Regional Disparities of Endocardial Atrial Activation in Paroxysmal Atrial Fibrillation

UNLABELLED: Previous experimental data suggest that atrial activity is homogeneously distributed during paroxysmal atrial fibrillation (AFib). Little is known about this in human paroxysmal AFib. METHODS: Twenty-five men and two women (mean age 49 +/- 11 years; five with structural heart disease) with paroxysmal AFib for a mean 5 +/- 6.2 years despite the use of a mean of 3.6 +/- 1.7 antiarrhythmic drugs underwent atrial mapping. The right atrium was divided into four regions: posterior (intercaval), lateral, anterior, and septal. A 14-pole catheter was positioned to assess complex electrical activity defined as the duration of continuous electrical activity or electrograms with FF intervals < 100 ms for 60 seconds (expressed as percentage of time). In addition, the left atrium (divided into three regions: posterior, anterior, and septal) was explored in 12 patients with a multipolar catheter. RESULTS: The complex electrical activity time between all the regions explored was significantly different. In the right atrium, the septal (74% +/- 32%; P = 0.02) and the posterior (63% +/- 32%; P = 0.04) areas were significantly more disorganized than the lateral (22% +/-23%) and anterior (21% +/- 26%) regions. In the left atrium, complex electrical activity was predominant and widely distributed (posterior: 87% +/- 11%; septal: 65% +/- 27%) except in the appendage area (anterior region: 18% +/- 14%). CONCLUSIONS: Quantitative assessment of complex electrical activity in both atria in humans shows heterogeneous temporal and spatial distribution. This may have implications for guiding catheter ablation of AFib.