Temporal trends, patient characteristics and hospital volume outcomes after alcohol septal ablation and septal myectomy for treatment of obstructive hypertrophic cardiomyopathy
Authors: Becher P M , Weimann J , Brunner F , Zengin-Sahm E , Remmel M , Schrage B , Patten M , Detter C , Reichenspurner H , Kirchhof P , Blankenberg S , Seiffert M 
Published: November 2023

Abstract

Background
Hypertrophic obstructive cardiomyopathy (HOCM) represents a clinically and morphologically diverse hereditary cardiac disease that is frequently associated with poor prognosis. Nationwide data on septal reduction therapy (SRT), alcohol septal ablation (ASA) and septal myectomy (SM), remains scarce. The aim of this study was to investigate (i) temporal trends, (ii) patient characteristics, (iii) in-hospital outcomes, and associations between institutional procedural volumes and outcomes after ASA and SM in a large-scale nationwide cohort.

Methods
Using data from the German Federal Bureau of Statistics, this study analyzed all patients with HOCM who were hospitalized for ASA or SM in a nationwide inpatient database in Germany between January 1, 2006, through December 31, 2019. Rates of adverse in-hospital events (in-hospital mortality, need for permanent pacemaker) were examined. Multivariate logistic regression analysis was performed to compare overall outcomes after each procedure based on tertiles of hospital volumes of ASA and SM.

Results
A total of 8,514 patients underwent SRT, of whom 5,293 (62.2%) underwent ASA and 3,221 (37.8%) SM. Annual numbers for SM and ASA steadily increased over time: ASA procedures increased from 329 in 2006 to 451 in 2019 and SM procedures increased from 191 in 2006 to 222 in 2019, respectively. Patients with SM were older (mean 67.4 vs. 60.2 years), less likely female (56.4% vs. 49.9%), and had a higher burden of comorbidities (e.g., diabetes, atrial fibrillation, heart failure, chronic kidney disease) compared to patients with ASA. Over an observational period of 14 years, the majority of both ASA and SM procedures were performed at hospitals in the lowest volume category (≤20 procedures). The overall in-hospital mortality was higher in patients with SM (6.8%) compared to patients with ASA (0.8%), whereas the need for pacemaker implantation was more often observed in patients with ASA (19.3% vs. 13.1%; p&lt;0.001). The lowest tertile of SM volume among hospitals was independently associated with an increased risk of in-hospital mortality (adjusted odds ratio (lowest vs. highest tertile), 2.64; 95% confidence interval, 1.49-4.66), whereas being in the lowest vs. the highest tertile of ASA by volume was not independently associated with risk of in-hospital mortality and adverse events.

Conclusion
In this contemporary cohort with more than 8,500 cases of SRT between 2006 and 2019, the majority of SRT was performed at centers with a low volume of SM and ASA procedures. Low SM volume was independently associated with increased in-hospital mortality, whereas low ASA volume was not associated with adverse outcomes. Our findings may help to further understand how institutional SRT procedural volumes affects outcomes and might encourage referral of patients with HOCM to centers of excellence for SRT.