Management of Suspected Heparin Resistance Among Patients in the Cardiac Intensive Care Setting

Abstract

Background:

Heparin resistance (HR) poses the risk for significant complications, as subtherapeutic anticoagulation may lead to thrombotic events; however, there remains a lack of guidance on standardized management strategies in cardiac intensive care unit (CICU) patients and those with mechanical circulatory support (MCS) devices.

Objective:

The purpose of this study is to describe current management strategies for patients with suspected HR and provide insights into its definition among critically ill cardiac patients.

Methods:

This retrospective study evaluated intensive care unit (ICU) patients receiving greater than or equal to 25 units/kg/h of unfractionated heparin (UFH) that failed to achieve 2 consecutive therapeutic activated partial thromboplastin time (aPTT) values. The primary outcome was incidence of patients transitioned to a direct thrombin inhibitor (DTI). Secondary outcomes included major bleeding, thrombosis, and antithrombin III supplementation. A subgroup analysis compared anticoagulation characteristics by agent (UFH vs. DTI), including anticoagulant infusion volume, and time to goal aPTT.

Results:

Of 76 patients receiving titratable UFH, 62 (81.6%) met inclusion criteria. Transition to a DTI occurred in 4 (6.5%) patients, all who received bivalirudin. Major bleeding occurred in 4 (6.5%) patients and thrombosis in 2 (3.2%) while receiving UFH. Median time to goal aPTT was 88 (interquartile range [IQR] = 55.3-123.3) hours with UFH vs. 6 (IQR = 3.7-11.3) hours with bivalirudin (P = 0.002). Median daily anticoagulant volume was 578 (IQR = 404.0-770.4) mL with UFH vs. 190 (IQR = 147.3-218.5) mL with bivalirudin (P = 0.001).

Conclusion and Relevance:

Our findings describe current management practices for suspected HR among critically ill cardiac patients. Although the small subset of patients transitioned to DTI limits generalizability, earlier recognition and individualized anticoagulation strategies may be warranted in MCS patients given their inherent thrombotic risk. Future studies are needed to further define HR and evaluate anticoagulation strategies in this population.