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Sleep Apnea & Ventricular
Arrhythmias: Interaction and Clinical
Implications
Henry Nguyen
Sarah Tierney
Document ID
Sleep Disordered Breathing (SDB)
Definition: Sleep-disordered breathing refers to an abnormal
respiratory pattern (ie, apneas, hypopneas, or respiratory effort
related arousals) or an abnormal reduction in gas exchange (ie,
hypoventilation) during sleep. It alters sleep duration and
architecture if repetitive, which may result in daytime symptoms,
signs, or organ system dysfunction. Definitions follow:
•Apneas: Cessation or near cessation of airflow
•Hypopneas: Reduction of airflow to a degree that is
insufficient to meet the criteria of apnea
•Respiratory effort related arousals (RERAs): A sequence
of breaths that lasts at least 10 seconds, characterized by
increasing respiratory effort or flattening of the nasal pressure
waveform, and leads to an arousal from sleep, but does not
meet the criteria of an apnea or hypopnea
•Abnormal reduction in gas exchange
[Iber, C et al, American Academy of Sleep Medicine. 2007]
Epidemiology
• Sleep apnea syndrome affects 5% of the North American
population [Young et al. Am J Respir Crit Care Med. 2005]
• Ventricular arrhythmias have been associated with Sleep
Disordered Breathing (SDB) [Mehra et al. Am J Respir Crit Care Med. 2006]
• Complex ventricular ectopy was found in 25% of patients with
SDB vs. 14.5% in those without SDB.
• Non-sustained ventricular tachycardia (NSVT) occurred in
5.3% of patients with SDB vs 1.2% of those without SDB.
Epidemiology-continued
•
Sleep Disordered Breathing has been associated with ventricular
arrhythmias
•
Patients with established ventricular arrhythmias, without
heart failure, were found to have a high prevalence of Sleep
Disordered Breathing (SDB). [Koshino et al. Am J Cardiol. 2008]
•
62% of asymptomatic patients with implantable cardiac
defibrillators (ICDs), due to decreased left ventricular
function, were found to meet the criteria for apnea.
[Grimm et al. Pacing and Clin Electrophysiol. 2009]
Diagnostic Criteria
Polysomnography is the gold standard for diagnosing Sleep
Disordered Breathing (SDB).
• Indexes used to assess the severity of SDB include:
• AHI: Apnea-hyponea index
Number of Apneic or hyponeic episodes per hour of sleep
AHI > 5 = OSA
• RDI: Respiratory disturbance index
Number of apneas, hypopneas, and RERAs per hour of sleep.
Generally larger than AHI due to RERA inclusion.
ECG identifies episodes of ventricular arrhythmia
Patients with known
SDB.....
Compared patients with and without Sleep Disordered Breathing (SDB) for presence of
ventricular arrhythmias
•Complex ventricular ectopy was found in 25% of patients with SDB Vs. 14.5% in
those without SDB.
• Non-sustained ventricular tachycardia (NSVT) was found in 5.3% of patients with
SDB Vs 1.2% in those without SDB.
After adjusting for confounding factors (age, sex, BMI, and coronary
heart disease), patients with Sleep Disordered Breathing (SDB) were
3.40 and 1.74 times more likely to experience Nonsustained
Ventricular Tachycardia (NSVT) and Complex Ventricular Ectopy
(CVE) as compared to patients without SDB respectively.
- This suggests that in the setting of SDB, there is an increased risk of
ventricular arrhythmias
• CPAP therapy decreases
cardiovascular related deaths vs that
of null treatment
• 7% of total untreated patients died
from sudden cardiac death vs 0% in
CPAP treated group
• Sudden cardiac death was
responsible for 44% of the total
cardiovascular deaths in the
untreated group and 0% in CPAP
treated group.
CPAP, as a treatment of Sleep Disordered Breathing (SDB), decreases
rates of Sudden Cardiac Death (SCD) which reinforces SDB as a risk
factor for SCD
• Patients with OSA were more likely to
suffer Sudden Cardiac Death (SCD) from
12-6AM
• Patients with an AHI score >40 were 2.61
times as likely to suffer SCD from 12-6AM
SUGGESTED VENTRICULAR ORIGIN OF
RHYTHM ABNORMALITIES IN OSA
PATIENTS:
Patients with known
cardiovascular disease....
Patients with ICDs who are asymptomatic for
Sleep Disordered Breathing (SDB), have a
higher rate of undiagnosed SDB
CSA = Central Sleep Apnea
OSA = Obstructive Sleep Apnea
Evaluated the prevalence of Sleep Disordered Breathing (SDB) in patients with severe ventricular
arrhythmias and normal left ventricular (LV) function
•Although higher prevalence of SDB in this population, there was no significant difference
seen between 2 groups evaluated
•However n of 35, and limited to patient cohort of Japanese origin so limited extrapolation
potential
• 41% of patients with known
coronary artery disease and no
suspected Sleep Disordered
Breathing (SDB) were found to
have an AHI>15
• Ventricular Premature
Contraction (VPC)
counts/minute were higher in
those with a larger AHI score
In patients with known coronary artery disease, and asymptomatic
for SDB:
- There exists a correlation between VPC counts/min and severity of
SDB (based on AHI score)
Interpretation of
these Findings...
