Device-dependent activated clotting time measurements during transseptal ablation under continuous anticoagulation:...

Monitoring activated clotting time (ACT) is essential during transseptal ablation. Despite having distinct analytical principles and potentially non-equivalent values, different point-of-care ACT systems are used interchangeably.

This study aimed to compare ACT values from a mechanical-optical and a microfluidic electrochemical system in patients treated with direct oral anticoagulant (DOAC) undergoing transseptal ablation and to quantify the impact of device-related bias on guideline-recommended ACT targets.

30 consecutive patients undergoing left-sided transseptal catheter ablation under uninterrupted DOAC therapy were studied. After transseptal puncture, unfractionated heparin was administered, and ACT was measured simultaneously with both systems at predefined time points. The primary analysis included 42 paired post-heparin measurements; a complementary analysis included all 55 paired measurements (pre- and post-heparin). Agreement was assessed using paired t-tests, linear regression, and Bland-Altman analysis. Thresholds of ≥250 seconds and ≥300 seconds were evaluated.

In the primary post-heparin analysis, mean ACT was 316.3 ± 51.5 seconds with the mechanical-optical system and 259.3 ± 29.8 seconds with the microfluidic system, yielding a mean bias of 57.0 seconds (95% confidence interval, 41.7-72.3; P < .001). Including all 55 measurements, the mean bias remained large at 48.4 seconds with strong per-measurement correlation. Using a threshold of ≥250 seconds, 90.0% vs 46.6% of measurements met the target; at ≥300 seconds, 60.0% vs 10.0%.

Mechanical-optical and microfluidic electrochemical ACT systems show a consistent positive offset of roughly 50-60 seconds. Uniform ACT cutoffs across devices may misclassify anticoagulation adequacy, supporting device- and cartridge-specific ACT targets during DOAC-treated transseptal ablation.