• Kovacs, A.
• Kolev, K.
• Merkely, B.
• Szabo, G.
• Szelid, Z.
• Szabo, L.
• Wohner, N.
• Nagy, A.

Abstract

<p><strong>Background: </strong>Thrombus architecture is an important determinant ofthrombus stability and affects the outcome of preventive and therapeutic interventions in acute myocardial infarction, stroke and peripheral arterial disease, but it is hardly accessible for evaluation in theeveryday clinical practice. Here we address the potential correlationsbetween routinely available clinical data and structure of thrombiremoved with percutaneous coronary intervention (PCI) or thrombendarterectomy of large arteries.</p><p><strong>Methods: </strong>Thrombus samples removed by PCI-thrombus aspirationfollowing acute myocardial infarction (<i>n</i> = 101) or surgical open repair(<i>n</i> = 50) in a heterogeneous group of patients (age range 36?98 years,male-female ratio 6:4) were processed in two parallel ways: glutaraldehyde-fixation for scanning electron microscopy or freezing at 80 ?Cfor cryosections and indirect immunostaining for fibrin and plateletreceptor GpIIb/IIIa. Ten to fifteen images were taken of each thrombus with both microscopic techniques, and then analyzed morphometrically to determine fibrin fiber diameter, relative occupancy by fibrin,platelet, red blood cells (RBC), white blood cells (WBC). The correlation between the measured ultrastructural characteristics and selectedclinical parameters (age, sex, location of vascular lesion, blood cellcounts, haematocrit, C-reactive protein (CRP) in plasma, ECG findings, anti-platelet medication, accompanying diseases) was assessedusing multiple hypothesis testing and regression analysis.</p><p><strong>Results: </strong>Fibrin content of peripheral thrombi showed positive correlation with CRP and male sex (<I>P</I> = 0.014 and <I>P</I> = 0.04, respectively),but no such dependence was observed in coronary thrombi. Plateletcontent of thrombi correlated stronger with the hematocrit(<I>P</I> = 3 x 10^-12, <I>R</I><SUP>2</SUP> = 0.75 coronary; <I>P</I> = 0.02, <I>R</I><SUP>2</SUP> = 0.238 peripheral)than with the platelet count in blood (<I>P</I> = 2 x 10^-4, <I>R</I><SUP>2</SUP> = 0.20). Aspirin premedication reduced the role of local factors seen as increaseddependence of thrombus platelet content on systemic platelet count(<I>P</I> = 4 x 10^-7, <I>R</I><SUP>2</SUP> = 0.54) and stronger dependence of fibrin structureon RBC count in blood. Fiber diameter of peripheral thrombidecreased at higher RBC counts (<I>P</I> = 0.009, <I>R</I><SUP>2</SUP> = 0.16) and the dependence was significantly stronger in the aspirin-treated group(<I>P</I> = 0.003, <I>R</I><SUP>2</SUP> = 0.29). No such effect was found for clopidogrel. Sorting thrombi by their vessel of origin revealed a marked difference infibrin-platelet ratio with lower values in the coronaries than in the iliofemoro-popliteal arterial region (<I>P</I> < 0.023 by Kuiper?s test for various combinations of subgroups). In line with this observation, plateletcontent was significantly higher in left anterior descending coronarythrombi than in the ilio-femoral subgroup (<I>P</I> = 0.037). In terms ofplatelet content and fibrin-platelet ratio coronary thrombi were similarto those of aortic origin. Neither the registered ECG findings, nor theaccompanying diseases proved to be important determinants of thrombus structure on their own, but complex regression models revealedeffects of combination of factors. For example, age at operation andCRP value had an additive effect on WBC content of thrombi inpatients with atherosclerosis (<I>P</I> = 0.003, <I>R</I><SUP>2</SUP> = 1) or hypertonia(<I>P</I> = 0.03, <I>R</I><SUP>2</SUP> = 0.95).</p><p><strong>Conclusion: </strong>The fibrin and platelet content of arterial thrombi as wellas their fibrin structure are differentially affected at different vascularlocations and by systemic blood cell counts. Conventional anti-plateletdrugs differ in their impact on thrombus structure. Improved individually tailored strategies for prevention of acute thrombotic events couldbe developed on the basis of these findings.</p>

Topics

• impedance spectroscopy
• scanning electron microscopy
• reactive