Clinical Outcomes Following Alcohol Septal Ablation vs Septal Myectomy

Alcohol septal ablation is associated with less left ventricular outflow tract (LVOT) pressure gradient reduction, significant increases in reoperation rates and permanent pacemaker implantations, and higher long-term mortality within at least 5 years of follow-up, according to findings published in the European Journal of Cardio-Thoracic Surgery.

Investigators sought to determine the optimal septal reduction therapy (alcohol septal ablation vs septal myectomy) for obstructive hypertrophic cardiomyopathy (HCM). All-cause mortality in studies with at least 1 year of follow-up was the primary outcome. Reoperations of LVOT and LVOT pressure gradient reduction were the secondary outcomes.

They conducted a meta-analysis of 27 observational studies (N=15,968 patients) identified by 2 independent investigators in the Cochrane CENTRAL, EMBASE, and MEDLINE databases from inception through mid-January 2023. Studies in which patients with obstructive HCM received alcohol septal ablation (n=6636) or septal myectomy (n=9332) were included. All of the included studies had low risk of bias determined by the Newcastle-Ottawa Scale for observational studies, and funnel plots showed no evidence of publication bias.

At baseline, proportions of concomitant systolic anterior motion and mitral regurgitation were similar between groups, as were rates of diabetes mellitus, syncope, and hypertension. Patients receiving alcohol septal ablation were older than patients in the septal myectomy group (weighted mean difference, 4.86 years; 95% CI, 2.47-7.24; P <.01). The alcohol septal ablation group vs the septal myectomy group had lower baseline septal thickness (weighted mean difference [MD], -0.74 mm Hg; 95% CI, -1.45 to -0.02; P =.04; I²=62%). Between-group preprocedural LVOT pressure gradients were similar.

Analysis showed similar all-cause mortality rates (hazard ratio [HR], 1.24; 95% CI, 0.88-1.76; P =.21; I²=56%). The alcohol septal ablation group compared with the septal myectomy group had a significantly higher rate of permanent pacemaker implantations (HR, 1.68; 95% CI, 1.28-2.20; P =.0002; I²=35%).

Alcohol septal ablation was associated with a higher reoperation rate (HR, 9.14; 95% CI, 6.55-12.75; P <.001; I²=0%) and less reduction of LVOT pressure gradient (weighted MD, 11.04 mm Hg; 95% CI, 5.60-16.48; P <.01; I²=64%). In subgroup analysis there was higher long-term mortality in the alcohol septal ablation group (HR, 1.50; 95% CI, 1.04-2.15; P =.03; I²=52%) during follow-up of at least 5 years. Both groups had similar 30-day mortality rates and cardiovascular mortality rates. The alcohol septal ablation group had less reduction of LVOT pressure gradients and higher postprocedural LVOT pressure gradients. The 2 groups had similar rates of stroke and the rate of rehospitalization due to heart failure showed no significant between-group difference.

Significant study limitations include the secondary outcomes and subgroup analyses being exploratory only.

“…ASA [alcohol septal ablation] was associated with a significant increase in permanent pacemaker implantations and reoperation rates, and less LVOT PG [pressure gradient] reduction,” the study authors wrote. “Long-term mortality with the data of 5 years [or longer] showed favorable outcome with SM [septal myectomy], although the results from the subgroup analysis and secondary outcomes are exploratory results.”