Journal of thrombosis and haemostasis : JTH
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J. Thromb. Haemost. · Dec 2005
Historical ArticleTo bleed or not to bleed? Is that the question for the PTT?
The activated partial thromboplastin time (PTT) is the grandchild of the Lee-White whole blood clot time (WBCT). Both tests were developed to assist the diagnostic process for patients who exhibited features consistent with hemophilia, i.e., the pretest probability was extremely high. ⋯ The question asked of the PTT has evolved from 'why does this patient bleed?' to 'will this patient bleed?' As the PTT was never intended to answer that question, one must be careful regarding interpretation of results of that test. As many situations not related to hemorrhage are associated with perturbations of the PTT, a prolonged PTT is not strongly predictive of hemorrhage nor does a normal PTT provide shelter against hemorrhagic risk.
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J. Thromb. Haemost. · Dec 2005
Randomized Controlled TrialEnhanced antiplatelet effect of clopidogrel in patients whose platelets are least inhibited by aspirin: a randomized crossover trial.
We aimed to determine whether adding clopidogrel to aspirin in patients at high risk of future cardiovascular events would suppress laboratory measures of the antiplatelet effects of aspirin; and have greater platelet inhibitory effects in patients with the least inhibition of platelets by aspirin. ⋯ The greatest platelet inhibitory effect of clopidogrel occurs in patients with the least inhibition of arachidonic acid-induced platelet aggregation by aspirin. This raises the possibility that the clinical benefits of adding clopidogrel to aspirin may be greatest in patients whose platelets are least inhibited by aspirin. Confirmation in clinical outcome studies may allow these patients to be targeted with antiplatelet drugs that inhibit the ADP receptor, thereby overcoming the problem of laboratory aspirin resistance.