Body Mass Index and Sudden Cardiac Death in Japanese Patients After Acute Myocardial Infarction: Data From the JCAD Study and HIJAMI-II Registry.

Background: Although an "obesity paradox" exists in patients after myocardial infarction, the association between obesity and the risk of sudden cardiac death (SCD) is limited. The aim of this study was to determine whether obesity is associated with an increased risk of SCD in Japanese survivors of acute myocardial infarction.

Methods And Results: Pooled data from 2 cohort studies in Japan, JCAD (Japanese Coronary Artery Disease) study and the Heart Institute of Japan Acute Myocardial Infarction-II (HIJAMI-II) registry, comprising of 6216 patients (mean age 65±11 years, 75.2% male) with acute myocardial infarction who were discharged alive, were studied. The patients were categorized into the following body mass index (BMI) groups at baseline according to the World Health Organization classification for Asian populations: BMI <18.5 kg/m (n=335), 18.5 to 23 kg/m (n=2371), 23 to 27.5 kg/m (n=2823), and ≥27.5 kg/m (n=687). The main outcomes were all-cause mortality and SCD. During an average follow-up period of 3.6±1.4 years, all-cause mortality was 10.1%, and SCD was 1.2%. Patients with BMI <18.5 kg/m had the highest rate of all-cause mortality (adjusted hazard ratio, 1.61; 95% confidence interval, 1.20-2.16), but high BMI (≥27.5 kg/m) was not associated with mortality compared with patients in the group with BMI ≥18.5 and <23 kg/m. However, the long-term risk of SCD was increased in the group with BMI ≥27.5 kg/m (adjusted hazard ratio, 2.97; 95% confidence interval, 1.24-7.15). Multivariate analysis revealed that BMI ≥27.5 kg/m was associated with an increased risk of SCD (hazard ratio, 2.78; 95% confidence interval, 1.35-5.74).

Conclusions: Obesity (BMI ≥27.5 kg/m) was associated with the risk of SCD in Japanese patients after myocardial infarction, although an obesity paradox was found for all-cause mortality.