Abstract 16266: Greater Variation in the Point of Care Activated Clotting Time During Ablation Procedures is Observed at Therapeutic Values
Introduction: Guidelines for atrial fibrillation (AF) ablation recommend procedural anticoagulation with unfractionated heparin and a target activated clotting time (ACT) of 300-400 seconds. There is great variation in testing reagents and results from many different commercially-available products for point of care ACT measurement. The optimal approach to ACT testing, particularly in the era of novel anticoagulants, continues to evolve.
Hypothesis: Paired ACT samples from patients undergoing AF ablation measured with 2 different devices (Hemochron Signature Elite (HS) and Hemochron Response (HR), Accriva Diagnostics) will differ significantly but correlate closely across a wide range of ACT values.
Methods: In 31 patients undergoing AF ablation, the ACT was measured at baseline and every 30 minutes during the procedure. After aspiration of 10 mL of blood for waste, 3 mL was drawn for analysis. From this sample the ACT was measured using both the HR and HS methods. Heparin dosing was according to the HR method which has been our lab standard with a low bleeding and stroke rate. Calibration and ACT testing adhered strictly to usage instructions.
Results: 229 paired samples from 31 patients were analyzed. The mean difference between the HR and HS ACT was 70 ± 54 seconds (27±18%). At HR ACT values of ≤ 200 seconds the average difference was 16% vs 29% for values > 200 seconds. There was a positive correlation between both methods for all paired samples, r = 0.74, p≤0.01 and R2 = 0.55. In samples with an HR ACT of 300-400, only 21/140 (15%) had a therapeutic HS ACT. In samples with an HS ACT of 300-400, 5/28 (18%) had an HR ACT of >400 seconds.
Conclusions: ACT values using the HR and HS methods vary significantly, particularly at therapeutic levels which are of greatest importance during AF ablation. The correlation between testing values is only modest. Different testing methods can significantly alter heparin dosing and should be further studied in trials of anticoagulation during AF ablation.
Author Disclosures: W.F. Dresen: None. P. Schmidt: None. V. Nagarajan: None. M.A. Murphy: None. A.E. Mealor: None. W.M. Camnitz: None. A.E. Darby: Research Grant; Modest; Boston Scientific, Medtronic. R. Malhotra: Research Grant; Modest; Boeringer Ingleheim. Speakers Bureau; Modest; Medtronic. K.C. Bilchick: None. P.K. Mason: Honoraria; Modest; Medtronic. J.M. Mangrum: None. J.P. DiMarco: None. J.D. Ferguson: Research Grant; Modest; Medtronic, Biosense Webster, St. Jude.
- © 2016 by American Heart Association, Inc.