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DECAAF: Atrial fibrosis a strong predictor of outcome in AF ablation
DENVER — Using delayed enhancement MRI, researchers for the DECAAF study demonstrated that atrial fibrosis is a strong, independent predictor of outcome in patients undergoing ablation for atrial fibrillation.
The prospective, double blind study included 330 patients (mean age, 59 years; 69% men; 64% paroxysmal AF) at 15 centers in Australia, Europe and the United States with varying degrees of expertise in cardiac MRI. All patients underwent high-resolution delayed enhancement MRI up to 30 days before ablation. AF ablation was performed and patients were followed up at 3, 6 and 12 months for recurrence using Holter monitors and ECGs.
Atrial fibrosis was successfully quantified in 273 patients (stage 1, <10% fibrosis; stage 2, 10% to 20%; stage 3, 20% to 30%; stage 4, >30%).
Patients were followed for 1 year after ablation. The final cohort included 261 patients with good delayed enhancement MRI scans who completed at least 90 days of follow-up. Seventeen percent of images could not be analyzed due to poor-quality MRI.
Nassir F. Marrouche
According to results, recurrent arrhythmia was observed in 94 of 261 patients. A multivariate Cox proportional hazards model was used to evaluate arrhythmia recurrence. Atrial fibrosis was strongly associated with arrhythmia recurrence independent of age, sex, participating site, atrial volume, AF type and medical comorbidities (HR=1.0562). On average, every 1% increase in fibrosis is associated with a 6.2% increase in the hazard of recurrence when other clinical factors are held constant, Nassir F. Marrouche, MD, director of the cardiac electrophysiology laboratories at University of Utah, said at a press conference. Patients with stage 1 fibrosis had an AF ablation success rate of 85%; stage 2, 67%; stage 3, 55%; and stage 4, 30%.
In this study, the only predictor of fibrosis was the presence of hypertension, Marrouche said.
“Delayed enhancement MRI-based quantification of atrial fibrosis is a strong predictor for AF ablation outcome. Moreover, delayed enhancement MRI detected atrial fibrosis in AF patients and was shown to be feasible and reproducible in multiple MRI-experienced as well as non-experienced centers across the world,” Marrouche said. – by Deb Dellapena
For more information:
Marrouche N. LB01-04. Presented at: Heart Rhythm Society’s Annual Scientific Sessions; May 8-11, 2013; Denver.
Disclosure: Marrouche reports receiving consulting fees from Boston Scientific Corp., eCardio, Estech and Sanofi-Aventis; equity interests in Surgivision; and research grants from eCardio and Estech.
Perspective
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This study tested the idea that the greater the extent of fibrosis, the less likely ablation or other therapies will eliminate AF. Strengths include the study design and the fact that it is multicenter. A weakness is the inability to quantify fibrosis in all patients.
The data provide strong support for the idea that even in a group of patients with what we might think of as ‘early’ AF (mostly paroxysmal), there is a strong relationship between extent of fibrosis and success of ablation. We cannot know from this study whether fibrosis directly accounts for the decreased success of ablation, but other lines of evidence support the concept that these are true and related. If that were the case, a logical next step is to consider trials assessing the long-term efficacy of very early intervention in patients at risk in whom fibrosis has not yet developed. How to identify and assess such patients and how to intervene in a very safe way (without generating a lot more fibrosis) are important questions to address before we implement such a strategy.
Another interesting question is why some patients develop more extensive fibrosis than others; answering that question might identify patients who should be considered for earlier intervention. These are all provocative ideas that need to be appropriately tested.
Perspective
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The Utah group, led by Dr. Marrouche, has pioneered the concept that atrial fibrosis correlates with ablation success. In the multicenter DECAAF trial, they found that atrial fibrosis is a strong predictor of ablation success. The current study has extended their prior work by demonstrating the feasibility of the imaging technique in multiple centers throughout the world. Importantly, atrial fibrosis was found to be helpful for risk stratifying ablation success even among patients with paroxysmal AF.
Further work will clearly be required to improve the success of image acquisition; however, such a technical limitation should not distract from the innovative aspects of the current work. In the future, it will be interesting to determine whether atrial fibrosis is correlated with other clinical outcomes, such HF or stroke, or whether such fibrosis can be modulated to alter the course of AF.