Coagulation and Fibrinolytic Activity of Tenecteplase and Alteplase in Acute Ischemic Stroke
Background and Purpose—We compared the fibrinolytic activity of tenecteplase and alteplase in patients with acute ischemic stroke, and explored the association between hypofibrinogenaemia and intracerebral hemorrhage.
Methods—Venous blood samples from a subgroup of participants in the Alteplase–Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST) study were obtained at pretreatment, 3 to 12 hours, and 24±3 hours post-intravenous thrombolysis for analyses of plasminogen, plasminogen activator inhibitor-1, d-dimer, factor V, fibrinogen, and fibrin(ogen) degradation products, in addition to routine coagulation assays. Related sample Wilcoxon signed-rank tests were used to test the within-group changes, and independent Mann–Whitney tests for between-group differences.
Results—Thirty patients were included (alteplase=14 and tenecteplase=16) with similar baseline demographics. Compared with baseline, alteplase caused significant hypofibrinogenaemia (P=0.002), prolonged prothrombin time (P=0.011), hypoplasminogenaemia (P=0.001), and lower factor V (P=0.002) at 3 to 12 hours after administration with persistent hypofibrinogenaemia at 24 hours (P=0.011), whereas only minor hypoplasminogenaemia (P=0.029) was seen in the tenecteplase group. Tenecteplase consumed less plasminogen (P<0.001) and fibrinogen (P=0.002) compared with alteplase.
Conclusions—In patients with acute ischemic stroke, alteplase 0.9 mg/kg caused significant disruption of the fibrinolytic system, whereas tenecteplase 0.25 mg/kg did not, consistent with the trend toward lower intracerebral hemorrhage incidence with tenecteplase in the ATTEST study.
Intravenous thrombolysis with alteplase in acute ischemic stroke improves clinical outcome, but is associated with an absolute risk of fatal intracerebral hemorrhage (ICH) of around 2.7%, ≈7-fold greater odds compared with placebo (odds ratio [95% confidence interval], 7.14 [3.98–12.79]).1 In 2 phase 2 trials in acute ischemic stroke,2,3 tenecteplase was associated with a trend toward fewer ICH complications.
As a substudy of the Alteplase–Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST) study, we compared the effects of the 2 agents on coagulation and the fibrinolytic system, and explored potential associations with ICH.
The study protocol of ATTEST has been detailed elsewhere.3 Eligible thrombolysis candidates within 4.5 hours of onset were randomized to receive a standard alteplase regime (0.9 mg/kg) or 0.25 mg/kg tenecteplase. This substudy was initiated partway through the main trial. All trial participants were approached after it commenced.
Venous blood samples were collected into citrate (final concentration 0.109 mol/L, Greiner Bio-One, Austria) at baseline (prethrombolysis; time point [TP] 1), 3 to 12 hours (TP2), and 24±3 hours (TP3) after the initiation of thrombolysis. Plasma was harvested by centrifugation immediately after sampling and stored at −80°C until analysis. We measured prothrombin time, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products, plasminogen, d-dimer, factor V (FV), plasminogen activator inhibitor-1 activity, and prothrombin fragment 1+2 (F1+2) at 3 TPs, respectively (assay methods are shown in detail in Table I in the online-only Data Supplement).
Baseline values were expressed as mean±SD, changes at TP2 and TP3 as mean±SD percent change from baseline. We used related sample Wilcoxon signed-rank tests to examine the within-groups differences (TP2 versus TP1 and TP3 versus TP1), using a Bonferroni correction to yield a significance level of P<0.025. Between-group effects were explored with independent Mann–Whitney test. An univariate binary logistic regression model was used to explore any association between the change of fibrinogen and ICH.
Of 104 participants in the main ATTEST trial, 30 participated in this substudy (alteplase=14 and tenecteplase=16; Figure I in the online-only Data Supplement). Key baseline characteristics were similar between groups (Table).
Effects on Coagulation and Fibrinolysis
Alteplase was associated with prolongation of prothrombin time (P=0.005), reduced fibrinogen (P=0.011) and plasminogen (P<0.001), elevated fibrin(ogen) degradation products (P=0.002) 24-hour post-thrombolysis, a transient drop of factor V (P=0.002), and increase of d-dimer (P=0.003) at TP2 (Figure; Table II in the online-only Data Supplement). In contrast, tenecteplase resulted only in elevation of fibrin(ogen) degradation products (P=0.009), d-dimer (P=0.008) ≤24 hours and transient reduction of plasminogen (P=0.029) at TP2.
