Author + information
- Pablo M. Ruiz Hernandez, PhD, MD,
- Gerard Loughlin, MD and
- Angel Arenal, PhD, MD∗ ()
- ↵∗Departamento de Cardiología, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Calle del Dr. Esquerdo, 46, 28007 Madrid, Spain
We read with interest the paper by Yokokawa et al. (1) and wanted to congratulate the authors for its valuable contributions. The ideal endpoint of ventricular tachycardia (VT) ablation procedures has not been definitively established (2,3). This study provides relevant data suggesting that elimination of all inducible VT could serve as a reliable endpoint. Nevertheless there are some concerns that we would like to address.
First, assumption of causality between 2 observations (i.e., persistence of inducibility and increased mortality) can only be deduced from randomized studies. In fact, it may be that post-procedure VT inducibility could simply be a marker of a worse prognosis, reflecting differences in scar extension and transmurality.
Second, the analysis is performed by comparing 2 rather artificial and unbalanced groups of patients: Patients who were noninducible post-ablation (also including in this group patients not inducible pre-ablation) with another group comprising patients who were inducible post-ablation and patients not tested for inducibility. These latter patients (who were probably sicker patients in poor clinical condition that precluded post-ablation VT induction) had an unadjusted nonsignificant trend toward increased mortality (23% excess, p = 0.28). There was a higher proportion of patients receiving amiodarone (56% vs. 37%, p < 0.0001) in the inducible group. Amiodarone is associated with increased mortality in patients in functional classes III to IV (4). An analysis focusing on comparing inducible with noninducible patients (excluding patients who were not tested) is not presented in the text nor as supplemental material and may provide a less biased comparison of both groups.
Could pursuit of this endpoint modify the outcome of the procedure? Implantable cardioverter-defibrillator shocks are associated with increased mortality. It can thus be reasoned that pursuing VT-inducibility suppression could lead to multiple VT inductions and shocks that could themselves have a negative impact on mortality. How many shocks were delivered to patients in whom VT was not suppressed? Was there a limit for VT inductions? We are concerned that patients with no endocardial substrate could receive multiple shocks in the pursuit of an unattainable objective.
In our opinion, this study does not provide sufficient evidence to support VT inducibility suppression as an end point. Such an ablation strategy could increase the risk of complications due to lengthening the procedure and the need for repeated VT induction and cardioversion (5). Randomized studies comparing complete eliminations of late potentials versus VT inducibility suppression are required to define the optimal ablation procedure.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
- Yokokawa M.,
- Kim H.M.,
- Baser K.,
- et al.
- Jaïs P.,
- Maury P.,
- Khairy P.,
- et al.