抗血小板療法の改善

ARMYDA-RELOADスタディの結果、急性冠症候群患者にはたとえ患者が既にクロピドグレルを内服していたとしても、導入用量のクロピドグレルを投与することにより有益性が認められることが示された
ARMYDA-RELOAD study finds benefit in giving patients with acute coronary syndrome a loading dose of clopidogrel even when they are already taking it
クロピドグレルを既に定期的に内服している急性冠症候群患者は血管形成術前に「再導入」をすることにより有意な有益性が認められる、とのLate-Breaking Clinical Trialの結果がAmerican College of Cardiology学会で発表された。ARMYDA-RELOADの研究者らは血管形成術の10日以上前からクロピドグレルを内服していた患者436人を組み入れた。うち167人（38%）は急性冠症候群の患者であった。患者らは、術前4～8時間に導入用量（600mg）のクロピドグレルまたはプラセボを内服する群に無作為に割り付けられた。30日後、全体の主要な心有害事象発現率は両群間で同等であった。しかし、急性冠症候群患者においては、クロピドグレルの再導入により主要な心有害事象発現率が有意に低下した（それぞれ7%対18%）。出血発現率には差はなかった（両群ともに5%）。
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Patients with acute coronary syndrome who take clopidogrel achieve significant benefit from a 'reloading' dose prior to angioplasty, according to a late-breaking clinical trial presented at the annual meeting of the American College of Cardiology.

Patients typically take 75 mg clopidogrel daily; in the Antiplatelet Therapy for Reduction of Myocardial Damage During Angioplasty-RELOAD (ARMYDA-RELOAD) study, such patients who were about to undergo angioplasty for an acute coronary syndrome event were given a 'reloading' dose of 600 mg.

Researchers found that the extra medication was associated with a nearly two thirds reduction in post procedural major adverse coronary event rate (combination of death, myocardial infarction, or repeat revascularization) without increase in risk for bleeding.

Prior to the current trial, no study has ever specifically examined the effect of clopidogrel reloading on patients with acute coronary syndrome.

"The implications of the study are self-evident: When a patient with acute coronary syndrome is undergoing percutaneous coronary intervention 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."

Researchers recruited 436 patients who had been taking clopidogrel for more than 10 days before their procedure. Of these, 167 (38 percent) had acute coronary syndrome. Patients were randomized to receive an additional 600-mg loading dose of clopidogrel or placebo four to eight hours before their procedure. Blood tests confirmed that platelet reactivity was significantly lower in the reload group compared with the placebo group in patients with acute coronary syndrome.

After 30 days, the overall rates of major adverse cardiac events were the same in the two groups: 7 percent in patients who received clopidogrel reloading versus 9 percent in the placebo group. A similar finding was observed in patients with stable chest pain (8 percent versus 4 percent, respectively).

However, in patients with acute coronary syndromes, clopidogrel reloading significantly reduced the major adverse cardiac event rate (7 percent versus 18 percent, respectively). 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 acute coronary syndrome, Dr. Di Sciascio said.

"Patients with acute coronary syndrome have higher platelet reactivity, higher inflammatory status and more intracoronary thrombus," he said. "This may make them more prone to benefit from clopidogrel reloading."