Progression from hypertrophic obstructive cardiomyopathy to typical dilated cardiomyopathy-like features in the end stage.

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Abstract
An autopsied patient who had shown typical dilated cardiomyopathy (DCM)-like feature in the end stage of familial obstructive hypertrophic cardiomyopathy (HCM) is presented. The patient, a 38 yr old male, had 2 sisters with HCM. Six yr before death, echocardiogram revealed marked asymmetric septal hypertrophy (ASH) with systolic anterior motion (SAM). The ventricular septum (VS) to left ventricular posterior wall (LVPW) ratio was 19 mm/10 mm and LVEDd [left ventricular end diastolic dimension] was 47 mm. Subsequently, the signs and symptoms of congestive heart failure became progressively worse and DCM-like findings appeared insidiously. Two mo. before death, the echocardiogram revealed LV dilatation (LVEDd = 55 mm) with diffus poor contraction, no ASH (VS/LVPW = 7 mm/9 mm) and no SAM. At autopy, the heart weighted 480 g and showed dilated LV hypertrophy with normal wall thickness (VS/LVPW = 9 mm/13 mm). Massive fibrosis (30% in the VS), diffuse disarray (18% in the VS) and severe marrowing of the intramural small arteries and arterioles were found in the middle and outer thirds of the VS and the anterior LV wall. The extramural coronary arteries were not stenosed. The insidious progression from HCM to typical DCM-like feature related to the chronic progression of necrosis and massive fibrosis, due to severe stenosis of the intramural coronary artery. Patients diagnosed clinically as DCM evidently may be HCM, especially in those with family history of HCM.