Effect of body mass index on outcome in patients with suspected coronary artery disease referred for stress echocardiography

摘要

In patients with hypertension, heart failure, or coronary artery disease (CAD), obese patients have been shown to have a lower cardiac event rate compared with normal weight counterparts. This phenomenon has been termed the "obesity paradox." We sought to determine whether the obesity paradox exists in a cohort of patients referred for stress echocardiography. We evaluated 4,103 patients with suspected CAD (58 ± 13 years; 42% men) undergoing stress echocardiography (52% exercise and 47% dobutamine). Patients were divided into 3 groups on the basis of body mass index (BMI): 18.5 to 24.9, 25 to 29.9, and 30 kg/m2. During the follow-up of 8.2 ± 3.6 years, there were 683 deaths (17%). Myocardial ischemia was present in 21% of the population. Myocardial ischemia was more prevalent in patients with a BMI of 18.5 to 24.9 kg/m2 (26%) than those with a BMI of 25 to 29.9 kg/m2 (21%) and 30 kg/m2 (18%). Patients with a BMI of 30 kg/m2 had the lowest death rate (1.2%/year) compared with those with a BMI of 25 to 29.9 kg/m2 (1.75%/year) and 18.5 to 24.9 kg/m2 (2.9%/year; p 0.001). After adjusting for significant clinical variables including exercise capacity, patients with higher BMI (30 kg/m2 and 25 to 29.9 kg/m2) had less risk of mortality compared with those with a BMI of 18.5 to 24.9 kg/m2 (hazard ratio 0.58, 95% confidence interval 0.47 to 0.72, p 0.0001 and hazard ratio 0.69, 95% confidence interval 0.57 to 0.82, p 0.0001, respectively). In conclusion, higher survival rate in patients with higher BMI as previously described in patients with hypertension, heart failure, and CAD extends to patients with suspected CAD referred for stress echocardiography, independent of exercise capacity.