Thrombolytics is a type of reperfusion therapy which has these previously mentioned characteristics. It involves injecting a thrombolytic, or clot-dissolving, agent into the patient in order to break down the thrombus on the cholesterol plaque and revive the blood supply to the heart muscle. The drug must be given within 1-3 hours of the heart attack in order for it to be effective against it. The earlier it's used, the better the chances are for it to work against the clot which is causing the heart attack. The difference is that nonselective agents activate plasminogen even without the presence of fibrin, whereas selective agents require the presence of fibrin in order to function effectively.
Selective agents tend to be more active at the site of the thrombus.
Both selective agents and nonselective agents have advantages and disadvantages. During this period, circulating fibrinogen is depleted and high level of fibrin degradation products are produced. The presence of substances which dissolve clots is prolonged, and the body's coagulation system, or ability to clot, does not function for approximately 24 to 48 hours. An advantage to this is a decreased risk of vessel reocclusion, or the blockage of arteries. A drawback is an increased likelihood of significant bleeding.