Compared to the standard dose, a high dose of Clopidogrel ( Plavix ) does not reduce the incidence of death, myocardial infarction or blood clots inside of stents in certain high-risk patients who have had drug-coated stents implanted to open blocked arteries.

Earlier studies have shown that the anti-clotting drug Clopidogrel works well in some patients who have received a stent to prop open a blocked artery, a procedure called percutaneous coronary intervention or PCI. However, other patients have what is called high residual platelet reactivity, meaning their blood is still prone to clotting despite taking the anti-clotting medication.

The patients with high residual platelet reactivity have a higher risk of major cardiovascular events after procedures to implant stents.

The main purpose of the GRAVITAS ( Gauging Responsiveness With A VerifyNow Assay - Impact on Thrombosis and Safety ) trial was to determine if high-dose Clopidogrel reduces cardiovascular events in patients with high residual platelet reactivity as determined by the VerifyNow platelet function test.

In GRAVITAS, researchers gave a loading dose followed by a high maintenance dose of Clopidogrel ( double the standard maintenance dose ) to those patients whose platelet function test showed they had high residual platelet reactivity.

The high dose of Clopidogrel didn’t improve outcomes.

Although the proposed regimen failed to cut risk of dangerous events, the study found it didn’t cause additional bleeding, so the patients didn’t suffer harm at the higher dose.

The six month trial, involving about 80 centers throughout the United States and Canada, randomized 2,214 patients who had a specific platelet function test after the PCI procedure that revealed they had high residual platelet activity. Those patients were randomly assigned to either receive a high dose of Clopidogrel, 150 milligrams daily, or the standard-dose of Clopidogrel, 75 milligrams daily, with an inactive placebo.
The composite end point ( the rate of death from cardiovascular causes, of heart attacks, and of blood clots in stents ) at six months in patients randomized to high-dose Clopidogrel was 2.3 percent, identical to that in patients randomized to standard dose Clopidogrel.

Source: American Heart Association’s Scientific Sessions, 2010

XagenaMedicine2010


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