Heparin Requirements in Patients Undergoing Atrial Fibrillation Ablation on Coumadin vs NOACs

Atrial fibrillation (AF) is the most common arrhythmia affecting the US population and accounts for 15% of strokes worldwide. Radiofrequency ablation has become a frequently used therapy for treatment of afib after failure of at least one anti-arrhythmic drug. Pulmonary Vein Isolation (PVI) remains the cornerstone of AF ablation and requires transseptal puncture and placement of catheters in the left atrium which can be thrombogenic and cause stroke. This is avoided by intra-procedural infusion of heparin and the anti-coagulation effect is monitored using Activated Clotting Time (ACT). With the approval of Novel Oral Anti-Coagulants (NOAC), increasing number of patients are undergoing AF ablation on these medications. It has been observed that patients on NOACs require much larger doses of heparin and take longer time to reach therapeutic ACT. Consequently, patients are at higher risk for thromboembolism and stroke. On the other hand, higher doses of heparin can expose patients to excessive bleeding complications. The investigators seek to explain the mechanism of "heparin resistance" in such a patient population and to develop a protocol that can achieve therapeutic anticoagulation quicker.