•
Benign Ventricular Premature Contractions (VPCs) likely serve as triggers
of complex arrhythmias during prolonged apnea episodes (when
sympathetic dominates over vagal activity)
• It creates an autonomic environment favoring perpetuation of the arrhythmia
•
Diagnosis and appropriate treatment of obstructive sleep apnea should be
beneficial in preventing SCD
• Treatment has been shown to:
 Decrease sympathetic activity,
 Ventricular ectopy,
 Ventricular tachycardia
 Fatal and non-fatal cardiovascular events (cases of severe obstructive sleep apnea)
• In patient populations referred for assessment of sleep apnea, apnea has
not been found to increase ventricular arrhythmias.
• This contrasts patients with coronary artery disease but no suspected
Sleep Disordered Breathing (SDB)
Summary - Sleep Apnea and Ventricular
Arrhythmia
• Sudden Cardiac Death (SCD), which has been linked to
Sleep Disordered Breathing (SDB), may be driven by
ventricular arrhythmias
CPAP (primary treatment for OSA) improves SCD
[Doherty et al. Chest. 2005]
Patients with SDB have a higher incidence of ventricular
arrhythmias [Mehra et al. Am J Respir Crit Care Med. 2006]
• The proposed pathophsyiologic mechanisms connecting
SDB to ventricular arrhythmias, and subsequently to SCD
are outlined below
Possible Mechanisms
1. Sleep Disordered Breathing (SDB) has an
increased incidence of cardiovascular events.
This is associated with increase risk of post-MI
associated arrhythmias.
Possible Mechanisms
2. Sleep Disordered Breathing (SDB) may have
detrimental effects of left ventricular function.
Deleterious effects of LVEF may lead to
hormonal or cellular changes. This predisposes
to cardiac death.
Possible Mechanisms
3. Premature Ventricular Contractions (PVCs) are
common in hypertensive patients with left
ventricular hypertrophy (LVH). Hypertension has
a significant association with sleep apnea.
Possible Mechanisms
4.
Intermittent hypoxemia occurs with Sleep Disordered
Breathing (SDB)
•
Severe acute episodes can induce ventricular ectopy.
•
Chronically repetitive oxidative stress may induce
ventricular remodeling predisposing to arrhythmia
[Shamsuzzaman et al.JAMA.2003]
[Gami et al. J Cardiovasc Electrophysiol.2008]
Possible Mechanisms
5. Impaired autonomic control is seen with SDB
Hypercapnia
Hypoxemia
Increased sympathetic activity
• Via initiation of central and peripheral
chemoreflexes
Apnea
Imbalance of
parasympathetic activity
Deleterious effects on HR
variability and cardiac coupling
with ventilatory input
•
Fluctuating autonomic activity seen in Sleep Disordered Breathing
(SDB) can effect beat to beat changes in ventricular repolarization,
which can predispose to ventricular arrhythmia. [Roche et al. 2003]
•
However, Barta et al reported there were no significant changes in
QT corrected and QT corrected dispersion. [Barta et al. Clin Cardiol. 2009]
Possible Mechanisms
6. Chronic elevation of sympathetic tone, as
seen in Sleep Disordered Breathing
(SDB), can lead to an increased risk of
Sudden Cardiac Death (SCD)
Recommendations
• Patients with known structural heart disease and are
symptomatic for Sleep Disordered Breathing (SDB) should
be referred for polysomnogram.
[Baranchuk and McIntyre. Iran Cardiovasc Research J. 2009; Watanabe
et al. Indian Pacing and Electrophysiol J. 2008]
• CPAP therapy should be initiated in patients with
identifiable SDB and underlying cardiac disease to prevent
Sudden Cardiac Death.
[Doherty et al. Chest. 2005]
• Treatment of SDB could reduce the therapies delivered by
ICDs in patients with proved SDB.
[Baranchuk and McIntyre. Arrhythmia and Electrophysiology Symposium.
2009]
Conclusion
• Sleep Disordered Breathing has been
linked to ventricular arrhythmia.
• Sleep Disordered Breathing has also been
linked to sudden cardiac death.
• Patients with known heart disease have
been shown to have a higher prevalence
of undiagnosed sleep disordered
breathing.
• As outlined above, there are proposed
mechanisms suggesting Sleep Disordered
Breathing drives the formation of
ventricular arrhythmias.
Conclusion
• These studies highlight the importance of
physician awareness and recognition of
potential ventricular arrhythmias in
patients with Sleep Disordered Breathing.
• Management goals should include CPAP
therapy to minimize Sleep Disordered
Breathing in order to reduce the risk of
Sudden Cardiac Death.