Body mass index and outcome of acute myocardial infarction - Is there an obesity paradox?

Background: Although there have been some studies focusing on the relationship between body mass index (BMI), coronary artery disease (CAD) and acute coronary syndrome, the clinical effects of BMI on outcomes after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) are not well known in a Taiwanese population. Methods: From January 2005 to December 2011, 1298 AMI patients who received PCI were enrolled from a single center in Taiwan. The patients were divided into 4 groups according to their BMI: underweight (BMI < 18.5 kg/m²); normal weight (18.5 ≦ BMI < 24 kg/m²); overweight (24 ≦ BMI < 27 kg/m²) and obese (BMI ≧ 27). All patients had been followed up for at least 12months, and 30-day and 5-year all-cause and cardiovascular-cause mortality were compared among the study groups. Results: The patients in the underweight group had a lower 30-day survival rate than the other 3 groups, and the underweight and normal weight patients had a lower 5-year survival rate than the overweight and obese patients. The multivariate regression analysis showed that Killip class≧2, non-use of statin, older age, hemoglobin < 12 g/dl and chronic kidney disease, but not BMI, are independent predictors of all-cause mortality. Conclusions: In this present study, the major factors affecting long-term survival are lack of using statin and older age, but not obese paradox.