Septal Myectomy for Isolated Midventricular Obstruction After Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy

Background: Alcohol septal ablation is an alternative to surgical myectomy for septal reduction in obstructive hypertrophic cardiomyopathy, particularly in high-risk surgical patients. However, alcohol septal ablation can sometimes result in residual left ventricular obstruction, typically in the subaortic area and, much more rarely, in the midventricular region. Methods: This report presents 3 unique cases of isolated midventricular obstruction without systolic anterior motion that required surgical myectomy after alcohol septal ablation. Results: Three patients presented with persistent or recurrent symptoms of left ventricular outflow obstruction after alcohol septal ablation. Surgical myectomy, performed through a transapical approach alone or in combination with a transaortic approach, successfully reduced intracavitary gradients and septal thickness in all 3 patients. One patient underwent cardiac transplantation 2 years after septal myectomy due to diastolic heart failure without obstruction. Conclusions: This case series highlights concerns about the use of alcohol septal ablation for patients with long-segment subaortic obstruction and midventricular involvement, suggesting that surgical myectomy may be a more suitable treatment option for this anatomic subtype.