Relationship between silent atrial fibrillation and the maximum heart rate in the 24-hour Holter: cross-sectional study

Abstract

CONTEXT AND OBJECTIVE: Occurrences of asymptomatic atrial fibrillation (AF) are common. It is important 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. RESUMO

CHA2DS2VASc Score as a Predictor of Cardiovascular Events in Ambulatory Patients without Atrial Fibrillation

“…One limitation of our study is the possibility of the underdiagnosis of cases of paroxysmal AF, which very often do not cause any clinical symptom. 16,17 It is not possible to state whether the risk conferred by the highest scores are due to the set of comorbidities (that are part of the score itself) or due to a greater chance of developing AF. We believe, however, that the second hypothesis is more reasonable to explain this phenomenon.…”

“…This arrhythmia carries by itself an increase in the risk of adverse events. One limitation of our study is the possibility of the underdiagnosis of cases of paroxysmal AF, which very often do not cause any clinical symptom . It is not possible to state whether the risk conferred by the highest scores are due to the set of comorbidities (that are part of the score itself) or due to a greater chance of developing AF.…”

Interpretation of uncommon ECG findings in patients with atrial flutter

“…(3,4). The most often AFL changes to atrial fibrillation (6,8,9); changes between different types of atrial flutter are less common. Figure 4 shows AFL with atrial rate of 175 per minute, regular 2:1 conduction and ventricular rate of 87 bpm spontaneously changing to AFL with atrial rate of 280 per minute, conduction 4:1 and ventricular rate 70 bpm.…”