AMSTERDAM — Delayed-enhancement MRI performed before atrial fibrillation ablation may stage the degree of atrial fibrosis and help physicians predict whether treatment will be successful, according to research presented at ESC Congress 2013.
The DECAAF trial enrolled 329 patients with AF who were undergoing ablation at 15 centers in the United States, Europe and Australia; 260 patients had usable preablation MRIs and satisfied follow-up criteria. The researchers performed high-resolution delayed-enhancement MRI up to 30 days before ablation to determine the extent of atrial fibrosis, and again at 90 days after ablation (n=117) to analyze the extent of ablation-induced scar and residual fibrosis determined as the preablation fibrosis regions not covered by postablation scar, according to the researchers.
“The DECAAF results show that stage of atrial fibrosis prior to ablation is a new, powerful, independent predictor of outcome,” Nassir F. Marrouche, MD, from the CARMA Center at the University of Utah, said in a press release.
“By performing this imaging before ablative treatment, we can triage patients according to likelihood of treatment success and avoid ablative procedures in those patients for whom it is unlikely to work. If a patient has late stage 3 or stage 4 fibrosis, the chance of being cured is only 30% to 35%, which is really low, but if they’re in an early stage, their chance of cure is 60% to 80%.”
Nassir F. Marrouche
At 90-day follow-up, arrhythmia recurrence had occurred in 33.8% of patients, based on Holter monitors and electrocardiograms.
Stage of atrial fibrosis before ablation and residual fibrosis after ablation were identified as independent predictors of successful ablation (P<.001 for both), according to multivariate analysis.
The researchers categorized patients into four groups based on the percentage of atrial tissue enhanced on preprocedure MRI: stage 1, less than 10% damaged atrial tissue; stage 2, 10% to 20% damaged atrial tissue; stage 3, 20% to 30% damaged atrial tissue; stage 4, more than 30% damaged atrial tissue. Stage 1 patients had an AF ablation procedure success rate of 85.8% compared with 63.3% for stage 2 patients, 55% for stage 3 patients and 31% for stage 4 patients.
For every increased percentage of atrial fibrosis before ablation, there was a 6.3% increased risk for recurrent AF symptoms after ablation. For every increased percentage in residual atrial fibrosis after ablation, there was an 8.2% increased risk for recurrent AF symptoms, he said during a press conference.
In other results, based on postablation imaging, type of ablation may impact success rates. When the researchers analyzed postablation images that showed whether pulmonary veins were completely encircled with ablation scar, they found that encirclement did not predict ablation success.
“The more of [fibrosis] you cover with ablation, the better the outcome. I would target fibrosis. That is what I am doing now, and it’s encouraging,” Marrouche said.
“When you look at an MRI, you can predict today the chances of the patient having recurrent symptoms, independent from the operator and the experience center, and the type of lesions,” he said.
In addition, Marrouche and colleagues reported that hypertension was the only independent predictor of atrial fibrosis in this study.
For more information:
Marrouche NF. Hot Line II: Late breaking trials on intervention and devices. Presented at: the European Society of Cardiology Congress; Aug. 31-Sept. 4, 2013; Amsterdam.
Disclosure: Marrouche reports financial relationships with Biotronik, Boehringer Ingelheim, Boston Scientific, eCardio, Estech, Marreck Inc., MRI-Interventions, Sanofi and Siemens.