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Platelet survival in patients with dilated cardiomyopathy
F Weidinger1, D Glogar, H Sochor
1Department of Cardiology, University of Vienna, Austria.
Insights
Patients with dilated cardiomyopathy show abnormal platelet function, indicated by shortened platelet survival and increased platelet uptake in the heart. This suggests an in vivo platelet abnormality contributes to thromboembolic complications in these patients.
Area of Science:
- Cardiology
- Hematology
- Biomedical Imaging
Background:
- Dilated cardiomyopathy (DCM) is linked to thromboembolic events.
- Visible left ventricular thrombus poorly predicts these complications.
- An underlying abnormality in platelet function in vivo may exist in DCM patients.
Purpose of the Study:
- To investigate in vivo platelet function abnormalities in patients with dilated cardiomyopathy.
- To assess platelet survival and activation markers in DCM.
- To evaluate platelet distribution in the heart using scintigraphy.
Main Methods:
- Platelet survival measured via autologous labeling with indium-111 oxine.
- Plasma levels of beta-thromboglobulin and platelet factor 4 assessed.
- Platelet scintigraphic imaging of the heart performed.
Main Results:
- Platelet survival was significantly shortened in DCM patients (idiopathic and ischemic) compared to controls.
- Increased plasma beta-thromboglobulin levels observed in DCM patients.
- Enhanced, diffuse platelet uptake over the heart detected by scintigraphy in DCM patients, absent in controls.
Conclusions:
- Patients with dilated cardiomyopathy exhibit impaired platelet survival and evidence of in vivo platelet activation.
- These platelet abnormalities may contribute to the thromboembolic risk associated with DCM.
- Scintigraphy reveals increased cardiac platelet accumulation in DCM, irrespective of ejection fraction or cardiothoracic ratio.
Abstract:
Dilated cardiomyopathy is associated with thromboembolic complications, which correlate poorly, however, with a visible left ventricular thrombus. Therefore, this study was performed to assess whether an abnormality of platelet function in vivo can be detected in patients with dilated cardiomyopathy. Platelet survival was measured after autologous labeling with indium-111 oxine in 28 patients with dilated cardiomyopathy and angiographically normal coronary arteries (mean ejection fraction 21 +/- 9% [standard deviation], range 4 to 39%) and in nine patients with coronary artery disease and similar left ventricular dysfunction (mean ejection fraction 21 +/- 10%). Plasma levels of beta-thromboglobulin and platelet factor 4 were measured in patients with idiopathic cardiomyopathy (n = 15) and platelet scintigraphic images of the heart (n = 24) were obtained in subsets of both patient groups. Platelet survival was significantly and similarly shortened in patients with idiopathic and ischemic cardiomyopathy (67 +/- 34 and 55 +/- 24 h, respectively) compared to controls (209 +/- 9 h, n = 12; p less than 0.001). Of the two platelet-specific proteins, beta-thromboglobulin was increased in the patients compared with controls (42 +/- 17 versus 22 +/- 6 ng/ml, p less than 0.001). Platelet scintigraphy 24 h (n = 24) and/or 48 h (n = 9) after labeling showed a diffuse pattern of enhanced platelet uptake over the heart which varied in intensity among patients, but which was never seen in controls (n = 6). This increased platelet uptake was similar in patients with idiopathic and ischemic cardiomyopathy but did not correlate with either ejection fraction or cardiothoracic ratio.(ABSTRACT TRUNCATED AT 250 WORDS)