Impact of body mass index on outcomes of enhanced external counterpulsation therapy

Abstract

Objectives: We evaluated the association of baseline body mass index (BMI) on the outcomes of enhanced external counterpulsation (EECP) therapy for chronic stable angina.

Background: We are in the midst of a pandemic of obesity, which is complicating the care of patients with coronary artery disease (CAD).

Methods: We examined 2730 patients enrolled from 2002 to 2004 in the IEPR-2. Baseline and outcome variables were stratified by the entry BMI in kilograms per meter squared.

Results: Obesity (BMI > 30 kg/m2) was common (40.6%) among patients with severe CAD referred for EECP. Within the total cohort, 2.6% was underweight (BMI < or = 20 kg/m2) and 4.5% was morbidly obese (BMI > 40 kg/m2). Prevalence of diabetes, hypertension, dyslipidemia, and heart failure (HF) was higher in obese patients. However, the rates of baseline angina and prior revascularization were similar among the groups. The peak diastolic augmentation ratio was similar between groups during the first (0.7 +/- 0.4 for lowest and highest BMI) and last hours of treatment (0.9 +/- 0.5 and 0.8 +/- 0.5). The cumulative hours of treatment, the change in angina class, and the Duke Activity Status Index were similar for all BMI groups. There was a greater reduction in weekly anginal episodes from baseline across ascending levels of BMI (-6.3 +/- 13.6 to -9.7 +/- 15.8, P = .03). The rates of discontinuation for clinical events were highest (14.3%) with skin breakdown being the most frequent cause (10.1%) in the underweight. The rates of clinical events including myocardial infarction, HF, and death trended higher across ascending levels of BMI (P = .52). Multivariate analysis found that older age, history of stroke, history of HF, and diabetes, but not BMI, were predictors of clinical events.

Conclusions: More than 40% of patients with severe CAD referred for EECP were obese. Underweight patients had higher rates of discontinuation of treatment mainly because of skin breakdown. Symptomatic benefit of EECP was similar among all BMI groups. However, despite symptomatic improvement, there was a nonsignificant trend for higher rates of myocardial infarction, HF, and death as BMI increased.