Long-Term Prognosis and Risk Heterogeneity of Heart Failure Complicating Acute Myocardial Infarction

Abstract

The Killip classification of acute heart failure was developed decades ago to predict short-term mortality in patients with acute myocardial infarction (AMI). The aim of this study was to determine the long-term prognosis of acute heart failure graded according to the Killip classification in 15,235 unselected patients hospitalized for AMI from 2000 to 2005. Vital status for each patient was ascertained, through to March 1, 2012, from linkage with national death records. A stepwise gradient in the adjusted hazard ratio (HR) for 12-year mortality was observed with increasing Killip class: class I (n = 10,123), HR 1.00 (reference group); class II (n = 2,913), HR 1.13 (95% confidence interval [CI] 1.06 to 1.21); class III (n = 1,217) HR 1.49 (95% CI 1.37 to 1.62); and class IV (n = 898), HR 2.80 (95% CI 2.53 to 3.10). Unexpectedly, in a landmark analysis excluding deaths <30 days after admission, patients in Killip class IV had lower adjusted long-term mortality than those in class III. The adjusted HR for 12-year mortality comparing Killip class IV with Killip class III in patients <60 years of age was 1.71 (95% CI 1.33 to 2.19, p <0.001) and in patients >60 years of age was 2.30 (95% CI 2.07 to 2.56, p <0.001). In conclusion, on the basis of simple clinical features, the Killip classification robustly predicted 12-year mortality after AMI. The heterogeneity in early versus late risk in patients with Killip class IV heart failure underscores the importance of appropriate early treatment in cardiogenic shock.