In the GRAVITAS trial, 5429 patients on the regular clopidogrel dose underwent platelet-function tests with the VerifyNow assay (Accumetrics, San Diego, CA) 12 to 24 hours after PCI. Of these, 2214 (41%) had high residual platelet reactivity (platelet reactivity units [PRU] >230) and were randomized to continue on the 75-mg regular clopidogrel dose or to receive another 600-mg loading dose and a higher maintenance dose of 150 mg daily.

Baseline characteristics showed that most patients were at relatively low risk, with 80% having stable coronary artery disease. At six months of follow-up, the composite end point of cardiovascular death/MI/stent thrombosis was identical in both groups, at 2.3%.

heartwire's Sue Hughes sits down with Dr Sunil Rao to talk about the clinical implications of these results and what they mean for the future of platelet-function testing.