Prognosis of Low Normal Left Ventricular Ejection Fraction in an Asymptomatic Population-Based Adult Cohort: The Multiethnic Study of Atherosclerosis

Background: Reduced left ventricular systolic function predicts worse outcomes. However, the optimal threshold for "normal" left ventricular ejection fraction (LVEF) is uncertain. In general, LVEF ≥ 55% is considered to be "normal" by guidelines, with a low normal designation for LVEF being 50%-55%. We assessed the prognosis of participants with low normal LVEF in the Multiethnic Study of Atherosclerosis. All participants were asymptomatic and had no known clinical cardiovascular disease at baseline.

Methods And Results: A total of 4926 out of 6814 had LVEF assessed with the use of cardiac magnetic resonance imaging (MRI), had no significant valvular disease, did not have myocardial infarction during follow-up, had complete data, and were included in this analysis. A total of 83/4926 (1.7%) had LVEF < 50% (low LVEF) and 101/4926 (2.1%) had low normal LVEF. Cox proportional hazard and cubic spline analyses were used to evaluate the association between LVEF category and 10 years of adjudicated incident congestive heart failure (CHF) and all-cause mortality adjusting for (model 1) age, sex, and race and (model 2) model 1 and diabetes mellitus, smoking, systolic blood pressure (BP), BP medications, body mass index, estimated glomerular filtration rate, low-density lipoprotein, family history of coronary heart disease, educational status, and LV mass. Mean age was 61 ± 10 years, 47% were men, 35% were on BP medications, 9% had diabetes. After 10.2 years of follow-up, 109 (2.2%) had CHF and 427 (8.7%) died. Compared with normal LVEF (≥55%), low normal LVEF and low LVEF were associated with an increased risk for incident CHF during follow-up in our multivariable Cox models: hazard ratios (HRs) 3.64 (95% CI 1.76-7.52) and 9.52 (5.63-17.52), respectively. Unlike low LVEF, low normal LVEF was not associated with increased risk of death compared with normal LVEF in our fully adjusted models: HRs 3.03 (1.94-4.73) and 1.32 (0.72-2.41), respectively. In the adjusted spline analysis HR of LVEF 55% as reference, LVEF had a U-shape association of future CHF risk and LVEF.

Conclusion: Low normal LVEF is as prevalent as low LVEF in asymptomatic community-dwelling adults. We observed a gradient-response association between the 3 categories of LVEF (low, low normal, and normal) and incident CHF but not for all-cause death.