The Effects of the Obesity Paradox and In-Hospital and One-Year Outcomes in Patients With ST Elevation Myocardial Infarction (STEMI): Results From a STEMI Registry.

Background: Obesity is strongly associated with increased cardiovascular diseases (CVD) and cardiovascular risk factors, such as diabetes mellitus, hypertension, and dyslipidemia. However, numerous studies have suggested the existence of an "obesity paradox" in which overweight and mildly obese patients often exhibit a better outcome than their leaner counterparts. Therefore, this study aimed to characterize the association between BMI and in-hospital and one-year outcomes.

Method: This hospital-based research was conducted as a part of the Kermanshah STEMI Registry. Following the application of inclusion criteria, a total of 2,397 STEMI patients were evaluated. The data were collected using a standardized case report developed by the European Observational Registry Program (EORP). Body mass index (BMI) (kg/m²) was classified into underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), class I/mild obese (30-34.9), and class II/extreme obese (≥35) categories. The independent predictors of the in-hospital and one-year outcomes were assessed using multivariable logistic regression models.

Results: Out of the 2397 patients, 43 (1.79%) were underweight, 934 (38.97%) were normal, 1038 (43.30%) were overweight, 322 (13.43%) were class I obese, and 60 (2.50%) were class II obese. The results of the crude analysis showed that class I obesity was protective against CV death (OR 0.50; 95% CI 0.30-0.84), MACE3 (MI, stroke, and death) (OR 0.47; 95% CI 0.29-0.76), and MACE5 (MACE3 plus unstable angina and heart failure) (OR 0.59; 95% CI 0.44-0.79).

Conclusions: Multivariate adjustment eliminated the protective effect of class I obesity against death and MACE events. Therefore, it is possible that this protective effect does not exist and instead reflects the impact of confounding variables such as age.