Radiofrequency catheter ablation (RFA) for treating AF may pose increased risk of silent cerebral ischemia according to a recently published study in Circulation. AF increases the risk of symptomatic stroke about 5 times compared to sinus rhythm and its treatment is aimed at reducing the risk of cerebral ischemia in addition to reduce AF symptoms. Pulmonary vein isolation using radiofrequency energy is commonly used to treat AF but is associated with risk of cerebral embolism due to intervention involving the left atrium.

Gaita et al. evaluated the risk of developing silent cerebral embolism by comparing the pre and post AF ablation MRIs. Of the 232 patients included in the study, among those who underwent AF ablation under standard protocol, 33 (14%) developed post ablation embolism of which only 1 (0.4%) had clinical transient ischemic attack.

They also reported that none of the clinical factors could predict silent cerebral infarcts. Meanwhile, procedural factors like the ACT < 250 seconds and need for cardioversion at the end of the procedure predicted increased risk of peri-procedural cerebral thromboembolism.

This prospective cohort of patients undergoing RFA was also compared with a cohort of patients undergoing elective cardioversion. The risk of acute cerebral thromboembolism as detected by MRI was much lower in patients undergoing only cardioversion without RFA. Based on this result, the authors postulate that the increased cerebral thromboembolism is related to RFA and not the cardioversion associated with the procedure.

In summary, this is the largest prospective study on silent cerebral ischemia associated with RFA for AF and shows that there is an increased risk of peri-procedural cerebral ischemic event with RFA. There is a need to compare this transient increased risk with long-term benefit in reduction of cerebral ischemic events with reversal to sinus rhythm. The immediate and long term clinical significance of silent cerebral ischemic events is unknown though some studies have shown an association with increased long-term risk of dementia.

Reference:

Gaita F, Caponi D, Pianelli M, Scaglione M, Toso E, Cesarani F, Boffano C, Gandini G, Valentini MC, De Ponti R, Halimi F, Leclercq JF. Radiofrequency catheter ablation of atrial fibrillation: a cause of silent thromboembolism? Magnetic resonance imaging assessment of cerebral thromboembolism in patients undergoing ablation of atrial fibrillation. Circulation. 2010 Oct 26;122(17):1667-73.