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Platelet activation in clinical coronary artery disease and spasm
Insights
Platelet activation in coronary artery disease (CAD) patients is confirmed by increased beta-thromboglobulin release. Coronary artery spasm (CAS) is linked to elevated thromboxane B2, indicating abnormal platelet activity in cardiovascular disease.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Pathophysiology
Background:
- Atherogenesis theories suggest platelets contribute to atherosclerotic lesions via alpha granule release.
- Platelets may induce vascular spasm through thromboxane A2 production.
Purpose of the Study:
- To investigate platelet activation in the coronary circulation of patients with coronary artery disease (CAD).
- To determine if platelet activation markers correlate with coronary artery spasm (CAS).
Main Methods:
- Radioimmunoassay measurement of beta-thromboglobulin (B-TG) and thromboxane B2 (TX B2) in aortic and coronary sinus plasma.
- Comparison of marker levels in patients with severe CAD, normal coronaries, and those evaluated for CAS.
Main Results:
- CAD patients showed significantly higher transmyocardial release of B-TG compared to controls.
- TX B2 gradients indicated a trend towards increased production in CAD patients, though not statistically significant.
- CAS development was associated with acute elevation in coronary sinus TX B2, while non-CAS patients had undetectable levels.
Conclusions:
- Abnormal platelet activation occurs in the coronary circulation of CAD patients.
- Acute myocardial ischemia from CAS is associated with increased coronary sinus TX B2 production.
Abstract:
Current concepts of atherogenesis, based on animal models, suggest a role for platelets in the development of atherosclerotic lesions, possibly through the release of alpha granule constituents. Platelets may also contribute to the development of vascular spasm through thromboxane A2 production. Platelet activation in the coronary circulation in patients with coronary artery disease (CAD) should occur if these hypotheses apply clinically. We measured aortic and coronary sinus plasma levels of the platelet alpha granule constituent beta-thromboglobulin (B-TG) and thromboxane B2 (TX B2) by radioimmunoassay in 15 patients with severe atherosclerotic CAD, seven patients with angiographically normal coronaries, and five patients undergoing evaluation for coronary artery spasm (CAS). Compared with the controls, CAD patients had significantly greater transmyocardial release of B-TG (11.1 +/- 8.1 ng/ml, mean +/- SEM vs 62.5 17.2, p less than 0.05 by rank sum test); TX B2 gradients showed a similar trend but the difference was not statistically significant (-0.08 +/- 0.03 ng/ml vs 0.22 +/- 0.02, 0.05 less than p less than 0.10). Three of the five patients studied developed CAS which was associated with acute elevation in coronary sinus TX B2; the two non-CAS patients with drug provocation had undetectable coronary sinus TX B2. We conclude that abnormal platelet activation takes place in the coronary circulation of CAD patients, and that production of acute myocardial ischemia by CAS occurs with increased coronary sinus TX B2.