Electrical Remodeling in Human Atrial Fibrillation Influences Post-Cardioversion Atrial Mechanical Dysfunction and Early Relapse

Abstract

Background:It has been demonstrated that atrial fibrillation (AF induces shortening of atrial refractory period, which was known as electrical remodeling, resulting in an increased vulnerability for reinduction of AF. Atrial mechanical function does not restore immediately after cardioversion, atrial stunning exists during this period in chronic AF. We hypothesized that electrical remodeling in chronic AF determines the atrial mechanical dysfu- nction after cardioversion and early relapse of AF. Method:Patients with chronic atrial fibrillation (CAF, n =17 who have been done transthoracic DC cardioversion, paroxysmal AF (PAF, n=11, and normal control (CON, n=5 were studied. Using MAP (monophasic action potential catheter, MAP duration 90% repolari- zition (MAPD90 and atrial effective refractory period (AERP were measured at 9 different sites in the right atrium. Magnitude of dispersion of these parameters was calculated by SD 2 (variance. Assessment of mitral inflow variables (peak velosities of A, E wave, and A/E ratio was performed at immediately after DC cardio- version, 1st day, 3rd days, 1 week, 4 weeks and 8 weeks by transthoracic pulse wave Doppler. Result:MA- PD90 significantly shortened in patients with CAF (235.4±38.1 ms compared with that of PAF (270.9±45.2 ms and control (274.0±51.9 ms, whereas AERP did not show significant differences. The magnitude of dispersion of MAPD90 and AERP was not different among the groups. AF recurred in 9 of 17 (53% patients with CAF particularly in whom A/E ratio was 0.4(250.9±52.9 ms, p=0.05. Conclusion:Electrical remodeling in chronic human AF characterized by shortening of monophasic action potential duration is one of the main factors that determines the atrial mechanical dysfunction after cardioversion and early relapse into AF. (Korean Circulation J 1999;29(8 :788-795