Evaluation of platelet activation after electric cardioversion
J. Gaugler, A. Schlagenhauf, B. Egner, W. Schwinger, E. Bisping, S. Gallistl, H. Haidl (Graz, Austria)
Platelets - Physiology and Disorders of platelet number and function
Time: 17:15 - 18:15
Objective: Atrial fibrillation is known to cause strokes. But also the time after cardioversion bears a risk for thromboembolism, making anticoagulation recommended for several weeks. Therefore anticoagulation is mandatory for these patients even after restoring normal sinus rhythm. This elevated risk of thromboembolism and stroke after intervention is explained with atrial stunning, the delayed return of full function of the atrium myocardium. As an alternative explanation we hypothesized that platelets activated by the electric cardioversion contribute to a higher coagulability and a higher risk of thromboembolism.
Methods: Patients with known atrial fibrillation planned for elective electric cardioversion were included into the study (n=6). Blood was drawn before and 1 h after cardioversion. Flow cytometry was used to detect platelet activation. The platelets were labelled with a CD41 antibody in whole blood. As activation marker CD62P (P-Selectin) and PAC-1 (activated integrin αIIbβ3) antibodies were chosen. Ratios of geometrical mean fluorescence intensities (receptor/isotype control) were used to evaluate changes in respective receptor expression before/after cardioversion.
Results: No significant differences were found in the expression of platelet activation markers before and after cardioversion. The mean changes from before to after cardioversion were -0,6 % (SEM 10,0 %) for CD62P (ratio CD62P/IgG κ) and + 89,9 % (SEM 79,9 %) for PAC-1 (ratio PAC-1/PAC-1 + RGDS).
Conclusion: As electric current has obvious influence on membrane stability of different cells, activation of platelets and a contribution to hypercoagulability is likely to occur. This idea is supported by the observation of thrombosis in the context of electrical accidents. However, these effects appear -if present at all- to be very subtle, so that in this study with small sample size no significant effect could be observed.