Left ventricular function in patients with hypertrophic nonobstructive cardiomyopathy.

From 1970 to 1977 the diagnosis of hypertrophic, nonobstructive cardiomyopathy was made by clinical, echocardiographic and hemodynamic findings in 13 patients (2 females and 11 males). Echocardiography showed asymmetric septal hypertrophy in 10 of the 12 evaluated patients (83%) and symmetric hypertrophy of the septum and the posterior wall in 2 patients (17%). Systolic anterior motion of the anterior mitral leaflet was found in 5 patients (42%) although there was no obstruction of the outflow tract. Significantly higher angiographic ejection parameters were present in the 13 patients with cardiomyopathy compared to 13 control patients and the angiographic lateral wall thickness was significantly larger in patients with cardiomyopathy than in controls. The clinical course was followed during 36 mth; a stable course was found in 8 (group A) and a deterioration in 5 patients (group B). Physical working capacity and left ventricular systolic ejection fraction were significantly higher in group A than in group B. Ejection fraction in group B was similar to that of the controls whereas physical working capacity was depressed. Thus, in nonobstructive cardiomyopathy a higher than normal ejection fraction is needed to maintain a normal physical working capacity. Th increased ejection performance seems, however, not to be related to an increase in muscle fiber shortening, but can be explained by geometric reasons.