Abstract 2028: Anatomical Remodeling of the Left Atrium in Paroxysmal Atrial Fibrillation by Multislice Computed Tomography In Comparison with Chronic Atrial Fibrillation and Normal Sinus Rhythm
Purpose: Anatomical remodeling of the left atrium (LA) in subjects with paroxysmal atrial fibrillation (PAF), chronic atrial fibrillation (CAF) and normal sinus rhythm (NSR) was examined by multislice computed tomography (MSCT).
Materials and Methods: 120 subjects (40 subjects each with CAF, PAF, and NSR, mean ages: 70, 66 and 64 years, respectively) underwent MSCT (Light Speed VCT, or Ultra 16, GE) to evaluate the pectinate muscles (PM) in the left atrial appendage (LAA), LAA enlargement, and contrast defect in the LAA in the early phase.
Results: Well-developed PM, poor PM, and no PM were observed in 18%, 41%, and 41% (CAF), 58%, 24%, and 18% (PAF), and 88%, 12%, and 0% (NSR), respectively. CAF subjects with no PM had longer periods of CAF than those with developed PM. LAA enlargement and contrast defects in the LAA were observed in 88% and 59% (CAF), 41%, and 24% (PAF), and 0% and 0% (NSR), respectively. Wall thickness and the ratio of abnormal late enhancement of the LA wall, indicating fibrosis or inflammation, were 2.1±0.4mm and 0% (CAF), 3.0±0.7mm and 22% (PAF), and 2.1±0.6mm and 0% (NSR), respectively. These values were significantly greater in PAF than in CAF and NSR. Transthoracic echocardiogram revealed mean LA sizes of 51.7mm (CAF), 39.5mm (PAF), and 37.6mm (NSR). The mean LA size was greater in CAF than PAF and NSR. A significant negative correlation was observed in CAF between the LA wall thickness and LA diameter (R=−0.57), and a positive, but weak correlation was observed in PAF and NSR between the LA wall thickness and LA diameter (R=0.39, 0.21, respectively).
Conclusions: Anatomical differences were observed between subjects with PAF, CAF and NSR. Lack of PM and LAA enlargement were influenced by the presence of CAF, the period of CAF, and LA diameter enlargement. Wall thickening and late enhancement of the LA wall suggest the anatomical remodeling of the LA in PAF. In addition, LA wall thickening with the presence of fibrosis or inflammation may represent an initial stage of LA remodeling. During transition from PAF to CAF, the LA wall may be stretched and, ultimately, LA wall thickness may decrease in CAF.