Prognostic implications of ejection fraction from linear echocardiographic dimensions: the Strong Heart Study

Abstract

Background: Although echocardiography is commonly used to assess left ventricular (LV) systolic function, few data are available concerning the prognostic significance of LV ejection fraction (EF) calculated from linear echocardiographic measurements or 2-dimensional (2-D) wall motion scores in population-based samples.

Methods: Echocardiography was used in the second Strong Heart Study (SHS) examination to calculate LV EF in 2948 American Indians without prevalent coronary heart disease; 2923 had 2-D wall motion scores.

Results: Mildly and severely reduced LV EF occurred in 10% and 2% of participants, was associated with older age, male sex, higher systolic pressure, heart rate and markers of renal disease and inflammation. During 37 +/- 9 months follow-up, cardiovascular death occurred in 2%, 5% and 12% of participants with normal, mildly reduced and severely reduced EF; all cause mortality rates were 6%, 10% and 32% (both P <.001). In Cox proportional hazards analyses, adjusting for covariates, cardiovascular death was higher with mildly reduced EF (risk ratio [RR] 2.9, 95% CI 1.6-5.4, P =.0007) and especially with severely reduced EF (RR 6.9, 95% CI 3.0-15.9, P <.0001); all-cause mortality was increased with severe LV dysfunction (RR 4.8, 95% CI 2.8-8.1, P <.001) and marginally with mildly reduced EF (odds ratio 1.4, 95% CI 0.95-2.15, P =.08). Segmental LV dysfunction and mildly and severely reduced EF from 2-D wall motion scores were associated with 3.3-fold (95% CI 1.1-9.4, P =.02), 3.5-fold (95% CI 2.1-5.8) and 3.8-fold (95% CI 1.9-7.6) (all P <.001) increased rates of cardiovascular death.

Conclusions: LV EF from linear echocardiographic measurements as well as segmental LV dysfunction and EF from 2-D wall motion scores strongly and independently predict cardiovascular mortality. Reduced EF by simple echocardiographic method has estimated population-attributable risks of about 35% for cardiovascular death and 12% for all-cause mortality in a population-based sample of middle-aged to elderly adults.