During atrial fibrillation ablation, which measurement is used to monitor anticoagulation status intra-procedurally?

• A. Activated clotting time (ACT)
• B. Electrocardiography
• C. Blood glucose
• D. Oxygen saturation

Answer: (A)

During atrial fibrillation ablation, preventing clot formation on catheters and within the heart is crucial, so anticoagulation is closely monitored. The measurement used to gauge the anticoagulant effect of heparin in real time is the activated clotting time. ACT reflects how long it takes for whole blood to clot after activation and responds rapidly to heparin, allowing the operator to titrate heparin to a target range throughout the procedure. A typical target is in the roughly 300–350 second range, balancing the risk of thromboembolism with bleeding risk. If ACT falls below the target, extra heparin is given; if it becomes too high, dosing can be reduced or paused. In contrast, electrocardiography monitors heart rhythm, while blood glucose and oxygen saturation monitor metabolic and respiratory status, not anticoagulation.