Prevalence of FXII-Deficiency and Its Relevance to Monitoring Anticoagulation in Adults Receiving Extracorporeal Membrane Oxygenation

Discrepancy between parallel anti-Xa and activated partial thromboplastin time is related to mortality in patients with Impella-supported cardiogenic shock

BACKGROUND

Managing unfractionated heparin (UFH) during percutaneous mechanical circulatory support for cardiogenic shock (CS) is challenging due to potential discrepancies between coagulation tests.

OBJECTIVES

To study the causes and consequences of discrepancies between anti-Xa and activated partial thromboplastin time (APTT) for UFH monitoring during microaxial flow pump support (Impella) for CS.

METHODS

We assessed patients in CS supported with Impella in 2 tertiary care centers over 62 months. UFH was titrated based on anti-Xa levels with parallel APTT measurements. In-range anti-Xa levels were considered between 0.20 and 0.30 IU/mL or 0.31 and 0.50IU/mL, and the corresponding APTT values were 40 to 55 seconds and 56 to 80 seconds, respectively. Pearson correlation was calculated between anti-Xa and APTT. Samples with in-range anti-Xa but prolonged APTT were analyzed for abnormalities in international normalized ratio (INR; ≥1.5) and/or fibrinogen (<1.5g/L). Mortality during Impella support was then compared in those with and without additional coagulation abnormalities (chi-squared test).

RESULTS

Correlation between anti-Xa and APTT was weak (r = 0.50, P < .001, N = 2447). When anti-Xa was in range (N = 1914 samples), 24% had short, 52% had in-range, and 24% had prolonged APTT. Of the 57 patients with prolonged APTT, 28 had abnormal same-day INR and/or fibrinogen, whereas 29 had normal fibrinogen and INR. Mortality was higher in patients with abnormal INR and/or fibrinogen than in those with normal fibrinogen and INR (32% vs 10%; P = .043).

CONCLUSION

Anti-Xa/APTT discrepancies are frequent during percutaneous mechanical circulatory support for CS, highlighting the importance of a multiple testing strategy. Outcomes of patients with prolonged APTT were related to the presence of abnormal INR and/or fibrinogen, suggesting a serious concomitant underlying disease.

Anticoagulation in venovenous extracorporeal membrane oxygenation

Venovenous extracorporeal membrane oxygenation (VV-ECMO) is a lifesaving therapy in severe acute respiratory distress syndrome (ARDS). Unfortunately, bleeding and thrombotic complications occur regularly due to coagulation disorders associated with the device, the underlying disease, and the anticoagulation management. To facilitate a personalized approach to hemostasis in individuals receiving ECMO support, it is essential to assess the coagulative state of the patient while simultaneously taking into account the underlying medical condition and administered therapies.

Anticoagulation with argatroban using hemoclot™ targets is safe and effective in CARDS patients receiving venovenous extracorporeal membrane oxygenation: An exploratory bi-centric cohort study

Direct thrombin inhibitors, including argatroban, are increasingly used for anticoagulation during venovenous extracorporeal membrane oxygenation (VV ECMO). In many centers activated partial thromboplastin time (aPTT) is used for monitoring, but it can be affected by several confounders. The aim of this study was to evaluate the safety and efficacy of anticoagulation with argatroban titrated according to diluted thrombin time targets (hemoclot™ assay) compared to anti-Xa guided anticoagulation with unfractionated heparin (UFH).

METHODS

This cohort study included adults at two tertiary care centers who required VV ECMO for severe COVID-19-related acute respiratory distress syndrome (CARDS). Patients received center-dependent argatroban or UFH for anticoagulation during ECMO. Argatroban was guided following a hemoclot™ target range of 0.4-0.6 μg/ml. UFH was guided by anti-factor Xa (antiXa) levels (0.2-0.3 IU/ml). The primary outcome was safety of argatroban compared to UFH, assessed by time to first clinically relevant bleeding event or death during ECMO. Secondary outcomes included efficacy (time to thromboembolism) and feasibility (proportion of anticoagulation targets within range).

RESULTS

From 2019 to 2021 57 patients were included in the study with 27 patients (47 %) receiving argatroban and 30 patients (53 %) receiving UFH. The time to the first clinically relevant bleeding or death during ECMO was similar between groups (HR (argatroban vs. UFH): 1.012, 95 % CI 0.44-2.35, p = 0.978). Argatroban was associated with a decreased risk for thromboembolism compared to UFH (HR 0.494 (95 % CI 0.26-0.95; p = 0.034)). The overall proportion of anticoagulation within target ranges was not different between groups (46 % (23-54 %) vs. 46 % (37 %-57 %), p = 0.45).

CONCLUSION

Anticoagulation with argatroban according to hemoclot™ targets (0.4-0.6 μg/ml) compared to antiXa guided UFH (0.2-0.3 IU/ml) is safe and may prolong thromboembolism-free time in patients with severe ARDS requiring VV ECMO.