Cardiologists are aware that the common type of sleep apnoea – obstructive sleep apnoea or OSA – is linked to a number of heart and blood vessel (cardiovascular) problems including high blood pressure (hypertension), artery disease – including coronary, aortic and carotid arteries – cardiomyopathy and heart failure.
Snoring is a marker of risk of OSA but most snorers (2 in 3) don’t have sleep apnoea; it is possible to have OSA and not be known to snore. In sleep apnoea, the airway collapses, partly or completely during sleep and normal breathing recovers because the brain briefly wakes up from sleep (called an ‘arousal’) promptly followed by sleep, snoring and obstruction. This cycle is repeated literally 100’s of times a night in more severely affected patients. It is often more severe in the deeper stages of sleep called slow wave and REM sleep. This loss or duration and quality of sleep can affect daytime performance greatly but most sufferers of OSA have no identifiable daytime symptoms.
OSA is often thought of as a disease of overweight middle-aged men, but it occurs at all ages, in men and women- including during pregnancy- and in slim as well as the obese.
Recent research has shown that heart rhythm problems such as atrial fibrillation (AF), slow heart rhythms (sinus bradycardia and heart block) as well as potentially serious arrhythmias like ventricular tachycardia (VT), are common in OSA especially when it is severe.
The consequences of these conditions may be heart attacks, strokes and even sudden death. Undetected or untreated OSA can adversely impact on treatment of heart disease with medications, electrical cardioversion, pacemakers or defibrillators.
A recent study from the Mayo Clinic showed that 80% of those admitted for electrical cardioversion of atrial fibrillation had OSA and only 1 in 3 (35%) were sleepy using the Epworth Sleepiness Scale. In a previous study the same group showed those with untreated or inadequately treated OSA were twice as likely to have gone back into AF over the next year.
Detecting and treating OSA can be beneficial to quality and length of life in those with risk factors or diagnosed heart disease. The lack of daytime sleepiness or tiredness in patients with OSA can make treatment by lifestyle changes, dental splints (MAS) or CPAP harder to adjust to than OSA patients motivated by improvement in daytime symptoms.
The condition is traditionally diagnosed by an overnight study in a sleep laboratory but increasingly we use simpler home testing equipment to screen for OSA.