The relation between mitral annulus motion and left ventricular ejection fraction in atrial fibrillation.

Mitral annulus motion (MAM) has recently been introduced as an index of left ventricular function. Previous studies have shown a good agreement between MAM (mm) x 5 and ejection fraction in middle-aged and elderly patients. These studies only included patients with sinus rhythm, while patients with atrial fibrillation were excluded. In the present study, MAM was reduced in patients with atrial fibrillation while ejection fraction (EF) did not differ from age-matched control patients with sinus rhythm. The 'conversion factor' (EF/MAM) was 7.2 in the group with atrial fibrillation and 5. 1 in controls with sinus rhythm. This difference must be taken into account when MAM is used to estimate left ventricular function in patients with atrial fibrillation. Patients with atrial fibrillation had lower stroke volume and higher heart rate than patients with sinus rhythm. A decreased systolic long-axis shortening was found (P<0.005) compared to patients with sinus rhythm, but no difference in short-axis diameter shortening.