Superiority of wall motion score index over left ventricle ejection fraction in predicting cardiovascular events after an acute myocardial infarction

Abstract

Background: There are few data on the prognostic significance of the wall motion score index compared with left ventricle ejection fraction after an acute myocardial infarction. Our objective was to compare them after the hyperacute phase. Methods: Transthoracic echocardiograms were performed in 352 consecutive patients with myocardial infarction, after the first 48 hours of admission and before hospital discharge (median 56.3 hours (48.2–83.1)). We evaluated the ability of the wall motion score index and left ventricular ejection fraction to predict the combined endpoint (mortality and rehospitalization for heart failure) as a primary objective and the independent events of the combined endpoint as a secondary objective. Results: In 80.7% of patients, the wall motion score index was high despite having an ejection fraction >40%. No patient had an ejection fraction <55% with a normal index. After a follow-up of 30.5 months (24.2–49.5), both variables were predictors of the composite endpoint and all-cause mortality ( p<0.0001), although only the wall motion score index was a predictor of readmission for heart failure ( p=0.007). By multivariate analysis, a wall motion score index >1.8 proved to be the most powerful predictor of the composite endpoint (hazard ratio: 8.5; 95% confidence interval 3.7–18.8; p<0.0001). The superiority of the wall motion score index over ejection fraction was especially significant in patients with less myocardial damage (non-ST elevation myocardial infarction, or left ventricle ejection fraction >40%). Conclusions: Both variables provide important prognostic information after a myocardial infarction. Beyond the hyperacute phase, wall motion score index is a more powerful prognostic predictor, especially in subgroups with less myocardial damage.