Background: The prognostic implications of low normal left ventricular (LV) ejection fraction (EF) are not well understood in African Americans. We hypothesized that low normal LV EF (LNEF) is associated with higher incident heart failure (HF) in a community-based cohort of African Americans.
Methods and Results: We evaluated LV EF using echocardiography in 4520 African Americans (mean age 55 years, 64% women) without a history of HF and without LV wall motion abnormalities in the Jackson Heart Study. From the baseline echocardiographic examination, participants were divided into three groups; 1) Reduced EF [REF, (<50%)], 2) LNEF (>=50%, <55%), and 3) Normal EF [NEF, (>=55%)]. Proportion of each EF category was REF 5.0%, LNEF 10.1%, and NEF 84.9%. The objective of this study was to examine the association of EF categories with incident HF hospitalization. Kaplan Meier survival curves and Cox proportional hazards models were used for the analyses. The LNEF group had a larger mean LV diastolic dimension and greater mean LV mass index than the NEF group (p<0.001 for all). Diastolic dysfunction grade was more severe in the LNEF group than the NEF group (p<0.001). There were 373 cases of incident HF hospitalization over a mean follow-up of 9.2 years (range 1-12.3). The LNEF groups had higher rates of incident HF hospitalization than the NEF group (log-rank p<0.05, Figure). After adjustment for conventional risk factors, the LNEF group had a higher rate of incident HF hospitalization than the NEF group (HR 1.84, 95%CI 1.30-2.61, p<0.001).
Conclusion: LNEF, associated with larger LV diastolic dimension, greater LV mass index, and more severe diastolic dysfunction is associated with a higher rate of incident HF hospitalization in comparison with NEF in a community-based cohort of African Americans. Further investigation is warranted to determine the appropriate cut-off value of normal LV EF, particularly in African Americans.