Left ventricular outflow tract obstruction as a primary phenotypic expression of hypertrophic cardiomyopathy in mutation carriers without hypertrophy

Abstract

The late and incomplete penetrance that characterizes hypertrophic cardiomyopathy (HCM), combined with the relatively low – 40–50% – yield of genetic testing, has stimulated the search for markers of early disease in “pre-hypertrophic” relatives of index patients. The main suggested aims of those markers are to identify relatives at risk of developing HCM in families where a causal mutation is not identified, or to predict the risk of developing disease in carriers of a causal mutation in a non-hypertrophic stage. The clinical value of identifying these markers remains to be validated. We describe a possible novel and clinical relevant marker of this subclinical/pre-hypertrophic stage, as we report two pathogenic mutation carriers without hypertrophy, where a significant latent left ventricular outflow tract (LVOT) gradient was identified by treadmill stress echocardiography.