http://www.theheart.org/web_slides/1158303.do A study on gauging responsiveness with a verifynow assay impact on thrombosis and safety (GRAVITAS) with helps of 5429 patients on the regular clopidogrel dose underwent platelet-function tests with the VerifyNow assay 12 to 24 hours after PCI

1. GRAVITAS (Gauging Responsiveness with
a VerifyNow Assay—Impact on
Thrombosis and Safety)

2. GRAVITAS (Gauging Responsiveness with a VerifyNow
Assay—Impact on Thrombosis and Safety)
M Price (Scripps Clinic, La Jolla, CA)
American Heart Association 2010 Scientific Sessions
• Population and treatment:
5429 patients on the regular clopidogrel dose underwent platelet-function tests
with the VerifyNow assay 12 to 24 hours after PCI
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 another 600-mg loading dose and a higher maintenance dose of 150 mg
• Primary outcome:
Composite end point of CV death/MI/stent thrombosis at six months

3. GRAVITAS: Results
• There was no benefit on CV outcomes or stent thrombosis with the double dose of
clopidogrel
• There was also no difference in bleeding
• The percentage of patients who had persistently high platelet reactivity was
significantly reduced at 30 days and at six months
Results: Primary end point and bleeding outcomes at six months
Outcome High-dose clopidogrel Standard-dose clopidogrel Hazard ratio (95% CI) p
(%) (%)
Primary end point 2.3 2.3 1.01 (0.58–1.76) 0.98
GUSTO severe/moderate bleeding 1.4 2.3 — 0.10
Any GUSTO bleeding 12.0 10.2 — 0.18

4. GRAVITAS: Commentary*
"Many physicians have been using high-dose clopidogrel as a default strategy in
patients who are nonresponsive to the drug. We show that this strategy is probably
ineffective."
- Dr Matthew Price
"This trial does not definitely rule out the benefit of tailoring therapy based on
platelet-function testing, but it suggests that in future we should be looking at
higher-risk populations, larger cohorts, and different drugs."
- Dr Jessica Mega
"Based on this trial, I am looking more favorably toward the genetic approach rather
than platelet-function testing."
- Dr Elliot Antman
*All comments from GRAVITAS: No benefit of doubling dose in clopidogrel nonresponders
(http://www.theheart.org/article/1150629.do)

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