Septal myotomy-myectomy and transcoronary septal alcohol ablation in hypertrophic obstructive cardiomyopathy. A comparison of clinical, haemodynamic and exercise outcomes.

AIMS: Surgical myectomy has been successfully used to treat patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM). More recently, alcohol septal ablation has been advocated as a less invasive, but equally effective alternative therapy. The aim of this non-randomized cohort study was to compare subjective and objective outcomes in patients undergoing these therapies.

METHODS: Forty-four patients (25 male; age 41+/-15 years) with symptomatic drug-refractory obstructive HCM were studied. Twenty-four patients underwent surgical myectomy and 20 alcohol septal ablation. All patients underwent clinical evaluation, echocardiography and upright maximal cardiopulmonary exercise testing using a cycle ergometer before and following their intervention.

RESULTS: Peak gradient was reduced to a similar extent by both modalities (myectomy: 83+/-23 to 15+/-10 mmHg (P<0.000001); ablation: 91+/-18 to 22+/-14 mmHg (P<0.000002);P =0.48 for myectomy vs ablation) and led to similar improvements in NYHA class (myectomy: 2.4+/-0.6 to 1.5+/-0.7 (P<0.00001); ablation: 2.3+/-0.5 to 1.7+/-0.8 (P<0.0001);P=0.3 for myectomy vs ablation). Myectomy resulted in a greater improvement in peak oxygen consumption (myectomy: 16.4+/-5.8 to 23.1+/-7.1 ml.kg(-1) min(-1) (P<0.00002); ablation: 16.2+/-5.2 to 19.3+/-6.1 ml.kg(-1) min(-1) (P<0.05);P <0.05 for myectomy vs ablation) and work rate achieved (myectomy: 130+/-57 to 161+/-60 watts (P<0.04); ablation: 121+/-53 to 137+/-51 watts (P=0.11);P <0.05 for myectomy vs ablation).

CONCLUSION: Surgical myectomy and alcohol septal ablation are equally effective at reducing obstruction and subjective exercise limitation in appropriately selected patients. However, the superior effect of surgical myectomy on exercise test parameters suggests that surgery remains the gold standard against which new treatment modalities should be compared.