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Aspirin dose and six-month outcome after an acute coronary syndrome
Martin J Quinn1, Herbert D Aronow, Robert M Califf
1St. Vincents University Hospital, Dublin, Ireland.
Insights
This study compared low and intermediate aspirin doses for acute coronary syndromes. Higher doses showed a trend toward reduced myocardial infarction but increased stroke risk, suggesting dose may influence outcomes.
Area of Science:
- Cardiology
- Clinical Pharmacology
Background:
- Limited data exists on the comparative efficacy of low versus intermediate aspirin doses in patients with acute coronary syndromes.
- Aspirin is a cornerstone therapy for acute coronary syndromes, but optimal dosing remains debated.
Purpose of the Study:
- To compare the efficacy of low (<150 mg) versus intermediate (>=150 mg) aspirin doses in patients with acute coronary syndromes.
- To evaluate the impact of discharge aspirin dose on six-month rates of death, myocardial infarction (MI), and stroke.
Main Methods:
- A secondary analysis of the GUSTO IIb and PURSUIT trials included 20,521 patients with unstable angina or acute MI.
- Patients were stratified by low (<150 mg) or intermediate (>=150 mg) aspirin dose at discharge.
- Multivariable and propensity analyses were used to adjust for baseline differences.
Main Results:
- No significant difference in the composite endpoint of death, MI, or stroke at six months between low and intermediate aspirin doses (HR 0.92; 95% CI 0.79-1.07).
- Intermediate aspirin doses were associated with a reduction in six-month MI (HR 0.79; 95% CI 0.64-0.98).
- Higher aspirin doses were linked to a significant increase in stroke (HR 1.74; 95% CI 1.01-3.02), with no significant effect on MI in propensity-matched analyses.
Conclusions:
- Non-randomized data suggest that aspirin dose at discharge may impact clinical outcomes in acute coronary syndromes.
- The findings highlight a potential trade-off between reducing MI and increasing stroke risk with higher aspirin doses.
Objectives:
This study was designed to compare the efficacy of low and intermediate aspirin doses in acute coronary syndromes.
Background:
Little is known of the comparative efficacy of low and intermediate aspirin doses in this setting.
Methods:
We compared six-month death, myocardial infarction (MI), and stroke in patients with unstable angina or acute MI discharged while receiving low (<150 mg) or intermediate (> or =150 mg) aspirin therapy in the GUSTO IIb and PURSUIT trials (n = 20,521). We used multivariable analysis and performed a propensity analysis in order to adjust for baseline imbalances between the groups.
Results:
Aspirin doses <150 mg were prescribed to 29.9% (6,128) of patients. By six months, 6.4% of the patients (1,310 of 20,521) had a primary event, 6.2% of the patients receiving <150 mg and 6.6% of the patients receiving aspirin doses > or =150 mg (hazard ratio [HR] 1.06 [95% confidence interval (CI) 0.94 to 1.19], p = 0.35). After adjusting for baseline imbalances and the propensity score for discharge aspirin dose, there was no effect of aspirin dose on the composite end point at six months (HR 0.92 [95% CI 0.79 to 1.07], p = 0.28). However, the higher aspirin dose was associated with a reduction in six-month MI (HR 0.79 [95% CI 0.64 to 0.98], p = 0.03). The outcome was similar when patients were matched on the basis of the propensity score for aspirin dose (HR for death/MI/stroke 0.94 [95% CI 0.80 to 1.12], p = 0.51), although stroke occurred significantly more frequently among patients receiving the higher aspirin dose (HR 1.74 [95% CI 1.01 to 3.02] p = 0.05) and the effect on MI was no longer apparent.
Conclusions:
Although these data are non-randomized, they suggest that the aspirin dose upon discharge may influence the clinical course after unstable angina or acute MI.
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