Mitral valve replacement and septal myomectomy in hypertrophic cardiomyopathy. Ten-year follow-up in 80 patients.

Between 1970 and 1980, 80 patients with hypertrophic cardiomyopathy were treated with mitral valve replacement (MVR) at our institution; 54 of these (Group 1) underwent MVR alone, and the remaining 26 (Group 2) underwent MVR plus septal myomectomy. The 1-month mortality was 7.4% for Group 1 and 7.6% for Group 2. After 10 years of follow-up, the annual mortality was 1.5% for Group 1 and 1.6% for Group 2 (this difference was not significant). Sixty-nine percent of the patients in both groups continued to experience marked symptomatic improvement. In Group 1, 96% of the patients had been assigned to New York Heart Association (NYHA) functional class III or IV before surgery; only 17% remained in these two classes postoperatively (p less than 0.01). In Group 2, 98% had been assigned to NYHA functional class III or IV before surgery, whereas only 20% remained in these two classes postoperatively (p less than 0.01). A comparison of preoperative and postoperative hemodynamic findings revealed that the left ventricular end-diastolic pressure was significantly reduced from 20 to 14 mm Hg in Group 1 and from 20 to 15 mm Hg in Group II (p less than 0.05). There was also a significant postoperative reduction in left ventricular outflow gradient at rest (from 79 to 6 mm Hg in Group 1 and from 75 to 7 mm Hg in Group 2) (p less than 0.01). These findings indicate that, in patients with hypertrophic cardiomyopathy who require surgical treatment, MVR alone or in conjunction with septal myomectomy offers significant improvement of symptoms and hemodynamic values.(ABSTRACT TRUNCATED AT 250 WORDS)