Reference Values for Real Time Three-Dimensional Echocardiography-Derived Left Ventricular Volumes and Ejection Fraction: Review and Meta-Analysis of Currently Available Studies

Current guidelines recommend three-dimensional echocardiography (3DE) as the reference technique to assess left ventricular (LV) volumes and ejection fraction (EF). We performed a metaanalysis to identify normative reference values by real time 3DE in healthy subjects. Methods: We searched MEDLINE and the Cochrane Library databases using the key search terms three-dimensional echocardiography, volumes, and healthy. Data were pooled using random-effects meta-analysis, and source of variation was investigated using meta-regression. After selection, 13 articles were included (2806 subjects). Four studies were conducted in children and young adolescents; one study provided data in an independent pediatric subgroup. Results: In adults, pooled mean value for LV EDV was 98.4 mL (95%CI, 87–110 mL), while LV ESV mean value was 37.0 mL (95%CI, 32–42 mL). LV EF mean value was 62.9% (95%CI 61.7–64.2%). Male subjects showed a significant increase in both LV EDV index (mean difference 5.3 mL/m2; P < 0.001) and LV ESV index (mean difference 3.3 mL/m2; P < 0.001). LV EF was significantly higher in female subjects (P = 0.003). In pediatric studies, LV EDV pooled mean value was 53.1 mL (95%CI, 38.1–68 mL), while for LV ESV, it was 19.8 mL (95%CI, 14.8–24.8 mL); LV EF mean value was 63.3% (95%CI, 61.6–65%). Significant heterogeneity and inconsistency were noted among studies. Age, systolic blood pressure, and heart rate were identified as a source of between-studies variation for LV volumes. Body surface area was a predictor of nonindexed LV volumes. Conclusions: Data from available studies of normative values for 3DE were summarized. Our findings may increase the generalizability of LV normative data by 3DE.