Results
We identified 4 RCTs 2–5 which included 505 patients (246 preventive ablation, 259 control) with 10,353 patient-years of follow-up. Mean age was 66.4 ± 9.0 years and 87.7% were male. The average left ventricular ejection fraction was 35 ± 9%, and time from prior myocardial infarction to randomization was 10.1 ± 9.0 years. Only 25.9% of patients were on AADs (Table 1 ).
Analysis found preventive ablation was associated with a reduced frequency of appropriate device therapies (HR=0.62; 95% CI=0.46-0.82; p<0.01; number-needed-to-treat [NNT]=7), driven largely by a significant reduction of appropriate ICD shocks (HR=0.52; 95% CI=0.36-0.75; p<0.01; NNT=8) compared with the control arm. The preventive ablation strategy was also associated with a significant reduction in frequency of sustained VT/VF (HR=0.74; 95% CI=0.55-0.99; p=0.04; NNT=11) compared to control. There were no differences in inappropriate device shocks (HR=0.80; 95% CI=0.38-1.71), any death (HR=0.93; 95% CI=0.53-1.64), cardiac death (HR=0.63; 95% CI=0.29-1.36), arrhythmic death (HR=0.26; 95% CI=0.05-1.31), or cardiac hospitalization (HR=0.79; 95% CI=0.57-1.11) between strategies (Figure 1 ). QOL was measured in 3 RCTs.2–4Preventive ablation was associated with improved SF-36 physical component (SMD=2.81; 95% CI-0.53-5.10; p=0.02), but scores were similar in the mental component (SMD=1.30; 95% CI=-2.06-4.66; p=0.45) (Figure 2 ).
There were 12 major complications (4.9% of patients) in the ablation group: tamponade in 3 (1.2%), major bleeding in 3 (1.2%), third-degree atrioventricular block in 3 (1.2%), stroke in 2 (0.8%) and cardiac perforation requiring surgical repair in 1 patient (0.4%).
Discussion
In this meta-analysis of RTCs evaluating preventative catheter ablation at time of ICD implantation for secondary prevention of VT/VF due to post-infarct cardiomyopathy, we found a significant reduction in appropriate device therapy and sustained VT/VF in patients undergoing preventative catheter ablation compared to routine care. In addition, ablation was associated with a significant improvement in the physical component of quality-of-life measures. Major complications in the ablation group were rare and there was no procedure-related mortality, indicating this strategy may have an acceptable risk profile.
Previous studies have demonstrated a significant reduction of VT recurrence with either amiodarone or catheter ablation among unselected patients (post-infarct and non-ischemic cardiomyopathy) with secondary prevention ICDs.6 However, most trials utilized catheter ablation only after multiple VT recurrences. In our investigation, the degree of reduction in appropriate ICD therapy was clinically meaningful, requiring only 7 patients undergo preemptive ablation for 1 to avoid ICD therapy. This degree of reduction, coupled with acceptable procedural safety and the benefit of avoiding the risks of chronic AADs, may confer clinically meaningful benefit. Moreover, preventative ablation produced meaningful improvements in quality-of-life, and may alleviate the debilitating effects of appropriate ICD shocks in these vulnerable patients.
Important differences between included studies exist, particularly with regard to inclusion criteria: SMS and SMASH-VT enrolled patients with unstable VT or VF, VTACH enrolled stable VT, and BERLIN VT enrolled both stable and unstable VT. Importantly, significant cross-over from the ICD alone arms to the preventive ablation arms were observed (ranging 2-22%). The first of these studies began enrollment in the year 2000,5 and the most recent one conducted enrollment in 2018.2 Thus, significant heterogeneity likely exists in mapping and ablation methods and technologies available to the investigators over this 18-year span. Furthermore, contemporary trends and guidelines likely influenced programming ICDs at higher rates and longer detection delays the more recent trials compared with the older ones.
Limitation of this study includes the relatively low number of enrolled patients and finite number of endpoints in analyzed trials. The lack of patient-level data prevents analysis of the influence of various mapping techniques, ablation strategies, device programming, and baseline AADs on the effects of preventive ablation. We hope the currently enrolling trials (PREVENTIVE VT [NCT03421834] and PAUSE-SCD [NCT02848781]) will provide further insights.