Left Atrial Appendage Function in Mitral Stenosis: Is It Determined by Cardiac Rhythm?

Background and aim of the study: The left atrial appendage (LAA) is a common source of cardiac thrombus formation associated with systemic embolism in patients with mitral stenosis (MS). Low flow velocities in the LAA are important factors in the development of thrombosis. Whilst oral anticoagulant therapy is used routinely in MS with atrial fibrillation (AF), the characteristics of LAA contractile functions and the protective role of oral anticoagulant treatment in patients with MS in sinus rhythm (SR) are unclear. The study aim was to compare LAA contractile functions in patients with MS who were either in SR or had AF. Methods: The study population comprised 51 patients with MS, who had undergone both standard transthoracic and transesophageal echocardiography. The patients were allocated to two groups, according to the presence of AF or SR. Ten healthy, gender-matched subjects were included in the study as a control group. Results: Except for age, the characteristics of the groups were similar. In patients with SR and AF, the LAA contractile functions were significantly lower than in controls. While the LAA contractile functions of the SR group were significantly lower than the AF group (LAA emptying/filling velocity: 26 +/- 7/24 +/- 8 versus 19 +/- 5/17 +/- 5 cm/s; p = 0.002 and p = 0.001, respectively, LAA maximum/minimum area: 5.4 +/- 1.2/3.2 +/- 0.9 versus 6.2 +/- 1.1/3.7 +/- 0.8 cm(2), p = 0.02 and p =0.02, respectively), no statistically significant differences were observed between patients in SR with mitral valve area (MVA) <= 1.5 cm(2) and patients in AF. Four SR patients (13%) and six AF patients (27%) had LAA thrombus. A strong correlation was observed between the MVA and LAA peak emptying/filling velocity in patients with MS in SR (r = 0.739, p = 0.0001 and r = 0.728, p = 0.0001, respectively). Conclusion: The study results showed that LAA contractile function is diminished in patients with moderate-severe MS in SR, and to a similar degree as patients in AF. It was concluded that patients with moderate-severe MS in SR have a higher risk for thromboembolic events than MS patients in AF.