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Grand Rounds
May 12, 1999

Advances in Molecular Genetics and Management of Hypertrophic Cardiomyopathy

Author Affiliations

Author Affiliation: Section of Clinical Electrophysiology and Inherited Cardiac Diseases, Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md.


Grand Rounds at the Clinical Center of the National Institutes of Health Section Editors: John I. Gallin, MD, the Clinical Center of the National Institutes of Health, Bethesda, Md; David S. Cooper, MD, Contributing Editor, JAMA.

JAMA. 1999;281(18):1746-1752. doi:10.1001/jama.281.18.1746

A 28-year-old woman was diagnosed as having obstructive hypertrophic cardiomyopathy (HCM) during a family screening 13 years ago. The patient was initially treated with atenolol and verapamil for chest pain, but after several years, she complained of increasing angina and dyspnea. Physical examination revealed a prominent apical impulse and a grade 2/6 precordial systolic murmur. The 12-lead electrocardiogram showed sinus rhythm at 79/min, PR interval of 205 milliseconds, normal QRS axis, and left ventricular (LV) hypertrophy plus associated ST-T wave changes. The echocardiogram showed a septal thickness of 19 mm (normal, ≤11 mm); LV free wall, 15 mm (normal, <11 mm); left atrium, 52 mm (normal, <40 mm); no systolic anterior motion of the mitral valve, but apposition of LV walls at the level of papillary muscles; mild mitral regurgitation; and predicted LV gradient of 85 mm Hg at rest. A cardiac magnetic resonance imaging study confirmed LV hypertrophy, most marked at the mid-LV cavity level, and an apical LV aneurysm. The pressures at cardiac catheterization were as follows: mean right atrium, 4 mm Hg; right ventricle, 36/4 mm Hg; pulmonary artery, 30/14 mm Hg; mean pulmonary arterial capillary wedge , 19 mm Hg; LV, 190/20 mm Hg; and aorta, 100/50 mm Hg. Hence, the intracavitary LV pressure gradient, measured at midcavity, was 90 mm Hg. Cardiac output was 4.7 L/min. An LV angiogram confirmed a diagnosis of midcavity obstructive HCM. Genetic studies showed that HCM in the patient's family is caused by an Met149Val mutation of a cardiac contractile protein called essential light chain of myosin.