Echocardiographic findings late after myectomy in hypertrophic obstructive cardiomyopathy.

Postoperative echocardiograms of 50 patients undergoing myectomy for hypertrophic obstructive cardiomyopathy between 1965 and 1982 have been evaluated. In 21 patients a comparison with preoperative echocardiograms showed that postoperatively there was a significant reduction of septal and free wall thickness, an increase of left ventricular end-diastolic as well as outflow tract dimensions and a reduction or disappearance of systolic anterior motion of the mitral leaflet. Postoperative examination at intervals greater than 3 years revealed a significant increase of left ventricular and left atrial cavity size with unchanged contractile parameters and little reduction of left ventricular hypertrophy. In 4 of 12 patients evaluated greater than 8 years after myectomy, left ventricular dilatation was observed and 3 of these 4 patients developed congestive heart failure. Development of left ventricular dilatation was independent of whether a transventricular and/or transaortic approach was used for myectomy. These data indicate that the late course after myectomy in hypertrophic obstructive cardiomyopathy may be complicated by dilatation of the left ventricular cavity.