Reliability of thromboelastometry for detecting the safe coagulation threshold in patients taking acenocoumarol after...

Reversal of anticoagulation can be needed in patients undergoing heart valve surgery. ROTEM® has been correlated with international normalized ratio (INR) in patients on warfarin but not with patients on acenocoumarol. This study investigates the reliability of ROTEM® for detecting INR values below the 1.5 threshold in patients on acenocoumarol therapy.

Patients on oral anticoagulation with acenocoumarol after elective heart valve replacement were prospectively included in the study. INR and the ROTEM® were measured simultaneously. ROTEM® parameters included coagulation time, clot formation time, alpha angle, and maximal clot firmness after tissue factor activation (EXTEM). Concordance between INR and ROTEM® was analyzed by Lin's concordance coefficient (LCC) and the correlation with Spearman's rho.

Fifty-four consecutive patients (40 female; median age 67years) were included. Clotting time (CT) was the parameter that best correlated with INR (r=0.81, p<0,001), and LCC was substantial (0.67). CT was able to predict INR values above or below 1.5: area under curve=0.998. CT≥84seconds, corresponding to a cut-off for likelihood ratio (LR+)=5, had a sensitivity and specificity of 100% and 80%, respectively, to detect an INR below 1.5. For the same INR threshold, CT≥84seconds had a predictive positive value of 92.9% and a predictive negative value of 100%.

Our preliminary results suggest that CT≥84seconds in the EXTEM ROTEM® test is a feasible method for predicting an insufficient reversion of oral anticoagulant therapy in patients taking acenocoumarol after elective heart valve surgery.