Background: Left atrial (LA) enlargement is a predictor of worse outcome after catheter ablation for atrial fibrillation (AF). We investigated the correspondence between single LA diameter and LA volume in patients undergoing catheter ablation for AF.
Methods: We analysed LA diameter assessed echocardiographically in parasternal long-axis view (LAd) and LA CARTO-derived volume (LAV) in 782 pts (546 males; aged 58 ± 11 yrs; paroxysmal AF in 56% of pts; 183 ± 50 CARTO points; CT image registration in 50% of cases) in 2 centres in the period of 2007–2011. The relation between LAd and LAV was described by linear regression.
Results: Mean LAd was 45 ± 6mm (median: 45; IQR: 41–49; range: 25–73mm) and mean LAV was 134 ± 42ml (median: 128; IQR: 103–160; range: 46–313ml). Pearson’s correlation coefficient between both variables was 0.57 (p<0.0001) with regression equation of LAV = -34.6 + 3.734 * LAd (Figure). Absolute and relative differences between measured and predicted LA volumes ranged from -93 to +134ml and from -64% to +116% and had standard deviations of 34ml and 25%, respectively. LAd > 45 mm had specificity of 66% and sensitivity of 69% for the detection of LAV > 130ml.
Conclusion: The correlation between LA diameter and volume is weak. LA size can be severely over- or underestimated by the use of single LA diameter assessed in parasternal long-axis view.