Prevalence of paroxysmal atrial fibrillation in a population assessed by continuous 24-hour monitoring

Abstract

Introduction: Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice and a major cause of morbidity, due to the associated risk of stroke. However, since it is often paroxysmal, it is commonly underdiagnosed and undertreated.

Objectives: The primary objective of this prospective study was to determine the prevalence of paroxysmal atrial fibrillation (PAF) in patients aged 40 and above in a population who underwent continuous 24-hour electrocardiographic monitoring. The secondary objectives were to determine the overall prevalence of AF/atrial flutter (AFL) regardless of the type and to compare the population with AF with the general population and patients with PAF with patients with AF.

Results: A total of 4843 consecutive patients were analyzed, 58% women, 26.2% aged 70-79 years (n=1269), 25.9% (n=1252) aged 60-69 years, and 19.0% (n=923) aged 50-59 years; the others were aged either >80 years (n=712, 14.7%) or <50 years (n=686, 14.2%). At least one episode of PAF was detected in 123 patients, a prevalence of 2.5% (95% CI: 2.1-3.0). The prevalence of persistent AF throughout the monitoring period was 9.4% (95% CI: 8.6-10.2) (n=454). Additionally, 39 cases of typical AFL were detected, but in 23 of them (sustained or paroxysmal) this appeared isolated, a prevalence of 0.8% (95% CI: 0.6-1.1). The overall prevalence of AF/AFL was thus 12.4%. The presence of some type of AF/AFL was significantly correlated with male gender (p<0.001), age (especially in the 70-79 and >80 age-groups) (p<0.001) and hypertension (p<0.001). This group had a significantly higher prevalence of previous stroke (56 patients [9.3%], p=0.001) and acute myocardial infarction (5.3%, p<0.001). Comparing the population with PAF and/or paroxysmal AFL (PAF/PAFL) to those with persistent AF (during 24-hour monitoring), significant differences were found: a higher prevalence of PAF/PAFL in younger individuals (40-49, 50-59 and 60-69 age-groups) and lower in older individuals (70-79 and >80 age-groups) (p<0.001), higher prevalence of history of stroke (p=0.024), and lower levels of hypertension (p<0.001). Only 12.8% of patients with PAF were taking anticoagulant drugs.

Conclusions: The prevalence of PAF found in a population referred for continuous 24-hour electrocardiographic monitoring for diverse reasons was 2.5% and the overall AF/AFL prevalence was 12.4%. PAF was more prevalent in younger patients. Patients with PAF showed a significantly lower prevalence of hypertension and significantly higher rates of stroke. Systematically detecting patients with PAF is a major public health concern, since early diagnosis is essential to identify candidates for oral anticoagulation and catheter ablation, which is frequently curative when applied at this stage.

Keywords: Electrocardiographic monitoring; Fatores de risco; Fibrilhação auricular paroxística; Monitorização eletrocardiográfica; Paroxysmal atrial fibrillation; Risk factors.