Background: Pulmonary vein isolation has increasingly been used to cure atrial fibrillation, but concerns have recently been raised that subclinical brain damage may occur because of microembolization during these procedures. We compared the occurrence of bubble formation seen on intracardiac echocardiography and the microembolic signals (MESs) detected by transcranial Doppler on the use of different ablation techniques and anticoagulation strategies.
Methods and results: This prospective study included 35 procedures in 34 consecutive patients (age, 52; SD, 12.8 years; female:male 9:25). Pulmonary vein isolation was performed with a cryoballoon and the conventional anticoagulation protocol (activated clotting time >250 s) in 10 procedures (group 1), with a multipolar duty-cycled radiofrequency pulmonary group 2), and with regime a pulmonary vein ablation catheter with an aggressive anticoagulation (activated clotting time >320 s) in 13 procedures (group 3). The mean total numbers of MESs detected during the procedures were 833.7 (SD, 727.4) in group 1, 3142.6 (SD, 1736.4) in group 2, and 2204.6 (SD, 1078.1) in group 3 (P=0.0005). MESs were detected mostly during energy delivery in the pulmonary vein ablation catheter groups, whereas a relatively even distribution of emboli formation was seen during cryoballoon ablations. A significant correlation was found in all groups between the degree of bubble formation on intracardiac echocardiography and the number of MESs (P=0.0000).
Conclusions: Duty-cycled radiofrequency ablation is associated with significantly more MESs, even when more aggressive anticoagulation is applied. With both techniques most of these microemboli are gaseous in nature.
Keywords: atrial fibrillation; cerebral microemboli; pulmonary vein isolation; transcranial Doppler.