"Thrombolytic" or "clot-busting" therapy is used to stop a
heart attack in its tracks. The drugs prevent or limit heart muscle damage by
dissolving clots that block an artery. This opens up the artery and restores
the blood flow.
Clot-busting drugs must be given immediately after heart attack symptoms
begin. The sooner they are started, the more good they do-and the greater the
chances are of a full recovery. To be most effective, they need to be
given within 1 hour of the start of heart attack symptoms.