Incomplete inhibition of thromboxane biosynthesis by acetylsalicylic acid: determinants and effect on cardiovascular risk.
BACKGROUND
Incomplete inhibition of platelet thromboxane generation, as measured by elevated urinary 11-dehydro thromboxane B(2) concentrations, has been associated with an increased risk of cardiovascular events. We aimed to determine the external validity of this association in aspirin-treated patients enrolled in the Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management and Avoidance (CHARISMA) trial and to determine whether there are any modifiable factors or interventions that lower urinary 11-dehydro thromboxane B(2) concentrations that could thereby reduce cardiovascular risk.


RESULTS
Urinary 11-dehydro thromboxane B(2) concentrations were measured in 3261 aspirin-treated patients at least 1 month after they had been randomly assigned to placebo or clopidogrel. Baseline urinary 11-dehydro thromboxane B(2) concentrations in the highest quartile were associated with an increased risk of stroke, myocardial infarction, or cardiovascular death compared with the lowest quartile (adjusted hazard ratio 1.66, 95% CI 1.06 to 2.61, P=0.03). Increasing age, female sex, history of peripheral artery disease, current smoking, and oral hypoglycemic or angiotensin-converting enzyme inhibitor therapy were independently associated with higher urinary concentrations of 11-dehydro thromboxane B(2), whereas aspirin dose > or =150 mg/d, history of treatment with nonsteroidal antiinflammatory drugs, history of hypercholesterolemia, and statin treatment were associated with lower concentrations. Randomization to clopidogrel (versus placebo) did not reduce the hazard of cardiovascular events in patients in the highest quartile of urinary 11-dehydro thromboxane B(2) levels.


CONCLUSIONS
In aspirin-treated patients, urinary concentrations of 11-dehydro thromboxane B(2) are an externally valid and potentially modifiable determinant of stroke, myocardial infarction, or cardiovascular death in patients at risk for atherothrombotic events.
McMaster University, Hamilton, Ontario, Canada.
John W
JW
Eikelboom
Graeme J
GJ
Hankey
Jim
J
Thom
Deepak L
DL
Bhatt
P Gabriel
PG
Steg
Gilles
G
Montalescot
S Claiborne
SC
Johnston
Steven R
SR
Steinhubl
Koon-Hou
KH
Mak
J Donald
JD
Easton
Christian
C
Hamm
Tingfei
T
Hu
Keith A A
KA
Fox
Eric J
EJ
Topol
D000368:Aged; D001241:Aspirin / Q000494:pharmacology / Q000652:urine*; D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality / Q000652:urine*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D038622:Internationality; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013929:Thromboxane B2 / Q000031:analogs & derivatives / Q000652:urine; D013931:Thromboxanes / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000652:urine
D016861:Cyclooxygenase Inhibitors; D013931:Thromboxanes; D013929:Thromboxane B2; C049235:11-dehydro-thromboxane B2; D001241:Aspirin