Risk stratification and survival in post myocardial infarction patients: a large prospective and multicenter study in Japan

Background: Recent clinical trials suggest that the mortality in high-risk patients with ischemic heart disease can be significantly reduced with the use of implantable cardioverter-defibrillator (ICD). Given the high cost and invasiveness of the procedure, it is important to apply it to the patients after myocardial infarction (MI) highly susceptible to sudden arrhythmic death. Objective: The purpose of this study was to assess clinical predictors of mortality in post-MI patients in Japan. Methods and Results: In 495 consecutive MI survivors, 350 (71%) received acute-reperfusion therapy, whereas 145 (29%) did not. Nonsustained ventricular tachycardia (NSVT) was present in 136 patients (28%) in 24-h ambulatory ECGs at 7±6 in-hospital days. Left ventricular dysfunction (LVEF≤35%) was present in 20/347 patients (5.7%) at 13±8 days. Forty-eight patients (9.7%) died during the follow-up period (48±13 months); 23 from cardiac and 25 from noncardiac causes. Kaplan–Meier survival analyses showed that mortality rates were higher among patients who were ≥70 years old (log-rank test, P<0.0001); had heart failure at admission (Killip scale≥2, P=0.001); did not receive acute-reperfusion (P=0.004); and had left ventricular dysfunction with LVEF≤35% (P=0.02). The presence of NSVT was a significant predictor of death (P=0.036) only in the patients who did not receive acute-reperfusion. Multivariate Cox regression analysis revealed that an independent predictor of total mortality was an age≥70 (odds ratio, 1.06; 95% confidence interval, 1.01–1.11; P<0.00001). Conclusions: High-risk patients after acute MI can be identified on the basis of age, ventricular dysfunction, heart failure and acute-reperfusion therapy. The presence of NSVT before discharge has a prognostic value only in the patients without acute-reperfusion.