Cheyne-stokes respiration in stroke: Relationship to hypocapnia and occult cardiac dysfunction

Background: Central sleep apnea (CSA) and Cheyne-Stokes respiration have been reported in association with stroke, but their pathophysiologic correlates have not been well described. Objective: To test the hypotheses that (1) CSA in patients with stroke is associated with nocturnal hypocapnia and (2) in those stroke patients with CSA and with left ventricular (LV) systolic dysfunction, periodic breathing (PB) will have a Cheyne-Stokes respiration pattern in which cycle duration is greater than in those without LV systolic dysfunction. Methods: We prospectively performed polysomnography and echocardiography in 93 patients with stroke. CSA was defined as central apneas and hypopneas occurring at a rate of 10 or more per hour of sleep. In patients with CSA, we compared PB cycle duration between those with normal and impaired LV systolic function (LV ejection fraction [LVEF] > 40% and ≤ 40%, respectively). Results: CSA was found in 19% of subjects who had lower nocturnal transcutaneous Pc_o2 (39.3 ± 0.9 vs. 42.8 ± 0.8 mm Hg, p = 0.015) and a higher prevalence of LVEF of 40% or less (22 vs. 5%, p = 0.043) than stroke patients without CSA. There was no significant difference in stroke location or type between the two groups. In patients with CSA, those with LVEF of 40% or less had a longer PB cycle than those with an LVEF of more than 40% (66.6 ± 5.6 vs. 46.6 ± 2.9 seconds, p = 0.006), but had no symptoms of heart failure. Conclusion: In patients with stroke, CSA is associated with hypocapnia and occult LV systolic dysfunction but is not related to the location or type of stroke. The presence of LV systolic dysfunction is associated with a Cheyne-Stokes pattern of hyperpnea.