Insulin Resistance and Short-Term Mortality in Patients with Acute Myocardial Infarction

Abstract

Background: Homeostasis Model Assessment (HOMA) is a widely used index to study the role of insulin resistance (IR).Our objective has been to clarify if IR would predict short-term mortality in patients with acute myocardial infarction (AMI). Methods: Observational prospective study in 518 consecutive patients with a clinical diagnosis of AMI with or without diabetes mellitus. We evaluated glucose and insulin levels at baseline in order to estimate IR and mortality. Association between IR and mortality was assessed by means of the Cox regression analysis, and discriminative accuracy of the multivariate model with the Harrell’s C statistic. Results: In-hospital mortality was 6% (32/518 of patients). Using ROC curve, in non-diabetic patients, IR index >2.2 was the best cut-off for predicting in-hospital mortality with a sensitivity of 71% and specificity of 80% (AUC=0,710) (p=0,008). An IR>2.2 was present in 27% (140 patients) and this group had higher rates of NYHA>2, Body Mass Index ≥30, hypertension and diabetes mellitus. Harrell’s C statistic of 0.967 was obtained when an IR>2.2 was used in the model to predict mortality. Furthermore, mortality rose as IR values increased, from 3% IR 3.5. In multivariate adjusted hazard ratio analysis IR>2.2 was an independent factor for in-hospital mortality (HR=3.4; 1.2-9) (p=0.017) in addition to age >70 years (HR=3.2; 1.04-10) (p=0.04) and Killip class >1 (HR=4; 1.4-14) (p=0.012). Conclusions:Beyond traditional cardiovascular risk factors, insulin resistance as assessed by HOMA index, seems to strongly influence prognosis and could be included in the routine clinical work up of patients with acute myocardial infarction.