Is there a synergic effect of propafenone associated with atrial overdrivepacing for atrial arrhythmia prevention? A randomised crossover study

Objective-To assess the effect of adding propafenone to atrial overdrive fo r the prevention of atrial arrhythmia episodes in patients with DDD pacemak ers. Design-22 patients (8 female, 14 male, mean (SD) age 67 (9) years, range 48 to 77) with DDD pacemakers and frequent paroxysmal atrial arrhythmia episo des were evaluated in a randomised crossover study. Setting-University hospital. Methods-Atrial overdrive was defined as a paced rate of 10 paced beats/min above the mean ventricular rate stored for the last 24 hours in the pacemak er memory function. The protocol consisted of two phases of one month each. The first phase consisted of atrial overdrive alone, while in the second p hase, propafenone (600 mg/day) was added to atrial overdrive (atrial overdr ive + propafenone). All 22 patients underwent the two phases in random orde r. Results-Mean ventricular rate was 72 (8) beats/min with atrial overdrive v 73 (6) with atrial overdrive + propafenone (NS). With atrial overdrive, 14 patients (64.6%) had no recorded atrial arrhythmia v 15 (68.2%) with atrial overdrive + propafenone (NS). There was no statistical difference between the atrial overdrive and atrial overdrive + propafenone phases with regard to the number of atrial arrhythmia episodes (14 (27) v 13 (28)), their tota l duration (30 (78) v 29 (63) h), and their maximum duration (41 (72) v 31 (58) min). However, in the brady-tachy subgroup with persistent atrial arrh ythmias, atrial overdrive + propafenone produced a shorter mean cumulative duration of atrial arrhythmia than atrial overdrive (104 (115) v 178 (149) h, p = 0.04), with a significant decrease in the number of atrial arrhythmi a episodes (134 (98) v 102 (83), p = 0.05). The proportion of asymptomatic atrial arrhythmia episodes increased only in the AV block group during atri al overdrive + propafenone (p = 0.03). Three patients had atrial arrhythmia s during atrial overdrive + propafenone but not with atrial overdrive alone . Conclusions-In DDD paced patients, the overall effect of propafenone during atrial overdrive is variable. Propafenone may increase the proportion of a symptomatic atrial arrhythmia episodes. A proarrhythmic effect of propafeno ne was documented (aggravation of aerial arrhythmias). These results need t o be confirmed by further larger randomised studies.