One hundred and thiry-four patients with hypertrophic cardiomyopathy were evaluated by standard 12-lead electrocardiography. Normal electrocardiograms were extremely uncommon, occurring in less than 7% of each subgroup of patients (i.e., those with or without either symptoms or obstruction to left ventricular outflow), with the exception of those who were both asymptomatic and had no left ventricular outflow obstruction. Even in this subgroup, however, normal electrocardiograms occurred in only 27% of patients. Repolarization abnormalities and left ventricular hypertrophy were the most common abnormalities, occurring in 81% and 62%, respectively, of the total population. A broad spectrum of other electrocardiographic abnormalities was found, but none was unique to hypertrophic cardiomyopathy. Patients with vs those without electrocardiographic left ventricular hypertrophy or left atrial abnormality had significantly (P less than 0.005) greater mean ventricular septal thickness (22 +/- 0.6 vs 19 +/- 0.6 mm) and left atrial dimension (48 +/- 1 vs 40 +/- 1 mm) measured by echocardiography, and signficantly (P less than 0.01) higher mean pulmonary capillary wedge pressure (16 +/- 1 vs 10 +/- 1 mm Hg) and left ventricular end-diastolic pressure (20 +/- 1 vs 15 +/- 1 mm Hg). The high prevalence and diverse nature of electrocardiographic abnormalities suggest that any patient with an unusual and unexplained electrocardiogram should be suspected of having hypertrophic cardiomyopathy even if the physical examination is normal, as is often the case in patients without obstruction.
SUMMARY Many patients with hypertrophic cardiomyopathy die suddenly and unexpectedly, a significant number perhaps due to arrhythmia. Of 100 patients initially evaluated for signs or symptoms suggestive of heart disease or a family history of hypertrophic cardiomyopathy, 51 were selected solely because they met the echocardiographic criteria for the disease, and 49 patients were selected primarily because they had: 1) normal sinus rhythm despite left atrial enlargement, 2) a history of syncope, 3) a family history of premature death, or 4) a history of paroxysmal atrial fibrillation. All 100 patients were studied by 24-hour ambulatory electrocardiographic monitoring and 74 of them also underwent treadmill exercise testing. More than 50% of patients in all subgroups (with or without symptoms or left ventricular outflow tract obstruction) had multiform or repetitive ventricular premature depolarizations, including 19% who had ventricular tachycardia. Monitoring was superior to exercise testing for exposing these arrhythmias. Two patients experienced cardiac arrest within 2 months of monitoring; in each, monitoring had revealed ventricular tachycardia. Two patients with paroxysms of supraventricular tachycardia during monitoring developed fixed atrial fibrillation within 1 year. These preliminary observations suggest that monitoring may help identify patients at increased risk for significant arrhythmic events.MANY SYMPTOMATIC PATIENTS with hypertrophic cardiomyopathy die suddenly and unexpectedly during the course of their disease.'`' We have identified several people with hypertrophic cardiomyopathy in whom sudden death was the initial manifestation of disease.5 Despite the clinical importance of this problem and the likelihood that many of these sudden deaths are arrhythmic in origin,6 surprisingly little is known about the propensity of patients with hypertrophic cardiomyopathy to develop arrhythmias.In the present investigation we used 24-hour ambulatory electrocardiographic monitoring and treadmill exercise testing to examine the frequency and types of arrhythmias that occur in a large population of patients with hypertrophic cardiomyopathy. We sought to determine whether subgroups of patients with this disease are particularly susceptible to the development of arrhythmias. We also compared the sensitivity of 24-hour ambulatory electrocardiographic monitoring with that of treadmill exercise testing in detecting arrhythmias. Finally, we made a preliminary attempt to determine whether any electrocardiographic findings were predictive of subsequent mortality.From the Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20014. Presented in part at the 50th Annual Scientific Sessions, American Heart Association, Miami Beach, Florida, November,
Methods Patient PopulationOne hundred patients with hypertrophic cardiomyopathy (asymmetric septal hypertrophy (ASH)) were studied after informed consent was secured. ASH was defined echocardiographically by a ven...
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