In-hospital Outcomes of Septal Myectomy Versus Alcohol Septal Ablation for Hypertrophic Cardiomyopathy with Outflow Tract Obstruction - An Update and Insights from The National Inpatient Sample from 2011-2019

Background Septal Myectomy (SM) and Alcohol Septal Ablation (ASA) improve symptoms in patients with Hypertrophic Cardiomyopathy with outflow tract obstruction (oHCM). However, outcomes data in this population is predominantly from specialized centers. Methods The National Inpatient Database was queried from 2011- 2019 for relevant ICD-9 and −10 diagnostic and procedural codes. We compared baseline characteristics and in-hospital outcomes of patients with oHCM who underwent SM vs. ASA. A p-value <0.001 was considered statistically significant. Results We identified 17,245 patients with oHCM who underwent septal reduction therapies, of whom 62.5% underwent SM, and 37.5% underwent ASA. Patients who underwent SM had higher all-cause mortality (OR:2.2 [1.7-2.9]), post-procedure ischemic stroke (OR: 2.4 [1.8-3.2]), acute kidney injury (OR: 1.9 [1.7-2.2]), vascular complications (OR: 4 [2.8-5.7]), ventricular septal defect (OR: 4.6 [3.5-6.1]), cardiogenic shock (OR: 2 [1.5-2.6]), sepsis (OR: 5.2 [3.3-8.1]), and left bundle branch block (OR: 3.2 [2.8-3.7]), compared to ASA. Patients who underwent ASA had higher post-procedure complete heart block (OR: 1.2 [1.1-1.4]), 2nd-degree AV Block (OR: 2 [1.4-3]), right bundle branch block (OR: 6.4 [5.3-7.8]), ventricular tachycardia (OR:2 [1.8-2.3]), supraventricular tachycardia (OR: 1.4 [1.2-1.7]), and more commonly required pacemaker (OR: 1.4 [1.2-1.6]) or implantable cardioverter-defibrillator insertion (OR: 1.3 [1.1-1.5]) (p<0.001 for all) compared to SM. Conclusions This nationwide analysis evidenced that patients undergoing SM had higher in-hospital mortality and periprocedural complications than ASA; however, those undergoing ASA had more post-procedure conduction abnormalities and pacemaker or ICD implantation. The implications of these findings warrant further investigation regarding patient selection strategies for these therapies.