Six-minute walk distance after coronary artery bypass grafting compared with medical therapy in ischaemic cardiomyopathy

Abstract

Background: In patients with ischaemic left ventricular dysfunction, coronary artery bypass surgery (CABG) may decrease mortality, but it is not known whether CABG improves functional capacity.

Objective: To determine whether CABG compared with medical therapy alone (MED) increases 6 min walk distance in patients with ischaemic left ventricular dysfunction and coronary artery disease amenable to revascularisation.

Methods: The Surgical Treatment in Ischemic Heart disease trial randomised 1212 patients with ischaemic left ventricular dysfunction to CABG or MED. A 6 min walk distance test was performed both at baseline and at least one follow-up assessment at 4, 12, 24 and/or 36 months in 409 patients randomised to CABG and 466 to MED. Change in 6 min walk distance between baseline and follow-up were compared by treatment allocation.

Results: 6 min walk distance at baseline for CABG was mean 340±117 m and for MED 339±118 m. Change in walk distance from baseline was similar for CABG and MED groups at 4 months (mean +38 vs +28 m), 12 months (+47 vs +36 m), 24 months (+31 vs +34 m) and 36 months (-7 vs +7 m), P>0.10 for all. Change in walk distance between CABG and MED groups over all assessments was also similar after adjusting for covariates and imputation for missing values (+8 m, 95% CI -7 to 23 m, P=0.29). Results were consistent for subgroups defined by angina, New York Heart Association class ≥3, left ventricular ejection fraction, baseline walk distance and geographic region.

Conclusion: In patients with ischaemic left ventricular dysfunction CABG compared with MED alone is known to reduce mortality but is unlikely to result in a clinically significant improvement in functional capacity.

Trial registration number: NCT00023595.

Keywords: clinical trial; coronary artery bypass grafting; exercise capacity; ischemic cardiomyopathy; six-minute walk distance.

Figure 1

Summary of STICH trial patients included in the analysis of 6 min walk distance. Reasons for non-inclusion at each follow-up time are given. CABG, coronary artery bypass surgery; STICH, Surgical Treatment for Ischemic Heart Failure.

Figure 2

Change in 6 min walk distance from baseline to each follow-up time for subjects randomised to CABG and to medical therapy alone. The median change and 25th and 75th percentiles are displayed. Differences by treatment group were not statistically significant at any time. CABG, coronary artery bypass surgery.

Figure 3

Change in 6 min walk distance at 12 months in subgroups defined by baseline characteristics. The mean (95% CI) for the difference between CABG and medical therapy groups for the change in 6 min walk distance between baseline and 12-month follow-up are presented. Walk distance is measured in metres. CABG, coronary artery bypass surgery; KCCQ, Kansas City Cardiomyopathy Questionnaire; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association.