Obesity Is Associated with Higher Odds of In-Hospital Mortality but Lower Risk of 5-Year Mortality in ST-Segment Elevation Myocardial Infarction Patients

Background: The ‘obesity paradox’, whereby obese patients demonstrate better clinical outcomes compared to normal-weight patients, has been reported in acute myocardial infarction, including ST-segment elevation myocardial infarction (STEMI). However, potential sex differences in this association remain largely unexplored. Methods: Using a prospective registry-based multicenter cohort of consecutive STEMI presentations, we evaluated the association between body mass index (BMI) and mortality in patients with STEMI. Patients were divided into three groups based on BMI: normal weight (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2), and obese (≥30.0 kg/m2). We studied the odds of in-hospital, hospital discharge-to-5-year, and presentation to 5-year all-cause mortality by BMI groups in the overall cohort and in sex-stratified analyses. Results: Among 4682 consecutive STEMI patients, 30.1% were female, and 22.2% were normal weight, 36.2% overweight, and 41.6% obese. In the overall cohort, compared to normal-weight patients, the odds of in-hospital mortality were higher in obese patients (aOR 1.73, 95% CI 1.08–2.8) and the risk of discharge-to-5-year mortality was lower in overweight (aHR 0.69, 95% CI 0.57–0.85) and obese (aHR 0.66, 95% CI 0.53–0.82) patients. In sex-stratified analysis, compared to normal-weight males, obese males had higher odds of in-hospital mortality (aOR 2.25, 95% CI 1.18–4.51). Overweight and obese males (aHR 0.63, 95% CI 0.49–0.82, aHR 0.64, 95% CI 0.48–0.85) and obese females (aHR 0.68, 95% CI 0.49–0.94) had a lower discharge-to-5-year mortality risk. Conclusions: In this large STEMI cohort, obesity was associated with higher odds of in-hospital mortality but lower risk of discharge-to-5-year mortality. Sex-stratified analyses demonstrated that obese males were at high odds of in-hospital mortality and both obese males and females were at lower risk of discharge-to-5-year mortality.