Safety of Lower Activated Clotting Times During Atrial Fibrillation Ablation Using Open Irrigated Tip Catheters and a Single Transseptal Puncture

Guidelines largely based on closed-tip catheters recommend activated clotting times (ACTs) >300 to 350 seconds during atrial fibrillation (AF) ablation to prevent thrombus and char formation. Open irrigated tip catheters (OITC) may decrease complications and permit lower ACTs. This study evaluated factors contributing to vascular and hemorrhagic complications during AF ablation with emphasis on catheter type, anticoagulation level, procedural and clinical variables, and gender. In 1,122 AF ablations we examined catheter used, ACT level, gender, and complications. Target ACTs initially were >300 seconds and were decreased to 225 seconds for the OITC. Average ACT ranges were created: <250, 250 to 299, 300 to 350, and >350 seconds. Average ACT was <250 seconds in 557 ablations (complication rate 1.62%). Cochran-Armitage analysis showed that complications increased linearly as ACT increased and peaked at 5.55% for ablations with ACTs >350 seconds (p = 0.038). Women were older (66 ± 10 vs 60 ± 10 years, p <0.001) and had more paroxysmal AF (43% vs 28%, p = 0.007) and more hypertension (50% vs 40%, p = 0.013). Women received less heparin but were over-represented in higher ACT ranges (p <0.0001) consistent with a pharmacokinetic gender difference. There was no difference in vascular or hemorrhagic complications between men and women (2.3% vs 2.9%, p = 0.668). Multivariate logistic regression showed that only use of the OITC was associated with lower complication rates (p = 0.024). In conclusion, AF ablation with the OITC is safe with a target ACT of 225 seconds.