Catheter Ablation for Ischemic Ventricular Tachycardia
February 1, 2025 4 minutes read
By Michael H. Crawford, MD, Editor
Synopsis: A multicenter, randomized trial of initial catheter ablation vs. antiarrhythmic drug therapy for ventricular tachycardia in ischemic cardiomyopathy patients with an implantable cardioverter defibrillator resulted in fewer subsequent ventricular tachycardia episodes with ablation.
Source: Sapp JL, Tang ASL, Parkash R, et al. Catheter ablation or antiarrhythmic drugs for ventricular tachycardia. N Engl J Med. 2024; Nov 16. doi: 10.1056/NEJMoa2409501. [Online ahead of print].
Two strategies have been employed to prevent ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM): antiarrhythmic drug therapy (ADT) and catheter ablation (CA). The Antiarrhythmics or Ablation in Ischemic Heart Disease (VANISH) trial showed that continuation of ADT therapy plus CA was associated with better outcomes than escalation of ADT alone. The VANISH II trial was designed to compare CA to ADT as first-line therapy for patients with ICM, an implantable cardioverter defibrillator (ICD), and VT.
VANISH II was a multicenter, open-label, randomized trial with blinded adjudication of endpoint events at 22 centers in Canada, the United States, and France. Patients with a history of myocardial infarction (MI) who had at least one of the following VT events in the last six months without ADT were recruited: sustained monomorphic VT terminated by ADT or electrical cardioversion; three or more episodes, including one symptomatic episode, of VT treated with antitachycardia pacing by an ICD; five or more episodes of monomorphic VT regardless of symptoms; one or more appropriate ICD shocks; or three episodes of sustained VT within 24 hours.
The trial continued until the last patient had been followed for two years. The primary endpoint was a composite of death from any cause more than 14 days after randomization, appropriate ICD shock, VT storm (at least three VT events within 24 hours), or treated sustained VT below the detection limit of the ICD.
Safety endpoints included serious adverse events, such as those leading to cardiovascular (CV) death and hospitalization for CV causes, and ADT-related adverse events, such as thyroid or liver dysfunction that led to drug discontinuation or dose reductions.
From 2016 to 2022, a total of 416 patients were randomized: 203 in the CA group and 213 in the ADT group. CA was accomplished in 200 of the 203 patients randomized to CA. After a 4.3-year median follow-up, the primary endpoint occurred in 103 patients (51%) in the CA group and 129 (61%) in the ADT group (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.58-0.97; P = 0.03). The individual components of the primary endpoint were not significantly different.
Serious non-fatal adverse events (AE) were similar in the two groups: 28% in the CA patients and 31% in the ADT group. During the trial, 63 patients in the ADT group had a CA performed. In the total of 263 patients who had CA, there were two deaths, two strokes, and one cardiac perforation. Among the ADT-treated patients, one patient died as the result of pulmonary toxicity and seven patients had infiltrations or lung fibrosis on imaging. The authors concluded that an initial strategy of CA resulted in a lower incidence of the composite primary endpoint of appropriate ICD shocks, VT storm, or treated VT below the limit of the ICD compared to ADT in patients with ICM and VT.
Commentary
This is an important study in a group of patients with a high risk of death. In fact, all-cause mortality was rather high in this study in both groups: 22% in the CA group and 25% in the ADT group (P = NS). Also, appropriate ICD shocks (30% vs. 38%, P = NS) and VT storm (22% vs. 24%, P = NS) were frequent. These findings highlight that VT is associated with worse outcomes despite the presence of an ICD.
Selecting the ideal therapy for VT in patients with ICM is important because both approaches have AE and imperfect efficacy. The usual practice is to start with ADT and, if it fails, move to CA because of the perceived higher incidence of AE with the CA procedure. In VANISH II, the incidence of serious AE was not significantly different between the CA and ADT groups. However, this does not consider the 25 patients in the ADT group who had amiodarone dosage adjustments or discontinuation as the result of AE. Also, amiodarone has potential long-term AE that could occur at later times than included in this study.
There are limitations to VANISH II. In the ADT group, 63 patients crossed over to CA during follow-up. Also, this was not designed or powered for a mortality endpoint. ICD shocks for VT below the programmed rate cutoff potentially could have been reduced by better programming. In addition, the primary outcome difference is not large. My take is that VANISH II shows that initial CA for VT in ICM patients can be appropriate in selected patients where the potential benefits would appear to outweigh the risks.
Michael H. Crawford, MD, is Professor of Medicine and Consulting Cardiologist, University of California Health, San Francisco.
A multicenter, randomized trial of initial catheter ablation vs. antiarrhythmic drug therapy for ventricular tachycardia in ischemic cardiomyopathy patients with an implantable cardioverter defibrillator resulted in fewer subsequent ventricular tachycardia episodes with ablation.
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