Significance of measurements of changes of plasma TXB2, 6-K-PGF1α levels in patients with atrial fibrillation

Objective: To study the changes of plasma levels of TXB2, 6-K-PGF1α in patients with atrial fibrillation (AF) and to explore the mechanism of prethrombotic state (PTS) induced by AF. Methods: Plasma levels of TXB2, 6-K-PGF1α were measured with RIA in 21 patients with isolated paroxysmal atrial fibrillation (IPAF) both during and one week after termination of the attack. Levels were also measured in 28 patients with isolated sustained AF (ISAF), 27 patients with rheumatic mitral stenosis associated with persistent AF (RHD), 32 patients with paroxysmal supraventricular tachycardia (PSVT) and 35 controls. Results Plasma levels of TXB2 and TXB2/6-K-PGF1α in: (1) patients with IPAF during AF, (2) patients with ISAF and (3) patients with RHD were significantly higher than those in (1) patients with IPAF one week after termination of attack, (2) patients with PSVT and (3) the controls, but there were little difference in plasma 6-K-PGF1α levels. Values in patients with PSVT were not much different from those in controls. Plasma TXB2 and TXB2/6-K-PGF1α levels were positively correlated to the duration of the attack, but bore no relation to such parameters as: age, sex, mitral valve area, ejection fraction and inner diameter of left atrium. Conclusion: These results indicate that the changes of TXB2 and TXB2/6-K-PGF1α levels in plasma in the patients with AF are caused by the irregular contractile activity of atrium. (authors)