Compared with tenecteplase, alteplase induced greater change of prothrombin time (P=0.037), fibrinogen (P=0.002), plasminogen (P<0.001), and factor V (P=0.002) at TP2, with sustained differences in prothrombin time (P=0.031), fibrinogen (P=0.011), and plasminogen (P=0.001) at 24 hours.
Association Between ICH and Depletion of Fibrinogen
Six patients had hemorrhage post-thrombolysis (4 with alteplase and 2 with tenecteplase), 4 classified as hemorrhagic infarction4 1, 1 as hemorrhagic infarction type2, and 1 had a small subarachnoid hemorrhage. None was considered symptomatic using either the second European Co-Operative Acute Stroke Study (ECASS 2) or the Safe Implementation of Thrombolysis for Stroke - Monitoring Study (SITS-MOST) criteria.5
Fibrinogen level dropped below 1 g/L at TP2 in 2 patients, both of whom received alteplase (2/30, 14%). This low level persisted at TP3 in 1, whose follow-up CT revealed hemorrhagic infarction type2; the other patient’s fibrinogen rose to 1.4 g/L at TP3, who had subarachnoid hemorrhage. Binary logistic regression found no association between ICH and the change of fibrinogen between TP2 and TP1 (P=0.37).
Tenecteplase has 15-fold higher fibrin specificity than alteplase.6 High fibrin affinity should translate into greater potency for thrombolysis, while preserving the integrity of systemic coagulation.7 Acute ischemic stroke trials suggest that tenecteplase may be associated with lower ICH risk with similar or superior recanalization compared with alteplase.2,3 In this sample, alteplase caused significant fibrinogen depletion and consumption of plasminogen, and degradation of factor V, whereas tenecteplase did not.
Early degradation of fibrinogen is associated with the occurrence of ICH. Matosevic et al8 reported that within 6-hours post-thrombolysis, a decrease of ≥2g/L in fibrinogen level was an independent predictor for bleeding of all kinds. Significant hypofibrinogaemia (a decrease of 2 g/L or 50% from baseline) occurs in about one fifth of those receiving intravenous alteplase, whereas a tenecteplase dose escalation study9 showed no severe hypofibrinogenaemia (fibrinogen <1 g/dL) in any dose (0.1–0.5 mg/kg) tested. Similarly, in our sample, tenecteplase treatment did not cause hypofibrinogenaemia using either of these criteria. We could not replicate an association between hypofibrinogenaemia and ICH, probably because of the small sample.
Limitations of our study include small sample size, variable time of sampling at TP2, and the low incidence of serious ICH (none having parenchymal hemorrhage or symptomatic clinical deterioration attributable to hemorrhage). Nonetheless, we found significant changes in coagulation and fibrinolysis after intravenous alteplase consistent with the literature, and minimal disruption with tenecteplase, consistent with a potentially better safety profile for tenecteplase, with retained fibrinolytic efficacy.
In acute ischemic stroke, tenecteplase caused significantly less disruption to the coagulation and fibrinolytic systems compared with alteplase. This finding was consistent with the trend toward reduced incidence of ICH observed in the ATTEST trial.
We thank Prof. Gary Ford and Dr M.J. MacLeod from the Trial Steering Committee; Prof. Kennedy R. Lees, Drs Mark Parsons, and Christopher Weir from Data Safety Monitoring Committee; and Prof. Michael Hill and Dr Andrew Demchuk from External adjudicators.
Sources of Funding
This study was supported by the Stroke Association (TSA2010/04) and National Health Service Endowment Fund (National Health Service Greater Glasgow & Clyde).
Dr Muir received a personal fee from Boehringer Ingelheim for speaking at a sponsored satellite meeting at European Stroke Conference 2013 on acute stroke treatment. Boehringer Ingelheim manufactures both drugs used in this trial. The other authors report no conflicts.
The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA.115.011290/-/DC1.
- Received August 26, 2015.
- Revision received August 26, 2015.
- Accepted September 9, 2015.
- © 2015 American Heart Association, Inc.
- Emberson J,
- Lees KR,
- Lyden P,
- Blackwell L,
- Albers G,
- Bluhmki E,
- et al
- Huang X,
- Cheripelli BK,
- Lloyd SM,
- Kalladka D,
- Moreton FC,
- Siddiqui A,
- et al
- Hacke W,
- Kaste M,
- Fieschi C,
- von Kummer R,
- Davalos A,
- Meier D,
- et al
- Haley EC Jr,
- Lyden PD,
- Johnston KC,
- Hemmen TM