Predictors of mitral annulus enlargement? A real-time three-dimensional transesophageal study

Background: Mitral annulus (MA) enlargement can be observed in various cardiac conditions but respective influence of left atrial (LA) and left ventricle (LV) size remained unclear.

Methods: In 120 patients who underwent a clinically indicated 3D-transesophageal-echocardiography, 30 atrial fibrillation (AF), 30 secondary mitral regurgitation (SMR), 30 primary myxomatous mitral regurgitation (PMR) and 30 mitral stenosis (MS), we evaluated the association between MA area (MA-area) and LA volume (LAvol) measured using the biplane area-length method, end-diastolic (LVEDV) and end-systolic (LVESV) volumes measured using the biplane Simpson method. MA-area was measured based on 3D datasets using QLab10.

Results: MA-area was correlated to LVEDV (r = 0.42, p < 0.0001), LVESV (r = 0.29, p = 0.001) but more markedly to LAvol (r = 0.62, p < 0.0001). Correlation between MA-area and LAvol was sustained in all subsets whereas MA-area was not correlated to LVEDV and LVESV in patients with SMR and with PMR (all p > 0.10). In multivariate analysis main predictors of MA-area were LAvol (p < 0.0001) and myxomatous etiology of MR (p = 0.0003) followed by LVEDV (p = 0.006) and LVESV (p = 0.02).

Conclusion: In a population of patients with a wide range of LA/LV size related to various conditions, LA volume and myxomatous MR etiology appeared as main predictors of MA size whereas LV size had a more modest influence.