The Association Between Body Mass Index and In-hospital Mortality in Patients with Acute Myocardial Infarction Undergoing Percutaneous Coronary Intervention

The relationship of body mass index (BMI) with clinical outcomes in patients with acute myocardial infarction (AMI) remains incompletely understood. In this study, 1113 patients with AMI who underwent percutaneous coronary intervention (PCI) were identified in the Rural AMI registry. Patients were divided into three groups based on BMI: underweight < 18.5 kg/ m², normoweight ≥ 18.5 to < 25.0 kg/ m², and overweight ≥ 25.0 kg/ m². The following data are given in this order. The endpoint of the study was in-hospital mortality. Underweight patients were older (77 ± 10 versus 69 ± 12 versus 63 ± 13 years; P < 0.001) and more likely to be female (38.5 versus 22.9 versus 20.2%; P = 0.009), and had a higher incidence of Killip class ≥ III (24.6 versus 12.7 versus 11.4%; P = 0.03). The median B-type natriuretic peptide levels on admission were 165 (interquartile range [IQR]: 73 - 565), 93 (IQR: 30 - 281), and 63 (IQR: 24 - 189) pg/mL (P < 0.001). The door-to-balloon time and postprocedural Thrombosis In Myocardial Infarction flow grades were similar among the BMI groups. During hospitalization, there were 65 all-cause deaths, with in-hospital mortality of 18.5%, 5.2%, and 4.7% in underweight, normoweight, and overweight patients, respectively (P = 0.001). In logistic regression analysis, the underweight group was significantly associated with in-hospital mortality using inverse probability of treatment weighting (odds ratio, 2.61; 95% confidence interval: 1.18 - 5.79, P = 0.02). These results suggest that assessment of BMI provides useful information for predicting in-hospital mortality in patients with AMI undergoing PCI.