From the Guidelines
Absolute laboratory contraindications to tissue plasminogen activator (tPA) include a platelet count less than 100,000/mm³ and an INR greater than 1.7, as these conditions significantly increase the risk of bleeding complications. When considering the administration of tPA, it is crucial to assess the patient's coagulation status and platelet count to minimize the risk of hemorrhagic complications. According to the guidelines outlined in 1, treatment with tPA can be initiated before the availability of coagulation study results but should be discontinued if the INR is > 1.7 or PT is elevated by local laboratory standards. Similarly, in patients without a history of thrombocytopenia, treatment with tPA can be initiated before the availability of platelet count but should be discontinued if the platelet count is < 100,000/mm³. The evidence from 1 suggests that these laboratory values are critical in determining the safety of tPA administration, and their presence can significantly impact the risk-benefit analysis of tPA treatment. In clinical practice, it is essential to prioritize these laboratory contraindications to ensure the safe and effective use of tPA in patients with acute ischemic stroke. Key considerations include:
- Platelet count less than 100,000/mm³
- INR greater than 1.7
- Elevated PT by local laboratory standards
- The need for urgent review of laboratory results before administering tPA
- The importance of discontinuing tPA if any of these laboratory abnormalities are present. Given the potential risks and benefits of tPA treatment, it is crucial to carefully evaluate each patient's laboratory results and clinical status to determine the safest and most effective course of treatment, as supported by the guidelines outlined in 1.
From the FDA Drug Label
CONTRAINDICATIONS Cathflo Activase should not be administered to patients with known hypersensitivity to Alteplase or any component of the formulation (see DESCRIPTION). The FDA drug label does not answer the question.
From the Research
Absolute Lab Contradiction to tPA
- The use of antiplatelet therapy before acute ischemic stroke and its impact on the risk of bleeding when treated with tPA has been studied 2.
- Patients receiving antiplatelet therapy before tPA administration had a higher risk for symptomatic intracranial hemorrhage (sICH) but better functional outcomes than those who were not receiving antiplatelet therapy 2.
- The risk of sICH was higher in patients receiving antiplatelet therapy, with an adjusted odds ratio of 1.18 and an absolute difference of +0.68% 2.
- Other studies have explored the development of "tPA helpers" to reduce the risk of bleeding complications and improve outcomes in patients with acute ischemic stroke 3.
- The use of tPA in patients taking non-vitamin K antagonist oral anticoagulants (NOACs) preceding stroke has also been investigated, with preliminary observations suggesting that tPA may be reasonably well tolerated without prohibitive risks of bleeding complications in selected patients on NOACs 4.
- Recent studies have also examined the correlation between tPA administration and favorable venous outflow profiles in acute ischemic stroke, with results showing that tPA administration was a strong independent predictor of favorable venous outflow profiles 5.
- Novel thrombolytic agents, such as platelet-targeted thrombolysis, are being developed to improve treatment outcomes for acute ischemic stroke, with promising results in experimental models 6.