[Prevalence and clinical significance of development of conduction disturbances in patients with hypertrophic cardiomyopathy].

To clarify the prognostic significance of electrocardiographic changes in hypertrophic cardiomyopathy, we retrospectively evaluated serial electrocardiograms of 77 patients with hypertrophic cardiomyopathy who were followed more than one year. Conduction disturbance was analyzed as an electrocardiographic feature. Excluding four cases of sudden death, various conduction disturbances developed in 32 of the 73 patients. Intraventricular conduction delay was the most frequent among them (47%). Left ventricular end-diastolic pressure at the initial investigation was significantly higher, and clinical deterioration developed more frequently in patients with conduction disturbances, as compared with those without conduction disturbances. Histopathological analyses showed that proliferation of collagen fibers in the left ventricle was frequently associated with conduction disturbances. However, the electrocardiographic changes did not develop in the four patients who died suddenly. It was concluded that conduction disturbances comprise a significant parameter suggestive of poor prognoses in patients with hypertrophic cardiomyopathy, but that they are not predictors of sudden death.