Effect of Therapeutic INR on Activated Clotting Times, Heparin Dosage, and Bleeding Risk During Ablation of Atrial Fibrillation

Objectives: To study the effect of INR on intraprocedural anticoagulation during ablation of AF. Methods: We retrospectively studied 427 consecutive patients over an 18-month period when we were transitioning to continuation of warfarin for AF ablation. Baseline INR, procedural ACT measurements, heparin doses and major complications were analyzed according to Group 1 with INR < 2.0 (n = 246) and Group 2 with INR >= 2.0 (n = 181). Results: In Group 1, the mean INR was lower (1.3 +/- 0.3 s vs 2.4 +/- 0.3; P < 0.001), and the mean heparin dose was greater (106.82 +/- 40.01 vs 77.03 +/- 18.5 U/kg; P < 0.001). A single heparin bolus achieved ACT >= 350 seconds throughout the procedure in 51 patients (20.7%) in Group 1 compared to 108 patients (59.7%) in Group 2 (P < 0.01). Mean ACT values were higher in Group 2. Symptomatic pericardial effusions were similar (2.4% in Group 1 and 2.2% in Group 2). There were 3 thromboembolic cerebrovascular events in Group 1 and none in Group 2. Femoral hematomas occurred more frequently in Group 1 (8.1%) than in Group 2 (3.3%) (P = 0.007). Conclusions: AF ablation with INR >= 2.0 provides a consistent anticoagulant milieu during the procedure, with lower heparin requirements that are important to anticipate. (J Cardiovasc Electrophysiol, Vol. 22, pp. 248-254, March 2011).