Is it dangerous to give a clot busting drug to someone who is having a stroke?
The timing depends a bit on age. If the patient is over 80, then giving TPA after 3 hours is considered very risky. If they are under 80, that window can be expanded out to 4.5 hours under certain circumstances.
TPA is EXTREMELY risky to give outside of the above time windows. It is a very potent clot buster. Once these time windows have elapsed, the stroke has generally completed itself and the arteries within the stroke area are also thought to have died and be extremely prone to bleeding. Even under ideal circumstances (where the time window guidelines are followed), there is about a 6% chance of bleeding in brain, and half of those patients will die from the bleeding. Going beyond the time window causes the chances of bleeding to go up substantially, negating any positive effect from giving the TPA, and making it a very dangerous and harmful drug.
Bottom line, yes it is very dangerous if given out of the time window. After the time window has elapsed, it serves very little usefulness for preventing stroke damage, and increases the bleeding risk substantially.
Isn't the other determining factor, the fact that it is difficult to determine if the stroke was caused by a clot or internal bleeding within the brain already. In the latter case, TPA would just make things much worse. As I recall (as I was laying in the emergency room) the debate was both the timeframe and what was actually causing the stroke. I will always remember the ER Doc saying multiple times "you just don't fit our profile" (I was 56 and had run 6 miles earlier that evening.) My wife was bugging him about using TPA. Turns out it was a clot and we will never know if TPA would have done any good or not.
i got tPA within an hour of getting to the hospital, so total time was around 90 minutes, I was 50 and it probably saved my life but still had significant dead areas, half the motor cortex and most of the pre-motor cortex.
