Activated clotting time in cardiac surgery, cardiological interventional procedures, vascular surgery, extracorporeal membrane oxygenation, and haemodialysis
Year: 2026
Type: article
Abstract: The activated clotting time (ACT) is a point-of-care test used to monitor unfractionated heparin (UFH) in acute care settings. Although widely recommended in cardiac surgery, interventional cardiology, vascular surgery, extracorporeal membrane oxygenation, and haemodialysis, important uncertainties remain regarding its use. Given the lack of interchangeability between ACT devices and consumables, clear information on targets and analytical systems is essential. We reviewed guideline documents published before November 1, 2025, as well as recommendations from major scientific societies, to assess ACT use, thresholds, and reported levels of evidence. Studies cited within these guidelines were also analysed, and the characteristics of ACT devices were compared with those currently available. A total of 24 guideline documents were identified, of which 17 specified ACT target values and only two mentioned the device or reagent used. The level of evidence was generally low or not graded. For example, during cardiopulmonary bypass, recommended ACT thresholds vary (e.g., 480 s without heparin-coated circuits or 400 s with the so-called maximal activation), without specification of the analytical system. Guidelines often rely on outdated studies using devices no longer available. Moreover, ACT analysers differ substantially in consumables, clot detection methods, blood volume, and reagents, which are rarely considered in recommendations. In conclusion, current guidelines provide limited guidance on ACT measurement despite significant inter-device variability. We recommend that future guidelines specify devices and consumables, or at least their sensitivity to UFH, to ensure reliable interpretation. Further studies are needed to optimise UFH monitoring in clinical practice.
Language: English
Subfield: Hematology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7224106631