Abstract 180: Differential Role of Endothelin-1 in Mitral Stenosis and Atrial Fibrillation
Background Chronic atrial stretch due to mitral stenosis is a major substrate for the development of atrial fibrillation (AF). It is well established that rhuematic mitral stenosis and AF are associated with an increased risk of thromboembolic events. Endothelin-1 (ET-1) is a potent vasoconstrictor and modulator of vascular function, and is known to play a role in thrombus formation. We therefore sought to compare ET-1 levels between patients with rheumatic mitral stenosis and AF.
Methods We measured plasma levels of ET-1 in blood samples from the femoral vein (FV), right atria (RA) and left atria (LA) obtained from 19 patients with rheumatic mitral stenosis, 12 patients with lone AF and 10 subjects with supraventricular tachycardia (reference subjects [REF]). Plasma ET-1 levels were measured by conventional ELISA techniques.
Results The FV concentrations of ET-1 were significantly higher in rheumatic mitral stenosis patients than in AF patients or REF subjects (Figure). However, there was no significant difference in the concentrations of ET-1 between AF patients and REF subjects. In rheumatic mitral stenosis patients and REF subjects there were no differences in concentrations of ET-1 between the FV, RA and LA. In contrast, ET-1 levels were highest in the femoral vein of AF patients (FV vs RA p<0.03 and FV vs LA p<0.06).
Conclusion Patients with rheumatic mitral stenosis have significantly higher ET-1 levels than AF patients. These data suggest that ET-1 plays a differential role in the pathophysiology of thrombus formation in mitral stenosis and AF. It highlights the importance of the underlying substrate to the risk of developing thrombus within the atria.
- © 2013 by American Heart Association, Inc.