Abstract
To clarify the prognostic significance of electrocardiographic changes in hypertrophic cardiomyopathy, we retrospectively evaluated serial electro-cardiograms in 77 patients with hypertrophic cardiomyopathy who were followed for more than 1 year. The electrocardiographic features analyzed were conduction disturbance and left precordial QRS voltage. There were 4 sudden deaths. Various conduction disturbances appeared in 32 (44%) of the remaining 73 patients. Intraventricular conduction delay was the most common (47%). The left precordial voltage decreased in 19 (26%), increased in 3, and did not change in 51. The left ventricular end-diastolic pressure at the initial investigation was significantly higher and clinical deterioration was more frequently seen in patients with a conduction disturbance or reductions increased significantly (from 4.4±0.6 to 4.8±0.7 cm in end-diastole and from 2.6±0.6 to 3.1±0.8 cm in end-systole; p<0.01, respectively) and left ventricular fractional shortening was reduced (from 41±8 to 36±11%; p<0.01) in the 32 patients with conduction disturbance during the follow-up period although absolute cavity size remained normal in 26 of these patients. These parameters did not change in those without conduction disturbance. Histopathological analysis of endomyocardial biopsies showed that myocardial fibrosis in the left ventricle was frequently associated with these electrocardiographic changes. However, such changes were not present in the sudden death patients. It is concluded that conduction disturbance and the reduction of QRS voltage are significant parameters which suggest a poor prognosis in patients with hypertrophic cardiomyopathy, but are not predictors of sudden death.
