LAUSR

BACKGROUND Left ventricular ejection fraction (EF) is the most commonly used echocardiographic measurement of LV systolic function. Myocardial contraction fraction (MCF) may be a more accurate assessment of LV systolic function than EF. Limited data are available regarding the prognostic value of MCF compared to EF in a population referred for echocardiography. OBJECTIVES To assess whether MCF was predictive of all-cause mortality in a population referred for echocardiography. METHODS All consecutive subjects undergoing echocardiography in a university-affiliated laboratory during a 5-year period were retrieved for analysis. MCF was calculated by dividing LV stroke volume (LV end diastolic volume-LV end systolic volume) by LV myocardial volume and multiplied by 100. All cause mortality was the primary endpoint. Multivariate Cox proportional hazards regression analysis was used to evaluate independent variables associated with survival. RESULTS 18,149 continuous subjects (median age 60 years, 53% male) were included. Median MCF in the cohort was 52% (interquartile range 40-64) while median EF was 64% (56-69). Any reduction in MCF from a value of 60 was significantly associated with survival on multivariable analysis. When echo parameters including EF, e:e', elevated TR gradient and significant MR were added to the model, MCF less than 50% remained significantly associated with mortality. MCF was also independently associated with both death and cardiovascular hospitalization. The AUC for MCF was .66 (95% confidence interval (CI): .65-.67) while for EF the AUC was only .58 (95% CI: .57-.59), a statistically significant difference (p < .0001). CONCLUSIONS Reduced MCF is independently associated with mortality in a large population referred for echocardiography.