Background: The natural history of Hypertrophic Obstructive Cardiomyopathy (HOCM), is well known from earlier investigations. The yearly death rate of medically or non-treated patients with HOCM is between 1.7% and 4%. After conservative management with beta-blockers and/or calcium antagonist, early improvement is followed in many patients by a symptomatic and clinical impairment, which today may lead to surgical or interventional treatment.
Methods: From 1963 to 12/1998 a total of 519 patients were operated by transaortic subvalvular myectomy (TSM). The mean age was 49 +/- 11 years (range 3 months - 82 years) in 292 males and 227 females.
Results: The early risk was related to the clinical class (NYHA) and the need for additional cardiac procedures during the same intervention. Total early mortality was 4.4% (n=23), in isolated myectomy 3.6% (n= 11). During the last 10 years it could be reduced to 1.9%. The first complete (100%) reinvestigation of 346 patients up to 26 years after surgery (1963-1991) demonstrated a disease-related mortality rate of 5.2% (n=20). The analysis of late deaths showed that disease-related lethal complications (sudden death, life-threatening arrhythmias, valve endocarditis, secondary LV dilatation) were relatively rare, the age-related death rate nearly followed the natural course because of other causes. The cumulative survival rate after 10 years was 88%, after 20-26 years 72%. The yearly disease-related death rate could be reduced to 0.6%. The long-lasting, symptomatic clinical improvement (NYHA I-II), and also the physical and mental capacity with enlargement of the acitivity radius and improvement of quality of life were remarkable. The positive effects of surgical enlargement of the LVOT could be confirmed in the meantime by hemodynamic, rhythmological, echocardiographic investigations as well as endurance tests.
Conclusion: We have examined the outcome of a large series of patients treated surgically for HOCM since 1963. The majority of patients were in NYHA class III and came to surgery after long-term medical, but finally insufficient, management. The perioperative risk could be reduced considerably during recent years, despite the advanced cardiomyopathy status. The long-term postoperative observation of the patients demonstrated an unexpectedly continuing good outcome. Therefore these results may serve as a standard for assessing the results after the less invasive alcohol-induced transcoronary ablation of septal hypertrophy.