Can Obstructive Sleep Apnoea Worsen Cardiovascular Disease?

Obstructive sleep apnoea is becoming more of a common sleep disorder nowadays. This disorder affects more males than females and gives out signs and symptoms such as habitual snoring and sleep disturbances as well as disturbances in daily cognitive function. Obstructive sleep apnoea has certain effects not only on the quality of sleep but also on daytime functioning. Excessive daytime sleepiness is one of the symptoms of obstructive sleep apnoea.
Obstructive sleep apnoea can be a risk factor for various dangerous medical conditions such as stroke, heart disease and type 2 diabetes mellitus. About 30 to 50% of patients with cardiovascular disease have obstructive sleep apnoea. This is why OSA needs to be diagnosed and treated as soon as possible.
OSA can be diagnosed using overnight polysomnography (PSG) which includes electroencephalogram, electromyogram, electrocardiogram (ECG), oximetery, oronasal air flow, and respiratory efforts. These parameters are used to determine the presence and magnitude of sleep apnoea. Other methods used to assess sleep apnoea include questionnaires that assess the disorder such as the Berlin questionnaire and Epworth Sleepiness Scale (ESS). A recent study assessed the prevalence of OSA and its relation to angiography's results in patients with cardiovascular diseases.
There have been studies in the past which have linked obstructive sleep apnoea to vascular diseases such as hypertension, congestive heart failure and atrial fibrillation. The recent study by Javadi et. al aimed to investigate the association of obstructive sleep apnoea hypopnoea syndrome (OSAHS) with coronary atherosclerotic disease (CAD).
To do this, a questionnaire survey based on Berlin questionnaire and Epworth Sleepiness Scale (ESS) was conducted among 406 patients to assess demographic data and the symptoms, such as excessive daytime sleepiness and snoring. The subjects also completed the Epworth Sleepiness Scale and the Berlin questionnaire. Biochemical tests were run on venous blood samples and characteristics of coronary arteries were collected from the angiographic reports. The subjects were divided into two groups: low risk patients for OSA and high risk patients for OSA.
The results showed that the severity of coronary artery involvement, daytime sleepiness, and electrocardiogram abnormalities was significantly higher in high risk patients for OSA compared with low risk patients. High risk patients were also found out to have higher levels of FBS and LDL and lower level of HDL cholesterol.
This study showed that there was high prevalence for obstructive sleep apnoea in patients who were scheduled for angiography. This only showed that obstructive sleep apnoea is a risk factor for cardiovascular diseases. Obstructive sleep apnoea can predispose one to have coronary heart disease. The intensity of coronary heart disease in patients with OSA is higher as compared to those without sleep apnoea. Those with 2 or 3 vessel have higher risks for sleep apnoea as compared to those with single vessel diseases. The mechanism behind this is still unknown but the researchers imply that breathing disorders during sleep can result in high systolic blood pressure. Studies in the past have also shown that obstructive sleep apnoea can result to increased fibrinogen and C-reactive protein levels, which can bring about thrombosis in the arteries of the heart.
The findings of this study showed that obstructive sleep apnoea can be a predisposing factor for heart diseases. This is why patients with cardiac disease or with high cholesterol levels should be screened for obstructive sleep apnoea.

Reference:
Javadi HR, Jalilolghadr S, Yazdi Z, Rezaie Majd Z. Correlation between Obstructive Sleep Apnoea Syndrome and Cardiac Disease Severity. Cardiovasc Psychiatry Neurol. 2014;2014:631380.

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