Contemporary Evaluation and Management of Hypertrophic Cardiomyopathy

This discussion of the evaluation and management of hypertrophic cardiomyopathy revolves around two illustrative cases. A 42-year-old woman was referred for evaluation of progressive exertional dyspnea and fatigue over the past 2 years. Both symptoms were greatly intensified during paroxysms of atrial fibrillation, which occur every 3 or 4 months. The patient was asymptomatic until 5 years ago, when she suffered a single syncopal episode precipitated by a bout of coughing in the erect position. She subsequently experienced episodes of presyncope under similar circumstances and at increasing frequency, but she learned to abort frank syncope by immediately lying or sitting down. Examination revealed a grade 3/6 systolic murmur along the left sternal border and at the apex. The diagnosis of obstructive hypertrophic cardiomyopathy (HCM) was established by 2-dimensional and Doppler echocardiography, which showed asymmetric septal hypertrophy, a subaortic systolic pressure gradient at rest estimated at 80 mm Hg, and mild mitral regurgitation. Her symptoms did not respond to the sequential administration of atenolol, verapamil, disopyramide, or the combination of atenolol and disopyramide. Although amiodarone reduced the frequency of the paroxysms of atrial fibrillation, she has required cardioversion for individual episodes and receives warfarin. HCM has been diagnosed by echocardiography in her 20-year-old daughter; her 11- and 9-year-old sons have shown no abnormalities on clinical examination. There is no history suggestive of HCM in her deceased grandparents, her living parents, or her 5 siblings. ### Explanation of the Clinical Presentation Obstruction to left ventricular outflow occurs in approximately 25% of patients with HCM. Indeed, many of the early reports of this condition occurred in patients initially believed to have congenital or valvular subaortic stenosis.1 Studies in the early 1960s revealed that the unique feature of the obstruction in HCM is its dynamic nature.2 Conditions that reduce left ventricular volume narrow the distance between the hypertrophied …