Welcome to InCirculation.net
InCirculation.net is a professional cardiovascular resource intended for a global audience of specialists, generalists, researchers, and other healthcare professionals
Cardiovascular news provides daily news updates to help you stay informed.
Alarm raised over INR threshold in stroke thrombolysis
9 March 2010
MedWire News: Stroke patients undergoing thrombolysis are at increased risk for symptomatic intracerebral hemorrhage (ICH) if they are taking warfarin, even if their international normalized ratio (INR) is within recommended limits, research suggests.
“Our preliminary data raise potential safety concerns regarding the currently accepted guideline of intravenous (iv) tissue plasminogen activator (tPA) use in warfarin-treated patients presenting with arterial ischemic stroke,” the researchers write in the Archives of Neurology.
Current American Heart Association/American Stroke Association guidelines permit use of tPA in patients taking oral anticoagulants if their INR is less than 1.7.
Thirteen (12.1%) of the 107 patients in the current study were taking warfarin; their median INR was 1.21. Warfarin users were older than nonusers, at 81 versus 68 years, and they were more likely to have atrial fibrillation (AF), at 69% versus 19%.
The team defined symptomatic ICH according to the relatively strict European Cooperative Acute Stroke Study criteria, of parenchymatous hemorrhage within 36 hours accompanied by a 4-point increase in National Institutes of Health Stroke Scale (NIHSS) score.
The overall rate of symptomatic ICH was 6.5%, but was 30.8% among warfarin users compared with just 3.2% among nonusers. Any ICH occurred in 38.5% and 5.3% of users and nonusers, respectively.
Patients with symptomatic ICH tended to have more severe stroke and longer onset-to-treatment times than those without, but this was not statistically significant.
Warfarin use remained strongly associated with symptomatic ICH after the researchers accounted for age, NIHSS score, AF, and INR.
Shyam Prabhakaran (Rush University Medical Center, Chicago, Illinois, USA) and colleagues stress that their registry data provide only a hypothesis-generating report and that more research should be undertaken.
They offer several reasons for the observed association, including that warfarin use may serve as a marker of patients with cardioembolic stroke, “in whom hemorrhagic transformation is more common and infarct volume is greater” than in those with atherothrombotic stroke.
Your opinion matters - help to shape the future of InCirculation.net by completing our short survey. 
