Author + information
- Takashi Kaneshiro, MD,
- Akihiko Nogami, MD∗ (, )
- Yoshiaki Kato, MD,
- Kenji Kuroki, MD,
- Yuki Komatsu, MD,
- Hiroshi Tada, MD,
- Yukio Sekiguchi, MD,
- Hitoshi Horigome, MD and
- Kazutaka Aonuma, MD
- ↵∗Department of Cardiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal arrhythmia that is characterized by bidirectional or polymorphic ventricular tachycardia (VT). CPVT leads to ventricular fibrillation (VF) and sudden cardiac death (SCD). Pharmacological therapy, including beta-blockers and flecainide, has been the first-line therapy for CPVT. For medically refractory cases, left cervical sympathetic denervation is another effective treatment option. However, several cases have been described in whom SCD was not prevented because implantable cardioverter-defibrillator (ICD) shock deliveries led to catecholamine release, which resulted in electrical storms.
Although successful catheter ablation for ventricular premature beats (VPBs) triggering VF in CPVT has been reported, the long-term efficacy of catheter ablation of trigger VPBs and complicated atrial arrhythmias has not been determined (1–3).
The present study population comprised 5 patients diagnosed with CPVT caused by a mutation of the cardiac ryanodine receptor gene (RYR2). Each study subject had experienced syncope since childhood, occurring at least once every year, up to several times per month.
We performed epinephrine stress testing to provoke bidirectional or monomorphic VPBs triggering VF and confirm that the provoked VPBs had the same morphologies as did those induced by exercise stress testing. The 9 targeted origins were located in the left anterior fascicular area (n = 2), left posterior fascicular area (n = 2), right (n = 2) and left (n = 1) ventricular outflow tract, left ventricle free wall (n = 1), and para-Hisian area (n = 1). Good activations and perfect pace matches were obtained at each origin. The mean activation time at the successful ablation sites was 40 ± 16 ms. Radiofrequency energy applications were delivered, and the targeted ventricular arrhythmias (VAs) disappeared after the transient accelerated beats. After catheter ablation, it was confirmed that all targeted VAs were not induced by exercise stress testing or epinephrine stress testing using a dose that was at least twice that which provoked the arrhythmia initially.
Catheter ablation of atrial tachyarrhythmias was performed in 2 patients with atrial fibrillation (AF). Patient 4 had AF complicated by polymorphic VT originating from the right ventricular outflow tract area. Pulmonary vein (PV) isolation was performed 1 year after the trigger VPB ablation. Patient 5 had experienced several syncope episodes due to AF with rapid ventricular response. Beta-blockers and flecainide could prevent the syncope, but symptomatic AF remained. Multiple atrial tachycardias (ATs) arose from both the left and right superior PVs and the coronary sinus ostium during isoproterenol infusion. A combination of extensive PV isolation and focal ablation of the AT at the coronary sinus ostium achieved noninducible ATs.
The outcome and clinical course of the study patients after catheter ablation (mean follow-up period: 71 ± 29 months) is shown in Table 1. Four of 5 patients experienced VA events requiring ICD or automated external defibrillator intervention. Although all patients had experienced syncope episodes at least once every year before ablation, the frequency of VA events was reduced after catheter ablation, and the mean interval between the last catheter ablation and the first VA event was 48 ± 40 months. Only 1 patient (Patient 3) experienced an electrical storm during the follow-up period. In this patient, the first event after catheter ablation was polymorphic VT, which was initiated after an inappropriate shock delivery for rapid AF. This polymorphic VT was not terminated with 9 consecutive ICD shock deliveries, and it terminated spontaneously several minutes after the shock deliveries. Therefore, this patient underwent PV isolation for AF and has not experienced ICD events for 20 months.
This is the first study to evaluate the long-term efficacy of catheter ablation of trigger VPBs and complicated atrial arrhythmias in CPVT. We could provoke multifocal VPBs triggering VF using epinephrine stress testing, and ablation for these triggering VPBs was feasible. Although VA events were not completely suppressed by ablation in 4 of 5 subjects in the long-term follow-up, these events had reduced and the mean duration from the ablation to the recurrence of VA events was approximately 4 years. Moreover, the electrical storm that occurred in 1 patient was due to an inappropriate shock for AF, and it was successfully suppressed by catheter ablation of AF. Ablation for complicated atrial arrhythmia is also beneficial in patients with CPVT.
Please note: Dr. Nogami has received endowments from Medtronic and Johnson & Johnson. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation
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