Differential effects of overweight/obesity depending on the severity of heart failure complicating acute myocardial infarction in Japan

Background: The existence of a paradoxical association between overweight/obesity and survival benefits, the so-called obesity paradox, in heart failure (HF) as well as coronary artery disease (CAD) remains contentious. Previously, we reported that a past history of CAD negated the obesity paradox in the general population with acute HF. Herein, we further focused on HF complicating acute myocardial infarction (AMI) and compared the prognostic effects of overweight/obesity with respect to the severity of HF.

Methods: We conducted a multicenter retrospective study of 7265 consecutive patients with AMI. The severity of HF was categorized according to the Killip classification. Overweight/obesity was defined as a body mass index (BMI) of ≥25 kg/m². The interaction between overweight/obesity and the Killip classification for in-hospital mortality was tested in the entire cohort. Multivariable logistic regression analyses were performed to examine the effects of overweight/obesity on in-hospital mortality.

Results: Across the entire study cohort, 1931 patients had HF. Overweight/obesity had a significant association with reductions in in-hospital mortality in patients with mild HF (Killip class II; odds ratio [OR], 0.284; P = 0.019). Conversely, overweight/obesity was a significant risk factor for in-hospital mortality in patients with severe HF (Killip class IV; OR, 2.152; P = 0.001). The effects of overweight/obesity on in-hospital mortality in patients with moderate HF (Killip class III) were intermediate between those with mild HF and severe HF.

Conclusion: Opposing effects of overweight/obesity on in-hospital mortality in patients with mild HF versus severe HF were demonstrated, suggesting a balance between beneficial and deleterious effects of overweight/obesity may be inclined toward the latter with the severity of HF complicating AMI.