Adamson_Cardiology_book_temp 26/10/2009 17:14 Page 71
Beyond the Apnea–Hypopnea Index
to REM sleep stages and can be quantified by using heart rate variability fibrillation.
13,14
Atrial fibrillation is associated with increased morbidity
analyses.
11
Myocardial infarction changes the autonomic characteristics of and mortality in heart failure, although it is not clear whether decreasing
discrete sleep stages
11
and would be expected to have further the burden of atrial fibrillation improves morbidity in heart failure.
derangement if sleep apnea and other cardiovascular diseases are Quantifying atrial and ventricular arrhythmias during sleep studies is
present. Cardiac autonomic control is important and can be used to very important and should be considered when evaluating therapies.
Mortality
Lack of consensus about the definition of
With any disease process, mortality is a significant end-point with both
what constitutes a hypopneic event,
the course of the disease and any treatment. Sleep apnea, defined as an
AHI greater than five, is associated with increased mortality.
15
Patients
coupled with difficulties in measuring
with sleep-disordered breathing are more likely to have an increase in
airflow, makes comparison of the
cardiovascular disease, including coronary artery disease and stroke.
16,17
Although mortality trials are difficult and expensive, certainly any
apnea–hypopnea index across clinical
treatment of sleep-disordered breathing that improved mortality would
trials difficult.
be accepted above any other outcome measurement available.
Conclusions
evaluate existing and novel therapies for sleep apnea. Reducing Sleep breathing disorders in patients with chronic heart failure
sympathetic activation and vagal withdrawal would be expected to represent an important source of pathology that theoretically promotes
favorably influence prognosis in any cardiovascular disease and especially adverse ventricular remodeling leading to progressive heart failure and
in the cardiovascular complications associated with sleep apnea. death. Clarity of diagnosis is essential in order to appropriately offer
therapies that may attenuate the effects of obstructive and central sleep
Arrhythmias apnea. Lack of consensus about the definition of what constitutes a
Sleep apnea has been associated with both atrial and ventricular hypopneic event, coupled with difficulties in measuring airflow, makes
arrhythmias. Ventricular arrhythmias have been reported in up to 66% of comparison of the AHI across clinical trials difficult. Theoretically, the AHI
patients with sleep-disordered breathing.
12
This is very important, as the alone may not be the best means to judge the effect of novel therapies
presence of sustained ventricular tachycardia in heart failure patients under development. Changes in other parameters that directly link to
correlates with mortality and leads to consideration of implantable the pathophysiology of heart disease should be considered as important
cardioverter–defibrillator placement. Additionally, atrial arrhythmias, end-points, which may at least develop hypotheses about an impact on
such as atrial fibrillation and flutter, are common comorbidities found outcomes such as morbidity and mortality. n
in patients with heart failure. The mechanisms of atrial arrhythmias in
heart failure are complex, but the presence of sleep-disordered
Philip Adamson, MD, FACC, is Medical Director of the Oklahoma Foundation for
breathing correlates with a higher risk for atrial rhythm disturbances.
Cardiovascular Research and founder of the Heart Failure Institute at Oklahoma Heart
This is probably true for both systolic and diastolic heart failure patients. Hospital. His research interests include the autonomic mechanisms involved in the genesis
Atrial arrhythmias interrupt atrial contribution to ventricular filling and
of lethal ventricular arrhythmias and progression of heart failure and the use of devices,
such as implantable cardioverter–defibrillators and cardiac resynchronization therapy
may cause worsening heart failure symptoms. Atrial rhythm disorders
pacemakers, to remotely monitor patients with heart failure. Additionally, Dr Adamson is
also increase the risk for cerebrovascular accidents, which often lead to involved in directing the clinical trial development of hemodynamic monitoring devices in
the clinical recommendation for chronic anticoagulation. Both
patients with chronic heart failure.
obstructive and central apnea have been associated with atrial
1. Iber C, ed., The AASM Manual for the Scoring of Sleep and mechanisms of regulation, measurement, and 12. Guilleminault C, Connolly SJ, Winkle RA, Cardiac
Associated Events: Rules, Terminology and Technical Specification. interpretation, Am J Physiol Regul Integr Comp Physiol, arrhythmia and conduction disturbances during sleep in
Westchester III: The American Academy of Sleep Medicine, 2009;296:R1473–95. 400 patients with sleep apnea syndrome, Am J Cardiol,
2007. 7. Fietze I, Dingli K, Diefenbach K, et al., Night-to night 1983;52:490–94.
2. Becker HF, et al., Effect of nasal continuous positive variation of the oxygen desaturation index in sleep 13. Gami AS, et al., Association of atrial fibrillation and
airway pressure treatment on blood pressure in patients apnoea syndrome, Eur Resp J, 2004;24:987–93. obstructive sleep apnea, Circulation, 2004;110(4):364–7.
in obstructive sleep apnea, Sleep, 2003;107(1):68–73. 8. Seicean S, Kirchner HL, Gottlieb DJ, et al., Sleep disordered 14. Mehra R, Benjamin EJ, Shahar E, et al., Association of
3. MacMahon S, et al., Blood pressure, stroke, and coronary breathing and impaired glucose metabolism in normal- nocturnal arrhythmias with sleep-disordered breathing:
heart disease. Part 1. Prolonged differences in blood weight and overweight/obese individuals, Diabetes Care, the sleep heart health study, Am J Respir Crit Care Med,
pressure: prospective observational studies corrected for 2008;31:1001–6. 2006:173:910–16.
the regression dilution bias, Lancet, 1990;335:765–74. 9. Gottlieb DJ, Redline S, Nieto FJ, et al., Association of usual 15. Javaheri S, Shukla R, Zeigler H, et al., Central sleep apnea,
4. Ruttanaumpawan P, Logan AG, Floras JS, et al., Effect of sleep duration with hypertension: the sleep heart health right ventricular dysfunction, and low diastolic blood
continuous chronic airway pressure on sleep structure in study, Sleep, 2006;29:1009–14. pressure are predictors of mortality in systolic heart
heart failure patients with central sleep apnea, Sleep, 10. Adamson PB, Smith AL, Abraham WT, et al., Continuous failure, J Am Coll Cardiol, 2007;49(20):2028–34.
2009;32:91–8. autonomic assessment in patients with symptomatic 16. Valham F, Mooe T, Rabben T, et al., Increased risk of stroke
5. Ruehland WR, Rochford PD, O’Donoghue FJ, et al., The new heart failure, Circulation, 2004;110:2389–94. in patients with coronary artery disease and sleep apnea,
AASM criteria for scoring hypopneas: impact on the 11. Vanoli E, Adamson PB, Ba-Lin, et al., Heart rate variability Circulation, 2008;188:955–60.
apnea hypopnea index, Sleep, 2009;32(2):150–7. during specific sleep stages. A comparison of healthy 17. Peker Y, Kraiczi H, Hedner J, et al., An independent
6. Ainslie PN, Duffin J, Integration of cerebrovascular CO
2
subjects with patients after myocardial infarction, association between obstructive sleep apnea and
reactivity and chemoreflex control of breathing: Circulation, 1995;91:1918–22. coronary artery disease, Eur Resp J, 1999;14:179–84.
US CARDIOLOGY 71