Atrial fibrillation is a common arrhythmia with associated complications of stroke and other adverse outcomes. We conducted a population‐based study of 1763 Japanese men aged 40–74 years to examine the association between the frequency of nocturnal oxygen desaturation, estimated by a pulse oximeter, and the prevalence of atrial fibrillation. We found a significant association between the severity of sleep‐disordered breathing (SDB) and the prevalence of atrial fibrillation; the odds ratios (ORs) were 2.47 for those with 5–15 events/h of 3% oxygen desaturation index (ODI) level and 5.66 for those with ⩾15 events/h of 3% ODI level (p for trend = 0.02).
Although the association of SDB with atrial fibrillation has been reported in recent clinical studies,1,2,3,4 no population‐based epidemiological study has examined this relationship. We investigated the association between the frequency of nocturnal oxygen desaturation and the prevalence of atrial fibrillation among community‐based subjects.
Methods
The subjects were 1763 Japanese men aged 40–74 years who lived in three Japanese communities. They participated in the 2000–2004 annual cardiovascular risk surveys and were recruited for the present sleep study, at a total recruitment rate of 84%. The sensor of the pulse oximeter (PULSOX‐3Si, Minolta, Japan) was attached to the index finger during all‐night sleep at home.5 We used a sleep log to exclude waking time from the analysis to minimise potential overestimation of sleep duration. Data from people with total recording time <4 h, or with artefacts likely due to frequent body movement, inadequate fitting of the probe or excessive pulse pressure (n = 100) were excluded, and data from 1663 men were used for the analyses.
A 3% ODI was used to define SDB: 5–<15 events/h was considered mild SDB and ⩾15 events/h was considered moderate to severe SDB.5 Standard 12‐lead electrocardiograms were recorded in the supine position. Each record was coded independently using the Minnesota Code by two trained cardiovascular doctors. The criterion for atrial fibrillation was Minnesota Code 8‐3.
To compare the mean values of selected cardiovascular characteristics, we used analysis of covariance with age as covariate. The logistic regression analysis was used to obtain the ORs of the prevalence of atrial fibrillation according to categories of 3% ODI levels (table 1) after adjustment for age, body mass index, alcohol intake, smoking status (never, former smoker, currently 1–19 cigarettes/day and currently ⩾20 cigarettes/day), systolic blood pressure and the use of anti‐hypertensive drugs. The study was approved by the medical ethics committee of the University of Tsukuba, Tsukuba, Japan, and written informed consent was obtained from all participants.
Table 1 Age‐adjusted means (SEM), prevalence of selected cardiovascular risk characteristics and multivariate‐adjusted prevalence of atrial fibrillation in electrocardiogram according to 3% oxygen desaturation index (ODI) among 1663 men.
| 3% ODI | p for trend | |||
|---|---|---|---|---|
| 0–4 | 5–14 | 15+ | ||
| n | 975 | 534 | 154 | |
| Age, year | 58.7 (0.3) | 59.8 (0.4) | 61.1 (0.7) | <0.001 |
| BMI, kg/m2 | 23.1 (0.1) | 25.0 (0.1) | 26.7 (0.2) | <0.001 |
| Current ethanol intake, g/day | 22.2 (0.8) | 25.2 (1.0) | 26.1 (1.9) | 0.014 |
| Current smokers, % | 44 | 38 | 32 | 0.001 |
| Systolic blood pressure, mm Hg | 130.8 (0.5) | 133.8 (0.7) | 137.6 (1.3) | <0.001 |
| Diastolic blood pressure, mm Hg | 80.7 (0.3) | 82.9 (0.4) | 84.9 (0.8) | <0.001 |
| Use of antihypertensive drugs, % | 18 | 25 | 35 | <0.001 |
| Hypertension,* % | 42 | 51 | 62 | <0.001 |
| Atrial fibrillation | ||||
| n | 7 | 11 | 8 | |
| Multivariate‐adjusted prevalence† | 0.8 | 1.9 | 4.9 | <0.001 |
| Multivariate‐adjusted OR (95% CI)† | 1 | 2.47 (0.91, 6.69) | 5.66 (1.75, 18.34) | 0.020 |
BMI, body mass index; OR, odds ratio.
*Hypertension was defined as systolic blood pressure ⩾140 mm Hg, diastolic blood pressure ⩾90 mm Hg or use of antihypertensive drugs.
†Adjusted for age, BMI, alcohol intake, smoking status, systolic blood pressure and use of antihypertensive drugs.
Results
The mean age, body mass index, alcohol intake, blood pressure, prevalence of use of anti‐hypertensive drugs and hypertension correlated positively with the 3% ODI level. After adjustment for these covariates, the ORs for atrial fibrillation were 2.47 (95% confidence interval (CI), 0.91 to 6.69) for those with 5–<15 of 3% ODI level (event/h) and 5.66 (95% CI 1.75 to 18.34) for those with ⩾15 of 3% ODI level (p for trend = 0.02).
Discussion
We found a significant positive association between the severity of SDB and the prevalence of atrial fibrillation among community‐dwelling Japanese men, independent of cardiovascular risk factors. The exact mechanisms for the association between SDB and atrial fibrillation are not clear but include chronic intermittent hypoxaemia, hypercapnia, intrathoracic pressure swing and activation of sympathetic nervous function, resulting in cardiac electric instability, distortion of cardiac configuration and hypertension.1,2,3,4 SDB is treatable through weight reduction and continuous positive airway pressure.1,2 A recent clinical case report showed that the onset of atrial fibrillation was preceded by a long apnoeic event, and spontaneous reversal to sinus rhythm occurred after a period without apnoeas.3 On the other hand, atrial fibrillation usually reduces cardiac output and the reduced cardiac output may lead to central apnoea during sleep, mainly owing to the chemoreflex enhancement and prolonged lag to ventilatory response.5 We should further clarify whether subjects with atrial fibrillation have a central apnoea pattern by polysomnography.
Atrial fibrillation is a common arrhythmia with associated complications of stroke and other adverse outcomes. Furthermore, atrial fibrillation is an extremely costly public health problem; the direct cost of atrial fibrillation was estimated as 459 million in the year 2000, equivalent to 0.97% of the total National Health Service expenditure.6 This study suggests that the detection of SDB and its successful treatment could be one of the public health approaches to reduce the risk and the cost of atrial fibrillation.
Acknowledgements
We thank Ms Minako Tabata and Yukiko Ichikawa for their cooperation.
Abbreviations
ODI - oxygen desaturation index
SDB - sleep‐disordered breathing
Footnotes
Funding: This study was supported partly by the Japanese Ministry of Education, Culture, Sports, Science and Technology (grant‐in‐aid for research B: 14370132), the Health and Labour Sciences Research Grant (Clinical Research for Evidence Based Medicine) and a research grant from FULHAP, Japan. The funding sources had no role in the study design, data collection, data analysis, data interpretation or writing of the report.
Competing interests: None declared.
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