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Updated: May 23, 2025
Utilizing Percutaneous Ventricular Assist Devices in Acute Myocardial Infarction Complicated by Cardiogenic Shock
Published on: June 12, 2021
Discrepancy between parallel anti-Xa and activated partial thromboplastin time is related to mortality in patients
Charlotte J Van Edom1, Francesca Fiorelli2, Tim Balthazar3
1Department of Cardiovascular Diseases, University Hospitals of Leuven, Leuven, Belgium; Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
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.
