ATS 2002 standard, than structured home walking advice — and are the gains accompanied by better dyspnoea, perceived exertion and heart-rate recovery?

In scope

• Adults aged 40–70 years, 3–6 weeks after elective isolated CABG, clinically stable, with physician clearance.
• Two groups over eight weeks in one tertiary cardiac hospital.
• 6MWT with Borg, SpO₂ and heart-rate measures at three time points.
• Adverse-event and adherence reporting.

Out of scope

• Combined valve surgery, emergency CABG, heart failure with severely reduced ejection fraction.
• Cardiopulmonary exercise testing with gas analysis.
• Long-term follow-up for readmission or mortality.

Study design: prospective, two-group, randomised comparative study (parallel groups, 1:1), with assessor blinding for the 6MWT.

Setting: cardiac rehabilitation unit and cardiothoracic OPD of a tertiary cardiac hospital.

Sample size: calculated in G*Power (t-tests, difference between two independent means) using the expected between-group difference in 6MWD change and its SD from a cited study or a pilot. For example, a difference of 45 m with SD 55 m (d ≈ 0.82), α = 0.05 and power 80% gives about 20 per group; allowing ~10% attrition gives 44 participants (22 per group). Replace these numbers with the values you justify.

Inclusion criteria: elective isolated CABG via median sternotomy; 3–6 weeks post-surgery; age 40–70; LVEF ≥ 35%; NYHA class I–II; clinically stable on medication; physician clearance; able to walk independently.

Exclusion criteria: unstable angina; complex ventricular arrhythmia; resting SBP > 180 or DBP > 110 mmHg; sternal instability or wound infection; severe COPD; orthopaedic or neurological limitation of walking; haemoglobin < 9 g/dL.

Randomisation: computer-generated block randomisation with allocation in sequentially numbered opaque sealed envelopes held by a person not involved in recruitment.

Interventions (8 weeks)

• Supervised group: 3 sessions/week, 60 minutes — 10 min warm-up; 20–30 min aerobic training on treadmill or cycle at 40–70% HRR (Karvonen), progressed to Borg RPE 11–14; light resistance training for major muscle groups within sternal precautions from week 4; 10 min cool-down and flexibility; education on risk factors, medication and warning symptoms; telemetry during the first sessions.
• Home group: printed and demonstrated walking programme (5 days/week, progressive 10 → 30 min at RPE 11–13), a walking diary and weekly phone follow-up.

Outcome measurement (ATS 2002): 30 m flat, straight corridor marked every 3 m; turnaround cones; rest 10 min before test; standard phrases of encouragement each minute; no walking alongside; pre- and post-test HR, SpO₂, BP, Borg dyspnoea and fatigue; stop if chest pain, intolerable dyspnoea, leg cramps, staggering, diaphoresis or pallor. Two tests at baseline with the better distance used.

Ethics and registration: IEC approval; CTRI registration before enrolment; informed consent in the participant's language per ICMR National Ethical Guidelines (2017); cardiologist on call; stopping criteria from ACSM guidelines.

Statistical analysis: Shapiro–Wilk; baseline comparison by t-test/chi-square; two-way mixed (group × time) repeated-measures ANOVA for 6MWD with Bonferroni post-hoc; independent t-test or Mann–Whitney for secondary outcomes; 95% CI and partial η²; intention-to-treat; p < 0.05; SPSS.