Relationship between silent atrial fibrillation and the maximum heart rate in the 24-hour Holter: cross-sectional study Relação entre fibrilação atrial silenciosa e frequência cardíaca máxima no Holter de 24 horas: estudo transversal

CONTEXT AND OBJECTIVE: Occurrences of asymptomatic atrial fibrillation (AF) are common. It is impor tant to identify AF because it increases morbidity and mortality. 24-hour Holter has been used to detect paroxysmal AF (PAF). The objective of this study was to investigate the relationship between occurrence of PAF in 24-hour Holter and the symptoms of the population studied. DESIGN AND SETTING: Cross-sectional study conducted at a cardiology hospital. METHODS: 11,321 consecutive 24-hour Holter tests performed at a referral service were analyzed. Patients with pacemakers or with AF throughout the recording were excluded. RESULTS: There were 75 tests (0.67%) with PAF. The mean age was 67 ± 13 years and 45% were female. The heart rate (HR) over the 24 hours was a minimum of 45 ± 8 bpm, mean of 74 ± 17 bpm and maximum of 151 ± 32 bpm. Among the tests showing PAF, only 26% had symptoms. The only factor tested that showed a correlation with symptomatic AF was maximum HR (165 ± 34 versus 147 ± 30 bpm) (P = 0.03). Use of beta blockers had a protective effect against occurrence of PAF symptoms (odds ratio: 0.24, P = 0.031). CONCLUSIONS: PAF is a rare event in 24-hour Holter. The maximum HR during the 24 hours was the only factor correlated with symptomatic AF, and use of beta blockers had a protective effect against AF symptom occurrence.