1030-10 The Severity of Left Ventricular Hypertrophy is Greater in Patients with Hypertrophic Cardiomyopathy Due to Malignant Mutations

Abstract

Genotype-phenotype correlation studies have shown that β myosin heavy chain ( β MHC) mutations are determinants of frognosis in patients with hypertrophic cardiomyopathy (HCM). While Arg 719 Trp mutation is associated with a high incidence of sudden cardiac death (SCD) and an average life expectancy of 38 years, the Val 606 Met mutation is associated with a near normal life expectancy in the families studied here. However, it is unknown whether the prognostic significance of HCM mutations correlates with the degree of left ventricular hypertrophy (LVH) associated with each mutation. Accordingly, we determined the left ventricular mass index (LVMI) and the extent of LVH in 12 patients with the Arg 719 Trp mutation and five patients with the Val 606 Met mutation. Left ventricular mass was derived by the arealength method using 2-D echocardiograms and indexed for body surface area (BSA). Extent of LVH was determined using a semi-quantitative point score method that takes into account the extent of involvement of the septum, apex, and lateral wall of the left ventricle. The mean LVMI was 147.0 ± 36 g/m 2 in patients with the Arg 719 Trp mutation and 111.7 ± 19 g/m 2 in patients with the Val606 Met mutation (p = 0.020). Similarly the extent of hypertrophywas greater in patients with the Arg 719 Trp mutation than in those with the Val 606 Met mutation (5.92 ± 2.3 vs. 3.2 ± 1.5, respectively, p = 0.015). The mean septal thickness was also greater in patients with the Arg 719 Trp mutation than in those with the Val60 Met mutation, however, this was not statistically significant (2.03 ± 0.7 vs. 1.62 ± 0.26, p = 0.095). There was no difference in the mean BSA, age, or gender among the two groups of patients. In conclusion, HCM patients, due to a malignant mutation such as the Arg 719 Trp, have greater LVH than patients with a benign mutation such as the VaI 606 Met. These results indicate the grave prognosis of HCM mutations are associated with expression of greater hypertrophy. This provides an easily detectable clinical parameter to further stratify patients at risk of sudden death that are candidates for invasive interventions such as implantation of cardiac defibrillators.