Outcomes of simultaneous unipolar radiofrequency catheter ablation for intramural septal ventricular tachycardia in nonischemic cardiomyopathy

Abstract

Background: Radiofrequency (RF) ablation of intramural septal ventricular tachycardia (VT) in patients with nonischemic cardiomyopathy (NICM) is challenging.

Objective: The purpose of this study was to investigate the outcomes of simultaneous unipolar RF ablation for intramural septal VT in NICM.

Methods: We included patients with NICM and mid-myocardial septal substrate referred for VT ablation. After failed prolonged sequential unipolar RF lesions, simultaneous unipolar RF was delivered using 2 open-irrigated catheters at the site of earliest activation and/or best entrainment or pace mapping and at an anatomically adjacent/opposite site (up to 40 W for up to 3 minutes; RF energy independently titrated for each catheter to achieve an impedance drop of at least 15% from the baseline values).

Results: A total of 6 patients (mean age 62±13 years; mean left ventricular ejection fraction 38%±17%) were included. The clinical VTs were mapped at the anterior interventricular septum in 2 (33%) patients and at the inferior septum in 4 (67%). In all patients, prolonged sequential unipolar RF at the best activation/entrainment/pace-mapping site and at an anatomically opposite/adjacent site failed to eliminate VT. In 3 cases (50%), late VT termination with VT reinducibility was observed after sequential unipolar RF. Simultaneous unipolar ablation was then delivered, resulting in VT elimination and noninducibility in all patients. No procedural complications and no steam pops were observed. After a median follow-up of 20 months (range 13-20 months), 4 patients (67%) remained free of VT recurrence.

Conclusion: In patients with NICM and intramural septal VT refractory to conventional RF ablation, simultaneous unipolar RF ablation is a safe and effective alternative ablation approach to improve long-term VT control.

Keywords: Catheter ablation; Nonischemic cardiomyopathy; Septal substrate; Simultaneous unipolar ablation; Ventricular tachycardia.