Clinical Research
Cardiovascular Effect of Sleep Apnea
Obstructive Sleep Apnea Syndrome: More Insights on Structural and Functional Cardiac Alterations, and the Effects of Treatment With Continuous Positive Airway Pressure

Presented in part at the European Society of Cardiology, Vienna, August 2003, and the Euroecho Scientific Sessions, Athens, Greece, December 2004.
https://doi.org/10.1016/j.jacc.2005.11.054Get rights and content
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Objectives

We studied structural and functional cardiac alterations in obstructive sleep apnea (OSA), their relationship to the severity of OSA, and the effects of treatment with continuous positive airway pressure (CPAP).

Background

Obstructive sleep apnea may influence the cardiac function by several mechanisms in the awake patient.

Methods

Left and right ventricular morphology and function were studied using echocardiography before and after treatment with CPAP in symptomatic patients (Epworth sleepiness score, 10 ± 4.8) with severe OSA (apnea-hypopnea index [AHI], 42 ± 24). The patients (n = 43, 32 men) had no known cardiac disease and were obese (body mass index, 31.6 ± 5.4 kg/m2). The same echocardiographic parameters were studied in age-matched overweight patients (n = 40; body mass index, 26.4 ± 2.3 kg/m2).

Results

The patients were hypertensive (systolic blood pressure, 153 ± 25 mm Hg), with a higher resting heart rate (77 ± 10 beats/min, p = 0.008) compared with age-matched control patients (n = 40). There was right ventricular dilatation, hypertrophic interventricular septum, reduced left ventricular stroke volume, tissue Doppler-determined systolic and diastolic velocities of the left and right ventricle, and normal pulmonary artery pressure. The structural and functional parameters were significantly associated with AHI (p < 0.004). Multiple stepwise regression showed the interventricular septum thickness, right ventricular free wall, and mitral annulus tissue Doppler systolic velocities to be predictive of a higher AHI (p < 0.001). Six months after treatment with CPAP, significant improvements were observed in the symptoms and hemodynamics, as well as left and right ventricular morphology and function.

Conclusions

The structural and functional consequences of OSA on the heart are influenced by the severity of AHI. These effects are reversible if the apneic episodes are abolished.

Abbreviations and Acronyms

AHI
apnea-hypopnea index
BMI
body mass index
CPAP
continuous positive airway pressure
EEG
electroencephalogram
ESS
Epworth sleepiness scale
OSA
obstructive sleep apnea

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