Differentiation of hypertrophic cardiomyopathy from other forms of left ventricular hypertrophy by means of three-dimensional echocardiography.

In clinical practice, differential diagnosis among different forms of left ventricular (LV) hypertrophy is not always easy, and hypertrophic cardiomyopathy (HC) can be misdiagnosed. In this study, it was hypothesized that a 3-dimensional echocardiographically derived index of LV regional mass distribution could be useful in differentiating HC from other forms of LV hypertrophy. Sixty-eight subjects underwent 2- and 3-dimensional echocardiography; of these, 20 were healthy volunteers, 18 were top-level athletes, 15 had essential hypertension, and 15 had HC. In off-line analysis, a 12-segment model was generated for segmental mass measurement. A mass dispersion index (MDI) was calculated as the average of the SDs of segmental mass values at the basal, middle, and apical layers. The ratio of ventricular septal thickness to posterior wall thickness was also calculated using 2-dimensional echocardiography. Patients with HC had significantly higher MDI values (1.75 +/- 0.43) than healthy volunteers (0.39 +/- 0.13) (p <0.0001), athletes (0.49 +/- 0.12) (p <0.0001), and patients with hypertension (0.38 +/- 0.10) (p <0.0001). The ratio of ventricular septal thickness to posterior wall thickness was significantly higher in patients with HC (1.31 +/- 0.23) than normal subjects (1.04 +/- 0.05) (p <0.0001), highly trained athletes (1.03 +/- 0.06) (p = 0.001), and patients with hypertension (1.06 +/- 0.06) (p = 0.002). However, receiver-operating characteristic analysis showed a higher sensitivity for MDI (93.3% for the cut-off value of 1.13) than the ratio of ventricular septal thickness to posterior wall thickness (66.7% for the cut-off value of 1.20), with excellent specificity for both (100%) in identifying patients with HC. In conclusion, the 3-dimensional echocardiographically derived MDI could be considered a useful and reliable additional tool in differentiating HC from other forms of LV hypertrophy.