What is the best test to determine the cause of atrial fibrillation in an obese patient with intermittent nocturnal hypoxemia?

From the Guidelines

The best test to determine the cause of atrial fibrillation in an obese patient with intermittent nocturnal hypoxemia is a polysomnography (sleep study). This comprehensive overnight test should be performed in a sleep laboratory where multiple physiological parameters can be monitored simultaneously, including brain activity, eye movements, heart rhythm, oxygen levels, breathing patterns, and body movements. Given the patient's obesity and nocturnal hypoxemia, obstructive sleep apnea (OSA) is highly suspected as a contributing factor to their atrial fibrillation, as supported by the 2016 European guidelines on cardiovascular disease prevention in clinical practice 1. OSA causes intermittent hypoxemia and significant fluctuations in intrathoracic pressure during apneic episodes, which can trigger atrial stretch, autonomic nervous system imbalances, and oxidative stress—all mechanisms that promote atrial fibrillation. The sleep study will quantify the severity of sleep apnea using the apnea-hypopnea index (AHI) and can guide appropriate treatment, which typically includes continuous positive airway pressure (CPAP) therapy. Treating the underlying sleep apnea can significantly reduce atrial fibrillation burden, improve rhythm control, and enhance the effectiveness of other atrial fibrillation treatments.

Some key points to consider in this patient's management include:

• The patient's obesity and history of hypertension, which are risk factors for both OSA and atrial fibrillation
• The presence of intermittent nocturnal hypoxemia, which suggests OSA as a potential contributing factor to the patient's atrial fibrillation
• The importance of comprehensive risk factor management, including weight loss and treatment of underlying sleep apnea, to reduce atrial fibrillation burden and improve outcomes, as recommended in the 2024 ESC guidelines for the management of atrial fibrillation 1
• The potential benefits of CPAP therapy in reducing atrial fibrillation burden and improving rhythm control in patients with OSA and atrial fibrillation.

Overall, a polysomnography (sleep study) is the most appropriate test to determine the cause of atrial fibrillation in this obese patient with intermittent nocturnal hypoxemia, given the strong association between OSA and atrial fibrillation, and the potential benefits of treating underlying sleep apnea in improving atrial fibrillation outcomes.

From the Research

Determining the Cause of Atrial Fibrillation

To determine the cause of atrial fibrillation in an obese patient with intermittent nocturnal hypoxemia, several factors and tests should be considered:

• The patient's symptoms, such as shortness of breath and palpitations, along with their medical history, including type 2 diabetes mellitus and hypertension, are crucial in identifying potential causes of atrial fibrillation.
• The presence of nocturnal hypoxemia, as indicated by oxygen saturation levels as low as 83%, suggests a possible link to obstructive sleep apnea (OSA), which is a known risk factor for atrial fibrillation 2, 3, 4, 5.
• Studies have shown that OSA is highly prevalent in patients with atrial fibrillation, and that treating OSA with continuous positive airway pressure (CPAP) can reduce the recurrence of atrial fibrillation 4, 5.

Recommended Test

Based on the evidence, the best test to determine the cause of atrial fibrillation in this patient would be:

• Polysomnography (PSG): This is the gold standard test for diagnosing OSA and would help to confirm the presence of OSA and its severity 2, 3, 6, 4, 5.
• PSG would provide detailed information on the patient's sleep patterns, including the frequency and duration of apneic events, hypopneas, and oxygen desaturation, which would be essential in determining the cause of atrial fibrillation.

Rationale

The rationale for choosing PSG is based on the strong association between OSA and atrial fibrillation, as well as the patient's symptoms and medical history. By diagnosing and treating OSA, it may be possible to reduce the risk of recurrent atrial fibrillation and improve the patient's overall health outcomes 2, 3, 4, 5.