Hetastarch and Bleeding Complications After Off-Pump Coronary Bypass Surgery

There has been continuing debate about whether use of hetastarch for volume replacement in coronary artery bypass surgery [CABG] increases the risk of postoperative bleeding. A recent meta-analysis of hetastarch use in on-pump CABG concluded that use of hetastarch in these procedures is associated with increased risk, but the safety of hetastarch use in off-pump procedures remains unresolved.

We designed a double-blinded randomized clinical trial to investigate this question. The study was designed as an equivalence trial. Statistical power calculations were performed taking this into consideration. Sealed assignments from a block randomization table developed prior nto initiation of the trial were unsealed in the operating room. These were used to assign patients scheduled for off-pump CABG to receive either 1 L of hetastarch or 1 L of albumin as part of intraoperative volume replacement. Albumin was used for all subsequent intraoperative and postoperative fluid replacement.

The rate of postoperative bleeding was assessed prospectively by monitoring hourly chest tube drainage and number of units of blood products transfused postoperatively in the Intensive Care Unit. Risk was assessed by a Data Safety Monitoring Committee (DSMC) established for this trial. The SAMC was scheduled per protocol to meet after the first 15 subjects (both groups combined) had 1000cc or more of chest tube drainage in the first 12 hours postoperative, and then subsequently either after 15 additional bleeds of this volume or following a schedule set at the discretion of the DSMC.

The trial was continued until 156 patients had been recruited. At that time, 78 participants each had been assigned to the hetastarch and albumin groups. DSMC review at that time determined that use of hetastarch is associated with a risk of postoperative bleeding which is greater than the risk associated with use of albumin and the DSMC accordingly halted the trial.