Atrial Fibrillation Ablation Outcome Is Predicted by Left Atrial Remodeling on MRI

Abstract

Background While catheter ablation therapy for atrial fibrillation (AF) is becoming more common, results vary widely and patient selection criteria remain poorly defined. We hypothesized that late gadolinium enhancement magnetic resonance imaging (LGE-MRI) can identify left atrial (LA) wall structural remodeling (SRM) and stratify patients who are likely or not to benefit from ablation therapy. Methods and Results LGE-MRI was performed on 426 consecutive AF patients without contraindications to MRI and before undergoing their first ablation procedure and on 21 non-AF control subjects. Patients were categorized by SRM stage (I–IV) based on percentage of LA wall enhancement for correlation with procedure outcomes. Histological validation of SRM was performed comparing LGE-MRI to surgical biopsy. A total of 386 patients (91%) with adequate LGE-MRI scans were included in the study. Post-ablation, 123 (31.9%) experienced recurrent atrial arrhythmias over one-year follow-up. Recurrent arrhythmias (failed ablations) occurred at higher SRM stages with 28/133 (21.0%) stage I, 40/140 (29.3%) stage II, 24/71 (33.8%) stage III, and 30/42 (71.4%) stage IV. In multi-variate analysis, ablation outcome was best predicted by advanced SRM stage (hazard ratio (HR) 4.89; p<0.0001) and diabetes (HR 1.64; p=0.036) while increased LA volume and persistent AF were not significant predictors. LA wall enhancement was significantly greater in AF patients vs. non-AF controls (16.6±11.2% vs. 3.1±1.9%, p<0.0001). Histological evidence of remodeling from surgical biopsy specimens correlated with SRM on LGE-MRI. Conclusions Atrial SRM is identified on LGE-MRI and extensive LGE (≥30% LA wall enhancement) predicts poor response to catheter ablation therapy for AF.

EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication

“…117,167,177,433,452,453 Magnetic resonance imaging techniques attempting to characterize the extent of myocardial fibrosis have demonstrated that this appears to be the strongest independent predictor of AF recurrence after ablation. 416,454 Whether the EHRAS classification has value for informing catheter ablation in human atria remains to be determined.…”

AF classification and ablation strategy: time for a new paradigm

“…A recent study showed that atrial scar burden predicts recurrence of AF following catheter ablation [6]. In another recent study by McCann et al [7], late gadolinium enhancement MRI was performed in 386 patients prior to undergoing their first ablation for AF. In the 123 patients with failed ablations, extent of late gadolinium enhancement correlated more with AF recurrence, rather than the presence of persistent AF.…”

Letter by Bisbal et al Regarding Article, “Repeat Left Atrial Catheter Ablation: Cardiac Magnetic Resonance Prediction of Endocardial Voltage and Gaps in Ablation Lesion Sets”

“…In addition to the aforementioned limitations, this technique has not been externally validated, and thus its superiority over other reported methodologies cannot be demonstrated. 2,4 However, voltage mapping also has not been validated as a reliable tool to predict PV reconnection. Considering that the spatial resolution of a point-bypoint map using a 3.5-mm tip catheter is ≈6 mm in diameter and that the voxel size of DE-CMR can be as small as 1.25×1.25×2.5 mm, 2,4 we consider it inappropriate to use voltage mapping as the gold standard.…”

“…2,4 However, voltage mapping also has not been validated as a reliable tool to predict PV reconnection. Considering that the spatial resolution of a point-bypoint map using a 3.5-mm tip catheter is ≈6 mm in diameter and that the voxel size of DE-CMR can be as small as 1.25×1.25×2.5 mm, 2,4 we consider it inappropriate to use voltage mapping as the gold standard. In light of these facts, we believe that the conclusions of the study by Harrison et al must be interpreted with caution and considered hypothesis-generating rather than as a definitive demonstration.…”