Early vs. deferred catheter ablation of ventricular tachycardia in patients of ischaemic substrate: systematic review and meta-analysis of clinical outcomes

Abstract

Aims: Ventricular tachycardia (VT) ablation has been shown to reduce the recurrence of VT episodes, but the timing of performing VT ablation (early; at the time of implantable cardioverter defibrillator implantation) or (deferred: after the patient has received ICD shocks) remains controversial. The objective is to conduct a systematic review and meta-analysis of published data from randomized controlled trials (RCTs) in patients with ischaemic cardiomyopathy (ICM) with the aim of comparing outcome of VT ablation stratified by procedural timing.

Methods and results: We conducted a meta-analysis of seven landmark RCTs which included patients with ICM who were either at a high risk of VT or experienced VT/ICD shocks. The primary outcome of VT recurrence was compared according to the timing of performing VT ablation (early vs. deferred). In addition, we also compared the secondary outcome of cardiac mortality. Following a comprehensive search strategy, a total of seven RCTs were included within the final analysis. Based on a pooled analysis, early VT ablation was associated with a significant reduction in the primary outcome [pooled odds ratio (OR) of 0.72, 95% confidence interval (CI): 0.55-0.95, P < 0.05] in comparison with a 'deferred VT ablation' strategy. The cumulative absolute risk reduction (ARR) for the primary outcome was 0.21, and number needed to treat (NNT) to prevent the outcome of VT recurrence was 4.81. Furthermore, the effect size of early VT ablation compared to a deferred VT ablation approach was more pronounced in reduction of ICD shocks in the subgroup of patients with LVEF > 30% vs. those with LVEF < 30% (pooled OR of 0.65, 95% CI of 0.54-0.79, P = 0.01). For the secondary outcomes, we observed that an earlier timing of VT ablation was also associated with both a decrease in cardiac mortality (pooled OR of 0.59, 95% CI of 0.43-0.82) and in the subsequent risk of VT storm (pooled OR of 0.63, 95% CI of 0.51-0.78) when compared with a deferred timing. The cumulative ARR for cardiac mortality was 0.07 and NNT was 15.

Conclusion: The findings from this pooled analysis of seven major RCTs suggest that performing early VT ablation may be beneficial in reducing recurrent VT, ICD shocks, and electrical storm and could also improve cardiac mortality. The benefit of performing early VT ablation was greater in patients with LVEF of >30% amongst this ICM cohort.

Keywords: Catheter ablation; Ventricular tachycardia.

Figure 1

PRISMA flow chart for study selection in our meta-analysis.

Figure 2

Forest plots comparing pooled odds ratios for recurrent ventricular tachycardia/VF (A) and ventricular tachycardia storm (B), cardiac mortality (C) between preventive vs. deferred ablation in patients with ventricular tachycardia.

Figure 3

Forest plots comparing pooled odds for the outcome of ICD shocks in the overall population (A) and then in the subgroup of patients with left ventricular ejection fraction of >30% (B) vs. those with left ventricular ejection fraction of <30% between early vs. deferred ventricular tachycardia ablation (C).

Figure 4

Funnel plot for assessment of publication bias in RCTs comparing preventive vs. deferred ablation for ventricular tachycardia. The plot displays the log odds ratios on the x-axis and standard errors on the y-axis. Each ‘X’ represents a single RCT, while the dashed line denotes the symmetry line, indicating where studies would align if no bias were present.