Association of activated clotting time with hemorrhagic or thromboembolic events controversial and limited, suggests research

Bleeding vs. Non-Bleeding ACT Studies

The review identified 8 studies reporting on ACT values in patients with and without bleeding, and 3 studies reporting on ACT values in patients with and without thrombosis. The meta-analysis of the 8 studies found no significant difference in mean ACT values between patients with and without bleeding (SMD = 0.69, 95% CI -0.05 to 1.43, p=0.069). However, there was high heterogeneity among the studies (I2=87.4%). After excluding one study that significantly contributed to the heterogeneity, the repeated meta-analysis still did not find a significant difference in ACT values between the groups (SMD = 0.40, 95% CI -0.01 to 0.82, p=0.058).

Thrombosis vs. Non-Thrombosis ACT Studies

The meta-analysis of the 3 studies reporting on thrombosis also did not find a significant difference in mean ACT values between patients with and without thrombotic events (SMD = 0.47, 95% CI -0.50 to 1.44, p=0.342), although there was high heterogeneity (I2=81.1%).

Use of ACT in ECMO

The review highlights that despite the widespread use of ACT for anticoagulation monitoring during ECMO, the evidence on its association with hemorrhagic or thromboembolic complications remains limited and controversial. Factors such as the timing of ACT measurements, as well as the intrinsic limitations of ACT (e.g. influence by hypothermia, platelet count/function, coagulation factors), may contribute to the inconsistent findings across studies. The authors conclude that further research is essential to elucidate the role of ACT in anticoagulation monitoring for ECMO patients. Prospective or randomized studies with standardized measurement protocols are needed to better understand the relationship between ACT and adverse events during ECMO support. Additionally, the development and evaluation of alternative anticoagulation monitoring strategies, such as anti-factor Xa and viscoelastic testing, may help clarify the most appropriate approach for this patient population.

Key Points

1. The systematic review and meta-analysis examined the association between activated clotting time (ACT)-guided anticoagulation monitoring and the occurrence of hemorrhagic or thromboembolic complications in patients receiving extracorporeal membrane oxygenation (ECMO) support.

2. The meta-analysis of 8 studies found no significant difference in mean ACT values between patients with and without bleeding, although there was high heterogeneity among the studies. After excluding one study, the repeated meta-analysis still did not find a significant difference in ACT values between the groups.

3. The meta-analysis of 3 studies reporting on thrombosis also did not find a significant difference in mean ACT values between patients with and without thrombotic events, although there was high heterogeneity.

4. The review highlights that despite the widespread use of ACT for anticoagulation monitoring during ECMO, the evidence on its association with hemorrhagic or thromboembolic complications remains limited and controversial.

5. Factors such as the timing of ACT measurements, as well as the intrinsic limitations of ACT (e.g. influence by hypothermia, platelet count/function, coagulation factors), may contribute to the inconsistent findings across studies.

6. The authors conclude that further research is essential to elucidate the role of ACT in anticoagulation monitoring for ECMO patients, and that prospective or randomized studies with standardized measurement protocols are needed. Additionally, the development and evaluation of alternative anticoagulation monitoring strategies, such as anti-factor Xa and viscoelastic testing, may help clarify the most appropriate approach for this patient population.

Reference –

Daniel Schwaiger et al. (2024). Association Of Activated Clotting Time-Guided Anticoagulation With Complications During Extracorporeal Membrane Oxygenation Support: A Systematic Review And Meta-Analysis.. *Journal Of Cardiothoracic And Vascular Anesthesia*. https://doi.org/10.1053/j.jvca.2024.09.003