Wall motion score index and ejection fraction for risk stratification after acute myocardial infarction

Background The prognostic importance of regional systolic function, as assessed by wall motion score index (WMSI), compared with global function, as assessed by left ventricular ejection fraction (LVEF), has not been assessed in large populations after acute myocardial infarction. Methods Echocardiograms, including the assessment of WMSI and LVEF, were performed in 767 patients with acute myocardial infarction at a median of 1 day (25th and 75th percentiles 0-2 days) after admission. Patients were followed for a median of 19 months (range 12-28 months). Cox proportional hazards models were constructed for the primary study end point (all-cause mortality) and for a secondary end point (hospitalization for congestive heart failure). Results During follow-up (median 40 months; range 32-50 months), 216 patients died and 54 patients were hospitalized for congestive heart failure. By univariate analysis, both LVEF (P < .0001) and WMSI (P < .0001) were powerful predictors of all-cause mortality. By a forward conditional Cox model, WMSI proved to be an independent predictor of death (hazard ratio 1.15 per 0.2-unit increase, 95% CI 1.10-1.21, P < .0001). When WMSI was included in the model, LVEF did not provide additional prognostic information (P = .77). Wall motion score index also proved to be an independent predictor of hospitalization for congestive heart failure (hazard ratio 1.21 per 0.2-unit increase, 95% CI 1.07-1.37, P = .002), whereas LVEF did not (P = .56). Conclusion Both LVEF and WMSI provide powerful prognostic information after acute myocardial infarction; however, the predictive power of WMSI is greater.