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7/23/2001

Different GP IIb/IIIa Inhibitors Have Distinct Uses

Kate Traynor

Recent clinical evidence suggests that the glycoprotein IIb/IIIa inhibitors abciximab, eptifibatide, and tirofiban are not interchangeable and that each product has a place in the treatment of acute coronary syndromes.

Three reports in the June 21 New England Journal of Medicine compared the use of the glycoprotein IIb/IIIa inhibitors in patients with acute coronary syndromes. According to an editorial in the same issue of the journal, the studies offer important new information to guide treatment decisions.

The editorialists, Hartford (Conn.) Hospital Director of Cardiology William E. Boden, M.D., and his colleague, Raymond G. McKay, M.D., incorporated the studies’ main points into a chart for managing the care of patients with acute coronary syndromes. At a minimum, hospitals that adopt the chart’s recommendations will need to keep tirofiban and at least one other glycoprotein IIb/IIIa inhibitor product in stock.

According to the chart, the only patients for whom a glycoprotein IIb/IIIa inhibitor is never recommended are those at low risk for coronary-vessel closure. Such patients lack elevated levels of cardiac isoenzymes, have no chest pain, and have electrocardiograms with an ST segment that is neither elevated nor depressed.

For patients with an intermediate or high risk of vessel closure, the Hartford cardiologists recommend early use of a glycoprotein IIb/IIIa inhibitor some of the time. Their advice is summarized below.

Chest pain, no ST-segment elevation. Tirofiban is recommended for all patients whose ST-segment depression has stabilized but who still have chest pain. Such patients are considered at intermediate risk for vessel closure.

Elevated isoenzymes, ST-segment depression. Patients with elevated levels of cardiac isoenzymes or troponins, ST-segment depression, and persistent angina while at rest are considered to be at high risk for vessel closure. If a cardiac catheterization laboratory is not available, these patients should be admitted to the coronary care unit and treated with tirofiban and heparin. Tirofiban is the preferred glycoprotein IIb/IIIa inhibitor in this type of case; however, eptifibatide would be acceptable.

If urgent percutaneous revascularization and stent insertion are planned, abciximab or eptifibatide should be given along with heparin. The drugs should be administered before the revascularization procedure begins.

Myocardial infarction with ST-segment elevation. A glycoprotein IIb/IIIa inhibitor should not be among the initial drugs used in patients with a myocardial infarction characterized by ST-segment elevation or a new left-bundle-branch block. For these patients, aggressive therapy with an anti-ischemic, antiplatelet, or antithrombin drug is recommended regardless of whether the patient will undergo immediate percutaneous revascularization.

If a cardiac catheterization laboratory is available, these patients should undergo percutaneous revascularization or receive a stent and abciximab therapy. Otherwise, patients should receive a fibrinolytic agent, with or without a glycoprotein IIb/IIIa inhibitor.