title: Effect of therapeutic INR on activated clotting times, heparin dosage, and bleeding risk during ablation of atrial fibrillation.
abstract: BACKGROUND
  Ablation of atrial fibrillation (AF) with international normalized ratio (INR) ≥ 2.0 is safe and may reduce thromboembolic complications. Heparin is administered during the procedure, but the effect of elevated INR on heparin requirements and target activation clotting times (ACT) ≥ 350 seconds during ablation is unknown.
  
  
  OBJECTIVE
  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.
authors.affiliation: Division of Cardiovascular Medicine, Brigham and Women's Hospital, 45 Francis St., Boston, MA 02115, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Gautam
authors.forename: Roy M
authors.initials: RM
authors.lastname: John
authors.forename: William G
authors.initials: WG
authors.lastname: Stevenson
authors.forename: Rahul
authors.initials: R
authors.lastname: Jain
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Epstein
authors.forename: Usha
authors.initials: U
authors.lastname: Tedrow
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Koplan
authors.forename: Seth
authors.initials: S
authors.lastname: McClennen
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Michaud
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000097:blood / Q000601:surgery*; D001777:Blood Coagulation / Q000187:drug effects*; D001900:Boston; D017115:Catheter Ablation / Q000009:adverse effects; D016009:Chi-Square Distribution; D004334:Drug Administration Schedule; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006470:Hemorrhage / Q000097:blood / Q000139:chemically induced*; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012044:Regression Analysis; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D006493:Heparin