Key Points:

•30.8% rate of intracerebral bleeding in ischemic stroke patients
already on warfarin who receive IV tPA
•3.2% in patients not taking warfarin at baseline
•INR within normal parameters for all patients
•safety concerns raised

By Jason Kahn
Monday, March 08, 2010

Patients treated with intravenous tissue plasminogen activator (tPA)
for acute ischemic stroke may be at higher risk of intracerebral
hemorrhage if they are already taking warfarin therapy, even if their
clotting function is within normal parameters, according to a report
published online March 8, 2010, ahead of print in the Archives of
Neurology.

Researchers led by Shyam K. Prabhakaran, MD, MS, of Rush University
Medical Center (Chicago, IL), looked at 107 acute ischemic stroke
patients treated with IV tPA at their institution between October 1,
2002, and February 28, 2009. Patients had a mean age of 69.2 years and
a median international normalized ratio (INR) of 1.04.

Overall, there was a 6.5% rate of symptomatic intracerebral
hemorrhage. However, the hemorrhage rate in 13 of the patients who
were on warfarin therapy at baseline was almost 10-fold higher than in
those who were not already taking the anticoagulant (30.8% vs. 3.2%; P
= 0.004). This occurred despite warfarin-treated patients having an
INR under 1.7 (median INR, 1.21; range, 1.04-1.61), the threshold
below which American Heart Association/American Stroke Association
guidelines permit the use of tPA for ischemic stroke. In-hospital
mortality, though, was not significantly different between patients on
warfarin vs. those not on warfarin at baseline (15.4% vs. 9.6%; P =
0.62).

There were some key differences between warfarin-treated and
non-warfarin-treated patients, including older age, more frequent
atrial fibrillation, and a higher initial INR (table 1).

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