Hypertrophic cardiomyopathy: genotype-positive, phenotype-"almost" negative. Diagnostic role of exercise in provocation of left ventricular outflow tract gradient.

It has been proposed to use exercise stress echocardiography in the upright position with left ventricular outflow tract gradient monitoring both during and after exercise as a marker of genotype-positive/phenotype negative hypertrophic cardiomyopathy (HCM). Doppler measurement of gradient has been a very helpful and diagnostic examination in several subgroups of subjects (especially in young persons, athletes). Recently, many noninvasive (bio)markers have been found to be very helpful in screening patients suspected of HCM before full expression of phenotype.