Body mass index and cardiovascular outcomes in patients with acute coronary syndrome by diabetes status: the obesity paradox in a Korean national cohort study

Background : The “obesity paradox” has not been elucidated in the long-term outcomes of acute coronary syndrome (ACS). We investigated the association between obesity and cardiovascular (CV) outcomes in ACS patients with and without diabetes. Methods: We identified 6,978 patients with ACS aged 40–79 years from the Korean National Health Insurance Service-Health Screening Cohort between 2002 and 2015. Baseline body mass index (BMI) was categorized as underweight (<18.5 kg/m 2 ), normal weight (18.5–22.9 kg/m 2 ), overweight (23.0–24.9 kg/m 2 ), obese class I (25.0–29.9 kg/m 2 ), and obese class II (≥30.0 kg/m 2 ). The primary outcome was major adverse CV events (MACE)—CV death, myocardial infarction (MI), and stroke. The secondary outcomes were the individual components of MACE, hospitalization for heart failure (HHF), and all-cause death. Results: After adjustment for confounding variables, compared to normal-weight patients without diabetes (reference group), obese class I patients with and without diabetes had a lower risk of MACE, but only significant in patients without diabetes (with diabetes: hazard ratio [HR] 0.95, 95% confidence interval [CI] 0.78–1.14; without diabetes: HR 0.78, 95% CI 0.62–0.97). Obese class II patient with diabetes had a higher risk of MACE with no statistical significance (HR 1.14, 95% CI 0.82–1.59). Underweight patients with and without diabetes had a higher risk of MACE, but only significant in patients with diabetes (with diabetes: HR 1.79, 95% CI 1.24–2.58; without diabetes: HR 1.23, 95% CI 0.77–1.97). Conclusion: In ACS patients, obesity had a protective effect on CV outcomes, especially in patients without diabetes.