Das et al. (1) describe the association of obesity as defined by body mass index (BMI) with outcomes of ST-segment elevation myocardial infarction (STEMI). The findings of this study need to be taken in the light of increasing recognition that BMI may not be a true index of body adiposity (2). This is reflected in a recent study looking at outcomes of acute coronary syndrome, in which waist circumference, a marker of visceral obesity, proved to be a more important discriminator in individuals with a BMI <25 kg/m² (3). Similarly, use of a lipid accumulation product, a relatively newer tool for identifying obese individuals, has been shown to be a better marker of all-cause cardiovascular mortality (4). The investigators also raise the possibility of “normal BMI representing unmeasured comorbidities and that overweight and mild obesity likely representing the more appropriate body mass in the post-MI setting” to explain the increased prevalence of adverse outcomes in a normal BMI group. Although interesting, this finding and conclusion need to be discussed in light of the fact that a BMI <30 kg/m² has poor sensitivity for detecting true body fat (5- 6).

The most important finding of this study was the significantly higher in-hospital mortality in patients with class III obesity. Whether this represents an adverse effect of extreme obesity on the disease (disease effect) or suboptimal treatment strategies (treatment effect) is not clear.

From the disease effect standpoint, this study recognized less extensive coronary artery disease in class III obesity, but these individuals may actually have more extensive vulnerable plaque. This remains speculation, however.

More important, treatment effect is a likely scenario. These high-risk patients, despite similar use of conventional medications and reperfusion strategies, may have been underdosed with cardioprotective drugs. For example, higher BMI subjects have lower platelet inhibition by clopidogrel (7). In the current study, clopidogrel was the most commonly used second antiplatelet agent in addition to aspirin. Along the same lines, Sarno et al. (8) reported a higher prevalence of stent thrombosis in obese individuals. Although speculative, these observations make a case for more aggressive weight-adjusted antiplatelet and other drugs in class III obese patients with STEMI.