Abstract
BACKGROUND: Transthoracic echocardiography derived left ventricular ejection fraction (LVEF) is a cornerstone in heart failure risk prevention. However, the lower limits of normal LVEF remains imprecisely defined. We aimed to define normal LVEF ranges by sex, age group, and self-reported race/ethnicity using data from population-based echocardiographic studies. METHODS: We systematically searched MEDLINE for studies published between January 1, 2000, and January 3, 2025, that reported the mean and standard deviation of LVEF measured by 2D or 3D echocardiography in healthy, community-based adult populations. RESULTS: In 10 studies (n = 10,427; female sex, 48%), the pooled mean LVEF was 62.8% (95% confidence interval, 61.0%-64.7%), with estimated lower and upper normal limits of 51.8% and 73.2%, respectively. Women had higher mean LVEF (63.7%) than men (61.9%), with corresponding lower normal limits of 52.7% and 51.7%, respectively. LVEF was similar across age groups. Individuals of Asian origin had 2 to 3 percentage points higher LVEF than Black or White individuals, with lower normal limits of 54% for women and 53% for men. Fewer than 1% of women and approximately 1% of men would be expected to have an LVEF below 50%. Across all demographic subgroups, the probability that an LVEF < 50% is within the normal range was < 5%. There was significant heterogeneity of the included studies (e.g., τ(2) = 8.82, I(2) = 99.7% for overall analysis) that appeared unexplained by sex, age, or echocardiography modality (2D vs. 3D). CONCLUSIONS: In healthy adults, the lower limit of normal LVEF is approximately 53% for women and 52% for men, with slightly higher thresholds among individuals of Asian origin. An LVEF < 50% is highly unlikely to reflect normal function, regardless of sex, age, or self-reported race/ethnicity. Given the high statistical heterogeneity, the results should be interpreted with caution.