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

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.