Comparison of two- and three-dimensional transthoracic echocardiography in the assessment of trabeculations and trabecular mass in left ventricular noncompaction.

Twenty-one patients (mean age 47.5 years, 9 females) with left ventricular noncompaction (LVNC) diagnosed by both two-dimensional transthoracic echocardiography (2DTTE) and live/real time three-dimensional transthoracic echocardiography (3DTTE) were included in the study. Left ventricular (LV) mass was calculated with epicardial and endocardial border tracings first including the LV trabeculations and then excluding them. LV trabecular mass was then derived as the difference between the two measurements. This was done by 2DTTE using the modified biplane Simpson's method and by live/real time 3DTTE using the Tom Tec imaging system. The number of trabeculations arising from each segment of LV walls as well as the segmental distribution of trabeculations were also assessed by both 2DTTE and 3DTTE. The calculated LV trabecular mass by 3DTTE (mean 11.8 +/- 5.5 g) was significantly greater than 2DTTE (mean 7.3 +/- 4.3 g, P = 0.005). The total number of trabeculations assessed by 3DTTE (mean 11.2 +/- 3.3) was also significantly greater than 2DTTE (mean 3.76 +/- 1.2, P < 0.0001). The values for inter- and intraobserver variability were lower for 3DTTE than 2DTTE. In conclusion, both LV trabecular mass as well as the total number of trabeculations in patients with LVNC were significantly underestimated by 2DTTE as compared to 3DTTE.