Platelet Activation In Coronary System Of Patients With Coronary Artery Stenosis (CAS)

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Abstract
Platelets and platelet mediator substances are thought to play a role in the genesis of atheroma and spasm of coronary arteries. In the present study, indices of platelet activation (PA) were studied in the basal state and under conditions of exercise [Pacing (P) ; Handgrip (HG)] in patients with CAS and controls (CO). Pat, and methods; 22 pat. (14 with CAS > 75% in angiography; 8 with normal coronary arteries). No premedication, heparin or contrast media; Judkins technique; simultaneous sampling in the sinus coronarius (CS) and in the aorta (A) (basal, 5 min. P, 3 min. HG). Measurements: Platelet counts (PC), Beta-thromboglobulin (B-TG), platelet factor 4 (PF 4) with RIA, thromboxane B2 (RIA), ADP/collagen induced platelet aggregation (MA). Results : In the basal state no difference between A and CS was demonstrable for CO and CAS with respect to any of the above parameters. Both after P and during HG, a significant (p < 0.05) increase of B-TG was found in CAS; however, a significant increase was found in CO. In contrast to literature, no change of PC was observed. However, under P and HG a significant decrease of collagen and ADP-induced platelet aggregation (p< 0.05) was observed in CAS but not in CO. In some, but not all, CAS-patients, elevated TXB2 was demonstrable in A and CS blood. Conclusion: The present study demonstrates PA in the coronary system of pat. with CAS. Reduced aggregability but no change of PC may be due to subthreshold activation in proximity to the stenosis. This study (which avoided the use of heparin and contrast agents) also shows that PA, as measured by local sampling, is neither a sensitive nor a specific indicator of CAS.

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