COMPARISON OF MYECTOMY ALONE OR IN COMBINATION WITH MITRAL-VALVE REPAIR FOR HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY

Between 1/84 and 6/91 56 patients were treated for hypertrophic obstructive cardiomyopathy (HOCM): the Morrow technique alone was performed on 40 patients (group 1), in 16 patients (group 2) an additional replacement (n = 13) or reconstruction (n = 3) of the mitral valve was indicated. In a total of 14 cases coronary artery bypass grafting and aortic valve replacement was performed in addition. Postoperatively (mean follow-up 4.2 yrs, 141 patient-years) left-ventricular diastolic and systolic function parameters, heart muscle mass, ECG findings, and symptomatology were recorded and the ratios of beta-adrenoreceptor density to density of the calcium channel were measured. Results: Pressure gradient decreased from 69.2 +/- 5.2 (group 1) and 75.1 +/- 4.8 (group 2) to 23.3 +/- 2.7 and 11.7 +/- 2.2 mmHg postoperatively. Likewise Sokolow-Lyon index decreased from 3.5 +/- 0.2/3.7 +/- 0.2 to 2.9 +/- 0.2/2.8 +/- 0.3. The quotient time-to-peak-velocity/left-ventricular-ejection-time decreased significantly in group 2 from 58.6 +/- 6.3 to 41.9 +/- 5.8 (p < 0.05). The heart muscle mass, determined echocardiographically, decreased from 680g to 430g (p < 0.05). Isovolumetric tension time, isovolumetric relaxation time, and E/A ratio at rest and after stress showed typical characteristics. Ca++-channel density was clearly raised in all patients, with no differences between the two groups being observable. We conclude from our results: - The most marked improvements in clinical and left-ventricular functional parameters were experienced by patients in group 2 (myectomy + MVR). - Myectomy alone achieved good results, but did not influence the severity of a concomitant low-grade mitral insufficiency: only in one patient of this group did we register a progression of the mitral insufficiency. - This observation allows us to conclude that deterioration in left-ventricular architecture, rather than a high intracavitary pressure gradient, is responsible for the development of mitral insufficiency in HOCM. Prognostic criteria for the development of accompanying mitral valve dysfunction could not be found. Thus, on the basis of a careful risk-benefit analysis, there appears to us to be no automatic justification for performing a combined myectomy and MVR, or MVR alone, in cases of HOCM generally.