Attenuation of electrical remodelling in chronic atrial fibrillation following oral treatment with verapamil

Aims Electrical remodelling with shortening of the atrial refractory period and increased fibrillatory rate occurs after onset of atrial fibrillation and can be attenuated by pre-treatment with intravenous verapamil. The aim of the present study was to investigate whether already established fibrill atory-induced shortening of atrial fibrillatory cycle length could be rever sed with oral verapamil. Methods and Results Thirteen patients (nine men; mean age 67 years) with ch ronic atrial fibrillation (CAF) were studied. The dominant atrial cycle len gth (DACL) was estimated non-invasively using the frequency analysis of fib rillatory ECG (FAF-ECG) method. Measurements were repeated following treatm ent with slow release oral verapamil. DACL increased from 147 +/- 13 ms to 156 +/- 21 ms after 1 day (P=0.02), to 164 +/- 18 ms after 5 days (P=0.005) and finally to 160 +/- 16 ms after 6 weeks (P=0.008). Conclusion Long-term oral treatment with verapamil increases the DACL signi ficantly in patients with CAF. The prolongation is evident after 1 day and is further developed during the first 5 days of treatment. Since DACL is be lieved to be an index of refractoriness, the findings of the present study suggest that this treatment increases the atrial refractory period in patie nts with CAF. (C) 1999 The European Society of Cardiology.