Effect of Body Mass Index on Clinical Events After Acute Coronary Syndromes

The association between body mass index (BMI) and major clinical events after acute coronary syndrome (ACS) remains controversial. We investigated the impact of BMI on major clinical events after ACS in a large individual patient data meta-analysis. Data on 81,553 patients from 45 different countries with ACS enrolled in 8 large randomized clinical trials were included, followed up for a median of 171 days. The mean age was 63.4 ± 11.7, 70% were male, and the mean BMI was 27.3 ± 4.7 kg/m². Compared with upper-normal-weight participants (BMI 21.75 to 24.9 kg/m², reference category), underweight participants (<18.5 kg/m²) had an increased risk of death (hazard ratio [HR] 1.35, 95% confidence interval [CI] 1.10 to 1.66, p = 0.004). Both overweight subcategories, BMI 25 to 27.5 kg/m² (HR 0.81, 95% CI 0.75 to 0.89, p <0.001) and BMI 27.5 to 29.9 kg/m² (HR 0.84, 95% CI 0.76 to 0.92, p <0.001), and type I obesity (30 to 34.9, HR 0.81, 95% CI 0.73 to 0.89, p <0.001) had a significantly lower mortality. Type II and III obesities were not significantly associated with mortality. Mortality was lowest at a BMI of 30.9 kg/m². Compared with normal-weight patients, overweight and obese categories were related with a significantly lower risk of bleeding and refractory ischemia. Overweight patients had a lower risk of myocardial infarction, heart failure hospitalizations, and heart failure-related deaths. There were no associations between BMI and revascularization rates or stroke. In conclusion, underweight and normal-weight patients were associated with an increased mortality risk, bleeding, ischemia, and heart failure compared with those with higher BMI after ACS.