Why Sleep Apnoea Increases Heart Disease Risk

Caption: About 15 per cent of Singaporeans have obstructive sleep apnoea (OSA), with studies showing that those with severe OSA tend to have higher calcium deposits in their coronary arteries. Dr Toh Song Tar, Senior Consultant, Department of Otolaryngology, and Director, Sleep Disorders Unit at Singapore General Hospital (SGH), and Dr Tan Swee Yaw, Senior Consultant, Department of Cardiology at National Heart Centre Singapore (NHCS), explain. (iStock photo)

Snoring can be more than just a nuisance for your bed partner. As a habitual snorer, you could be suffering from a potentially serious sleep disorder called obstructive sleep apnoea (OSA).

What causes obstructive sleep apnoea (OSA)?

OSA occurs when something – the tongue or fatty tissues – partly or completely blocks the airways during sleep, reducing the flow of oxygen to the brain. The brain then sends a signal to rouse the person to reopen his airways and breathe. People with severe OSA can get more than 30 such episodes a night, explained Dr Toh Song Tar, Senior Consultant, Department of Otolaryngology (ENT) , and Director, Sleep Disorders Clinic at Singapore General Hospital (SGH), a member of the SingHealth group.

Related article: Doctor recommended tips to stop snoring

Relation between OSA and calcium buildup in arteries

In a study conducted by SGH and National Heart Centre Singapore (NHCS), also a member of the SingHealth group, on 150 patients in their 50s with OSA, nearly half were found to have atherosclerosis (artery hardening and narrowing) while 8.7 per cent had a calcium score of more than 400.

"The calcium score tells you indirectly how much atherosclerosis has occurred," said Dr Tan Swee Yaw, Senior Consultant, Department of Cardiology, NHCS, and principal investigator of the study. The risk of a heart attack is 0.1 per cent for someone with a zero score, but 10 times more than normal for someone with a score of more than 100, and 25 times more than normal for a score of more than 400.

Related article: Why women have it worse when it comes to heart attacks

Dr Toh elaborated, "It may be because oxygen desaturation (that occurs during the sleep cycle of OSA patients) causes inflammation and damage to the blood vessels, which then becomes the trigger for lipids and calcium to be deposited in the arteries."

How does calcium buildup lead to heart disease?

Calcium deposits or calcifications are a sign of heart disease as the deposits narrow and harden the arteries, reducing the flow of oxygen-rich blood to the heart. Over time, this can cause problems like chest pain and heart attack. "No matter how little, once calcium starts to build up, it means the process of atherosclerosis (artery hardening and narrowing) has started," said Dr Tan.

Related article: Can having sleep apnoea also cause eye diseases?


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