Current operative treatment of obstructive hypertrophic cardiomyopathy

Abstract

Operation remains an important and rational therapeutic alternative when drug therapy is unsuccessful in relieving or controlling the severe symptoms experienced by many patients with obstructive HCM. After operative relief of outflow obstruction and normalization of left ventricular systolic pressure, the vast majority of patients experience an important benefit in symptoms, functional limitation, and quality of life that are often long lasting. However, even though operation results in permanent relief of outflow obstruction, it cannot be regarded as curative because patients may ultimately develop progressive cardiac symptoms or die from their cardiomyopathy because of impaired left ventricular filling, myocardial ischemia, atrial fibrillation, ventricular arrhythmias, or other undefined components of the disease. Long-term annual mortality rate related to HCM is about 2% during an average follow-up period of 11.5 years (ranging to 25 years). The greater awareness and understanding of the morphological spectrum of HCM afforded by the application of two-dimensional echocardiography (including intraoperative imaging) has had an important impact on the operative management of patients with this disease. In particular, preoperative characterization of the distribution of ventricular septal hypertrophy before operation permits the myotomy-myectomy operation to be planned and performed so that muscle is resected only from sufficiently thickened regions of the septum, thereby minimizing the risk of iatrogenic ventricular septal defect. With these considerations in mind, those patients with particularly modest degree of septal hypertrophy (< 18 mm wall thickness) or heterogeneous patterns of septal thickening may be judged to be more appropriate candidates for mitral valve replacement than for myotomy-myectomy. Prosthetic mitral valve replacement provides hemodynamic benefits similar to myotomy-myectomy, but the long-term clinical outcome of those patients undergoing valve replacement is not yet known.