Risks of Untreated Complex Sleep Apnea
Untreated complex sleep apnea significantly increases mortality risk with a 3-fold increased risk of vascular events, including fatal and non-fatal cardiovascular events and stroke, compared to individuals without sleep apnea. 1, 2
Understanding Complex Sleep Apnea
Complex sleep apnea syndrome (CompSAS) is characterized by the presence of both obstructive and central sleep apnea components. It often manifests when central apneas persist or emerge following treatment of obstructive events with positive airway pressure therapy 3, 4.
Cardiovascular Risks
Stroke Risk
- Increased risk of ischemic stroke with dose-response relationship:
- 25% prevalence of silent brain infarctions in moderate-to-severe OSA vs. 6.7% in controls 1
Cardiovascular Disease
- 3.17-fold increased risk of nonfatal cardiovascular events 1, 2
- 2.87-fold increased risk of cardiovascular death 1, 2
- Increased risk of coronary artery disease, congestive heart failure, and cardiac remodeling 5
Hypertension
- Progressive increase in hypertension risk with OSA severity:
- Mild OSA: 20% higher odds
- Moderate OSA: 25% higher odds
- Severe OSA: 37% higher odds 1
- Strong association with resistant hypertension (uncontrolled despite ≥3 medications) 1
Arrhythmias
- Higher prevalence of atrial fibrillation, particularly chronic persistent and permanent forms 2
- Cardiac arrhythmias and atrioventricular block occur when oxyhemoglobin saturation falls below 65% 2
Metabolic Risks
- Independent risk factor for developing type 2 diabetes 1, 5
- Associated with metabolic dysregulation and impaired glucose control 1
- Contributes to obesity and metabolic syndrome 6
Neurocognitive Risks
- Impaired vigilance, concentration, and cognitive function 1
- Increased risk of motor vehicle accidents (5-fold higher in untreated patients) 1
- Reduced quality of life and social functioning 1
- Associated with depression and other mental health disorders 1
Mortality Risk
- Increased all-cause mortality 1
- 1.92-fold increased risk of death from all causes 1
- 1.79-fold increased risk for cardiovascular disease mortality 1
- 2.15-fold increased risk for fatal and nonfatal stroke 1
Pathophysiological Mechanisms
The risks of complex sleep apnea are driven by several mechanisms:
- Recurrent hypoxemia and hypercarbia 5
- Increased sympathetic and decreased parasympathetic nervous system activity 5
- Oxidative stress and vascular endothelial dysfunction 5
- Sleep fragmentation leading to daytime sleepiness and cognitive impairment 1
- Ventilatory instability with oscillations in PaCO2 3
Healthcare Utilization Impact
- Significant burden on healthcare system with increased utilization 1
- Higher healthcare costs for untreated patients 1
- Increased risk of perioperative complications 1
Treatment Benefits
The risks of untreated complex sleep apnea can be significantly reduced with appropriate treatment:
- CPAP treatment reduces cardiovascular event risk (adjusted HR: 0.34) 1, 2
- 10-year event-free survival: 83.1% in CPAP-treated vs. 51.8% in untreated patients 2
- In stroke patients, recurrent stroke rates: 14% in CPAP users vs. 32% in non-users 2
- For complex sleep apnea specifically, adaptive servoventilation (ASV) has shown effectiveness in reducing AHI from a median of 48 to 5 events per hour 7
Risk Factors for Worse Outcomes
Factors that increase the severity of risks in untreated complex sleep apnea:
- Age >35 years 6
- BMI ≥25 kg/m² 6
- Alcohol consumption 6
- Higher oxygen desaturation index 6
- Longer mean apnea duration 6
- Nocturnal oxygen desaturation 6
Understanding these risks emphasizes the importance of proper diagnosis and treatment of complex sleep apnea to prevent serious health consequences and improve quality of life.