Severe functional limitation in patients with hypertrophic cardiomyopathy and only mild localized left ventricular hypertrophy

Ten patients with nonobstructive hypertrophic cardiomyopathy and only mild localized left ventricular hypertrophy who had severe symptoms of cardiac failure are described. During a mean follow-up period of 7 years, 6 of these 10 patients showed a substantial increase in left ventricular internal dimension (6 to 15 mm, mean 10) as assessed with M-mode echocardiography, although absolute left ventricular cavity size remained within normal limits in 5 of the 6. Four patients demonstrated substantial septal thinning (5 to 14 mm, mean 8). Left ventricular diastolic function, assessed by radionuclide angiography in nine patients, was impaired in eight who showed decreased peak filling rate (< 2.5 end-diastolic volumes/s) and prolonged time to peak rate of filling (≥ 180 ms). Furthermore, left ventricular systolic function, usually supernormal in patients with hypertrophic cardiomyopathy, was depressed (ejection fraction ≤45% I in six patients. Hence, a subset of patients was identified with nonobstructive hypertophic cardiomyopathy and only mild localized left ventricular hypertrophy who experienced severe cardiac symptoms. The majority of these patients showed both systolic and diastolic left ventricular dysfunction in the presence of a progressive increase in left ventricular internal dimension (but without absolute left ventricular dilation) or ventricular septal thinning or both. Such patients may represent an important component of the natural history of hypertrophic cardiomyopathy which has not been previously fully appreciated.