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(Stroke. 2004;35:2762.)
© 2004 American Heart Association, Inc.
Letters to the Editor |
Department of Neurology, Stroke Program, Indiana University School of Medicine, Indianapolis, Indiana
To the Editor:
I read with interest the study by Trouillas et al from Lyon, France,1 describing a plasma marker associated with parenchymal brain hemorrhage in patients treated with intravenous recombinant tissue plasminogen activator (rtPA) for acute stroke. Unusually high D-dimer levels measured at 2 hours after beginning rtPA were associated with increased risk of parenchymal hemorrhage within 24 hours. This is useful information that could be translated to patients treated elsewhere with a similar protocol. However, the currently adopted protocol for intravenous rtPA treatment of acute stroke in the United States and many other countries is according to the American Stroke Association (ASA)2 and the American Academy of Neurology (AAN)3 guidelines, and these guidelines differ in 2 important ways from the protocol used in Lyon. I would like to point out that because of these differences, the findings from Lyon may not translate to centers that follow the ASA/AAN guidelines.
First, the ASA/AAN guidelines do not recommend treatment beyond 3 hours after symptom onset, compared with up to 7 hours in Lyon. The mean delay to starting intravenous rtPA in Lyon was nearly 4 hours (based on a previous publication from that center),4 which is approximately 90 minutes later than in the United States. This difference may be important as longer exposure to brain ischemia, with greater injury to the blood vessels and surrounding tissue, may predispose to hemorrhagic complications more than shorter exposure.
Second, the ASA/AAN guidelines advise against anticoagulation within 24 hours after rtPA treatment, compared with anticoagulation immediately after rtPA infusion in a considerable proportion of the patients in Lyon (exact proportion not stated). Anticoagulation is a well-established risk for parenchymal brain hemorrhage in multiple settings.
Thus, elevated D-dimer levels in acute stroke patients treated with intravenous rtPA according to the ASA/AAN guidelines may not be predictive of parenchymal hemorrhage, as they are in patients treated with the Lyon study protocol. It would be useful to validate the findings from Lyon in patients treated within the ASA/AAN guidelines.
References
Cerebrovascular Unit, Neurological Hospital, Lyon, France
Hemostasis Department, Cardiological Hospital, Lyon, France
Biostatistical Laboratory, Lyon, France
Hemostasis Laboratory, Lyon, France
We have been interested by the constructive remarks of Dr Bruno, who points out the need of further studies on hemostasis in rtPA protocols using ASA/AAN guidelines, in order to confirm the predictive value of degradation factors. Some clarifications must, however, be given.
First, in our study,1 we measured fibrin(ogen) degradation products (FDP), which involve fragments of fibrinogen and fibrin, while D-dimers originate exclusively from fibrin.2 This postthrombolytic increase of FDP at 2 hours (early fibrinogen degradation coagulopathy) was correlated with a fibrinogen decrease, indicating an impact of rtPA, at least partial, on circulating fibrinogen. It may be possible that D-dimers, which have a different biological significance, would not be predictive of early parenchymal hematoma. However, this measurement is now included in our prospective hemostasis evaluation.
Second, the Lyon protocol3,4 was designed in 1993, before the NINDS rtPA Study4 was published. At that time, the dose of rtPA, the window of administration, and the anticoagulant regimens were not standardized. However, the dose chosen was remarkably similar to that of the NINDS study (0.8 mg/kg). After the publication of the NINDS study results, we decided to continue the trial up to 200 patients, because our protocol was the unique opportunity to know what gave a slightly lower rtPA dose with a longer infusion time (90 minutes), a wider time window (7 hours), and precise postthrombolytic heparin regimens. In the cohort of 157 patients with hemostasis screening,1 the rate of symptomatic hemorrhage (3.8%) was lower than in part 1 (6%) and in part 2 (7%) of the NINDS study.4 Thus, the hemostasis disturbances that we described are not linked to a more intense hemorrhagic process.
Third, the postthrombolytic FDP coagulopathy does not seem to be influenced by heparin. In our cohort, only 20.3% of patients had a regimen with immediate postthrombolytic unfractionated heparin. In several myocardial infarction trials including immediate use of intravenous heparin, an early FDP increase took place and was demonstrated to be correlated with bleeding complications, general or cerebral.511
Thus, there is a chance that early fibrinogen degradation coagulopathy, predictive of early parenchymal hematomas, may be confirmed in rtPA protocols following the ASA/AAN guidelines, without heparin during the 24 first hours, as well as in intraarterial protocols like PROACT II using postthrombolytic heparin.12 Another answer may be given by the FRALYSE study, ongoing in France: this randomized, assessment blinded study, compares arms with the NINDS and Lyon protocols, with hemostasis and clinical parameters.
References
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