Medications

Medications

Thrombolytic, also called clot-busting or fibrinolytic, drugs are now mainstays in the early treatment of many patients with heart attacks. These drugs dissolve the clot, or thrombus, responsible for causing artery blockage and heart-muscle tissue death.

Specific Thrombolytics

The standard thrombolytic drugs are recombinant tissue plasminogen activators or rt-PAs. They include alteplase (Activase and reteplase (Retavase). Both are similar in effectiveness, although reteplase is easier to administer. Tenecteplase (TNKase), a newer drug, can be delivered more rapidly than alteplase, and to date, survival rates are similar. Streptokinase (Kabikinase, Streptase) is sometimes used but is somewhat less effective that the others.

Thrombolytic Administration

The sooner that thrombolytic drugs are given after a heart attack, the better. The benefits of thrombolytics are highest within the first 3 hours. They can still help if given within 12 hours of a heart attack.

A thrombolytic drug, such as alteplase or tenecteplase, is typically given by IV along with heparin, an anticoagulant drug. (Heparin, like aspirin, cannot destroy existing blood clots but can prevent clots from reforming after they are broken up.) Enoproxin, a form of heparin called low-molecular weight heparin, may be more beneficial than standard heparin.

Other anticlotting drugs are being tested in combination with thrombolytic drugs for emergency treatment following a severe heart attack. Several 2005 studies have indicated that the antiplatelet drug clopidogrel (Plavix) can help prevent arteries from reclosing, and a second heart attack, when given along with aspirin and thrombolytic drugs. The studies evaluated patients who received thrombolytic drugs for treatment of STEMI (severe heart attacks with complete artery blockage.)

Complications

Hemorrhagic stroke, usually occurring during the first day, is the most serious complication of thrombolytic therapy, but fortunately it is rare. Streptokinase given without heparin poses the lowest risk (although it is also less effective than other regimens in restoring blood flow). In general, the mortality rate from bleeding is only 3 in every 1,000 patients treated with thrombolytics, whereas 39 patients out of 1,000 would die without these clot-busting drugs. Recent evidence suggests that the survival benefits of thrombolytic therapy, particularly in combination with aspirin, last for years.

Aspirin and Other Anti-Clotting Drugs

Anticlotting drugs that prevent or break up blood clots are used at every stage of heart disease. They are generally either antiplatelets or anticoagulants. Investigators are also studying combinations of anticlotting drugs, which may be useful in patients with severe heart disease. All anticlotting therapies carry the risk of bleeding, which can lead to dangerous situations, including stroke.

Anti-platelet Drugs. These drugs prevent formation of blood platelets. Platelets are very small disc-shaped blood cells that are important for blood-clotting.