Bivalirudin during cardiopulmonary bypass in patients with previous or acute heparin-induced thrombocytopenia and heparin antibodies: results of the CHOOSE-ON trial.

Background: The coronary artery bypass grafting (CABG) heparin-induced thrombocytopenia thrombosis syndrome (HITTS) on- and off-pump safety and efficacy (CHOOSE-ON) trial was designed as a safety and efficacy trial of bivalirudin for use in anticoagulation during cardiopulmonary bypass (CPB) in patients with confirmed or suspected HIT and (or) antiplatelet factor 4/heparin (anti-PF4/H) antibodies.

Methods: In an open-label, multicenter trial, 50 patients were enrolled prospectively. The primary study endpoint was in-hospital acute procedural success, defined as the absence of death, Q-wave myocardial infarction (MI), repeat operation for coronary revascularization, and stroke at day seven after surgery or hospital discharge, whichever occurred first. The secondary study endpoints were procedural success, defined as the absence of death, Q-wave MI, repeat operation for coronary revascularization, and stroke, at 30 days and 12 weeks after surgery. Perioperative blood loss, transfusions, and the incidence of major bleeding events were also captured.

Results: There were 49 patients treated with bivalirudin of which 43 had acute HIT and thrombosis syndrome (HITTS) with antibodies at time of surgery. Procedural success in-hospital or at 7 days was achieved in 46 (94%) patients. At day 30 procedural success was achieved in 42 (86%) patients, and after 12 weeks in 40 (82%) patients. Mean intraoperative blood loss was 575 +/- 524 mL, and mean 24-hour postoperative blood loss was 998 +/- 595 mL. Forty-one (84%) patients received transfusions before day 7 or discharge with a mean of 5.6 +/- 3.8 units of red blood cells, 8.6 +/- 7.2 units of platelets, and 6.0 +/- 4.7 units of fresh frozen plasma. No differences in outcome among bivalirudin-treated patients were observed between those in the overall group and those with moderately impaired renal function (n = 10).

Conclusions: The current investigation expands the experience of safe and effective anticoagulation with bivalirudin during CPB to patients with confirmed or suspected HIT and anti-PF4/H antibodies, including in the setting of impaired renal function.