Clinical and hemodynamic results after mitral valve replacement in patients with obstructive hypertrophic cardiomyopathy.

Mitral valve replacement has been performed in patients with obstructive hypertrophic cardiomyopathy if: (1) the interventricular septum is smaller than 18 mm in the region of usual resection; (2) atypical septal morphology is encountered; (3) a previous left ventricular myomectomy has been performed but residual major obstruction and symptoms persist; or (4) intrinsic mitral valve disease exists. Since 1983, mitral valve replacement has been performed in 58 patients with obstructive HCM only. Thirty-three female patients (mean age, 47.9 years) and 25 men (mean age, 45.7 years) met criteria 1 through 3 for mitral valve replacement. Patients with intrinsic mitral valve disease (criterion 4) were omitted from this study. All patients were in New York Heart Association functional class III or IV and had failed optimal medical therapy. Low-profile mechanical prostheses and bioprostheses were implanted, and the early mortality (less than 30 days or in the hospital) was 8.6% (5/58). Six patients (11.3%) died late, 3 suddenly of probably arrhythmia, 2 of respiratory failure, and 1 of an anticoagulant-related complication. After mitral valve replacement, 40 (83%) of 48 patients surviving operation and returning for evaluation were in functional class I or II, whereas 8 patients were in functional class III. Hemodynamic data obtained 6 months postoperatively showed that pulmonary artery wedge pressure was normal (13.7 +/- 4 mm Hg [+/- standard deviation]), left ventricular end-diastolic pressure had decreased (10.9 +/- 3.4 mm Hg), cardiac index was maintained (2.6 +/- 0.6 L/min/m2), and resting and provoked gradients were unremarkable. Mean follow-up was 24.2 months, actuarial survival was 86% at 3 years, and survival free from thromboembolism, anticoagulant-related complication, reoperation, and congestive heart failure for the same interval was 68%. Complications such as ventricular septal defect and complete heart block are avoided in patients undergoing mitral valve replacement, but device-related and cardiac-related complications can add to the morbidity and mortality in these patients in the long term.