OSA and Depression Are Common and Independently Associated With Refractory Angina in Patients With Coronary Artery Disease
Is obstructive sleep apnea (OSA) more common and more severe among patients with refractory angina than in patients with stable coronary artery disease (CAD)?
Consecutive patients with refractory angina were recruited from a tertiary university hospital between 2011 and 2013, and compared to a control group with stable angina. Refractory angina is defined as angina present >3 months and not amenable to angioplasty, bypass, or medical therapy. Besides detailed history and physical and laboratory studies, all patients completed the Epworth Sleepiness Scale (ESS), Beck depression inventory (BDI) questionnaires, as well as an overnight polysomnography.
A total of 79 consecutive patients with refractory angina were evaluated, and 9 were excluded. The control group was comprised of 70 patients awaiting elective bypass surgery. Patients with refractory angina compared with patients with stable CAD were similar in gender (male, 61.5% vs. 75.5%; p = 0.07) and body mass index (29.5 ± 4 kg/m2 vs. 28.5 ± 4 kg/m2, p = 0.06), and were older (61 ± 10 years vs. 57 ± 7 years, p = 0.013). Patients with refractory angina had significantly more symptoms of daytime sleepiness (ESS score, 12 ± 6 vs. 8 ± 5; p < 0.001), and had higher depression symptom scores (BDI score, 19 ± 8 vs. 10 ± 8; p < 0.001) despite greater use of antidepressants. The patients with refractory angina had a higher apnea-hypopnea index (AHI) (AHI, 37 ± 30 events/hour vs. 23 ± 20 events/hour; p = 0.001), a higher proportion of oxygen saturation <90% during sleep (8% ± 13 vs. 4% ± 9, p = 0.04), and a higher proportion of severe OSA (AHI ≥30 events/hour, 48% vs. 27%; p = 0.009) than patients with stable CAD. In a multivariate analysis, OSA, ESS, and lower sleep efficiency were independently associated with refractory angina.
The authors concluded that OSA is more common and severe in patients with refractory angina than in patients with stable CAD. Also, patients with refractory angina have more symptoms of depression despite their greater use of antidepressants than patients with stable CAD.
This observational study among a small group of patients with coronary atherosclerosis (refractory angina prevalence among CAD patients, 10-15%) is hypothesis generating. Both depression and OSA may stimulate mechanisms that accelerate pathways that are deleterious for development and/or progression of atherosclerosis. Future studies are necessary to elucidate these mechanisms since patients with refractory angina (by definition) have no option to treat their symptoms.
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