Introduction: High-density (HD) mapping with multipolar catheter for ventricular arrhythmias with structural heart disease is well described. However, evidence of its efficacy in ablation of outflow tract (OT) origin premature ventricular contractions (PVC) is lacking. This study aims to: 1) compare procedural and clinical outcomes of point-by-point (PBP) mapping against HD mapping in patients undergoing OT PVC ablation; and 2) identify potential predictors for favourable outcome in patients undergoing OT PVC ablations.
Methods: This single-centre study enrolled consecutive patients indicated for symptomatic OT PVC ablation between April 2016 and April 2021. Patients requiring epicardial ablations were excluded. Use of HD mapping catheter was at the operator’s discretion. Pre-and post-ablation PVC burden was assessed using a 12-lead Holter monitor. Potential demographic, clinical and procedural predictors of arrhythmia-free survival were assessed. Kaplan–Meier and Cox regression analyses were performed.
Results: Seventy-nine patients (mean age 49 ± 17 years, 39% males, left ventricular ejection fraction 52 ± 10%) underwent successful endocardial ablations for PVCs from right ventricular OT (RVOT, n=64) or left ventricular OT (LVOT, n=15). One patient required ablation from both RVOT and LVOT. Baseline demographics and antiarrhythmic profile did not differ between the PBP (n=56) and HD (n=23) groups. Pre-ablation PVC burden was similar between the two groups (PBP 25 ± 12% vs HD 27 ± 11%; p=ns). Compared with LVOT ablations, ablation of RVOT PVCs demonstrated shorter procedure duration (170 ± 67 min vs 212 ± 74 min; p=0.04) and fluoroscopy time (12 ± 11 min vs 21 ± 16 min; p<0.05) but similar mapping time (61 ± 29 min vs 70 ± 43 min; p=ns) and ablation time (443 ± 320 s vs 588 ± 615 s; p=ns). Procedure duration, ablation time and fluoroscopy time were higher in the HD group driven by RVOT procedures. Complete PVC abolishment was achieved in 94% of cases. Intraprocedural complication rate was 3.8%, with two patients in the HD group developing heart block and one patient in PBP group developing cardiac tamponade. Over a follow-up period of 28 ± 25 months, the RVOT group demonstrated superior symptom- and arrhythmia-free survival compared with the LVOT group (Figure 1). Site of PVC origin was a significant predictor of symptom and arrhythmia recurrence with LVOT origin demonstrating unfavourable outcome (HR 6.9, p=0.05). Use of HD mapping catheters and presence of structural heart disease did not predict symptomatic PVC recurrence.
Conclusion: Catheter ablation of OT PVCs guided by HD mapping catheters was safe and noninferior to conventional PBP mapping. Long-term clinical outcome was driven by site of PVC origin. Larger, prospective data are required to assess short- and long-term benefits of HD mapping-guided ablation of OT PVCs.
