By Angela Gonzalez
Atrial fibrosis detected using delayed enhancement magnetic resonance imaging (DE-MRI) seems to be an independent predictor of procedural outcome in patients undergoing ablation of atrial fibrillation, according to results of the DECAAF (Delayed enhancement-MRI determinant of successful catheter ablation of atrial fibrillation) study
Results on the “Analysis of post ablation scar and outcome” of the DECAAF trial were presented by lead investigator, Nassir Marrouche, CARMA Center, University of Utah, Salt Lake City, USA, at a late-breaking trial session of the ESC congress.
“The DECAAF results show that the stage of atrial fibrotic disease prior to ablation is a new, powerful, independent predictor of outcome,” said Marrouche.
Although Marrouche and colleagues had previously demonstrated the impact of left atrial fibrosis on outcomes after ablation in atrial fibrillation, retrospectively, in a single centre cohort, this study sought to demonstrate the reproducibility of DE-MRI in this setting across several centres, and to investigate the clinical utility of staging atrial disease in this manner.
Marrouche presented preliminary results of the DECAAF study at Heart Rhythm 2013 (8–11 May, Denver, USA) showing that DE-MRI of left atrial fibrosis is feasible.
Three hundred and twenty nine patients from 15 centres in USA, Europe and Australia were included and followed-up for at least 12 months after ablation. The patients were assigned to four groups based on their degree of atrial fibrosis (stage I=<10%; stage II=≥10% to <20%; stage III=≥20% to <30%; stage IV=≥30%). In total, 260 patients completed follow-up, 64% of those had paroxysmal atrial fibrillation.
Marrouche told delegates that DE-MRI was performed up to 30 days before ablation in all patients to determine the presence and extent of atrial fibrosis, while post-ablation DE-MRI was performed at 90-days follow-up in 177 of the subjects, to determine the extent of residual ablation.
After multivariate model analysis, left atrial fibrosis was the only independent predictor of atrial fibrillation recurrence in this study population, not the ablation centre or the type of ablation, commented Marrouche.
The results showed that patients with stage I fibrosis had an 85.8% success rate, those with stage II had a 63.3% success rate, those with stage III had a 55% success rate and those with stage IV had a 31% success rate. For every increased percentage of fibrosis before ablation, there was 6.3% increased risk of recurrent symptoms after ablation (hazard ratio [HR] 1.063), said Marrouche. Similarly, for every percentage of residual fibrosis there was an 8.2% increased risk of recurrent symptoms (HR 1.082).
Another important finding in this study, said Marrouche, is that pulmonary vein isolation is not the best ablative approach. “What DECAAF told us is that encircling the pulmonary veins with lesions is not important to improve ablation procedure success. On the contrary, targeting diseased tissue with ablation lesions seems to be the most powerful predictor of success,” Marrouche told Cardiac Rhythm News.
In conclusion, he said: “Atrial fibrosis detected using DE-MRI seems to be an independent predictor of procedural outcome in patients undergoing ablation of atrial fibrillation. DECAAF showed that a lower atrial fibrosis following ablation was associated with improved procedural outcome”.
These findings “should help individualise ablative treatment of atrial fibrillation,” he added. Gerhard Hindricks, Leipzig, Germany, discussant of Marrouche’s presentation said: “This study has a significant impact on the decision-making for the different therapeutic options that we have for patients with atrial fibrillation.”
“For the first time, the DECAAF study has shown that it is feasible to visualise fibrosis on the atrial level […] this should open-up a window for new treatment strategies for atrial fibrillation to influence that process.”
Marrouche told Cardiac Rhythm News: “Practising physicians should re-think an invasive approach in patients with advanced and diffuse atrial disease detected using MRI.”