Enoxaparin anticoagulation monitoring in the catheterization laboratory using a new bedside test

This study evaluated the ability of the bedside test Hemochron Jr. Hemonox (International Technidyne Corporation, Edison, New Jersey) to identify patients with insufficient anti-Xa activity level in the catheterization laboratory.

Inadequate anticoagulation in patients undergoing percutaneous coronary intervention (PCI) is associated with increased periprocedural ischemic events.

In 296 unselected patients undergoing catheterization and/or PCI, whole blood Hemonox clotting time (CT) and activated partial thromboplastin time (aPTT) were measured at baseline (T1) and 10 min after the intravenous administration of enoxaparin (T2) in patients receiving additional enoxaparin and compared with plasma chromogenic anti-Xa activity level.

Median values were 0.1 IU/ml (interquartile range [IQR]: 0.1 to 0.1 IU/ml) and 0.87 IU/ml (IQR: 0.74 to 1.03 IU/ml) for anti-Xa; 74 s (IQR: 70 to 81 s) and 143 s (IQR: 114 to 206 s) for Hemonox CT; and 44 s (IQR: 39 to 50 s) and 72 s (IQR: 58 to 93 s) for aPTT at T1 and T2, respectively. When using Hemonox CT to discriminate patients with anti-Xa level <0.5 IU/ml, the area under the receiver operating characteristic curve was 0.95 +/- 0.01 (95% confidence interval [CI]: 0.93 to 0.97) versus 0.89 +/- 0.01 (95% CI: 0.86 to 0.92) for aPTT. The threshold value of 120 s was associated with a 94.9% (95% CI: 91.1% to 97.4%) sensitivity and a 73.3% (95% CI: 67.6% to 78.5%) specificity to detect patients with inadequate anti-Xa level (<0.5 IU/ml) and positive predictive and negative predictive values of 73.9% (95% CI: 68.7% to 79.0%) and 94.78% (95% CI: 91.8% to 97.8%), respectively.

Hemonox CT appears to be a fast and reliable bedside test for detecting patients insufficiently anticoagulated and needing adjustment of anticoagulation therapy with enoxaparin before PCI.