Post-infarct VT substrate ablation based on evoked delayed potential elimination as well-defined target: results from a prospective multicenter study

Background

In patients with VT after myocardial infarction (MI), substrate-based ablation is superior to approaches that target clinical and tolerated VTs only. Different substrate modification strategies have been reported. However, proposed ablation targets are prone to operator interpretation (e.g. abnormal electrograms). Accordingly, ablation results can also be operator dependent. Evoked delayed potentials (EDP) are a well-defined target. Elimination of EDP has been effective to prevent VT recurrence in a retrospective, single center cohort.

Aim

(1)To evaluate the outcome of EDP ablation in a prospective cohort of patients included on an intention-to-treat principle and (2)to assess the outcome of EDP ablation following one uniform protocol when performed in centers without prior experience with this strategy.

Methods

Consecutive patients referred for post-MI VT ablation were prospectively enrolled in one center with extensive experience in EDP ablation and 5 centers with no prior experience. Substrate mapping focused on EDP identification followed a uniform protocol across all centers. In brief, all electrograms located within the infarct area were analyzed during sinus rhythm, RV pacing at a fixed rate and during the application of one short-coupled RV extra-stimulus (S2). Sites showing low-voltage, nearfield electrograms with >10ms delay or block in response to S2 were categorized as EDP and targeted for ablation. After ablation, re-mapping to confirm EDP elimination and a complete stimulation protocol (up to 4 extra's from RV and LV) were performed. Patients were followed for VT recurrence and mortality.

Results

130 patients (69±10 years, 87% men, 42% anterior MI, LVEF 34% (IQR 24–43), 71% NYHA II–III, 42% on amiodarone, 52% ≥1 ICD shock, 22% with electrical storm or incessant VT) were included. The extra-stimulation protocol was systematically conducted in 127 (98%) patients and in 121 (93%), EDPs were identified. EDPs were successfully eliminated in 117/121 (97%) patients. After 23 (IQR 14–35) min of RF, 102 (78%) patients were rendered non-inducible. Median procedural duration was 212 (IQR 179–262) min. During follow-up of 14 (IQR 8–18) months, 36 (28%) patients had VT recurrence and 13 (10%) died or received a LVAD. VT-free survival was 79% (95% CI: 72–86) and 72% (95% CI: 63–80) at 6 and 12 months follow-up. Of note, VT-free survival at 12 month was not significantly different between patients undergoing the procedure in centers with and without prior experience in EDP ablation (76% (95% CI: 61–90) vs. 70% (95% CI: 59–81); P=0.269).

Conclusion

In a large prospective cohort of patients with post-MI VT, substrate ablation based on EDP elimination resulted in excellent long-term outcome. Of importance, procedural outcomes were similar in centers with or without experience in EDP ablation, indicating that this approach can be easily reproduced by operators previously not familiar with the technique.

Funding Acknowledgement

Type of funding sources: None.

Post-infarct VT substrate ablation based on evoked delayed potential elimination as well-defined target : results from a prospective multicenter study

Funding Acknowledgements

Type of funding sources: None.

Background

Substrate ablation is superior to approaches that target clinical and tolerated VTs in patients with post-myocardial infarction (MI) VT. Different substrate modification strategies have been reported. However, proposed ablation targets are prone to operator interpretation (e.g. abnormal electrograms). Accordingly, ablation results can also be operator dependent. Evoked delayed potentials (EDP) are a well-defined target. Elimination of EDP has been effective to prevent VT recurrence in a retrospective, single center cohort.

Aim

(1)To evaluate the outcome of EDP ablation in a prospective cohort of patients included on an intention-to-treat principle and (2)to assess the outcome of EDP ablation following one uniform protocol when performed in centers without prior experience with this strategy.

Methods

Consecutive patients referred for post-MI VT ablation were prospectively enrolled in one center with extensive experience in EDP ablation and 5 centers with no prior experience. Substrate mapping focused on EDP identification followed a uniform protocol across all centers. In brief, all electrograms located within the infarct area were analyzed during sinus rhythm, RV pacing at a fixed rate and during the application of one short-coupled RV extra (S2). Sites showing low-voltage, nearfield electrograms with >10ms delay or block in response to S2 were categorized as EDP and targeted for ablation. After ablation, re-mapping to confirm EDP elimination and a complete stimulation protocol (up to 4 extra’s from RV and LV) were performed.

Results

131 patients (69±10 years, 87% men, 42% anterior MI, LVEF 33±11%, 70% NYHA II-III, 43% on amiodarone, 52% ≥1 ICD shock, 34% with electrical storm or incessant VT) were included. Multipolar catheters or catheters with micro-electrodes in the tip were used in 53%. The extra-stimulation protocol was systematically conducted in 127 (97% ) patients and in 121 (92%), EDPs were identified. EDPs were successfully eliminated in 117/121 (97%) patients. After 23 (IQR 14-35) min of RF, 101 (77%) patients were rendered non-inducible. Median procedural duration was 213 (IQR 180-267) min. During follow-up of 14 (IQR 8-19) months, 36 (27%) patients had VT recurrence and 14 (11%) died or received a LVAD. VT-free survival was 78% (CI95% 71-85) and 71% (CI95% 63-80) at 6 and 12 months follow-up. Of note, VT-free survival at 12 month was not significantly different between patients undergoing the procedure in centers with and without prior experience in EDP ablation (76% (CI95% 62-90) vs. 69% (CI95% 59-80); P=0.269).

Conclusion

In a large prospective cohort of patients with post-MI VT, substrate ablation based on EDP elimination resulted in excellent long-term outcome. Of importance, procedural outcomes were similar in centers with or without experience in EDP ablation, indicating that this approach can be easily reproduced by operators previously not familiar with the technique.

Novel cryoballoon to isolate pulmonary veins in patients with paroxysmal atrial fibrillation: one-year outcomes in a multicenter study

Background

Recently, a novel cryoballoon (CB; POLARx) has been developed with increased steerability which maintains size and pressure throughout the ablation. Initial clinical data has demonstrated acute procedural safety and efficacy in de novo pulmonary vein isolation (PVI) procedures in patients with paroxysmal atrial fibrillation (AF). However, there are limited studies demonstrating the long-term efficacy of the CB.

Purpose

To evaluate the long-term safety and efficacy of the novel CB in treating paroxysmal AF.

Methods

This was a non-randomized, prospective, multi-center study. Fifty-eight consecutive patients with paroxysmal AF were enrolled at 4 centers for de novo PVI procedures. Cryoablation was delivered for 180s if time to isolation was ≤60s. Otherwise a 240s cryoablation was performed. PVI was confirmed with entrance and exit block testing. Patients were followed for 1 year with 24-hour Holter monitoring at 3, 6, and 12 months. After a 3-month blanking period, recurrence was defined as having any documented, symptomatic episode(s) of AF or atrial tachycardia.

Results

Acute isolation with the CB was achieved in 230 of 231 pulmonary veins (99.6%) with 5.2±1.5 cryoapplications per patient (1.3±0.6 cryoapplications per vein). There were 4 patients (6.9%) with phrenic nerve injury (3 resolved during the index procedure; 1 resolved at 6 months follow-up). One serious adverse device event was reported: femoral arterial embolism event occurring 2 weeks post index procedure (1.7%). Of the 56 patients that had complete 12-month follow-up, 43 (76.8%) were free from recurrent atrial arrhythmias.

Conclusion

Initial multicenter clinical experience with the novel CB has demonstrated long-term safety and efficacy of PVI in patients with paroxysmal AF. Further studies are underway to confirm these findings.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Boston Scientific