Normal Values of Left Ventricular Mass Index Assessed by Transthoracic Three-Dimensional Echocardiography

Background: Pathologic left ventricular (LV) hypertrophy is closely coupled with adverse cardiovascular events. However, normal values of LV mass determined by three-dimensional echocardiography (3DE) have not been established in a large number of healthy subjects over a wide age range. The aims of this study were to (1) validate the accuracy of 3DE for LV mass measurements against cardiac magnetic resonance (CMR), (2) establish the normal range of LV mass index in healthy subjects, and (3) investigate the effects of age, gender, and ethnic diversity on LV mass index. Methods: In protocol 1, both transthoracic 3DE and CMR were performed on the same day in 57 patients who underwent clinically indicated CMR examinations. In protocol 2, full-volume data sets were acquired with 3DE in 390 healthy subjects. The LV endocardial and epicardial borders were semiautomatically determined at end-diastole using three-dimensional echocardiographic software. LV mass was calculated as (LV epicardial volume - LV endocardial volume) x 1.05. Results: Excellent correlation was observed between three-dimensional echocardiographic and CMR measurements of LV mass (r = 0.96). Bland-Altman analysis revealed bias of -4.8 g (-3.9% of the mean), with 95% limits of agreement of +/- 27.7 g. Normal values of LV mass indexed to body surface area were found to be 70 +/- 9 g/m(2) in men and 61 +/- 8 g/m(2) in women. Significant age and gender dependence, but no racial dependence, was observed for LV mass index. Conclusions: Three-dimensional echocardiography is an accurate method for measuring LV mass. Age and gender dependence, but no ethnic dependence, of LV mass index was observed in Japanese and American populations. The reported normal reference values of 3DE-determined LV mass index according to age and gender could potentially be useful for diagnosing LV hypertrophy with excellent accuracy.