Background: Nocturnal hypoxemic burden (T90) has been linked to increased cardiovascular morbidity and mortality. Several previuous studies fell short to identify, in addition to sleep-disordered breathing (SDB), common diseases that may contribute to increased nocturnal T90.

Aims and objectives: to evaluate the association of relevant common diseases with distinctive metrics of nocturnal T90 with and without repetitive desaturations.

Methods: In this sub-analysis of the prospective observational study, CONSIDER-AF (NCT02877745) portable SDB monitoring was performed in 429 patients with severe coronary artery disease. Nocturnal T90 was defined by total recording time spent with oxygen saturation <90%. Distinctive metrics included T90 due to intermittent hypoxemia (T90_desaturation) and T90 due to non-specific and non-cyclic SpO₂-drifts (T90_non-specific).

Results: Multivariable linear regression analysis identified SDB (apnea-hypopnea-index ?15/hour; B [95% CI]: 8.2 [3.3;13.1], p=0.001), obesity (8.5 [3.6;13.3], p=0.001) and mild to moderate chronic obstructive pulmonary disease (COPD, 16.9 [6.9;26.9], p=0.001) as predictors of increased T90. While SDB, obesity and chronic heart failure (HF) were significantly associated with an elevated T90_desaturation, obesity and COPD were significant modulators of T90_non-specific.

Conclusions: In addition to SDB, also obesity and COPD, but not chronic HF, contribute to increased nocturnal T90. SDB and leading causes for SDB, such as obesity and chronic HF, are associated with an increased nocturnal T90_desaturation. Potential causes for hypoventilation syndromes such as obesity and COPD are linked to an increased nocturnal T90_non-specific.