Reasons for Recurrent Ventricular Tachycardia After Catheter Ablation of Post-Infarction Ventricular Tachycardia
What are the determinants of ventricular tachycardia (VT) recurrence in patients who underwent VT ablation for post-infarction VT?
Catheter ablation was performed in 98 consecutive patients (88 males [90%]; mean age 67 ± 10 years; ejection fraction 27 ±13%) with post-infarction VT. Electrograms from the implantable cardioverter-defibrillator were analyzed, and VTs were classified as clinical, nonclinical, or new clinical. Discrete variables were compared by using the Fisher exact test or by chi-square analysis, as appropriate.
A total of 725 VTs were induced during the ablation procedure. All VTs were targeted. In 76 patients, 105 clinical VTs were inducible. Critical sites were identified with entrainment mapping and pace-mapping (≥10 of 12 matching leads) for 75 of 105 clinical VTs (71%) and for 278 of 620 nonclinical VTs (45%). Post-ablation, the clinical VT was not inducible in any patient, and all VTs were rendered noninducible in 63% of the patients. Over a mean follow-up period of 35 ± 23 months, 65 of 98 patients (66%) had no recurrent VTs and 33 (34%) had VT recurrence. A new VT occurred in 26 of 33 patients (79%), and a prior clinical VT recurred in 7 patients (21%). Patients with recurrent VT had a larger scar area, as assessed by electroanatomic mapping, compared with patients without recurrent VTs (93 ± 40 cm2 vs. 69 ± 30 cm2; p = 0.002). In patients with repeat procedures, the majority of inducible VTs for which a critical area could be identified were at a distance of 6 ± 3 mm to the prior ablation lesions.
The authors concluded that most recurrent VTs were new, and the majority of these VTs were mapped to the vicinity of prior ablation lesions in patients with repeat procedures.
The current study reports that VT recurred in approximately one third of their patients and the main reason for VT recurrence was the occurrence of new VTs that were most often mapped to sites adjacent to scar from prior ablation lesions or areas that were initially not thought to contain VT circuits. Although there was no difference in mortality in this small study, it was not powered to detect a difference in mortality between patients with and without recurrence. Future studies need to assess how to minimize VT recurrences and whether avoiding recurrences may have a survival benefit.
Keywords: Body Surface Potential Mapping, Infarction, Recurrence, Tachycardia, Ventricular, Follow-Up Studies, Electrophysiologic Techniques, Cardiac, Catheter Ablation, Defibrillators, Implantable
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