Impact of Intramural Scar on Mapping and Ablation of Premature Ventricular Complexes.

Objectives: This study sought to determine intramural scar characteristics associated with successful premature ventricular complex (PVC) ablations.

Background: Ablating ventricular arrhythmias (VAs) originating from intramural scarring can be challenging. Imaging of intramural scar location may help to determine whether the scar is within reach of the ablation catheter.

Methods: Mapping and ablation of premature ventricular complexes (PVCs) was performed in a consecutive series of patients with intramural scarring and frequent PVCs. Data from delayed enhanced cardiac magnetic resonance were assessed and the proximity of the endocardium containing the breakout site to the intramural scar was correlated with outcomes.

Results: Fifty-six patients were included, and intramural VAs were successfully targeted in 42 patients (75%) and ablation failed in 14 patients (25%). Scarring was more superficial to the endocardium in patients with successful ablations compared with patients with failed procedures (0.35 mm [interquartile range (IQR): 0.22 to 1.20 mm] vs. 2.45 mm [IQR: 1.60 to 3.13 mm]; p < 0.001). In 18 (32%) patients, ablation at the breakout site resulted in a significant change of the PVC-QRS morphology that could successfully be ablated in 9 of 12 patients from another anatomical aspect of the wall harboring the intramural scar. The scar was larger in size (1.79 cm [IQR: 1.25 to 2.85 cm] vs. 1.00 cm [IQR: 0.59 to 1.68 cm]; p < 0.005) compared with patients who did not have a change in the PVC-QRS morphology with ablation.

Conclusions: VAs in patients with intramural scaring can be successfully ablated especially if the intramural scar is within close proximity to the anatomic area containing the breakout site. Changes in the QRS-PVC morphology often precede successful ablation at another breakout site and indicate larger intramural scars.