Aims: The mechanism of atrial fibrillation recurrence following cardioversion is unknown, although experimental studies have indicated that changes in dispersion of atrial refractoriness may play a role. The aims of this study were to assess (1) if dispersion of atrial refractoriness is relevant to atrial fibrillation recurrence and (2) if dispersion of refractoriness is part of the atrial electrical remodelling process in humans.
Methods and results: Thirty-seven consecutive patients underwent internal cardioversion (CV1) of persistent atrial fibrillation. Patients were monitored by daily transtelephonic recordings following discharge and if there was spontaneous atrial fibrillation recurrence they were rapidly admitted for repeat cardioversion (CV2). We used the 5th percentile of 100 consecutive atrial fibrillation cycle lengths (AFCL(P5)) and the atrial effective refractory period (AERP) as measures of atrial refractoriness at four different atrial sites. Dispersion of AFCL(P5)at CV1 was significantly higher in those who had subsequent recurrence of atrial fibrillation than in those who remained in sinus rhythm for at least 1 month after cardioversion (35+/-17 ms vs 9+/-13 ms;P<0.02). Dispersion of AFCL(P5)measured at CV2 was significantly lower than that measured in the same patients at CV1 (19+/-8 ms vs 35+/-11 ms;P=0.02). i.e. dispersion of AFCL(P5)had reduced following a period of sinus rhythm. In contrast, there was no difference in dispersion of AERP between the recurrers and non-recurrers. Dispersion of AERP between CV1 and CV2 did not change following a period of sinus rhythm.
Conclusion: Dispersion of AFCL is relevant to atrial fibrillation recurrence and may represent a manifestation of atrial electrical remodelling in humans. Treatment directed at AFCL dispersion may be useful in the suppression of atrial fibrillation recurrence following cardioversion.
Copyright 2001 The European Society of Cardiology.