Clopidogrel reloading worthwhile in acute coronary syndromes

Many patients who come to the cardiac catheterization laboratory for percutaneous coronary intervention (PCI) are already taking 75mg of clopidogrel daily to prevent unwanted blood clotting. Even so, an additional 600 mg "reloading" dose of clopidogrel significantly improves clinical outcomes without increasing the risk of bleeding – but only in patients with acute coronary syndromes (ACS), according to the Antiplatelet Therapy for Reduction of Myocardial Damage During Angioplasty-RELOAD (ARMYDA-RELOAD) study.

The study is presented in a Late-Breaking Clinical Trials session at the SCAI Annual Scientific Sessions in Partnership with ACC i2 Summit (SCAI-ACCi2) in Chicago April 1st. SCAI-ACCi2 is a scientific meeting for practicing cardiovascular interventionalists sponsored by the Society for Cardiovascular Angiography and Interventions (SCAI) in partnership with the American College of Cardiology (ACC).

The ARMYDA-RELOAD study found that clopidogrel reloading reduces the combined risk of death, heart attack or repeat coronary procedure by nearly two-thirds in patients with ACS, although it offers no benefit to those with stable chest pain. Until now, no study has ever specifically examined the effect of clopidogrel reloading on patients with acute coronary syndromes, a condition that encompasses both unstable angina and a form of heart attack known as non-ST-segment-elevation myocardial infarction (NSTEMI). Clopidogrel is used to prevent the formation of blood clots, or thrombi, which could block the coronary artery and cut off blood flow to the heart muscle.

"The implications of the study are self-evident: When a patient with ACS is undergoing PCI and has been taking clopidogrel before, it is a very good idea to give a further loading dose of 600 mg prior to the procedure. This will protect against ischemic complications, without fear of more bleeding," said Germano Di Sciascio, MD, professor and chairman of cardiology at Campus Biomedico, University of Rome, Italy. "In patients with stable syndromes, ongoing preexisting clopidogrel may supply sufficient anti-platelet effect to safely undergo the procedure."

For the study, Dr. Di Sciascio and his colleagues recruited a total of 436 patients who had been taking clopidogrel for more than 10 days before PCI. Of these, 167 (38 percent) had ACS. Patients were randomly assigned to receive an additional 600-mg loading dose of clopidogrel four to eight hours before PCI or to receive a placebo. Blood tests confirmed that platelet reactivity was significantly lower in the reload group when compared with the placebo group in patients with ACS.

After 30 days’ follow-up, the overall rates of major adverse cardiac events (MACE)-consisting of death, heart attack, or repeat PCI or bypass surgery-were the same in the two groups: 7 percent in patients who received clopidogrel reloading vs. 9 percent in the placebo group (p=0.70). A similar finding was observed in patients with stable chest pain (8 percent vs. 4 percent, respectively, p=0.23). However, in patients with acute coronary syndromes, clopidogrel reloading significantly reduced the MACE rate (7 percent vs. 18 percent, respectively; odds ratio: 0.36; p=0.035). There was no difference in the rates of bleeding (5 percent in both groups).

Fundamental differences in the cardiovascular conditions that characterize acute and stable chest pain may explain the effectiveness of clopidogrel reloading in patients with ACS, Dr. Di Sciascio said. "Patients with ACS have higher platelet reactivity, higher inflammatory status and more intracoronary thrombus," he said. "This may make them more prone to benefit from clopidogrel reloading."

(Source: SCAI Annual Scientific Sessions in Partnership with ACC i2 Summit: Kathy Boyd David: Weber Shandwick Worldwide: April 2008)