Prevalence of aspirin resistance in patients with an evolving acute myocardial infarction.
OBJECTIVE
To study the prevalence and importance of aspirin resistance in patients with an evolving acute myocardial infarction (AMI) by use of the Platelet Function Analyzer-100.


BACKGROUND
Previous studies have demonstrated the existence of aspirin resistance, but the clinical relevance of the phenomenon remains to be clarified. If aspirin resistant patients comprise a high-risk subgroup, it might be expected that the prevalence of aspirin resistance in patients with AMI would be higher than in patients without AMI. We hypothesized that the prevalence of aspirin resistance in patients with AMI was twice the prevalence in patients without AMI.


METHODS
We included 298 consecutive patients with known cardiovascular disease who were admitted to hospital with symptoms suggestive of an AMI. All had been taking aspirin 150 mg/day for at least 7 days prior to hospital admission. Platelet function was measured immediately at admission, and aspirin resistance was defined as a collagen/epinephrine Closure Time (CT(CEPI))<165 s.


RESULTS
We found that 70 (23.5%) patients were aspirin resistant, and 70 (23.5%) patients ended up with the diagnosis of an AMI. The prevalence of aspirin resistance was significantly higher in patients with AMI as compared to patients without (36% versus 20%, OR 2.26, CI 95% 1.19-4.22, p=0.0058). The CT(CEPI) measured at admission was an independent factor associated with an AMI.


CONCLUSIONS
Aspirin resistance is present in almost one fourth of patients admitted to hospital with symptoms suggestive of an AMI, and aspirin resistance is significantly associated with the diagnosis of a definite AMI.
Poulsen
Tina Svenstrup
TS
Department of Cardiology, Odense University Hospital, Sdr Boulevard 29, DK-5000 Odense C, Denmark. tina.poulsen@ouh.fyns-amt.dk
Jørgensen
Bo
B
Korsholm
Lars
L
Licht
Peter Bjørn
PB
Haghfelt
Torben
T
Mickley
Hans
H
D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage; D001241:Aspirin / Q000008:administration & dosage*; D018450:Disease Progression; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy*; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests; D011446:Prospective Studies; D012044:Regression Analysis; D014057:Tomography, X-Ray Computed
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001241:Aspirin