P-184 Is There Any Wall Motion Abnormality of Left Atrium in Paroxysmal Atrial Fibrillation? Novel Finding of Dynamic Computed Tomography

Introduction: Atrial fibrosis and ischemia were related to the genesis of atrial fibrillation (AF). It remains to be answered whether the structural abnormalities lead to the functional changes of LA in paroxysmal AF? Methods: Sixty-five AF patients and 29 controls were included. The ECG gated and 64 slices multi-detector computed tomography was performed during sinus rhythm before ablation. The atrial images at end-diastolic and endsystolic phases were obtained. Nine hundred points at left atrium (LA) contour were sampled and the spatial differences of each point were compared between the two phases. They were further integrated into 18 segments in the bull-eye plots. Therefore, the ejection fraction (EF) the regional wall motion of LA could be assessed. Results: The EF of LA body and LA appendage were significantly reduced in AF compared with controls (LA: 26.9±13.4 versus 38.1±11.6%, p < 0.001; appendage: 36.5±20.2 versus 53.0±13.5%, p < 0.001). The magnitudes of wall motion of the 18 segments were all significantly reduced in AF compared to control. In addition, an unique pattern of LA contraction was illustrated. The magnitudes of wall motion in AF was smallest in the upper third LA, medium in the middle third LA and greatest in the lower third LA (5.15±0.51 versus 7.42±1.16 versus 9.52±1.48mm, p < 0.01). The pattern of LAmovement was similar in controls. Conclusion: The contractility of LA body and appendage were reduced in paroxysmal AF. This was attributed to the global hypokinesia of LA. No apparent regional wall motion abnormalities could be demonstrated in AF