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  • OSA is a risk factor for hypertension and

    2019-05-13

    OSA is a risk factor for hypertension and stroke in particular [6,7]. Continuous positive airway pressure (CPAP) treatment reduces deaths and cardiovascular events, and improves hypertension control [8,9]. The role of CPAP therapy on the treatment of cardiac arrhythmia is still limited. Here, we reported a case of OSA-induced AF and successful AF conversion by CPAP therapy.
    Case history A 65-year-old Thai man presented with dizziness. His physical examination was unremarkable except for an irregular pulse. His electrocardiography (EKG) result was compatible with AF (Fig. 1). He underwent laboratory examinations for causes of AF, including echocardiography (Table 1) and thyroid function test. The left atrium (LA) size was 32mm. All investigations were normal. He was sent to a sleep clinic because of a history of snoring, daytime somnolence (Epworth Sleepiness Scale score of 18/24), morning headache, and AF. Physical examination revealed a body mass index of 30kg/m2, neck circumference of 42cm, Mallampati class 4, no tonsillar enlargement, no retrognathia, and no torus. His sleep was monitored using a portable monitoring device (Embletta)®. The apnea-hypopnea index (AHI) was 63.6times/h (supine AHI, 64.5h−1; non-supine AHI, 63.5h−1). Details of AHI values are provided in Table 2. Other polysomnographic data were as follows: CPAP therapy was introduced, and treatment was successful. A CPAP pressure of 10cm H2O reduced the AHI to 3.2h−1. The patient had good compliance with CPAP therapy and reported refreshed sleep. At the 2 months follow-up examination, his pulse rate became regular with an EKG finding of a normal sinus rhythm (Fig. 2). Unfortunately, he developed left facial palsy due to squamous cell carcinoma of the inner ear 6 months later. He stopped complying with CPAP therapy owing to poor mask fitting. His cardiac rhythm returned to AF at 2 months after he stopped using CPAP. He died of cysteine protease metastasis.
    Discussion The condition of this patient was diagnosed as OSA-induced AF because no other possible cause was identified. OSA has been shown to be independently associated with AF development [10]. The prevalence rate of OSA-induced AF may be high as 50% [2]. There are several underlying mechanisms. Intermittent desaturation at night is the main mechanism of cardiac arrhythmia caused by OSA [1,11]. Nighttime hypoxemia from OSA causes atrial remodeling and dilatation, conduction abnormalities, vagal tone hyperfunction, pulmonary vasoconstriction/hypertension, or increase in inflammatory markers [11–16]. This case shows that effective CPAP treatment with good compliance may convert AF to normal sinus rhythm. CPAP therapy resolves all underlying mechanisms of AF induced by OSA. To our knowledge, there is no previous report on using CPAP to convert the AF cardiac rhythm to sinus rhythm in an OSA patient, without cardioversion or antiarrhythmic drugs. Previously, CPAP therapy was shown to reduce the recurrence rate of AF after successful cardioversion to sinus rhythm at the 12 months follow-up examination [17]. Unfortunately, the present patient was able to comply with the CPAP therapy for only a short period. Therefore, the long-term effects of CPAP therapy on cardiac arrhythmia were not evaluated in this patient. Although attended polysomnography, which allows evaluation of sleep stages, was not performed in this patient, the portable sleep study was approved for the diagnosis of OSA in patients at risk [18,19]. Pro-brain natriuretic peptide and high-sensitivity C-reactive protein levels were not measured because of the normal echocardiogram and the absence of clinical features of heart failure, coronary artery disease, or other structural heart diseases. We believed that the AF in this patient was persistent and converted by CPAP therapy. The clinical symptoms of OSA and palpitations were also improved after CPAP therapy without any other treatments for AF. When the patient quit CPAP therapy, the AF recurred for >1 month, suggesting persistent AF. Therefore, CPAP therapy may convert AF to sinus rhythm in an OSA patient if the LA size is still normal [20]. An LA size of <40mm is considered normal.