The Diagnostic Accuracy of EXTEM and HEPTEM Clotting Times Versus Standard Laboratory Tests in Cardiac Surgical Patients With and Without Normal FIBTEM Values

Abstract

ObjectiveThere is extensive evidence to support the use of FIBTEM to identify hypofibrinogenemia during cardiac surgery, but less to support the use of EXTEM and INTEM Clotting Times (CTs) to identify other plasmatic coagulation factor deficiencies. The aim of the current study was to assess the diagnostic accuracy of EXTEM, INTEM, and HEPTEM CTs, using laboratory INR and aPTT as reference standards. DesignRetrospective diagnostic accuracy study. SettingTertiary Referral Hospital. Participants176 cardiac surgical patients InterventionsINR, aPTT, ROTEM EXTEM, INTEM, and HEPTEM were measured post-heparin reversal after cardiopulmonary bypass. Measurements and Main ResultsSensitivity, specificity, and positive (PPV) and negative predictive values (NPV) for EXTEM CT>80s and HEPTEM CT>280s to detect INR≥2.0, and for INTEM CT>205s to detect aPTT≥38.5s were calculated for all patients, and for the subset with normal FIBTEM A5 (>6mm). INR≥2.0 prevalence was 13%. EXTEM CT>80s had a sensitivity of 1.00, specificity 0.25, PPV 0.17 and NPV 1.00. HEPTEM CT>280s had a sensitivity of 0.91, specificity 0.38, PPV 0.18, and NPV 0.97. INTEM CT>205s had sensitivity of 0.97, specificity 0.11, PPV 0.57 and NPV 0.75 for aPTT≥38.5s. These values were similar for the subset of patients with normal FIBTEM A5. ConclusionsEXTEM CT>80s and HEPTEM CT>280s have high sensitivities and NPVs for INR>2.0, which would effectively ‘rule out’ INR>2.0 as a cause for excessive bleeding. However, the low specificities and PPVs indicate they would be less effective to rule it in. INTEM CT>205s had both low PPV and NPV to identify aPTT>38.5s.