The Study
Role of Autonomic Tone in the Initiation and Termination of Paroxysmal Atrial Fibrillation in Patients Without Structural Heart Disease
This study looked at how heart rate patterns changed right before and after a type of irregular heartbeat in 23 people. It found that the heart’s rhythm seemed to act differently at night versus during the day, but it didn’t prove that those changes caused the heartbeat problem—they just happened around the same time.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
This study found that when your heart suddenly races due to a harmless flutter (PAF), it's often because your body's 'calm down' system (vagus nerve) is too active at night, but your 'stress' system (sympathetic) is too active during the day.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 533 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this suggests your body’s natural rhythms control when these harmless heart flutters happen, which could help tailor treatments based on time of day.
- 2At night: HF and LF heart rate signals went up before the race, then down after.
- 3During the day: only the LF/HF ratio went up before and down after; HF stayed the same.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Cardiovascular Electrophysiology
Year
2003
Authors
T. Tomita, M. Takei, Y. Saikawa, T. Hanaoka, S. Uchikawa, H. Tsutsui, M. Aruga, T. Miyashita, Y. Yazaki, H. Imamura, O. Kinoshita, M. Owa, K. Kubo
Related Content
Claims (6)
In people without structural heart disease, heart palpitations occur due to an imbalance between the nervous system pathways that speed up and slow down the heart.
In people without structural heart disease, nighttime episodes of irregular heart rhythm are preceded by a measurable rise in both high- and low-frequency heart rate fluctuations, followed by a sharp decline after the episode ends, indicating a link to increased activity of the vagus nerve.
In people without structural heart disease, the fluctuations in heart rate variability during brief episodes of irregular heartbeat are not affected by how long the episode lasts or when it ends.
In people without structural heart disease, the part of heart rate variability linked to parasympathetic activity does not change during daytime episodes of sudden atrial fibrillation, even though other heart rate variability measures do change.
In people without structural heart disease, changes in heart rate variability before and after episodes of sudden irregular heartbeat are different depending on whether the episode happens during the day or at night.
In people without structural heart disease, daytime episodes of irregular heart rhythm are accompanied by a measurable increase in sympathetic nervous system activity before the episode starts and a decrease after it ends.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.