Asymptomatic atrial fibrillation in patients with atrial fibrillation and implanted pacemaker.

INTRODUCTION: Atrial fibrillation is the most common chronic arrhythmia. Due to diagnostic difficulties, the exact prevalence of silent atrial fibrillation is not precisely defined.

AIM: The main aim of the present study was to assess the prevalence of asymptomatic atrial fibrillation and the relation between clinical status and presence of symptoms of atrial fibrillation.

MATERIAL AND METHODS: Fifty patients with implanted pacemaker with atrial fibrillation recording function and diagnosed paroxysmal atrial fibrillation were enrolled to the study in order to detect episodes of atrial fibrillation. Episodes lasting >1min were included into analysis. Patients were evaluated for presence of atrial fibrillation symptoms.

RESULTS: A total of 870 atrial fibrillation episodes were registered, the majority (93%) were asymptomatic. Episodes occurred more often during the day than during the night (p<0.001). Asymptomatic episodes occurred 13 times more frequently than symptomatic (p<0.001). Majority of episodes lasting up to 5min were asymptomatic, while episodes lasting over 24h were usually symptomatic (p<0.001). Furthermore, there were association between silent atrial fibrillation and lower HR (p=0.003), higher percentage of atrial (p=0.01) and ventricular pacing (p<0.001), male gender (p<0.001), presence of atrioventricular block (p<0.003), lower NYHA class (p<0.002), and calcium channel blockers (p=0.033) and diuretics intake (p<0.001).

CONCLUSION: In patients with bradycardia permanent pacemakers and paroxysmal atrial fibrillation, the proportion of asymptomatic episodes is very high. It was observed that shorter duration of the episodes, male gender, lower heart rate, presence of atrioventricular block, lower NYHA class, higher percentage of atrial and ventricular pacing, Ca2+ blockers, and diuretics intake predisposed to silent atrial fibrillation.