Evaluation and Reduction of Asymptomatic Cerebral Embolism in Ablation of Atrial Fibrillation, But High Prevalence of Chronic Silent Infarction: Results of the Evaluation of Reduction of Asymptomatic Cerebral Embolism Trial

Background— This prospective, multicenter study sought to evaluate the incidence of asymptomatic cerebral emboli (ACE) during ablation of atrial fibrillation (AF) using a multielectrode radiofrequency (MER) system when specific procedural changes were applied. Methods and Results— Sixty subjects (age 60±10 years; 87% paroxysmal; CHADS2 score, 0.6±0.7) undergoing AF ablation with a circular MER catheter were studied. Three procedural changes were specified: (1) ablation was performed under therapeutic vitamin K antagonist and heparin to maintain activated clotting time >350 seconds; (2) submerged loading of the catheter into the introducer before sheath insertion to minimize air ingress; and (3) either the distal or proximal electrode of the circular MER catheter was deactivated to prevent inadvertent bipolar radiofrequency interaction. MRI was performed <7 days preablation and 2 days postablation. Subjects with new cerebral findings after ablation underwent repeat MRI after 1 month. An acute ACE lesion was defined by a new hyperintensity on diffusion-weighted and fluid-attenuated inversion recovery cerebral MRI sequences. Neurological function was evaluated at baseline, postablation, and 1 month. All target pulmonary veins were isolated. In 60% (36/60) of patients, pre-existing cerebral lesions were seen on the preprocedure MRI (8 lesions per subject; interquartile range, 3–22). New postprocedural ACE occurred in only 1/60 patients (incidence, 1.7%; 95% confidence interval, 0.04–8.9), which was no longer visible on MRI after 1 month. Conclusions— Applying procedural changes to MER ablation significantly reduces the ACE incidence to 1.7%, which is on the low end of reported ACE rates of any technology. Clinical Trial Registration Information— ClinicalTrials.gov; Identifier: NCT01520532.