The impact of obesity on mortality in UA/non-ST-segment elevation myocardial infarction

Aims Obesity is associated with diabetes mellitus and advanced coronary artery disease (CAD). Once a non-ST-elevation acute coronary syndrome has occurred, the association between obesity and prognosis is poorly defined. This study was designed to assess the impact of obesity on outcome after unstable angina/non-ST-segment elevation myocardial infarction (UA/NSTEMI) treated with early revascularization. Methods and results In a prospective cohort study in 1676 consecutive patients with UA/NSTEMI we examined the association between presence of obesity and all-cause mortality. All patients underwent coronary angiography and, if appropriate, early catheter-based revascularization. Patients were divided into four groups according to body mass index (BMI): normal, 18.5-24.9 (n = 551); overweight, 25-29.9 (n 824); obese, 30-34.9 (n = 244); and very obese, above 35 (n = 48). Obese and very obese patients were younger and had a higher incidence of hypertension, diabetes mellitus, elevated cardiac troponin T, and C-reactive protein levels. The angiographic extent of CAD was similar among the BMI groups. Median follow-up was 17 (interquartile range 6-31) months. Cumulative 3-year mortality rates were 9.9% for normal BMI, 7.7% for overweight, 3.6% for obese, and 0 (no death) for very obese (log-rank P = 0.043). Obese and very obese patients had less than half the long-term mortality when compared with normal BMI patients [hazard ratio (HR) 0.38, 95% confidence interval (CI) 0. 18-0.81, P = 0.012]. This result remained significant after adjustment for confounding prognostic factors including coronary status and left ventricular function (adjusted HR 0.27, 95% CI 0.08-0.92, P= 0.036). Conclusion Obesity is associated with improved outcome after UA/NSTEMI treated with early revascularization.