DISPERSION OF REPOLARIZATION IN PAROXYSMAL ATRIAL-FIBRILLATION

Widened dispersion of refractoriness has been considered to lead to an increase in atrial vulnerability. In this study, we obtained simultan eous monophasic action potential recordings by 2 special catheters fro m 2 different loci in the right atrium in 9 normal subjects (Group 1) and in 7 patients with paroxysmal atrial fibrillation (Group 2). We me asured action potential duration at 50% (APD50) and 90% (APD(90)) repo larization from both loci in the right atrium during steady-state thro ugh one of the two catheters. The differences between APD(50) and APD( 90) recorded by the two catheters were designated as dispersion of APD (50) and dispersion of APD(90), respectively. While, the mean APD(50) and APD(90) were 149.7 +/- 16.9 and 228.3 +/- 44.7 ms respectively in Group 1, the corresponding values for Group 2 were 145.7 +/- 33.5 and 213.5 +/- 53.1 ms. The difference between the 2 groups was not statist ically significant. However, the dispersion of APD(50) and APD(90) wer e 13.8 +/- 13.8 and 10.0 +/- 9.7 ms in Group 1 and 42.8 +/- 19.6 and 5 7.1 +/- 32.4 in Group 2, respectively and the difference between the 2 groups for both measurements was statistically significant (P<0.01). Another finding was a high correlation between age and dispersion of A PD(90) in the whole population studied (r=0.82, P<0.001). With these f indings, although one can not derive the conclusion that patients with paroxysmal atrial fibrillation have a greater dispersion of repolariz ation, our finding of increasing dispersion of repolarization with age could be an explanatory factor for the increased prevalence of atrial fibrillation with advanced age. (C) 1998 Elsevier Science Ireland Ltd .