Evaluating the Impact of Sleep Disordered Breathing on Adverse Cardiovascular Outcomes After Bariatric Surgery

Introduction: Sleep disordered breathing (SDB), including ob- structive sleep apnea (OSA) and obesity-associated sleep hypo- ventilation (OASH), has well-characterized adverse effects on the cardiovascular system and increases morbidity and mortality. Long- term impact on cardiovascular outcomes post-bariatric surgery, how- ever, remains unclear. We hypothesize that patients with SDB have increased frequency of major adverse cardiovascular events (MACE) post-bariatric surgery than those without.

Methods: Patients undergoing polysomnography (PSG) prior to bariatric surgery at The Cleveland Clinic from 2011–2018 were retrospectively examined and followed up from date of last surgery to 2019, including the perioperative period. Primary predictors in- clude moderate-severe OSA, i.e. apnea hypopnea index(AHI)>15, and OASH, i.e. body mass index (BMI)≥30kg/m2 and either end- tidal CO2≥45mmHg or serum bicarbonate≥27mEq/L. MACE (cor- onary artery events, cerebrovascular events, heart failure or atrial fibrillation)-free probability was compared using hazard ratios esti- mated from Cox proportional hazards models on four groups: OASH with moderate-severe OSA (N=492), OASH-only (N=442), moderate- severe OSA-only (N=203), and a reference group without OASH or moderate-severe OSA (N=243). Multivariable Cox proportional haz- ards models adjusting for age, sex, BMI were fit on MACE survival. Analysis was performed based on an overall significance level of 0.05, using SAS software (version 9.4, Cary, NC).

Results: The sample comprised 1380 patients: age: 43.5±12 years, BMI: 49±9 kg/m2, 17.7% male, 63.7% White. Risk of MACE across the groups bordered significance (p=0.051). Compared to the reference group, the OASH with moderate-severe OSA group had higher risk of MACE (HR2.53, 95%CI:1.07–6.00,p=0.035). Patients with moderate- severe OSA had higher risk of MACE than those with AHI<15 (HR1.94, 95%CI:1.20–3.13,p=0.007). Patients with severe OSA had higher risk of MACE than those AHI<30 (HR2.01, 95%CI:1.28– 3.14,p=0.002). For every 5-unit AHI increase, risk of MACE increased by 6% (HR1.056, 95%CI:1.029–1.084,p<0.001) with slight reduction in point estimates in adjusted models.

Conclusion: Preliminary data from this largest-to-date sample of sys- tematically phenotyped patients with SDB undergoing bariatric sur- gery show significant differences in risk of MACE and MACE-free survival mitigated after consideration of obesity. Further investigation to elucidate effect modification by obesity and metabolic factors is needed.

Support (if any): Cleveland Clinic Transformative Resource Neuroscience Award