Obstructive Sleep Apnea and Cardiovascular Risk Factors

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Obstructive Sleep Apnea and Cardiovascular Risk
Factors

• Shirine Allam, MD

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Obstructive Sleep Apnea
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• Airway narrowing/obstruction
• Decreased air flow
• Increased effort
• Oxygen saturation swings and hypoxia
• Increased BP and HR
• Disrupted sleep

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OSA and Cardiovascular disease

• There is a clear association between OSA and
  cardiovascular disease
• Higher incidence of adverse cardiovascular events
  in untreated patients with OSA

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200730(3)291-304 CHEST 2008 133793-804 Proc
Am Thorac Soc 2008 5200-206
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OSA and Cardiovascular disease
Peker 7 yrs f/u Marin and Doherty10 yrs f/u
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OSA and Hypertension
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OSA is an independent risk for hypertension
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OSA and HypertensionWhy does it happen?

• OSA can lead to hypoxia (low oxygen levels),
  repetitive changes in oxygen saturations, and
  large swings in intrathoracic pressures
• These changes are detected by receptors in the
  brain and in the periphery (carotid bodies)
• Stimulate a sympathetic response (fight or
  flight response, stress response)? increased
  heart rate and blood pressure

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OSA and HypertensionWhy does it happen?

• Repeated stimulation?Increased sympathetic tone
  during the day? High blood pressure
• Studies have showed
• Increased tonic chemoreflex drive
• Abnormalities in HR and BP variabilities during
  normal waking hours in patients with OSA

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OSA and HypertensionSome Numbers

• Wisconsin prospective sleep cohort (2000)
• 709 patients with OSA
• Risk of developing HTN over 4 years
• Minimal OSA 1.42 x normal
• Mild-moderate 2.03 x normal
• Moderate-severe 2.89 x normal

After adjusting for other risk factors
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OSA and HypertensionSome Numbers

• 40 of people with OSA have high blood pressure
  while awake
• 40-80 of people with non-controlled HTN have OSA

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OSA and Hypertension How to treat it?

• Effective CPAP therapy can reduce BP
• One study showed a fall in systolic BP by 10
  after 4 weeks of CPAP
• Improvement in blood pressure correlated with
  improvement in sleepiness

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OSA and Coronary Artery Disease
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OSA and Heart Attacks

• People with sleep disordered breathing (SDB) have
  a high prevalence of heart disease (CAD)
• People with CAD have a high prevalence of SDB

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OSA and Heart Attacks Why does it Happen?

• Multiple nightly stresses on the heart
• Repetitive fluctuations in oxygen levels,
• Increased blood pressure surges and
• High sympathetic nervous system tone

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OSA and Heart Attacks

• Marin et al. 2005
• 10 year follow-up study looking at CV events and
  OSA (including heart attacks and strokes)
• Included 264 healthy men, 377 snorers, 403
  untreated mild-mod OSA, 235 untreated severe OSA
  and 372 treated with CPAP

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OSA and Heart Attacks

• Gami et al. looked at 112 patients who underwent
  a sleep study
• Followed them for 5 years
• Sudden death from cardiac causes (between
  midnight and 6 am) occurred in 46 of pts with
  OSA vs 16 of general population

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OSA and Heart Failure
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OSA and Heart Failure

• Heart Failure definition
• CSA is the SDB most commonly associated with HF
  (Javaheri 2006, 49 with CHF have SDB, 37 CSA,
  12 OSA)
• Heart Failure is 2.38 x more common in
  mild-moderate OSA then in no OSA

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OSA and Heart Failure

• Observation Increasing obesity is a predictor of
  development of new onset HF (Framingham study)
• Although OSA not taken into account, levels of
  obesity also made OSA very high prob

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OSA and Heart FailureWhy does it happen?

• Hypertension
• Left ventricular diastolic dysfunction
• Atrial fibrillation

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OSA and Heart FailureEffect of treatment

• 2 randomized studies of CPAP for OSA in CHF,
  showed some improvement in EF over 1-3 months
• Effect of CPAP treatment on mortality/morbidity
  from heart failure is unknown

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OSA and Abnormal Heart Rhythms
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OSA and Abnormal Heart Rhythms

• Abnormal heart rhythms have been associated with
  OSA
• 1983 Guilleminault et al.
• 400 pts with OSA
• 48 had cardiac arrhythmias at night
• 2 sustained VT, 11 sinus arrest, 8 AV block,
  19 PVC

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OSA and Abnormal Heart RhythmsAtrial
Fibrillation

• Four times increased risk of AF in pts with OSA
  (AHI30) (Sleep Heart Health Study 2006)
• Onset of 75 of persistent Afib episodes in pts
  with OSA occur at night (8pm-8am)
• A fib recurrence after cardioversion twice as
  high in untreated OSA
• Observational review over 17 yrs suggests that
  nocturnal hypoxemia influences the onset of A fib
  

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OSA and Abnormal Heart RhythmsVentricular
arrhythmias

• Reported in pts with OSA
• Causative role not proven
• NEJM 2005 study observed higher incidence of
  sudden death during night hours (12am-6am) in pts
  with OSA, suggesting but not proving a causative
  effect

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OSA and Strokes
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OSA and Strokes

• OSA is a risk factor for stroke
• 2 prospective cohort studies following 1022 and
  1651 pts found a higher incidence of stroke in OSA

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OSA and Strokes Why does it happen?

• Increased CRP (inflammation) and atherogenesis
• Increased thrombotic risks (clotting of blood)
• Increased blood pressure
• Hypoxia
• Theoretically PFO?

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OSA and StrokesTreatment effect

• No randomized controlled trials
• Observational studies controversial on whether
  treatment of OSA would prevent strokes or not

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Thank you!

• Question?