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Characterization of platelet activation and thrombin generation accompanying percutaneous transluminal coronary
P T Vaitkus1, M W Watkins, W T Witmer
1Department of Medicine, University of Vermont College of Medicine, Burlington 05401, USA.
Background:
Despite anticoagulant therapy, intracoronary thrombus formation can accompany or be induced by percutaneous transluminal coronary angioplasty (PTCA). Clinical trials for the assessment of the efficacy of novel prophylactic regimens are expensive and difficult. Accordingly, we sought to develop an approach for investigating thrombogenesis accompanying PTCA that would facilitate the assessment of protective regimens in a relatively small number of patients.
Methods:
Markers of in-vivo generation and activity of thrombin with plasma fibrinopeptide A (FPA) and platelet degranulation with beta-thromboglobulin (BTG) were measured in coronary sinus blood in patients undergoing PTCA. In an initial pilot study, we obtained peripheral venous blood samples through heparin-bonded sampling catheters to determine whether sampling affected values of the markers measured. We then measured FPA and BTG in coronary sinus blood samples, obtained from patients undergoing coronary angiography, to define the effects of injections of contrast media. Subsequently, we studied nine patients undergoing elective PTCA. Coronary sinus FPA and BTG were measured serially under baseline conditions during and after the procedure.
Results:
The catheters used elicited negligible effects on FPA and BTG values over a 30 min sampling interval. Similarly, coronary angiography had no detectable effect on coronary sinus FPA and BTG values. PTCA did not increase FPA (mean value at the conclusion of PTCA 1.17 +/- 0.31) or BTG (mean 30.9 +/- 15.9) in the PTCA group as a whole. However, in one patient the values increased markedly. For two patients, baseline values were elevated but declined with the re-establishment of brisk coronary flow after successful PTCA.
Conclusions:
We have shown that coronary sinus samples can be obtained under conditions permitting assessment of ongoing thrombosis in patients undergoing PTCA. Samples can be obtained without introduction of artifactual elevations of FPA or BTG, facilitating assessment of the efficacy of novel antithrombotic regimens in preventing thrombogenesis otherwise seen in an important minority of patients undergoing coronary interventions.