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Letter: Atrial fibrillation and platelet reactivity: in International Journal of Cardiology(ISSN 0167-5273)(EISSN 1874-1754)
Linköping University, Department of Social and Welfare Studies, Health, Activity, Care. Linköping University, Faculty of Health Sciences.
Östergötlands Läns Landsting, Local Health Care Services in the East of Östergötland, Department of Internal Medicine VHN.
Linköping University, Department of Social and Welfare Studies, Health, Activity, Care. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in the East of Östergötland, Department of Internal Medicine VHN. (ISV)
Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in the East of Östergötland, Department of Internal Medicine VHN.
2010 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 145, no 2, 357-358 p.Article in journal, Letter (Other academic) Published
Abstract [en]

BACKGROUND: The impact of atrial fibrillation (AF) upon platelet reactivity has not been investigated.

METHODS: Subjects were 33 individuals with AF who consented to elective electrical cardioversion (ECV) immediately before ECV determination of surface-bound fibrinogen after stimulation i.e. platelet reactivity was carried out. A flow cytometer was employed. ADP (1.7 and 8.5mumol/L) and a thrombin receptor activating peptide (54 and 74mumol/L) were used as agonists. The analyses were repeated after 26+/-8(SD) months.

RESULTS: Compared to day 1 subjects with AF (n=18) had a trend towards lower platelet reactivity at study end. It reached significance when using 1.7mumol/L ADP. In contrast, after 26+/-8(SD) months sinus rhythm (SR) (n=15) was associated with significant lower reactivity with all agonists.

CONCLUSION: After 26+/-8(SD) months patients returning with AF had higher platelet reactivity than those who remained with SR.

Place, publisher, year, edition, pages
Ireland: Elsevier , 2010. Vol. 145, no 2, 357-358 p.
Keyword [en]
Atrial fibrillation, Flow cytometry, platelet reactivity, platelet activity
National Category
Cardiac and Cardiovascular Systems
Identifiers
URN: urn:nbn:se:liu:diva-59612DOI: 10.1016/j.ijcard.2010.02.030OAI: oai:DiVA.org:liu-59612DiVA: diva2:352638
Note
Original Publication: Micha Milovanovic, Elisabeth Fransson, Claes Hallert and Petter Järemo, Letter: Atrial fibrillation and platelet reactivity, International Journal of Cardiology, 2010. http://dx.doi.org/10.1016/j.ijcard.2010.02.030 Copyright: ElsevierAvailable from: 2010-09-29 Created: 2010-09-21 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Platelets: with special reference to platelet density subpopulations, stable coronary heart disease and atrial fibrillation
Open this publication in new window or tab >>Platelets: with special reference to platelet density subpopulations, stable coronary heart disease and atrial fibrillation
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The current thesis was divided into two parts. Basic platelet research is the topic of the first section. The subsequent clinical part examines platelet reactivity in stable angina pectoris (AP) and in atrial fibrillation.

Platelet heterogeneity was investigated in the first section (papers 1 and 2). The cells were separated according to density using linear Percoll™ (a density medium) gradients. The latter contained EDTA, prostaglandin E1 and theophylline to prevent platelet in vitro activity. The platelet population was then divided into density subpopulations (n = 16 - 20). Membrane attached fibrinogen was determined with a flow cytometer technique and used as a marker reflecting platelet in vivo activity. Platelet P-Selectin content was employed to estimate the quantity of platelet α-granules. Paper I examined healthy blood donors (n = 3). The second report (paper II) compared healthy volunteers (n = 2) and subjects with essential thrombocythemia (ET) (n = 2). The latter is a clonal disease being characterized by an excessive platelet production. Platelet counts were determined in all fractions. In manuscripts I and II determination of surface bound fibrinogen and intracellular P-Selectin was carried out in 12 and 16 platelet density fractions, respectively.

High density platelets displayed more surface bound fibrinogen indicating in vivo activity. They also contained less P-Selectin. The latter finding implies platelet in vivo release reactions. Low density platelets circulated with more surface bound fibrinogen as well. Compared with peak density platelets, lighter cells contained more P-Selectin. ET was characterized by a similar platelet density pattern in that high and low density platelets displayed more surface bound fibrinogen. The similarity may explain why severe bleedings do not occur more frequently in ET. It is also obvious from the current thesis that the significance of platelet heterogeneity remains unclear and stimulates to further research. In particular, future work must involve more patients.

The second part (papers III-VI) of the thesis was devoted to stable AP and atrial fibrillation. Determination of platelet reactivity i.e. platelet bound fibrinogen after stimulation was carried out in whole blood. A flow cytometer technique was employed (papers III-VI). Adenosine diphosphate (ADP) (1.7 and 8.5 μmol/L) and a thrombin-receptor activating peptide (TRAP-6) (57 and 74 μmol/L) were used as stimulating agents. Determination of peak platelet density (kg/L) was utilized as a further measure reflecting platelet reactivity (paper V). Surface bound and soluble P-Selectin were employed as platelet activity markers (paper VI).

Gender differences with respect to platelet reactivity were investigated in paper III. Paper IV examined platelets in stable AP without significant coronary flow obstruction(s) as determined by coronary angiography. In a following study platelet reactivity was analysed in diabetes type II complicated by stable AP (paper V). Finally, long-term (more than 2 years) outcome of atrial fibrillation was related to platelet reactivity and activity (paper VI). In this study the subjects were investigated at the initial electrical cardioversion and the analysis were repeated after more than 2 years.

Postmenopausal women with stable AP demonstrated more reactive platelets when stimulating with TRAP-6. They had higher platelet counts (paper III) as well. Stable AP without significant coronary flow obstruction(s) was associated with elevated platelet reactivity (paper IV). Diabetes type II was linked to higher peak platelet density and elevated platelet reactivity (paper V). Augmented platelet reactivity proved to be a feature of subjects remaining in atrial fibrillation more than 2 years after the electrical cardioversion (paper VI). In contrast, the irregular heart rhythm did not affect platelet activity.

It is to assume that platelets at least partly are responsible for the sometimes atypical symptoms of females with stable AP. It is also conceivable to speculate that platelets contribute to chest pain in AP free from significant coronary flow obstruction(s). Theoretically, enhanced platelet reactivity could at least partly explain why diabetes type II affects the prognosis of coronary heart disease. The thesis further shows a possible theoretical link between atrial fibrillation, increased platelet reactivity and clot formation.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 85 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1220
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-62630 (URN)978-91-7393-272-1 (ISBN)
Public defence
2010-12-10, K3, Campus Norrköping, Linköpings univeristet, Norrköping, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2010-12-01 Created: 2010-12-01 Last updated: 2010-12-01Bibliographically approved

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