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Association of Atrial Tissue Fibrosis Identified by Delayed Enhancement MRI and Atrial Fibrillation Catheter Ablation: The DECAAF Study
Study Questions:
Is left atrial (LA) fibrosis identified by delayed-enhancement magnetic resonance imaging (MRI) associated with recurrent atrial fibrillation (AF) following catheter ablation?
Methods:
In DECAAF, a prospective multicenter study, 272 patients with AF undergoing delayed-enhancement cardiac MRI prior to first catheter ablation procedure were evaluated, after exclusion of 57 patients with nondiagnostic MRI studies. Extent of LA fibrosis was graded as stages 1 (<10%), 2 (≥10%-<20%), 3 (≥20%-<30%), or 4 (≥30% of atrial wall); the relationship between extent of LA fibrosis, and recurrence of AF was assessed at days 325 and 475 after a 90-day blanking period.
Results:
Mean age was 59 ± 10 years, and 69% were male. Persistent, paroxysmal, and permanent AF were observed in 29%, 65%, and 7% of individuals, respectively. Stages 1-4 of LA fibrosis were noted in 19%, 41%, 31%, and 9% of patients. Among demographics, clinical factors, and procedural characteristics, only the presence of mitral valve disease (hazard ratio [HR], 3.45; 95% confidence interval [CI], 1.78-6.68; p < 0.001) and increased LA fibrosis (HR, 1.06 per +1% in fibrosis; 95% CI, 1.03-1.08; p < 0.001) were associated with AF recurrence. Adjusted risk of AF recurrence at 325 days was 12%, 31%, 45%, and 55% for stages 1-4; adjusted risk at 475 days was 14%, 36%, 49%, and 65%, respectively. Adding LA fibrosis to a model of AF recurrence including traditional covariates demonstrated an improved c-statistic from 0.65 to 0.69.
Conclusions:
In patients treated with catheter ablation for AF, increased extent of LA fibrosis on MRI is associated with higher risk of recurrence.
Perspective:
Recurrence of AF following catheter ablation procedures is not uncommon, and there is a clinical need to improve our identification of individuals at risk of this. Mitral valve disease and extent of LA fibrosis were the only significant univariate predictors of AF recurrence in this study, and the extent of LA fibrosis was independently associated with recurrence. These findings suggest that measuring LA fibrosis on MRI may be clinically helpful in patients considered for catheter ablation of AF, particularly in cases where MRI is already planned for preprocedural mapping.
Keywords: Heart Atria, Demography, Atrial Fibrillation, Catheter Ablation, Magnetic Resonance Imaging, Mitral Valve
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