## 3 Results  
A total of 107 patients were included in this study (mean age of 55.8\(\pm\) 9.8 years, 74.8% male). The mean weight of the patients was 80.3 \(\pm\) 15.5 kg and the mean BMI was 29.6 \(\pm\) 6.0. The majority of the patients had paroxysmal atrial fibrillation (57.1%) and the rest had persistent AF (42.9%). The mean LV systolic diameter was 52.4 \(\pm\) 5.8 mm  
Figure 1: Diameters of the mitral annulus are depicted in the image. With red color indicating transverse diameter; with green color indicating longitudinal diameter. Figure 2: Assessment of mitral valve dimensions using MDCT. (**A**) White line shows measurement of the transverse diameter of the mitral annulus. (**B**) White line shows measurement of the longitudinal diameter of the mitral annulus. (**C**) Measurement of the mitral valve area and perimeter. The system calculates the perimeter and area based on the points defining the mitral annulus; perimeter = 12.2 cm, area = 10.8 cm\({}^{2}\). and the mean LV diastolic diameter was 37.6 \(\pm\) 6.8 mm; the mean ejection fraction of the left ventricle was 54.2 \(\pm\) 4.2%. All the patients underwent multiple-detector computed tomography angiography (MDCT) of the left atrium and pulmonary veins prior to catheter ablation of atrial fibrillation. The mean LA volume was 139 \(\pm\) 56.3 mL and the total area of the left atrium was 247 \(\pm\) 65.7 cm\({}^{2}\). Only 15 patients (14%) had a left atrial volume of \(<\)90 mL, with the rest presenting dilated left atria (Table 1). The dimensions of the mitral annulus (MA) were as follows: Longitudinal diameter = 41.8 \(\pm\) 8.3 mm; transversal diameter = 29.8 \(\pm\) 4.9 mm; MA area = 13.0 \(\pm\) 4.5 cm\({}^{2}\); MA circumference = 14.4 \(\pm\) 3.2 cm (Table 1). There was a significant difference in terms of age, AP diameter of the LA, and longitudinal diameter of the mitral valve between patients with paroxysmal and persistent atrial fibrillation (Table 2). As expected, a good correlation between the longitudinal and transverse diameters of the mitral valve was noted (R = 0.726, \(p\) < 0.0001). Furthermore, there was a statistically significant correlation between the longitudinal LA diameter and the longitudinal MV diameter (R = 0.576, \(p\) < 0.0001), as well as a significant correlation between the transverse LA diameter and the transverse MA diameter (R = 0.594, \(p\) < 0.0001) (Table 3). Most importantly, we identified a significant correlation between the left atrial volume and the mitral valve area, which could further be expressed by the following formula that estimates LA volume based on MA area: LA volume = 12 \(\times\) MA area + 50 mL (Figure 3). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & \multicolumn{4}{c}{**MITRAL ANNULUS**} & \multicolumn{4}{c}{**LEFT ATRIUM**} \\ \hline  & \begin{tabular}{c} **Long** \\ **Diameter** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Transversal** \\ **Diameter** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Circumference** \\ **(cm)** \\ \end{tabular} & \begin{tabular}{c} **Area (cm\({}^{2}\))** \\ **(cm)** \\ \end{tabular} & \begin{tabular}{c} **AP** \\ **Diameter** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **LL Diameter** \\ **(mm)** \\ \end{tabular} & \
\begin{tabular}{c} **SI Diameter** \\ **(mm)** \\ \end{tabular} &
\begin{tabular}{c} **Volume** \\ **(mm)** \\ \end{tabular} \\ \hline Mean \(\pm\) SD & 41.9 \(\pm\) 7.6 & 29.9 \(\pm\) 5.3 & 15.0 \(\pm\) 3.5 & 14.2 \(\pm\) 4.6 & 41.1 \(\pm\) 9.6 & 56.5 \(\pm\) 10.7 & 48.2 \(\pm\) 9.7 & 139 \(\pm\) 56.3 \\ \hline Range (Min-Max) & 23.9–57.1 & 21.3–39.4 & 9.6–23.6 & 6.4–22.0 & 26–71 & 39–88 & 27–68 & 101–349.6 \\ \hline \end{tabular}
\end{table} 
Table 1: Means and standard deviation for mitral annulus and left atrial dimensions.