In familial hypertrophic cardiomyopathy, QT duration was significantly increased in genetically affected subjects compared to controls (p≤0.001), even without left ventricular hypertrophy.
Observational (n=206)
Does the presence of familial hypertrophic cardiomyopathy mutations increase QT duration independently of left ventricular hypertrophy?
Prolonged QT duration in familial hypertrophic cardiomyopathy is influenced not only by the degree of left ventricular hypertrophy but also directly by the specific causative genetic mutation.
p-value: p=≤0.001
BACKGROUND: QT abnormalities have been reported in left ventricular hypertrophy and hypertrophic cardiomyopathy. OBJECTIVE: To determine the relation between left ventricular hypertrophy and increased QT interval in familial hypertrophic cardiomyopathy. METHODS: The QT interval was measured in 206 genotyped adult subjects with familial hypertrophic cardiomyopathy from 15 unrelated families carrying mutations in the beta myosin heavy chain (beta-MHC) gene (five families, n = 68) or the cardiac myosin binding protein C (MyBPC) gene (10 families, n = 138). Subjects were classified as genetically unaffected (controls, n = 112), affected with left ventricular hypertrophy (penetrants, n = 58), or affected without left ventricular hypertrophy (non-penetrants, n = 36). RESULTS: There was a significant increase in QTmax and QTmin from controls to non-penetrants and penetrants for both the MyBPC group (p < or = 0.001 and p < or = 0.001, respectively) and the beta-MHC group (p < or = 0.001 and p < or = 0.001, respectively). In the MyBPC group, the increase in the QT interval could be explained by increased left ventricular hypertrophy. In the beta-MHC group, non-penetrants had a significantly longer QTmax than controls despite the absence of left ventricular hypertrophy, and a similar QT interval to penetrants despite a lesser degree of left ventricular hypertrophy. CONCLUSIONS: In familial hypertrophic cardiomyopathy, genetically affected subjects without left ventricular hypertrophy may have a prolonged QT duration, which depends not only on the degree of left ventricular hypertrophy, when present, but also on the causative mutation.
X. Jouven (Sun,) conducted a observational in Familial hypertrophic cardiomyopathy (n=206). beta-MHC or MyBPC gene mutations vs. Genetically unaffected controls was evaluated on QTmax and QTmin (p=≤0.001). In familial hypertrophic cardiomyopathy, QT duration was significantly increased in genetically affected subjects compared to controls (p≤0.001), even without left ventricular hypertrophy.