Monitoring the progression of the atrial electrical remodeling in patients with paroxysmal atrial fibrillation.

It is important to clarify how electrical remodeling develops in clinical cases of paroxysmal atrial fibrillation (PAF), because it has been suggested that this electrophysiological phenomenon promotes an increase in the frequency of PAF. In the present study, the f-f interval during PAF was analyzed from the ambulatory ECG recordings of 21 patients with PAF (total PAF duration >2/24 h with normal atrial size) to monitor the atrial electrophysiological changes. The patients were clinically followed-up for 6 months without any antiarrhythmic drugs. Before and after the follow-up period 24-h Holter monitoring was carried out and the duration of both the PAF and the f-f intervals during the PAF episode were evaluated. In selected cases, the atrial effective refractory period (ERP) was evaluated in an electrophysiologic study before and after the follow-up period. The total PAF duration was prolonged from 187±50 to 223±79 min (p=0.034) and the f-f interval was shortened from 0.14±0.03 to 0.12±0.02 ms (p=0.003). There was an inverse relationship between the changes in total PAF duration and f-f interval (p=0.027). The ERP was shortened from 214±15 to 194±5 ms (n=5, p=0.025) and there was a direct correlation between the changes in ERP and f-f interval (p=0.048). In clinical cases, the prolongation of the PAF was related to the shortening of the f-f interval during the PAF episodes and to the shortening of the atrial ERP. Electrical remodeling plays a role in promoting the development of the atrial fibrillation in patients with PAF. (Circ J 2003; 67: 133 - 138)