Cor Vasa 2025, 67(5):561-570 | DOI: 10.33678/cor.2025.101

Endocardial radiofrequency ablation of septal hypertrophy in the interventional treatment of the hypertrophic obstructive cardiomyopathy; comparison with the alcohol septal ablation, pilot data of the randomized trial

Katarína Doležalová^{a, b, c}, Zdeněk Stárek^{a, b, c}, Martin Pešl^{a, b, c}, Filip Souček^{a, b, c}, Jan Sitar^a, Tomáš Honěk^{a, b, c}, Jan Krejčí^{a, b, c}

^a International Clinical Research Center, St. Anne's University Hospital Brno, Brno, the Czech Republic

^b First Department of Internal Medicine/Cardioangiology, Masaryk University, St. Anne's Hospital, Brno, the Czech Republic

^c Faculty of Medicine, Masaryk University, Brno, the Czech Republic

Introduction: Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by dynamic left ventricular outflow tract (LVOT) obstruction due to asymmetric septal hypertrophy and systolic anterior motion (SAM) of the mitral valve. In patients with persistent symptoms despite optimized medical therapy, septal reduction therapy is indicated. While alcohol septal ablation (ASA) is a well-established catheter-based treatment, endocardial radiofrequency ablation of septal hypertrophy (ERASH) has recently emerged as a promising alternative. Aim of our study is to report the pilot data of the randomized study comparing efficacy and safety of ERASH versus ASA.

Methods: This single-center, prospective, randomized pilot study compared the efficacy and safety of ERASH versus ASA in symptomatic patients with obstructive HOCM refractory to medical therapy. ERASH procedure is catheter radiofrequency ablation of septal hypertrophy using contact force-sensing irrigated ablation catheters guided by 3D electroanatomical mapping with use of intracardiac echocardiography. ASA is based on injection of 96% alcohol into the septal branch of the left coronary artery to induce a small, controlled infarction of the hypertrophic septum and consequently abolishes the dynamic outflow obstruction. LVOT gradients were measured invasively at baseline and immediately post-procedure, and patients were followed at 3, 6, and 12 months for clinical and echocardiographic reassessment.

Results: Nineteen patients were randomized to undergo ERASH (n = 10) or ASA (n = 9) from May 2021 to Feb- ruary 2023. Procedural duration was significantly longer in the ERASH group (median 180 vs. 30 minutes, p <0.001), while fluoroscopy time and dose (6,24 min/11000 mGy/cm² ERASH group vs 7,18 min/11151 mGy/cm² ASA group, p = 0.391/0,967) were comparable. Both groups achieved substantial immediate reductions in LVOT gradients. In the ERASH group, resting LVOT gradient decreased from a median of 103 mmHg to 22.5 mmHg, and provocable gradient from 205 mmHg to 67 mmHg. In the ASA group, resting gra- dient decreased from 72 mmHg to 20 mmHg, and provocable gradient from 155 mmHg to 54.5 mmHg. At 12-month follow-up, resting gradients remained low (17.5 mmHg in ERASH vs. 15.5 mmHg in ASA), and NYHA functional class improved to 2.25 and 1.75, respectively. ERASH patients showed a greater improvement in 6-minute walk distance (395.9 m vs. 311.9 m, p = 0.264). Periprocedural complications were more frequent in the ERASH group, including two pericardial effusions and one permanent arioventricular (AV) block, mostly occurring in patients with pre-existing conduction disorders.

Conclusion: In this randomized pilot study, ERASH demonstrated comparable clinical and hemodynamic efficacy to ASA in reducing LVOT gradients and improving symptoms. While the complication rate was higher with ERASH, it may reflect procedural learning curve and baseline patient risk. ERASH may offer an alternative in patients with unsuitable coronary anatomy or different contraindications to ASA. Larger studies are needed to confirm these results and optimize patient selection.

Keywords: Alcohol septal ablation, Endocardial radiofrequency ablation of septal hypertrophy, Functional NYHA class improvement, Hypertrophic obstructive cardiomyopathy, Left ventricle outflow tract gradient

Received: September 18, 2025; Revised: September 18, 2025; Accepted: September 21, 2025; Prepublished online: June 2, 2012; Published: November 6, 2025  Show citation