Depends on where you read it.
The general rule is that the clot-busting drug (click here to read more about tPA) should be given within 3 and 4.5 hours, depending on who you ask.
One recent article leans toward the three hours:
"From analyzing all the available data, tPA [tissue plasminogen activator] after 3 hours for stroke patients may not be of any benefit but has a definite risk of fatal bleeding," Dr Alper told Medscape Medical News.
He pointed out that most guidelines on tPA in stroke recommend its use up to 4.5 hours after symptom onset, including those by the American Heart Association/American Stroke Association (AHA/ASA), which give tPA a Class 1 recommendation in this time window, but he says the data do not justify such recommendations.
"Other societies give weaker recommendations but the latest guidelines of the Canadian Association of Emergency Physicians give a weak recommendation against use of tPA after 3 hours. They are recognizing the uncertainty of the benefit and the greater consistency in harm," he added.
"Unless and until there are data showing unequivocal benefits to outweigh known harms, we believe that there should not be any strong recommendation or encouragement for the use of alteplase beyond 3 hours after stroke," Dr Alper and colleagues conclude in the BMJ paper.But, on a different tack from a different story and a different study, you can find the suggestion for widening the use of tPA - not by time, but by type of patient. The article suggests that tPA could be used more widely for stroke patients:
The team found that it is only patients with a fresh clot blocking an artery in the brain alongside signs of brain tissue damage caused by other conditions prior to suffering stroke who have an increased risk of hemorrhage with alteplase treatment. These indicators - the researchers say - can be easily spotted with CT scans.
In detail, the researchers reveal that 14% of patients with a fresh blood clot and pre-existing brain tissue damage experienced a hemorrhage, compared with only 3% of patients who did not exhibit these signs on CT brain scans.
Because these risk factors can be easily identified in brain scans, the team says they could be used to help doctors decide whether patients at risk of ischemic stroke are likely to benefit from treatment with alteplase.
"The presence of combinations of imaging signs in patients after stroke might provide additional information to decision-making when clinical uncertainty exists about the likely benefit of alteplase - e.g., in a patient presenting close to the latest time window or for whom the likelihood of benefit was marginal," they explain.I had good results from tPA in 1998, which was quite early for the small hospital where I was a patient (click here to read the story). And health care providers are still tweaking its rules on when to use it. That sounds a little negative, but I actually find it good news that researchers are still trying to improve the decision-making process of using this powerful drug.