Effect of Apixaban Pretreatment on Alteplase-Induced Thrombolysis: An In Vitro Study

Abstract

Benefit of thrombolytic therapy in patients with acute stroke, who are on anticoagulant treatment, is not well addressed. The aim of this study was to investigate whether apixaban can modify the thrombolytic efficacy of alteplase in vitro. Static and flow models and two variants of red blood cell (RBC) dominant clots, with and without apixaban, were used. Clots were prepared from the blood of healthy human donors and subsequently exposed to alteplase treatment. Apixaban and alteplase were used in clinically relevant concentrations. Clot lysis in the static model was determined both by clot weight and spectrophotometric determination of RBC release. Clot lysis in the flow model was determined by measuring recanalization time, clot length and spectrophotometric determination of RBC release. In the static model, clots without apixaban; compared to those with apixaban had alteplase-induced mass loss 54 ± 8% vs. 53 ± 8%, p = 1.00; RBC release 0.14 ± 0.04 vs. 0.12 ± 0.04, p = 0.14, respectively. Very similar results were obtained if plasma was used instead of physiological buffered saline as the incubation medium. In the flow model, clot lysis without apixaban; compared to those with apixaban was as follows: recanalization time 107 ± 46 min vs. 127 ± 31 min, p = 1.00; recanalization frequency 90 ± 22% vs. 90 ± 22%, p = 1.00; clot volume reduction 32 ± 15% vs. 34 ± 10%, p = 1.00; RBC release 0.029 ± 0.007 vs. 0.022 ± 0.007, p = 0.16, respectively. Apixaban had no positive effect on alteplase-induced thrombolysis in both the in vitro static and flow models. Our data support current clinical practice, such that thrombolysis is contraindicated in stroke treatment for patients who have been treated with anticoagulants.

Keywords: alteplase; apixaban; clot; in vitro; stroke; thrombolysis.

FIGURE 1

Static model: clot lysis expressed as relative clot mass loss. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 54–57 for incubation in PBS and 12–15 for incubation in plasma. Results demonstrate that alteplase treatment provided efficient thrombolysis, e.g., documented as greater clot mass loss compared to untreated group in plasma (52 ± 9% vs. 33 ± 9%, p < 0.01). For clots with and without apixaban, alteplase-induced lysis did not differ, e.g., in plasma clot mass loss was 51 ± 11% vs. 52 ± 9%, p = 1.00. See Supplementary Table S1 for more details.

FIGURE 2

Static model: clot lysis expressed as red blood cell release into incubation media. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 54–57 for incubation in PBS and 12–15 for incubation in plasma. Results demonstrate that alteplase treatment provided efficient thrombolysis, e.g., documented as greater red blood cell release compared to untreated group in plasma (0.12 ± 0.04 vs. 0.05 ± 0.03, p < 0.01). For clots with and without apixaban, alteplase-induced lysis did not differ, e.g., in plasma red blood cell release was 0.09 ± 0.04 vs. 0.12 ± 0.04, p = 0.18. See Supplementary Table S2 for more details.

FIGURE 3

Flow model: time to recanalization of in vitro vessel. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 9–10. Dashed line shows experiment time window. Results demonstrate that alteplase treatment provided efficient thrombolysis, e.g. documented as lower recanalization time compared to untreated group (107 ± 46 min vs. 180 ± 0 min, p < 0.01). For clots with and without apixaban, alteplase-induced lysis did not differ, e.g. recanalization time was 127 ± 31 min vs. 107 ± 46 min, p = 1.00. See Supplementary Table S3 for more details.

FIGURE 4

Flow model: recanalization frequency of in vitro vessel. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 5. Results demonstrate that alteplase treatment provided efficient thrombolysis, e.g. documented as greater recanalization frequency compared to untreated group (90 ± 22% vs. 0 ± 0%, p < 0.01). For clots with and without apixaban, alteplase-induced lysis did not differ, e.g., recanalization frequency was 90 ± 22% vs. 90 ± 22%, p = 1.00. See Supplementary Table S3 for more details.

FIGURE 5

Flow model: clot lysis expressed as relative clot volume reduction. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 9–10. Results demonstrate that alteplase treatment provided efficient thrombolysis, e.g., documented as greater clot volume reduction compared to untreated group (32 ± 15% vs. 14 ± 15%, p = 0.02). For clots with and without apixaban, alteplase-induced lysis did not differ, e.g., clot volume reduction was 34 ± 10% vs. 32 ± 15%, p = 1.00. See Supplementary Table S3 for more details.

FIGURE 6

Flow model: clot lysis expressed as red blood cell release into incubation media. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 9–10. Results demonstrate that alteplase treatment provided efficient thrombolysis, e.g. documented as greater red blood cell release compared to untreated group (0.029 ± 0.007 vs. 0.012 ± 0.007, p < 0.01). For clots with and without apixaban, alteplase-induced lysis marginally increased red blood cell release for clots without apixaban (0.022 ± 0.007 vs. 0.029 ± 0.007, p = 0.16). See Supplementary Table S3 for more details.

FIGURE 7

Clot weight after 5-h of clotting. The forest plot shows mean values (square) and 95% confidence interval (whiskers). n = 142 (clots without apixaban), n = 137 (apixaban-supplemented clots). Results demonstrate that apixaban supplementation provided lower clot weight after 5-h of clotting compared to clots without apixaban (0.07 ± 0.01 g vs. 0.08 ± 0.01 g, p < 0.01).