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Circulating aggregated platelets in coronary artery disease
Insights
Platelet aggregation is elevated in stable angina, unstable angina, and acute myocardial infarction (AMI) patients compared to healthy individuals. Early, reversible platelet activation may play a key role in unstable angina and AMI pathogenesis.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Platelet Physiology
Background:
- Platelet aggregation is a critical factor in thrombotic cardiovascular diseases.
- Understanding the dynamics of platelet aggregation in different ischemic heart conditions is essential for diagnosis and treatment.
Purpose of the Study:
- To quantify and differentiate circulating reversible and irreversible platelet aggregates in patients with stable angina, unstable angina, and acute myocardial infarction (AMI).
- To investigate the role of platelet activation phases in the pathogenesis of these conditions.
Main Methods:
- Blood samples from 30 stable angina, 22 unstable angina, 50 AMI patients, 50 healthy, and 20 noncardiac controls were analyzed.
- Platelet aggregates were quantified in two solutions: one with EDTA and formalin (reversible and irreversible) and one with EDTA alone (irreversible only).
- Reversible aggregates were calculated by subtracting irreversible from total aggregates.
Main Results:
- Patients with stable angina showed significantly higher platelet aggregation (15 ± 4%) than controls (7 ± 2%).
- Unstable angina and AMI groups exhibited similar, significantly higher platelet aggregation (24 ± 13% and 24 ± 10%, respectively) compared to stable angina.
- In stable angina and AMI, a higher proportion of aggregates were reversible (89% and 83%) than irreversible (11% and 17%).
Conclusions:
- Elevated circulating platelet aggregates are present across stable angina, unstable angina, and AMI.
- The findings suggest that early, reversible platelet activation is significantly involved in the pathogenesis of unstable angina and AMI.
Abstract:
Circulating aggregated platelets were assessed in 30 patients with stable angina, 22 with unstable angina and 50 with acute myocardial infarction (AMI). Fifty healthy volunteers and 20 noncardiac patients served as controls. One milliliter of venous blood was separated into 2 solutions: 1 composed of ethylenediamine tetraacetic acid (EDTA) and formalin containing reversible and aggregates and 1 composed of EDTA alone containing irreversible aggregates only. By direct microscopic readings the percentage of platelets forming aggregates/1,000 counted platelets was determined in the 2 solutions. The number of reversibly aggregated platelets was estimated by subtracting the percentage of aggregated platelets in the second solution from that in the first solution. In patients with stable angina the percentage of aggregated platelets was higher than in control subjects (15 +/- 4% vs 7 +/- 2%, p less than 0.001). Most aggregated platelets (72% and 76%, respectively) were irreversibly aggregated. In the unstable angina group the percentage of aggregated platelets was similar to that of the AMI group (24 +/- 13% and 24 +/- 10%) and significantly higher than in the stable angina group. Only 11% and 17% of aggregated platelets in patients with stable angina and AMI were irreversibly aggregated and 89% and 83% of them were reversibly aggregated. Participation of platelets in the pathogenesis of unstable angina and AMI may be related to the early reversible phase of platelet activation.