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High prevalence of recurrent nocturnal desaturations in systemic AL amyloidosis: a cross-sectional pilot study
Shameem Mahmood1, Milind Sovani2, Peter Smith2
1National Amyloidosis Centre, Division of Medicine, Royal Free Hospital Campus, University College of London Medical School, London, UK.
Objectives:
Cardiac involvement and/or macroglossia with soft tissue deposits are risk factors for central sleep apnoea (CSA) and obstructive sleep apnoea (OSA), and common features of systemic AL amyloidosis. Little data exist on the occurrence of sleep-disordered breathing (SDB) or recurrent nocturnal hypoxia in amyloidosis, which this study sought to investigate.
Methods:
A total of 72 consecutive patients with systemic amyloidosis (mean age 69 years and mean BMI 25) were evaluated for occurrence of SDB, by overnight continuous pulse oximetry, and completed Epworth Sleepiness Score (ESS) and STOPBANG questionnaires. Patients included: AL cardiac (AL-C), AL macroglossia (AL-M), AL both (AL-CM) and transthyretin (ATTR).
Results:
Mean overnight oxygen saturations were 93% (SD ± 2, 95% CI 87-96) with abnormal oximetry (4% oxygen desaturation index (ODI) >5/hour): AC-C 84%, AL-M 57%, AL-CM 62% and ATTR 47%. NYHA class directly correlated with a higher 4% ODI, NYHA class I vs 3, (p = 0.01). Two-thirds of patients had STOPBANG scores >3 and abnormally high ESS scores (>10) were seen in up to 30% of patients.
Conclusion:
Recurrent nocturnal hypoxaemia, suggestive of sleep-disordered breathing, is frequent in systemic AL amyloidosis. The higher incidence in cardiac amyloidosis highlights CSA and recurrent hypoxia as possible mechanisms for morbidity/mortality in these cases. A detailed polysomnography study is planned to clarify and further investigate these findings.