Introduction: Ablation of atrial fibrillation (AF) by cryoenergy preserves intact extracellular matrix and the endothelium of the left atrium and appears to be less thrombogenic than radiofrequency energy (1). Current guidelines recommend anticoagulant therapy (OAC) for a minimum of 8 weeks after ablation of AF (2). There are no published data on the safety of acetylsalicylic acid (ASA) as the only antithrombotic drug after cryoballoon ablation of pulmonary veins.

Patients and Methods: We performed a retrospective analysis of patients with paroxysmal atrial fibrillation that underwent isolation of pulmonary veins (PVI) by second generation cryoballoon (CB-A) in our institution. All patients had CHADSVASc Score 0 and were followed for a minimum of 3 months after the procedure. None of the patients before ablation were taking OAC. After the procedure, introduction of oral anticoagulants or ASA was left to the discretion of the operator. The cryoballoon procedure itself was carried out under local anesthesia with sedation as described previously (3).

Results: A total of 16 patients (15 men, average age 51.2±9.8) were analyzed who met the inclusion criteria. Eight patients (50%) after the procedure did not receive OAC (ASA group), while the other half received new oral anticoagulants (5; 31.2%) or a vitamin K antagonist (3; 18.8%) (OAC group). The two groups did not differ considering the relevant clinical and procedural characteristics. In both groups, there were no thromboembolic, nor hemorrhagic events peri- and post- procedurally. Considering the other complications, we noted only one permanent and one transient phrenic nerve paresis in the OAC group (12.5%). In the mean follow-up of 7.7±3.3 months, 2 patients (12.5%) had recurrent atrial arrhythmias after “blanking” period (both in the ASA group).

Conclusion: Anticoagulant therapy is recommended universally after PVI, but other than protection from thromboembolic events, it increases the risk of bleeding (most often local vascular complications). This small pilot study suggests that the hemorrhagic complications might be avoided without compromising the safety in patients with low basic thromboembolic risk when using second generation cryoballoon. Larger studies are needed to confirm the above findings.