Evaluation of a novel standardized protocol for heparinization during left atrial ablation procedures

Background: Catheter ablation is increasingly performed in patients with atrial fibrillation (AF) and other left atrial arrhythmias. Effective systemic anticoagulation during left atrial ablation is a major safety concern to prevent thromboembolic complications. Current guidelines recommend intraprocedural administration of unfractionated heparin targeting an activated clotting time (ACT) >300 s. However, ineffective intraprocedural anticoagulation with the risk of thromboembolism as well as excessive anticoagulative states with the risk of bleeding are potential clinical problems during percutaneous cardiac interventions.

Aims: To evaluate a novel standardized heparinization protocol in a prospective patient cohort undergoing left atrial ablation procedures in terms of effectivity of anticoagulation and patient safety.

Methods: Consecutive patients undergoing left atrial catheter ablation for AF or atrial tachycardia between 03/2022 and 05/2023 were prospectively enrolled. A novel institutional standardized heparinization protocol was implemented in each patient. Direct oral anticoagulation (DOAC) was withheld the morning before ablation and vitamin K antagonists were given without interruption aiming at an INR <3. All patients received initially 5000 I.U. of heparin after groin puncture. After transseptal puncture patients received for each ten kilograms above a bodyweight of 50 kilograms further 1000 I.U. of heparin. ACT measurements were then conducted every 20 minutes. In cases of ACT values <300s further heparin was administered following the standardized institutional protocol based on body weight and ACT. The primary endpoint was defined as at least one ACT >300s.

Results: A total of 655 patients (218 females, 33.2%) with a mean age of 65.2±11.0 years and a mean BMI of 28.7±5.5 kg/m² were included. Median CHA₂DS₂-VASC score was 2 {1;3} with 59 patients (9%) having a history of stroke or transient ischemic attack. Median HAS-BLED score was 1 {1;2} with one patient (0.2%) having a history of anticoagulation associated major bleeding. Ablation was performed for paroxysmal AF in 222 patients (33.9%), persistent AF in 405 patients (61.8%) and left atrial tachycardia in 28 patients (4.3%). Table 1 shows further baseline data.  Radiofrequency based PVI or left atrial ablation was performed in 313 (52.7%) patients, cryoballoon PVI in 154 (25.9%) patients and pulsed field ablation in 128 (21.5%) patients. Detailed procedural data is shown table 2. Mean number of ACT measurements per procedure were 2.2±1.2. Mean peak ACT was 325.3±74.6 s and mean lowest ACT 263.6±41.6 s with a total heparin administration of 12570.7±4905.0 IU per patient. In 554 patients (84.6%) the primary endpoint was reached and in 90 patients (13.7%) all ACT measurements were >300s. Periprocedural complications occurred in 14 patients (2.1%): 3 AV fistulas (0.5%), 3 pseudoaneurysms (0.5%), three pericardial tamponades (0.5%) and 3 periprocedural TIAs/strokes (0.5%). Notably, the three patients who experienced a TIA/stroke had an effective ACT>300s at the end of the procedure.

Conclusions: A standardized heparinization protocol allows for facilitated intraprocedural ACT management. In the majority of patients effective ACTs were achieved using our novel heparin protocol with successful prevention of excessively high or low ACT values.

 Table 1: Baseline data

 

Table 2: Procedural data