Left Atrial Volume Correlates with Mitral Annulus Size: An MDCT Study

Aim: Although the association between left ventricular dilation and mitral annulus dilation is well understood, the potential variation in the size of the mitral annulus during dilation of the left atrium is currently unknown. In order to investigate the link between the two variables, we used multidetector computed tomography (MDCT) and looked at patients who had a dilated left atrium, assessing if the mitral valve also dilates. Materials and Methods: The study included 107 patients with paroxysmal and persistent atrial fibrillation, in whom catheter ablation was performed using pulmonary vein isolation ± atrial substrate modification. Eighty patients were male (74.8%), with a mean age of 55.8 years (±9.87 with a minimum age of 26 years and a maximum age of 79 years), of which 57.1% had paroxysmal AF and the rest had persistent fibrillation. All the patients underwent multiple-detector CT (MDCT) with contrast medium before the ablation. CT images were integrated into the three-dimensional mapping system CARTO 3, after which the diameters of the mitral annulus, area, and circumference were measured. Left atrial size was evaluated by measuring the diameters, area, and volume. Results: The left atrial area was 247 ± 65.7 cm2 and the left atrial volume was 139 ± 56.3 mL. The transverse mitral annulus (MA) was 29.9 ± 5.3 mm and the longitudinal diameter was 41.9 ± 7.6 mm. The MA circumference and area were 15.0 ± 3.5 cm and 14.2 ± 4.6 cm2, respectively. The following statistically significant correlation was identified between the dimensions of the mitral annulus and the diameters of the left atrium: the transverse mitral annulus correlates with the antero-posterior (AP) LA diameter (R = 0.594, p < 0.01) and the longitudinal MA diameter correlates with the latero-lateral (LL) LA diameter (R = 0.576, p < 0.01). Furthermore, the MA area correlates with the LA volume (R = 0.639, p < 0.001). Conclusions: The volume of the left atrium correlates with the area of the mitral annulus. In patients with paroxysmal and persistent AF, an increase in left atrial dimensions is further associated with an increase in mitral valve dimensions.