Clinical impact of screening for sleep related breathing disorders in atrial fibrillation

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Abstract

Objective

The aim of this study was to quantify daytime symptoms in atrial fibrillation (AF) patients with and without sleep related breathing disorders (SRBD).

Background

SRBD are common in patients with AF but little is known about daytime symptoms among those with SRBD.

Methods

Patients with AF admitted to clinics of two tertiary referral hospitals for a variety of different cardiovascular diseases were screened with a trans-nasal airflow measurement device allowing measurement of the apnea–hypopnea-index. Data on cardiac risk factors, left ventricular ejection fraction (LVEF) and cardiac medication were collected. Presence of SRBD was defined as an AHI  15/h. The Epworth sleepiness scale (ESS) was used to quantify daytime symptoms.

Results

Of 102 screened patients 8 were excluded due to device malfunction (n = 1), dislocation of nasal cannula (n = 6), or hyperthyroidism (n = 1). Among the remaining 94 patients, 40 (43%) were diagnosed with SRBD. Patients with and without SRBD had similar age, body mass index, LVEF and cardiac medication. The prevalence of coronary artery disease was higher in patients with SRBD than in those without (50 vs. 17%; p = 0.0007). ESS score was low and similar in both groups (no SRBD: median 4, interquartile range (IQR) 2–4 vs. SRBD: 5, IQR 3–8; p = 0.14). Only 6/40 (5%) of the patients underwent overnight polysomnography and 2 (5%) started CPAP ventilation during follow-up.

Conclusions

Even though SRBD are common in patients with AF, the prevalence of daytime symptoms is rare. Consequently, most patients will not initiate CPAP ventilation after positive SRBD screening.

Introduction

Approximately 1–5% of the adult population of western countries suffer from sleep related breathing disorders (SRBD) [1], [2]. In recent years several studies demonstrated a relationship between SRBD and AF in subjects with a variety of cardiovascular conditions, including patients with congestive heart failure and patients with a primary diagnosis of AF [3], [4]. Although known risk factors, such as age, arterial hypertension and obesity are common in patients with AF and SRBD, an independent association between both conditions is suspected.

Gami et al. first described a high prevalence of sleep apnea syndrome diagnosed by questionnaire in patients with a variety of cardiovascular conditions including heart failure [3]. Recurrence of AF after electrical cardioversion has been shown to be lower in subjects with appropriate treatment for SRBD compared to those without [5]. An association between SRBD and AF has also been described in subjects without evidence of structural heart disease and normal LVEF [4] whereas another study found sleep apnea to be common in subjects with lone AF but not more common compared to control subjects without AF [6].

Proposed pathophysiological mechanisms to explain the occurrence of AF in patients with SRBD include a reduction in oxygen saturation and hypercapnic phases due to repetitive hypopneic and apneic phases leading e.g. to chemoreceptor activation and arousals with consecutive increasing sympathetic neural activity [7]. In general, SRBD is suspected in the presence of combined night- and daytime symptoms, such as nightly gasping or excessive daytime sleepiness, especially in the presence of SRBD risk factors. However, cardiologists rarely refer their AF patients for SRBD screening. This study sought to investigate the prevalence of SRBD in patients with AF using an overnight screening analysis and to quantify daytime symptoms by questionnaire in those with and without SRBD.

Section snippets

Materials and methods

Patients with paroxysmal or persistent non-valvular AF admitted to two tertiary referral hospitals due to a variety of cardiac conditions were screened for the presence of SRBD with a validated device based on trans-nasal airflow measurement [8] (MicroMesam®, ResMed GmbH & Co. KG, Switzerland). The device allows overnight respiratory pressure measurements via a nasal cannula and automated analysis of apnea, hypopnea and snoring episodes. Apnea was defined as cessation of airflow > 10 s and

Results

One-hundred-and-two patients with persistent (73%) and paroxysmal (27%) AF were screened for the presence of SRBD. Eight patients were excluded due to device malfunction (n = 1), dislocation of nasal cannula (n = 6) and hyperthyroidism (n = 1). In the remaining 94 patients (age 69 ± 11 years), 43% (40/94) were diagnosed with SRBD. Baseline characteristics of the study population are presented in Table 1.

There were no significant differences between patients with and without SRBD with respect to

Discussion

In patients with a variety of cardiovascular diseases and concomitant persistent or paroxysmal non-valvular AF we determined a prevalence of 43% of SRBD using an overnight screening device based on trans-nasal airflow pressure measurement. This finding is consistent with previous studies, which used different methods to diagnose SRBD [3], [12]. The novel finding of our study is that daytime sleepiness was low in patients with SRBD, even in subjects with high AHI.

Daytime sleepiness has been

Conclusions

SRBD is frequent in patients with AF but typical symptoms of SRBD such as daytime sleepiness and obesity as a risk factor for OSA are rare. Although every effort had been made to convince patients with SRBD to undergo PSG, only 15% underwent PSG and in only 5% of patients CPAP ventilation was started on.

Acknowledgements

The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology. We would like to thank Mirjam Schefer for her tireless efforts in patient recruitment and data collection [22].

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    David R. Altmann and Hans Rickli contributed equally to the work.

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