Abstract 641: Left Atrial Wall Thickness is a Predictor of Transition from the Paroxysmal Atrial Fibrillation to Chronic Form: Comparisons of Chronic Atrial Fibrillation and Normal Sinus Rhythm
Purpose We used ECG-gated multislice CT to evaluate alterations in the left atrial (LA) wall that may suggest the occurrence of structural remodeling in patients with paroxysmal atrial fibrillation (AF) (PAF) and compared the results with those of patients with chronic AF (CAF) and normal sinus rhythm (NSR).
Materials and methods We enrolled 3 groups, each consisting of 62 patients with either recurrent PAF (48 males, 65 ± 11 yrs), CAF (43 males, 69 ± 9 yrs), or NSR without any history of AF (40 males, 64 ± 11 yrs) for a total of 186 study patients. In CT, the absolute LA wall thickness (LAT) and LA volumes were calculated. To evaluate important predictors of the transition from PAF to CAF in patients with PAF, the area under the receiver operating characteristics (ROC) curve for each parameter was estimated. Furthermore, to analyze the difference in the rate of transition from PAF to CAF, Kaplan-Meier analysis and log-rank test were used.
Results: In transthoracic echocardiogram (TTE), patients with CAF had significantly larger LA diameter (LAD) than those with either PAF or NSR (48.3 ± 8.4 mm in CAF, > 38.6 ± 5.0 mm in PAF or 36.7 ± 4.6 mm in NSR, respectively. p <0.01). In CT, patients with PAF had significantly thicker LAT than those with either CAF or NSR (2.4 ± 0.2 mm in PAF >2.1 ± 0.2 mm in CAF or 1.9 ± 0.2 mm in NSR, p <0.01). Patients with CAF had significantly larger LA volume than those with either PAF or NSR (p <0.01). Subsequently, 9 of the 62 patients with PAF developed CAF over a mean follow-up period of 19 ± 22 months. The mean LAT was significantly thinner in patients who had transitioned from PAF to CAF than in those who had not (2.2 ± 0.2 mm and 2.4 ± 0.2 mm, respectively) (p <0.01). ROC analysis demonstrated that the area under the curve for LAT was greater than that for LA volume in CT and LAD in TTE. The proportion of patients transitioning from PAF to CAF was 52% with LAT < 2.4 mm and 17% with LAT ≥ 2.4 mm respectively and in the Kaplan-Meier analysis, the transition from PAF to CAF was observed more frequently in patients with LAT ≥ 2.4 mm than in those with LAT ≥ 2.4 mm (p = 0.018).
Conclusions Alteration of the LA wall may suggest a part of structural remodeling in AF before the occurrence of LA dilatation. LA wall thickness in CT seems to be a useful predictor of the transition from PAF to CAF in patients with PAF.