Clinical Profile and Sex-Specific Recovery With Cardiac Rehabilitation After Coronary Artery Bypass Grafting Surgery

Abstract

Background: Cardiac rehabilitation (CR) improves major adverse cardiac outcomes in patients recovering from myocardial infarction. CR influences outcomes through attenuation of cardiac risk factors, lifestyle changes, and biological effects on endothelial function. The clinical profile and sex-specific outcomes with CR after coronary artery bypass grafting (CABG) is less well defined.

Methods: This retrospective cohort study of consecutive patients undergoing elective or urgent CABG was performed between 2014 and 2016 at a single site. Patients requiring concomitant procedures were excluded. Patients received referral to a 12-week, 36-session CR program standardized through the health care system and tracked via electronic health records. Clinical data and complications during hospitalization were abstracted from Society of Thoracic Surgeons (STS) registry and matched with 12-months outcomes from electronic health records. Primary composite outcomes were mortality and STS-defined complications within 12 months after CABG. Kaplan-Meier plots for mortality were generated from conditional 6-month survival data.

Findings: Of 756 patients undergoing CABG, 420 met the eligibility criteria (mean age, 66 years). Women (18%) had a similar cardiac risk profile to men except for a higher hemoglobin A_1c level and lower hematocrit before surgery. Women had similar extent of revascularization to men but had higher rates of intraoperative (30% vs 8%; p < 0.001) and postoperative blood transfusions (43% vs 29%; p = 0.014) compared with men. Only 66% of women qualified for direct discharge to home compared with 85% of men (p = 0.0003). Twelve-month mortality was 1.3% and 2%, respectively (p > 0.05). Half of the cohort got referred for CR, and 32% of men and 23% of women underwent CR. Twelve-month composite outcomes did not differ by referral to cardiac rehabilitation (odds ratio = 0.77; 95% CI, 0.36-1.64) or engagement with CR (odds ratio = 0.67; 95% CI -0.05 to 0.086), adjusting for age, sex, body mass index, and diabetes. Kaplan-Meier analysis found no significant difference in survival between those who did and did not undergo CR. Men experienced increases in metabolic equivalents (38%, P = 0.014), grip strength (11%, P < 0.0001), and sense of physical well-being (40.9%, P < 0.0001), whereas women experienced increases in aerobic exercise duration (15.5%, P = 0.02) and a trend in improved sense for physical well-being (93.3%, P = 0.06).

Implications: Sex differences exist with CR after CABG. Future studies should confirm these findings in larger cohorts and corroborate the effect on endothelial function and other biological markers.

Keywords: cardiac rehabilitation; coronary artery bypass surgery; outcomes; sex difference.