(911) Low- Versus Standard-Intensity Heparin Infusion in Patients at Risk for Rebleeding

Introduction: Guidance on unfractionated heparin (UFH) infusion in patients at risk of bleeding is limited. Observational studies comparing UFH infusions with lower aPTT targets and standard-intensity infusions have mixed results in bleeding incidence. Our study aims to clarify the role of low-intensity UFH infusions in patients at risk of rebleeding.

Methods: This was an IRB approved, retrospective cohort study. Reports of UFH infusion orders between September 2018 and April 2024 were generated. Data was collected by individual chart review. The facility uses a standard-intensity aPTT goal of 50-90 seconds and 40-60 seconds for low-intensity which correspond to anti-Xa levels of 0.3 – 0.7 IU/mL and 0.2 – 0.4 IU/mL, respectively. Adults were included if they met ISTH major bleed criteria within 30 days prior to infusion and were admitted to an ICU. Patients were excluded if they received ECMO, EKOS, pregnant, incarcerated, or if the infusion was held for any reason other than bleeding or supratherapeutic aPTT. The primary outcome was recurrence of ISTH major bleeding in the initial 72 hours of infusion. Secondary outcomes included any bleeding within 72 hours, mean and peak aPTT within 72 hours, time to aPTT goal, new or worse thromboembolism, and 30-day all-cause mortality.

Results: A total of 505 patients were screened and 28 were included. Fifteen patients received standard-intensity and 13 received low-intensity. For the primary outcome, ISTH major bleeding recurred in 3 (20%) patients in the standard-intensity group and in 1 (7.7%) patient in the low-intensity group (p=0.6). Six patients in the standard-intensity group experienced any bleeding within the first 72 hours of infusion versus 3 with low-intensity (p=0.44). The median aPTT in 72 hours was within the goal range for each group. The median time to goal aPTT was similar between groups. There were no incidences of new/worse thromboembolism in either group. Thirty-day all-cause mortality was similar between the groups.

Conclusions: Low-intensity UFH resulted in numerically less major bleeding in patients with a recent major bleed. This finding was not statistically significant and the study was not powered to detect a difference in this outcome. Randomized-controlled trials are needed to analyze safety between the dosing strategies.