Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium

OBJECTIVES The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA). BACKGROUND Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood. METHODS A total of 53 patients with PAF (25 patients, mean age 59 ± 6.1 years, 3 women) and CAF (28 patients, mean age 59 ± 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system. RESULTS Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 ± 19 vs. 104 ± 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71). CONCLUSIONS Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.