An advanced form of familial hypertrophic cardiomyopathy showing massive myocardial fibrosis with intramural small arterial thickening. An autopsy case.

An autopsy case of an advanced form of hypertrophic cardiomyopathy (HCM) showing marked fibrosis with intramural small arterial abnormalities is presented in this report. A 52-year-old woman, who had a positive family history of HCM, was admitted because of palpitations. The chest roentgenogram showed a mildly enlarged cardiac silhouette and the electrocardiogram revealed abnormal Q waves and R wave and T wave abnormalities. The echocardiogram revealed hypokinesis with thinning of the interventricular septum and the anterior wall of the left ventricle. Percutaneous right ventricular endomyocardial biopsies demonstrated moderate interstitial fibrosis with small arterial thickening. At necropsy, the anterior and posterior walls of the left ventricle and the interventricular septum were markedly thinned and showed a massive transmural fibrosis. Moreover, the intramural small arteries, 50-300 microns in diameter, showed marked intimal and medial hypertrophy with proliferation of elastic fibers and smooth muscle cells. From these findings, it is suggested that this was originally a case of HCM which progressed to a decompensated stage because of the abnormal intramural small arteries. The significance of small arterial lesions in HCM is discussed.