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.