By Charles A. Pilcher MD FACEP
September/October, 2011
Under current guidelines from the American Stroke Association, tissue plasminogen activator (tPA, commonly known as a “clot buster” drug) should be administered within 3-4.5 hours of “last seen normal” – and 1 hour of patient arrival – to potentially ameliorate a new onset stroke. (“Last seen normal” means exactly what it says. A patient who went to bed at 10 PM and awoke with slurred speech at 6 AM was “last seen normal” 8 hours prior.) Specifically, the ASA goal timelines for the initial evaluation part of the process are:
- Initial patient screening – completed within 10 minutes of arrival.
- Stroke team notification – completed within 15 minutes of arrival.
- CT initiation – completed within 25 minutes of arrival
If the goal is to provide “optimal care” by beginning the tPA infusion within 60 minutes of patient arrival, that leaves only 35 minutes for the rest of the process. That includes reading and reporting the CT, notifying the pharmacy and preparing the tPA infusion, delivering the infusion to the ED, informing the patient and family of the relative risks, benefits, options, etc., and obtaining consent to administer the drug. The latter 2 steps are crucial when offering a treatment with such a narrow range between benefit and harm.
This means that any patient arriving 2 hours or more after “last seen normal” may not be eligible for the drug.
Dr. Gregg Fonarow et al. reported their findings on the timeliness of tPA treatment in acute ischemic stroke in a February 22 article in Circulation.
Their report outlines “optimal care,” and finds that optimal care is not yet standard. This adds to the difficulty of pursuing a malpractice claim for “loss of chance” in the case of failure to administer tPA, the “clot buster drug.” Alleging that tPA could have made a difference is easier than proving that the care was substandard and the stroke could have been ameliorated. They point out 3 key facts in their article:
- Most patients (some studies day 98%) arrive after, or well into, the 3 hour time window from “last seen normal.”
- The FDA has yet to approve the 4.5 hour window for the administration of tPA, though most stroke centers have extended the old limit of 3 hours based on data published in late 2009.
- Only 29.1% of patients treated with tPA in 2009 had a door-to-needle time of less than 60 minutes, the standard set by the American Stroke Association.
tPA is strongly time dependent. Because of this, good outcomes are not guaranteed. Some researchers estimate that between 1-3 hours, every 10 minute delay results in 1 less patient having an improved disability outcome. This suggests that only 12 of 100 patients will benefit from the drug, while 88 will not, a figure within reported ranges of efficacy .
In the study by Fonorow et al. only 29.1% patients treated with tPA had door-to-needle times of no more than 60 minutes – and these results were from 1082 hospitals who had joined the ASA’s “Get with the Guidelines” quality improvement program. Interestingly, door to needle time was shorter the later in the 3 hour window the patient presented, illustrating the stroke team’s “need for speed” and indicating that greater speed is achievable under pressure.
While tPA remains the standard of care, outcomes are not guaranteed and risks are significant. Doctors need to remain diligent and aggressive, while patients and families need to know the risks and benefits. Every case is different. Clearly, reducing the time needed to deliver clot-busting tPA to patients with ischemic stroke presenting to an emergency department will improve the patient’s odds – but that remains a difficult task.