The association between body mass index and coronary artery disease severity: a comparison of black and white patients

Despite known associations between obesity and cardiovascular disease, the relationship between obesity as reflected by body mass index (BMI) and angiographic coronary artery disease (CAD) is not fully understood. Moreover, this relationship has not been adequately defined in black patients, a group demonstrated to have lower rates of angiographic CAD despite higher rates of CAD risk factors, cardiovascular events, and CAD-related mortality.

Using an angiography database from an academic hospital, we studied patients undergoing first-time, nonemergent coronary angiography. From this cohort, we selected those without previous CAD diagnosis and with complete anthropomorphic measures and outcome data. Using models that controlled for patient demographics and CAD risk factors, we compared rates of angiographic CAD for blacks and whites by BMI.

Black patients had higher rates of CAD risk factors, including obesity and morbid obesity. Nevertheless, black patients were less likely to have a significant stenosis than white patients. Morbid obesity was associated with significantly less CAD in both race groups. Controlling for black-white differences in BMI and the prevalence of morbid obesity did not change the odds ratio for CAD among black patients.

Racial differences in BMI and prevalence of morbid obesity do not contribute to black-white differences in CAD detected during elective angiography. The paradoxical association of morbid obesity with a lower burden of atherosclerosis may be attributed in part to the limitations of noninvasive screening in the morbidly obese and subsequent referral of patients without disease for angiography.