Clinical applicability of anti-Xa measurements to monitor unfractionated heparin activity during arterial procedures: a scoping review

The anti-Xa test is regarded as the standard assay to measure unfractionated heparin activity in a laboratory setting, but its use during arterial procedures has not been established. The objectives of this systematic review, designed as a scoping review, were to structure the existing body of evidence, identify possible research gaps, and provide guidance for future research on the applicability of anti-Xa to measure the heparin activity during arterial procedures. Literature search resulted in 55 included reports (cardiac procedures: 44 reports; noncardiac procedures: 9 reports; cardiac and noncardiac procedures: 2 reports). During arterial procedures, anti-Xa is widely used as reference laboratory test to validate heparin point-of-care assays, compare different heparinization strategies and measure residual heparin activity at the end of the procedure or after heparin reversal using protamine. There is considerable heterogeneity among included reports, which hampers the ability to draw firm conclusions. The available literature is insufficient to define optimal periprocedural heparin activity measured by anti-Xa. Currently, anti-Xa is not used as a primary heparin monitoring assay during arterial procedures. The impact of alterations in periprocedural anti-Xa activity on clinical outcomes has been rarely investigated. Anti-Xa measurements appear to be reproducible compared with point-of-care heparin activity essays but require standardization. In conclusion, anti-Xa is useful as a reference test to evaluate point-of-care heparin testing and compare heparin strategies during arterial procedures, but there is a high need for studies to investigate correlation of anti-Xa levels with clinical outcomes and to determine optimal anti-Xa levels for arterial procedures.