Atrial fibrosis helps select the appropriate patient and strategy in catheter ablation of atrial fibrillation: a DE-MRI guided approach

Abstract

MRI for AF Patient Selection and Ablation Approach.

Introduction: Left atrial (LA) fibrosis and ablation related scarring are major predictors of success in rhythm control of atrial fibrillation (AF). We used delayed enhancement MRI (DE-MRI) to stratify AF patients based on pre-ablation fibrosis and also to evaluate ablation-induced scarring in order to identify predictors of a successful ablation.

Methods and results: One hundred and forty-four patients were staged by percent of fibrosis quantified with DE-MRI, relative to the LA wall volume: minimal or Utah stage 1; <5%, mild or Utah stage 2; 5-20%, moderate or Utah stage 3; 20-35%, and extensive or Utah stage 4; >35%. All patients underwent pulmonary vein (PV) isolation and posterior wall and septal debulking. Overall, LA scarring was quantified and PV antra were evaluated for circumferential scarring 3 months post ablation. LA scarring post ablation was comparable across the 4 stages. Most patients had either no (36.8%) or 1 PV (32.6%) antrum circumferentially scarred. Forty-two patients (29%) had recurrent AF over 283 ± 167 days. No recurrences were noted in Utah stage 1. Recurrence was 28% in Utah stage 2, 35% in Utah stage 3, and 56% in Utah stage 4. Recurrence was predicted by circumferential PV scarring in Utah stage 2 and by overall LA wall scarring in Utah stage 3. No recurrence predictors were identified in Utah stage 4.

Conclusions: Circumferential PV antral scarring predicts ablation success in mild LA fibrosis, while posterior wall and septal scarring is needed for moderate fibrosis. This may help select the proper candidate and strategy in catheter ablation of AF.

Figure 1

A series of left atrial MRI 3D reconstructions displayed in the RAO and PA projections illustrating areas of fibrosis (bright green) across the 4 stages of fibrosis. Utah stage 1: <5% fibrosis, Utah stage 2: 5–20% fibrosis, Utah stage 3: 20–25% fibrosis, Utah stage 4: >35% fibrosis.

Figure 2

Distribution of paroxysmal and persistent atrial fibrillation across the 4 stages of fibrosis. Note that each stage is a heterogeneous mix of both AF phenotypes with more predominant persistent AF in advanced stages.

Figure 3

Evaluation of the overall left atrial scarring as well as pulmonary vein encirclement with ablation scar. The left panel shows a patient with 11.9% overall LA wall scar 3 months postablation with only one vein circumferentially encircled. The middle and right panels show another patient with 32.4% overall scarring of the LA wall with all 4 pulmonary veins circumferentially encircled.

Figure 4

Pie chart depicting the success of ablation in creating circumferential scarring around the pulmonary vein antra. Only a small proportion of patients (7%) had complete encirclement of all 4 pulmonary veins.

Figure 5

Kaplan–Meier depicting AF recurrence stratified over the different stages of structural remodeling. Utah stage 1: <5% fibrosis, Utah stage 2: 5–20% fibrosis, Utah stage 3: 20–35% fibrosis, Utah stage 4: >35% fibrosis.