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

OBJECTIVES

There 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 international normalized ratio (INR) and activated partial thromboplastin time (aPTT) as reference standards.

DESIGN

This was a retrospective diagnostic accuracy study.

SETTING

The work took place at a tertiary referral hospital.

PARTICIPANTS

A total of 176 cardiac surgical patients were enrolled.

INTERVENTIONS

INR, aPTT, ROTEM EXTEM, INTEM, and HEPTEM were measured post-heparin reversal after cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Sensitivity, specificity, and positive (PPVs) and negative predictive values (NPVs) for EXTEM CT >80 seconds and HEPTEM CT >280 seconds to detect INR ≥2.0, and INTEM CT >205 seconds to detect aPTT ≥38.5 seconds were calculated for all patients and the subset with normal FIBTEM A5 (>6 mm). The prevalence of INR ≥2.0 was 13%. EXTEM CT >80 seconds had a sensitivity of 1.00, specificity of 0.25, PPV of 0.17, and NPV of 1.00. HEPTEM CT >280 seconds had a sensitivity of 0.91, specificity of 0.38, PPV of 0.18, and NPV of 0.97. INTEM CT >205 seconds had a sensitivity of 0.97, specificity of 0.11, PPV of 0.57, and NPV of 0.75 for aPTT ≥38.5 seconds. These values were similar for the subset of patients with normal FIBTEM A5.

CONCLUSIONS

EXTEM CT >80 seconds and HEPTEM CT >280 seconds 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 in ruling it in. INTEM CT >205 seconds had low PPV and NPV in identifying aPTT >38.5 seconds.