A physiology-based approach to ROTEM interpretation for bleeding management in cardiac surgery: A narrative review

Perioperative bleeding after cardiac surgery is common, multifactorial, and resource intensive. Conventional coagulation tests are often delayed and do not describe clot development in whole blood, whereas rotational thromboelastometry (ROTEM) provides point-of-care information about clot initiation, clot firmness, residual heparin effect, and fibrinolysis. This narrative review summarizes guideline statements, randomized trials, systematic reviews, and clinically relevant mechanistic literature on viscoelastic testing in cardiac surgery. Literature was identified through targeted searches of PubMed-indexed and major cardiothoracic anesthesia sources, prioritizing patient blood management guidelines, studies of ROTEM- or thromboelastometry-guided transfusion algorithms, and evidence relevant to FIBTEM, HEPTEM, protamine, fibrinogen replacement, platelet contribution, and antifibrinolytic therapy. The review proposes a stepwise approach that begins with clinical context, evaluates EXTEM clotting time, integrates early EXTEM and FIBTEM clot amplitude, uses INTEM and HEPTEM to distinguish residual heparin from non-heparin causes of delayed clot initiation, screens for hyperfibrinolysis, and requires repeat testing after targeted intervention. The framework is intended to complement local transfusion protocols and patient blood management programs, support interdisciplinary communication, and reduce empiric transfusion.