ELECTRICAL ATRIAL REMODELING ASSESSED BY MONOPHASIC ACTION-POTENTIAL AND ATRIAL REFRACTORINESS IN PATIENTS WITH STRUCTURAL HEART-DISEASE

The present study was performed to assess the effect of induced atrial fibrillation (AF) on atrial monophasic action potentials (MAPs) and a trial refractory period (ERP) in patients with structural heart diseas e. An electrode MAP catheter was placed in the right atrium to continu ously measure atrial potential duration (APD(90)) in 13 patients (coro nary artery disease, 10 patients; dilated cardiomyopathy, 2 patients; hypertrophic cardiomyopathy, 1 patient) without spontaneous AF episode s. AF was induced by rapid atrial Stimulation (300-1500/min). If sinus rhythm returned within 10 minutes, AF wets reinduced. The atrial ERP was measured during atrial pacing at a basic cycle length of 550 ms be fore AF induction and after its conversion. Results: The mean atrial E RP and the atrial APD(90) before AF was 242 +/- 34 ms and 256 +/- 23 m s, respectively. ERP and APD(90) shortening was observed after 3 minut es of AF. After 11 +/- 0.5 min (10 min 20 s-13 min 10 s) of AF, ERP an d APD(90) reached their minimal values of 72% +/- 13% and 71 % +/- 10% of baseline, respectively. ERP and APD(90) returned to their initial values within 20 minutes after conversion of AF. A tendency toward lon ger duration of consecutive AF episodes and facilitation of their indu ction was observed. Conclusion: The present study confirms that short episodes of AF modify the electrophysiological properties of the atria in humans. In patients with structural heart disease, induced atrial fibrillation shortens the atrial ERP as well as the atrial APD(90). Th e changes were reversible within 10 minutes after arrhythmia terminati on.