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.

Bivalirudin Anticoagulation for a Patient with Hypercoagulable Immune Syndromes Undergoing Mitral Valve Surgery

Unfractionated heparin has been a near universal anticoagulant for cardiac surgery; however it is contraindicated in heparin-induced thrombocytopenia type II. Alternative anticoagulants such as bivalirudin (a direct thrombin inhibitor) are being utilized. Bivalirudin was successfully used in an immunologically complex patient (diagnoses of heparin-induced thrombocytopenia type II, systemic lupus erythematosus, antiphospholipid syndrome, and dialysis-dependent renal failure) requiring cardiopulmonary bypass. Thrombotic events are common in antiphospholipid syndrome patients undergoing cardiac surgery utilizing high-dose heparin. This may represent unrecognized heparin-induced thrombocytopenia type II. Our patient did not experience perioperative thrombotic or bleeding complications. The possible cross-reactivity between heparin induced thrombocytopenia type II and antiphospholipid syndrome has not been investigated.

A comparison of bivalirudin to heparin with protamine reversal in patients undergoing cardiac surgery with cardiopulmonary bypass: The EVOLUTION-ON study

OBJECTIVES

Unfractionated heparin and its antidote, protamine sulfate, allow for rapid and reversible anticoagulation during cardiac surgery with cardiopulmonary bypass, yet limitations exist, including a variable dose-response, dependence on a cofactor for anticoagulant effect, and antigenic potential. This trial was performed to evaluate the safety and efficacy of bivalirudin as an alternative to heparin with protamine reversal in on-pump cardiac surgery.

METHODS

We conducted a randomized, open-label, multicenter trial comparing heparin with protamine reversal to bivalirudin in patients undergoing cardiac surgery with cardiopulmonary bypass. The primary objective was to demonstrate comparable rates of in-hospital procedural success defined as freedom from death, Q-wave myocardial infarction, stroke, or repeat revascularization. Twenty-one institutions enrolled 101 patients randomized to bivalirudin and 49 patients to heparin treatment.

RESULTS

The primary end point of procedural success was not significantly different between the bivalirudin arm and the heparin/protamine arms at 7 days, 30 days, or 12 weeks' follow-up. Adequate anticoagulation was achieved in all patients. Secondary end points including mortality, 24-hour blood loss, overall incidence of transfusions, and duration of surgery were similar between the two arms.

CONCLUSIONS

Bivalirudin is a safe and effective anticoagulant for patients undergoing a wide range of cardiac surgical procedures with cardiopulmonary bypass. Procedural success rates with bivalirudin were similar to rates in patients receiving heparin anticoagulation, with no difference in mortality. Avoidance of blood stasis and attention to the intraoperative medical management of patients is critical for successful use of bivalirudin during cardiopulmonary bypass.

Anticoagulation with bivalirudin for off-pump coronary artery bypass grafting: the results of the EVOLUTION-OFF study

OBJECTIVES

Unfractionated heparin has many shortcomings, including indirect and partial inhibition of thrombin, antibody formation, and platelet activation. Bivalirudin, a short-acting direct thrombin inhibitor, avoids these limitations and has superior outcomes during percutaneous revascularization. This trial was performed to evaluate the safety and efficacy of bivalirudin in off-pump coronary artery bypass grafting.

METHODS

An open-label, multicenter randomized trial compared heparin with protamine reversal to bivalirudin in patients undergoing off-pump coronary artery bypass. The primary objective was safety as demonstrated by similar rates of procedural success defined as freedom from a composite of death, myocardial infarction, stroke, and repeat revascularization. Twenty-one institutions randomized 105 patients to receive bivalirudin and 52 patients to receive heparin.

RESULTS

The mean age was 65 years for both groups. The bivalirudin group had more grafts: 3.0 +/- 1 versus 2.5 +/- 1. Procedural success rates at 30 days were identical in bivalirudin- and heparin-treated patients (93%). Operative times, total blood loss, reoperations for bleeding, and major adverse events were not significantly different. Strokes were more frequent in the heparin group: 5.5% versus 0; P = .05. Mortality was 2% in each group. Repeat revascularization was required in 3% of bivalirudin- and 2% of the heparin-treated patients.

CONCLUSIONS

For patients undergoing off-pump coronary artery bypass grafting, bivalirudin was an effective anticoagulant, without excessive bleeding and with a safety profile similar to that of heparin. Further trials are warranted to assess whether anticoagulation with bivalirudin improves clinical outcomes.