The Effect of Anticoagulation on Bleeding and Thrombotic Events during Extracorporeal Membrane Oxygenation Support for Postcardiotomy Shock

Abstract

Postcardiotomy shock patients supported with venoarterial extracorporeal membrane oxygenation (VA ECMO) are at high-risk for thrombotic and bleeding complications. No standardized anticoagulation guideline exists for these complex patients. We investigated the incidence of bleeding and thrombotic complications and their relation to anticoagulation therapy during VA ECMO in postcardiotomy shock patients. Between December 2007 and June 2018, VA ECMO was used to support 150 patients with postcardiotomy shock at our hospital. We conducted a retrospective review of this cohort. Bleeding events were defined as bleeding requiring transfusion or re-intervention occurring during VA ECMO support. Thrombotic events included circuit thrombosis, venous or arterial system thrombosis, intracardiac thrombus, and vascular catheter thrombosis. Logistic regression was performed to determine predictors of bleeding and thrombotic events. The median patient age was 65 years (interquartile range [IQR] 55-73). The median duration of VA ECMO support was 4.65 days (IQR 2.75-8.00). 116 patients (77%) were anticoagulated with heparin. The median length from initiation of VA ECMO to anticoagulation was 27 hours (IQR 10-59). The median activated partial thromboplastin time (aPTT) for the duration of support was 43 seconds (IQR 37-50). Bleeding occurred in 42 patients (28%), of which 32 received heparin. Thrombosis occurred in 32 patients (21%), of which 30 received heparin. Both bleeding and thrombosis occurred in 10 patients (6%). The average aPTT in those with bleeding did not differ from those without bleeding (50 vs. 51s, p = 0.719). The average aPTT in those with thrombosis was less than in those without thrombosis (45 vs. 52s, p = 0.047). Multivariable logistic regression demonstrated that bleeding complications were associated with increased length of support (p = 0.005) and female sex (p = 0.004), while thrombotic events were associated with male sex (p = 0.03), history of atrial fibrillation (p = 0.05), and history of hypertension (p = 0.01). Bleeding and thrombotic events are common complications during VA ECMO support for postcarditomy shock. aPTT values during VA ECMO may not adequately reflect the risk of bleeding but may better reflect the risk of thrombosis.