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The effect of different antithrombotic regimens on platelet aggregation after myocardial infarction
M Hurlen1, I Seljeflot, H Arnesen
1Department of Cardiology, Ullevål University Hospital, Oslo, Norway.
Insights
Platelet aggregate ratio (PAR) was measured in patients post-acute myocardial infarction (AMI). Some patients showed non-response to aspirin, indicating a need for further clinical investigation.
Area of Science:
- Cardiology
- Hematology
- Pharmacology
Background:
- Platelet aggregation plays a crucial role in acute myocardial infarction (AMI).
- Assessing platelet function is important for optimizing antiplatelet therapy.
- The platelet aggregate ratio (PAR) is a measure of platelet aggregation.
Purpose of the Study:
- To evaluate the platelet aggregate ratio (PAR) in patients following acute myocardial infarction (AMI).
- To compare the efficacy of different antiplatelet and anticoagulant regimens, including aspirin and warfarin.
- To identify patients who may not respond adequately to aspirin therapy.
Main Methods:
- Platelet aggregate ratio (PAR) was measured using the Wu & Hoak method.
- 143 patients post-AMI and 54 controls were included.
- Patients were randomized to aspirin (160 mg/d or 75 mg/d) with or without warfarin.
Main Results:
- Median PAR was significantly lower in patients treated with warfarin (0.85), warfarin + aspirin (0.91), and aspirin alone (0.94) compared to controls (0.97).
- 14 patients (secondary aspirin non-responders) exhibited PARs below 0.82 despite aspirin treatment.
- PAR increased significantly 2 hours after aspirin intake, but two patients (primary aspirin non-responders) showed persistently low PARs.
Conclusions:
- Aspirin therapy may not be effective in all patients with acute myocardial infarction (AMI).
- Identification of aspirin non-responders is crucial for personalized treatment strategies.
- Further research is needed to determine the clinical implications of aspirin non-responsiveness.
Abstract:
Platelet aggregate ratio (PAR) was measured according to the method of Wu & Hoak in 143 patients after acute myocardial infarction (AMI) and in 54 controls. A PAR < 1 expresses the presence of platelet aggregates. The patients were randomized to aspirin 160 mg/d, or warfarin, or aspirin 75 mg/d + warfarin. In patients on aspirin, PAR was measured 24 h after aspirin intake, and in 76 patients also 2 h after aspirin. The median PAR in patients on warfarin was 0.85, on warfarin + aspirin 0.91 and on aspirin alone 0.94, all significantly lower than the median PAR of 0.97 in the controls. In 14 patients on aspirin the PARs were below a cut-off point of 0.82 (secondary aspirin non-responders). PAR increase significantly 2 h after aspirin intake. In two patients, however, PAR remained low (primary aspirin non-responders). It is concluded that some patients do not seem to respond to aspirin, the clinical implication of which has yet to be determined.