Lupus Anticoagulant Testing: Taipan Snake Venom Time with Ecarin Time as Confirmatory Test

Testing for the lupus anticoagulant: the good, the bad, and the ugly

“…For example, our laboratories still use mixing studies as a strategy for minimizing the effects of anticoagulant interference, including VKAs, as once recommended [ 23 ], but no longer favored by some experts [ 11 , 12 ]; our reasoning is that this may represent a lesser evil than alternate options. If available, alternate methods to aPTT and dRVVT less affected by VKAs and DOACs could be considered, with the TSVT used as an LA screen and ECT as a confirmatory test in patients on VKAs or on anti-Xa agents [ 19 , 20 ].…”

“…Additional tests are used in some situations, for example, when there is a strong suspicion of LA but aPTT and dRVVT are inconclusive or if there is assay interference (eg, from clinical anticoagulants). Such tests include the Taipan snake venom time (TSVT), the Ecarin clotting time (ECT), and the dilute prothrombin time (PT) [ [18] , [19] , [20] ]. Instead of the aPTT, an alternative sensitive assay based on a similar principle (ie, contact activation) is the silica clotting time [ 16 ].…”

“…An alternative, provided by at least one manufacturer [ 73 ], is to have different options for CaCl 2 reagents, as used to initiate coagulation in the aPTT assay, specifically with and without added heparin neutralizers—these would be applied differentially for use in LA testing vs UFH monitoring. Further development of LA tests less affected by anticoagulants (eg, Taipan- and Ecarin-based tests) could be progressed or made more widely available [ 19 , 20 ]. Such tests have been validated in an ISTH study for use in patients on VKA or direct FXa inhibitor DOACs [ 20 ].…”