Catheter ablation as first line treatment in patients with ischemic cardiomyopathy, tolerated ventricular tachycardia and left ventricular ejection fraction over 35%: long term outcomes
Authors: Rademaker R , Riva Silva M , Kimura Y , Piers S R D , Wijnmaalen A P , Zeppenfeld K 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
Patients with ischemic cardiomyopathy (ICM) and monomorphic, sustained ventricular tachycardia (VT) are considered to be at risk for arrhythmia-related sudden cardiac death (SCD). Prior studies have suggested that patients with well-tolerated VTs and preserved or moderately reduced left ventricular ejection fraction (LVEF) and successful VT ablation may not benefit from cardioverter defibrillator implantation (ICD Current guidelines indicate that in selected patients catheter ablation should be considered instead of ICD, but supporting evidence is limited.

Aim
This study aims to analyze arrhythmia outcomes of ICM patients referred for VT ablation without prior ICD implantation according to LVEF, hemodynamical stability during VT and ablation outcome.

Methods
ICM patients without prior ICD implantation undergoing VT ablation in a tertiary center between 2009 and 2022 were included. Patients who presented with a first episode of tolerated VT and w a LVEF≥35% were offered catheter ablation (CA) as first-line therapy. Patients were categorized according to (1) LVEF, (2) clinical presentation (hemodynamically tolerated/non-tolerated VT) and (3) acute ablation outcome. According to the institutional protocol, ICD was offered to all patients after ablation, but was subject to shared decision making, explaining the available evidence supporting ICDs for the different categories.

Results
Eighty-six ICM patients without ICD underwent ablation for VT. Mean age was 69±9 years and 72 (84%) were men, mean LVEF was 41±9% and 34 patients (28%) were using anti-arrhythmic drugs (AAD). The median VT cycle length (VTCL) at presentation was 323ms [300 – 375] and VT was tolerated in 58 (67%) patients (median tolerated VTCL 325ms [300 – 371]). In 66 (77%) patients, the LVEF was ≥35% of which 51 had well-tolerated VT. Of these 51 patients, 37 (73%) were rendered non-inducible after ablation and in 14 patients non-clinical VTs remained inducible (median remaining VTCL 238ms [203-288]). In 5/37 non-inducible and in 11/14 inducible patients, an ICD was implanted. Of the 35 patients who had LVEF&lt;35% and/or non-tolerated VTs, 7 refused ICD implantation. (Figure 1)
During a median follow-up of 35 [22 – 53] months, 10 patients (12%) had VT-recurrence and one patient with an ICD had SCD. Mortality was 22%. In the 37 patients with LVEF≥35%, tolerated VT and non-inducibility post procedure, no SCD or VT-recurrence was observed. Also, in this group no patient was using AAD for VT at last follow-up. In the 14 remaining patients with LVEF≥35% and tolerated VT who were still inducible after ablation, no SCD occurred but VT recurred in 29% (median VTCL 303ms [200-374]) with AAD-use for VT in 29%.

Conclusion
This study supports that ICM patients without prior ICD and LVEF≥35% who present with hemodynamically well-tolerated VT and are non-inducible after ablation have an excellent prognosis. Successful CA without ICD implantation seems to be safe in these selected patients.