ORIGINAL ARTICLE  CARDIAC SECTION 

The Journal of Cardiovascular Surgery 2020 October;61(5):648-56

DOI: 10.23736/S0021-9509.20.11200-X

Copyright © 2020 EDIZIONI MINERVA MEDICA

language: English

A prospective five-year cohort study of undiagnosed sleep apnea in patients undergoing coronary artery bypass graft surgery

Alexandra M. HOGAN ^{1, 2, 3} ✉, Sammra IBRAHIM ², Melanie J. MOYLAN ^{4, 5}, David J. MCCORMACK ⁶, Ann-Marie OPENSHAW ², Francesca CORMACK ⁷, Alex SHIPOLINI ²

¹ Department of Anesthetics, Addenbrooke’s Hospital, Cambridge University Hospitals Foundation Trust, Cambridge, UK; ² Barts Heart Centre, Barts Health NHS Trust, London, UK; ³ Cognitive Neurosciences and Neuropsychiatry, UCL Great Ormond Street Institute of Child Health, London, UK; ⁴ Department of Biostatistics and Epidemiology, Auckland University of Technology, Auckland, New Zealand; ⁵ School of Psychology, University of Western Australia, Perth, Australia; ⁶ Waikato Cardiothoracic Unit, Waikato Hospital, Waikato Institute of Surgical Education and Research, University of Auckland, Auckland, New Zealand; ⁷ Cambridge Cognition, Department of Psychiatry, University of Cambridge, Cambridge, UK

BACKGROUND: We aimed to study prospectively the nature and effect of sleep apnea-hypopnea syndrome (SAHS) in patients undergoing coronary artery bypass graft (CABG) surgery over five years of follow-up.
METHODS: Patients undergoing CABG surgery (N.=145) were assessed longitudinally (baseline, 1 year, and 5 years post-surgery) using the ‘STOP-BANG’ screen of sleep apnea risk. Additionally, all patients had a preoperative multiple-channel sleep-study, providing acceptable data for an obstructive and central apnea, and desaturation index in 97 patients.
RESULTS: Preoperatively, over half (63%) of patients obtained an apnea-hypopnea index score (combining apnea types) in the moderate-severe range for SAHS, and STOP-BANG threshold score (>3/8) was reached by most (95%) patients. Despite some improvement in ‘STOP symptoms’ at 1-year follow-up, most patients (98%) remained at risk of SAHS at 5 years post-surgery. There was an underlying and chronic relationship between STOP-BANG score and cardiac symptoms at both baseline and 5-year follow-up. Additionally, SAHS variables were associated with greater incidence of acute postoperative events, and generally with increased length of stay on the intensive care unit.
CONCLUSIONS: We confirm that SAHS is common in CABG-surgery patients, presenting additional clinical challenges and cost implications. The underlying pathophysiology is complex, including upper airway obstruction and cardiorespiratory changes of heart failure. In patients presenting for CABG-surgery, we show chronic susceptibility to SAHS, likely associated with traditional risk factors e.g. obesity but perhaps also with gradual decline in heart function itself. Superimposed on this, there is potential for exacerbated risk of morbidity at the time of CABG surgery itself.

KEY WORDS: Sleep apnea syndromes; Coronary artery bypass; Perioperative medicine