Impact of Killip classification on acute myocardial infarction: data from the SAIKUMA registry

Therapeutic devices for acute myocardial infarction (AMI) have evolved dramatically in recent years. However, the impact of the Killip classification of AMI outcomes in patients undergoing aggressive percutaneous coronary intervention remains unclear. We performed a 10-year retrospective review of 2062 patients diagnosed with AMI, and divided the data into two 5-year intervals: 2005-2009 (n = 1071), and 2010-2014 (n = 991). No difference was observed in in-hospital mortality rate between the two periods (first period, 11.5% vs second period, 9.7%; P = 0.19). The incidence of stent thrombosis was not significantly different between the two periods, and very few thrombi occurred in patients who received second-generation drug-eluting stents (DES) (0.98%: 5/511). In-hospital mortality due to stent thrombosis was high in the full cohort (15%). During the second period, in-hospital mortality was lower in Killip class 4 patients, although the difference was not significant (59.1 vs 47.5%, P = 0.07). Multivariable logistic regression identified several factors that significantly affected in-hospital mortality, including age [odds ratio (OR) 1.07], left main trunk (OR 2.47), peak CPK value above 5000 IU/L (OR 3.18), and Killip class 4 (OR 15.63). We evaluated trends in in-hospital mortality among patients with AMI over a 10-year period. New DES and the frequent use of mechanical support in patients with hemodynamic compromise tended to improve in-hospital mortality, but the effect was not significant. Notably, Killip class 4 on admission was associated with an estimated 16-fold increased risk of in-hospital death.