What is the risk of cardiac events in patients with mild to moderate Obstructive Sleep Apnea (OSA) when treated with Positive Airway Pressure (PAP) therapy versus when left untreated?

Risk of Cardiac Events in Mild to Moderate OSA: Treated vs. Untreated with PAP Therapy

There is insufficient and inconclusive evidence to recommend PAP therapy for mild to moderate OSA solely to reduce cardiovascular events, as meta-analyses of randomized controlled trials have not demonstrated clinically significant improvements in cardiovascular outcomes or mortality. 1

Evidence on Cardiovascular Risk in OSA

Observational vs. Randomized Evidence

• Meta-analyses of observational studies suggest PAP therapy reduces cardiovascular events and mortality in OSA patients 1, 2
• However, meta-analyses of randomized controlled trials show no clinically significant improvements in cardiovascular events or mortality 1, 2
• The quality of evidence for cardiovascular events and mortality ranges from very low to moderate due to study type limitations and imprecision 1

OSA Severity and Cardiovascular Risk

• OSA is associated with increased cardiovascular risk, with relative risks of:
  • 1.79 for cardiovascular disease
  • 2.15 for fatal and nonfatal stroke
  • 1.92 for death from all causes 1
• Compared to individuals with AHI <1.5 events/hour, the adjusted odds of hypertension increase by:
  • 20% for mild OSA (5-15 events/hour)
  • 25% for moderate OSA (15-30 events/hour)
  • 37% for severe OSA (>30 events/hour) 1

Blood Pressure Effects of PAP Therapy

• PAP therapy demonstrates clinically significant reductions in blood pressure when treating OSA 1, 2
• Most significant effects are seen in:
  • Nocturnal blood pressure measurements
  • Patients with resistant hypertension
  • Patients with established hypertension 1
• The American Academy of Sleep Medicine suggests using PAP therapy to treat OSA in adults with comorbid hypertension (conditional recommendation) 1
• Blood pressure improvements can be seen within the first few weeks of starting treatment 1

Cardiovascular Outcomes with PAP Therapy

Dose-Response Relationship

• Real-world data suggests a dose-response relationship between PAP adherence and cardiovascular outcomes 3
• Compared to non-adherent patients (0-4 hours/night), adjusted hazard ratios for major adverse cardiovascular events were:
  • 0.87 for 4-6 hours/night use
  • 0.75 for 6-7 hours/night use
  • 0.78 for ≥7 hours/night use 3

Special Populations

• PAP therapy shows greater cardiovascular benefit in:
  • Male patients
  • Patients without overt cardiovascular disease at diagnosis
  • Patients with excessive daytime sleepiness 3
• In surgical patients with OSA, PAP therapy is associated with:
  • 28% reduction in postoperative respiratory complications in non-cardiac surgery
  • 37% reduction in postoperative cardiac complications in cardiac surgery
  • 41% reduction in postoperative atrial fibrillation in cardiac surgery 4

Clinical Approach to Mild-Moderate OSA

When to Consider PAP for Cardiovascular Risk Reduction

• PAP therapy should be prioritized for OSA patients with:
  • Comorbid hypertension, especially resistant hypertension 1, 2
  • Symptomatic OSA (excessive sleepiness, impaired sleep-related quality of life) 1
  • History of stroke (PAP reduces mortality after stroke) 1
  • Atrial fibrillation (PAP reduces recurrence) 1

Important Caveats

• Patient adherence is critical for cardiovascular benefit 3
• Most studies evaluating PAP impact on blood pressure recruited patients with predominantly moderate to severe OSA 1
• The American Academy of Sleep Medicine Task Force concluded there is insufficient evidence to recommend PAP solely for cardiovascular event or mortality reduction 1
• Patients may have different values regarding treatment when OSA is asymptomatic but cardiovascular risk is present 1

Conclusion

For patients with mild to moderate OSA, the decision to use PAP therapy should be based primarily on symptoms and comorbidities rather than solely for cardiovascular risk reduction. While observational data suggests potential cardiovascular benefits with good adherence, randomized controlled trials have not confirmed these benefits. PAP therapy should be strongly considered in patients with hypertension, particularly resistant hypertension, as this represents the most established cardiovascular benefit.