Comparison of mechanical/optical and microfluidic electrochemical point-of-care ACT systems during transseptal ablation under continuous anticoagulation

Background Monitoring activated clotting time (ACT) is essential during transseptal ablation procedures to ensure adequate intraprocedural anticoagulation [1]. Although multiple point-of-care ACT systems are used interchangeably, they are based on different analytical principles, which may result in non-equivalent values and affect anticoagulation targets [2]. Purpose To compare ACT values obtained from two commonly used point-of-care systems during transseptal ablation procedures performed under uninterrupted oral anticoagulation. Methods Thirty consecutive patients undergoing transseptal catheter ablation (25 pulmonary vein isolations, 4 ventricular tachycardia ablations, 1 supraventricular tachycardia ablation) were included. All patients continued direct oral anticoagulant therapy on the day of the procedure. Following transseptal puncture, unfractionated heparin was administered, with the initial activated clotting time measurement obtained at 30 minutes. Further heparin dosing was adjusted at the discretion of the electrophysiologist to maintain therapeutic ACT. ACT was measured simultaneously using a microfluidic electrochemical cartridge-based system and a mechanical optical clot-detection system. The therapeutic thresholds of ≥250 s and ≥300 s were evaluated in accordance with the established Guidelines [1]. Results A total of 55 paired measurements were collected (mean 1.87 ± 0.97 per patient). Mean activated clotting time was 316.3 ± 51.5 s using the mechanical/optical system and 254.8 ± 40.5 s using the microfluidic electrochemical system. A paired t-test was conducted, which revealed a significant systematic bias, with the mechanical/optical system measuring 61.5 s higher on average (95% CI 44.7–78.4 s, p = 3.18 × 10−8). Using a ≥250 s threshold, adequate anticoagulation was achieved in 90% vs 46.6% of patients; using ≥300 s, 60% vs 10%, respectively. Conclusion Substantial and systematic differences exist between activated clotting time measurement systems during transseptal ablation procedures under uninterrupted anticoagulation. These differences reflect underlying analytical methodology and indicate that therapeutic ACT thresholds must be interpreted relative to the measurement system used. The implementation of a uniform cutoff value across diverse devices has the potential to result in unintended under- or over-anticoagulation.