Question: Recently, after transporting a stroke bypass patient we were told they could not be treated for the stroke (with thrombolytic) due to the patient's history of warfarin use. How does this fall under our protocol but outside theirs? If blood thinners (either in conjunction with a specific disease or as a certain dose) are a roadblock to thrombolytic therapy why isn't it listed as a contraindication to the bypass protocol? We did not have time to discuss the rationale behind the statement and have been wondering since if we misinterpreted the statement or if warfarin and similar drugs really do prevent thrombolytic use with CVA's? I know there have been studies linking problems with tPA in patients with warfarin history but didn't know that played an active role in the exclusion criteria at stroke centers now. If this is the case why not change the protocol to eliminate needless transport (especially when transporting from outside of the city/county where the center is located?
Great question! As you know, the Stroke Bypass program inclusion criteria are created out of a joint working group which includes EMS physicians and stroke neurologists as part of the Ontario Stroke Strategy. Last Spring, Dr Lewell actually presented an update both in London and in Huron County on this topic and this very question was addressed.
Audio from the Huron presentation can be found on our website here:
You are absolutely correct, when giving tPA, there is an increased risk of bleeding, specifically intracerebral bleeding, if the patient is already anticoagulated from taking Warfarin. However until the INR is measured, the practitioner has no way of knowing whether the patient's blood is "too thin" or not to receive tPA. Therefore although most patients who take Warfarin will not be candidates to receive tPA, some will be and there is no way of telling who that is until they are assessed at a Stroke Centre. So taking Warfarin does not automatically exclude a patient from being transported on Stroke Bypass.
The other answer from the stroke neurologists who actually insist that these patients on warfarin are transported to the stroke centre is that these patients may not be compliant with their medications. If this was the case, the coagulation profile may actually be completely within the normal range thus enabling this subset of patients to still receive TPA. In fact, it very well may be that warfarin non compliance may be the actual cause of an embolic stroke in a patient with atrial fibrillation and as such, failure to transport these patients to a stroke centre capable of administering TPA could have devastating consequences.