This study aimed to investigate the relationship between acquired antithrombin deficiency in patients undergoing postcardiotomy extracorporeal membrane oxygenation (PC-ECMO) and thromboembolic or haemorrhagic events such as bleeding, peripheral arterial thromboembolism, and ischemic cerebrovascular events.

The study was designed as a single-center, prospective study and conducted at our hospital between November 2019 and June 2021. 50 patients who underwent ECMO due to postcardiotomy cardiogenic shock were included in the study. Antithrombin (AT) activity testing was performed immediately after ECMO placement and continued for 5 days. The total of haemorrhagic or thromboembolic events was defined as morbidity. The entire patient population was assessed daily for AT measurements according to morbidity status, and ROC analysis was applied to determine the cut-off point. The correlation between clinical outcomes and morbidities with antithrombin levels was analysed.

In our study, we identified a cut-off for AT levels on the first postoperative day. The risk of both bleeding (p = .006) and thromboembolism (p = .012) was significantly higher in patients below the 48.9% cut-off value. AT levels were compared with data on separation from PC-ECMO. The rate of separation from ECMO was 7.969 times higher in cases with AT levels above 51.8 on the third postoperative day and 5.6 times higher in cases with AT levels above 47.5 on the fourth postoperative day.

Acquired antithrombin deficiency may develop in adults undergoing PC-ECMO. In our study, we demonstrated that in patients with low antithrombin levels, the risk of bleeding and thromboembolism increased. Additionally, since AT levels were higher in survivors, this can be considered an indicator of severity. This study is the first prospective study related to determining target antithrombin levels in adult patients undergoing PC-ECMO.