Catheter Ablation for Refractory Ventricular Tachycardia Early After Acute Myocardial Infarction: Management, electrophysiological characteristics and outcomes.

Background and aims: Refractory ventricular tachycardia (VT) is a rare but lethal condition in the early phase of acute myocardial infarction (AMI). Its intracardiac mechanism and role of catheter ablation is under-determined. The current study is to evaluate the feasibility and safety of catheter ablation for refractory ventricular tachycardia in early AMI.

Methods: Between 2022 to 2024, 12,835 consecutive patients with AMI were screened and VT/ventricular fibrillation (VF) was developed in 261(2.0%) patients, among them 51 (19.5%) were identified as refractory VT storm necessitating intensive intervention and finally 19 patients received bailout ablation for incessant VT. Their clinical, electrophysiological characteristics and outcomes were collected and analyzed.

Results: For these 19 patients underwent rescue ablation, VT was developed at a median of 4 days after the onset of AMI and became incessant two days after the first VT occurrence, despite revascularization, antiarrhythmic agents, sedation and hemodynamic support. Through intracardiac mapping, VT were all identified as scar-related reentry within the territory of the culprit artery. The endocardial mappable cycle length was 65.3±7.6% to total cycle length. Energy delivery at the either component of critical isthmus from endocardium successfully eliminated VT and no foci trigger was observed after VT termination. Subsequent substrate modification was performed around the termination site. After the index procedure, recurrent sustained VT was documented in 2 and one patient received repeated ablation. After a total of 20 procedures, VTs were all well subsided after the index procedure in all except for one patient who died of cerebral hemorrhage. The remaining patients were discharged alive. After a median of 18-month follow-up, one patient developed recurrent VF, and no sudden cardiac death occurred.

Conclusions: Scar-related reentry is responsible for refractory VT early after AMI and ablation at critical isthmus is effective in VT suppression. Its indication and optimal timing of catheter ablation should be evaluated in prospective analysis.