The use of a HEMOCHRON JR. HEMONOX point of care test in monitoring the anticoagulant effects of enoxaparin during interventional coronary procedures.

BACKGROUND

Enoxaparin is increasingly used for the anticoagulation of patients undergoing percutaneous coronary intervention (PCI). Several reports have suggested the utility of using point of care tests in monitoring the anticoagulation levels of enoxaparin in patients undergoing PCI. The objective of this study was to evaluate a new point-of-care test (POCT) HEMONOX in monitoring the anticoagulant effect of enoxaparin in non citrated fresh whole blood samples from patients undergoing elective PCI procedure.

METHODS

Following IRB approval, blood samples were obtained from fifty-four patients who received two sequential intravenous doses of enoxaparin; 0.1 mg/kg followed 5 min later by 0.4 mg/kg for a total of 0.5 mg/kg. Blood was drawn at baseline and at 5, 10, 30 and 60 min post first bolus for evaluation in the clot-based POCT HEMONOX, ACT and aPTT and the chromogenic anti-Xa activity assay.

RESULTS

HEMONOX clotting time (CT) at baseline was 62.6 +/- 6.2 secs, (n = 32) in healthy donors and statistically higher in PCI patients (71.6 +/- 9.1 secs, p = 0.0001). The peak HEMONOX response that was always achieved at 10 min post bolus was >100 secs in all 54 patients, of these 83% yielded CT >150 secs (range: 150-466). There was no detectable anti-Xa activity level at baseline while peak HEMONOX CT corresponded to therapeutic levels (0.85 +/- 0.14 U/ml; range: 0.61-1.34). Both HEMONOX CT and anti-Xa level significantly decreased at the time of sheath removal. HEMONOX CT at peak response suggested 3 patient subgroups with different levels of sensitivity to enoxaparin: low, intermediate and high responders. The correlation between anti-Xa activity level and HEMONOX CT was >or=0.85 in each patient subgroup when data from the 3 critical time points; baseline (absence of drug), peak response (10 min post bolus) and sheath removal (60 min post bolus) were analyzed. The correlation diminished to >or=0.83 when the analyses included data from all 5 time points [baseline, 5, 10, 30, and 60 min post bolus]. The HEMONOX test was the most sensitive POCT to measure the anticoagulant effects of enoxaparin. All patients completed PCI successfully.

CONCLUSION

The HEMONOX test may be able to guide anticoagulation with enoxaparin during PCI. The HEMONOX assay is a one step whole blood coagulation test performed on the HEMOCHRON Jr. Signature + POC system. The method was evaluated to monitor the anticoagulant level of enoxaparin in blood samples from patients undergoing PCI after receiving an intravenous dose of 0.5 mg/kg. The results suggest a clear distinction of HEMONOX CT between the baseline value of untreated patients and patients achieving therapeutic enoxaparin levels.