Atrial fibrillation ablation using open-irrigated tip radiofrequency: Experience with intraprocedural activated clotting times ≤ 210 seconds

BACKGROUND Atrial fibrillation (AF) ablation procedures generally use intraprocedural activated clotting time (ACT) of >300-350 seconds to prevent thromboembolic events. OBJECTIVE To evaluate bleeding and thromboembolic procedural complications in patients with symptomatic AF undergoing ablation procedures with low intraprocedural ACT. METHODS We examined a subset of 372 of 2334 (15.9%) AF ablation procedures using open-irrigated tip radiofrequency catheters at 50W, interrupted oral anticoagulation, and a target ACT of 225 seconds, with average ACT <= 210 seconds. RESULTS There were 372 ablation procedures in 339 patients with average ACT <= 210 seconds. Patient demographic characteristics were as follows: age 60.9 +/- 9.4 years, men 269 (79.3%), left atrial (LA) size 4.27 +/- 0.65 cm, prior stroke/transient ischemic attack 24 (7.1%), CHADS(2) score 0.94 +/- 0.98, and CHA(2)DS(2)-VASc score 1.53 +/- 1.35. AF type was categorized as paroxysmal in 107 (31.6%), persistent in 200 (59.0%), and long-standing persistent in 32 (9.4%). Procedural and LA times were 119 +/- 26 and 82 +/- 24 minutes. Patients underwent preprocedure transesophageal echocardiography. The heparin bolus (8738 +/- 2823 units, 93.4 mg/kg) was given after LA access, and the maintenance infusion was 1000 units/hour via a single transseptal sheath with subsequent adjustments based on ACT values. The average ACT was 202 +/- 7.5 seconds per procedure, with 116 patients with average ACT <200 seconds and 16 patients with all ACTs <200 seconds. Complications occurred in 7 of 372 (1.9%) ablation procedures, including 2 pericardial tamponades (0.54%), 1 groin pseudoaneurysm (0.27%), and 1 pulmonary embolus, several weeks postablation. There were no other bleeding events and no strokes/transient ischemic attacks or systemic thromboemboli. CONCLUSION Using open-irrigated tip radiofrequency catheters at 50 W and preablation transesophageal echocardiography as well as infusing maintenance heparin through a single transseptal sheath, AF ablation can be performed safely despite ACT averaging <= 210 seconds. While we are not advocating target ACTs this low, our data suggest that long ACTs may not be absolutely necessary for preventing thromboembolic events. Lower target ACTs may potentially reduce bleeding complications.