ABC | Volume 112, Nº4, April 2019

Original Article Ciuffo et al LA Remodeling and Dyssynchrony Arq Bras Cardiol. 2019; 112(4):441-450 Figure 1 – Quantification of left atrial regional function using cine cardiac magnetic resonance. The figures show a total of 12 color-coded segments within the left atrium. A: Two-chamber view with six equal-length segments; B: Four-chamber view with six equal-length segments. Figure 2 – Strain curves of all 12 segments. Green dots, standard deviation of the time to peak strain (SD-TPS) of each segment; Blue dots, standard deviation of the time to peak pre-atrial strain (SD-TPS preA ) of each segment. 60 50 40 30 20 10 0 0 200 400 600 800 1000 1200 Time (msec) (%) SD–TPS SD–TPS predA Simpson’s method, which was validated using the area-length method 19-21 and the maximum LA volume (V max ), pre-atrial contraction LA volume (V preA ), and minimum LA volume (V min ) were extracted. All LA volumes were normalized by body surface area based on the Haycock’s formula. 22 The LA emptying fractions (EF) were calculated as follows: LA total EF = (V max - V min ) × 100% / V max ; LA passive EF = (V max - V preA ) × 100% / V max ; and LA active EF = (V preA - V min ) × 100% / V preA . Ablation Protocol PVI catheter ablation of AF was performed using an electroanatomic mapping system with an image integration module (CARTO and CARTOMERGE®, Biosense Webster, Irvine, CA, USA) to merge preprocedural CMR. The electrical isolation of the pulmonary veins was confirmed by a circular multipolar electrode mapping catheter (Lasso, Biosense Webster, Irvine, CA, USA). In cases of persistent AF, the ablation procedure usually included complementary ablation strategies. Ablation was performed with either an open‑irrigated radiofrequency ablation catheter with or without force sensing, or a cryoballoon ablation catheter. Reproducibility Intra-reader reproducibility was established by one reader who performed analysis of the 15 studies twice, with an interval of 7 days between the two analyses. Inter-reader reproducibility was assessed by two readers who analyzed the same 15 cases. The second reader was blinded regarding the results of the first reader. Statistical analysis Data are presented as mean ± SD for normally distributed continuous variables, median and interquartile range (IQR) for non-normally distributed continuous variables, and percentages for categorical variables. Comparison between groups was performed using Student’s t test, chi-square test, and, Fisher’s exact test, as appropriate. Multivariable linear regression 443