Cangrelor with Heparin for Patients with Heparin-Induced Thrombocytopenia Undergoing Pulmonary Thromboendarterectomy

Abstract

Optimal intraoperative anticoagulation strategy for patients with heparin-induced thrombocytopenia (HIT) undergoing pulmonary thromboendarterectomy (PTE) that necessitates deep hypothermic circulatory arrest (DHCA) remains controversial. Cangrelor is an intravenous direct-acting P2Y12 platelet receptor antagonist that achieves therapeutic effect and eliminates rapidly. Its antiplatelet activity is unaffected by stagnation of blood, nor is it influenced by patient's age, renal status or hepatic function. We report our novel strategy and experience in utilizing cangrelor in combination with heparin for anticoagulation during cardiopulmonary bypass (CPB) and DHCA in HIT patients undergoing PTE. Retrospective chart review of 297 patients who underwent PTE from January 2018 through June 2019 was performed. Patients with suspected, acute, subacute A/B, and remote HIT at the time of procedure were identified (n=7). All 7 patients received cangrelor with heparin intraoperatively for anticoagulation during CPB and DHCA. Our institutional intraoperative anticoagulation strategy for HIT patients is to administer a loading dose of cangrelor (30 μg/kg) prior to giving full-dose heparin for CPB. Cangrelor infusion is initiated at 4 μg/kg/min and is adjusted throughout CPB depending on the intraoperative VerifyNow P2Y12 reaction unit values. Cangrelor infusion is stopped 10 minutes before heparin reversal with protamine. Postoperatively, bivalirudin and warfarin were used for anticoagulation. Of these 7 patients, HIT was suspected in 3 patients (43%) at the time of procedure, whilst 1 patient had subacute B HIT and 1 patient had remote HIT. Acute HIT was confirmed by serotonin release assay in 2 patients (29%) who underwent emergent PTE. All patients survived the procedure. Intraoperative platelet transfusion was required by 4 patients (57%). There were no serious postoperative thrombotic events nor major bleeding complications that required re-operation. One in-hospital death was associated with advanced intracardiac malignancy. The mean postoperative hospital stay was 10.6±5.5 days. In patients with various phases of HIT who require PTE, the use of cangrelor in combination with heparin may be a promising alternative intraoperative anticoagulation strategy providing acceptable outcomes.