What is your approach to bridging anticoagulation in patients with history of recent HIT?

One should not re-expose patients with past HIT to heparins. Even with remote HIT, there is a high rate of serologic recurrence (eg, Warkentin and Anderson, PMID 27114458) and while the rate of overt HIT relapse may be low with proper precautions, I have seen and published a couple of fatal HIT recurrences. An exception is that re-exposure is permitted for on-pump vascular surgery because of the unique advantages of heparin in this situation (reversibility; established monitoring protocols). In those cases, post-operative alternative anticoagulants should be given while antibody levels are monitored. In others with a history of HIT who require prophylactic or therapeutic anticoagulation, there are suitable alternative anticoagulants available, such as fondaparinux, bivalirudin, argatroban, and DOACs. So why expose your patient to the risk of HIT recurrence?

Also, are you sure that “bridging anticoagulation” is wise for your patient? Emerging data indicate that bridging may not have a favorable risk/benefit ratio for many anticoagulated patients and should be reserved for those at the highest risk for thrombosis during short-term anticoagulant discontinuation.