Five New Zealand hospitals, including Dunedin, Christchurch and Hamilton, are participating in a 5000-strong international sleep study and are seeking further volunteers.
About 1200 people are already taking part in the multi-year study, including 14 in Dunedin, where researchers wish to recruit a total of 30 volunteers.
Participants being sought are aged between 45 and 75, snore loudly and have experienced a heart attack or stroke, angina, bypass surgery, a coronary artery stent or a transient ischemic attack (TIA).
The sleep apnoea cardiovascular endpoints study (Save), is seeking to discover if the use of continuous positive airway pressure can reduce the risk of heart attack, stroke or heart failure in patients with sleep apnoea.
The treatment uses a mask to push air into the airways, helping sleepers breathe more easily.
Prof Robin Taylor, who leads the Otago respiratory research unit at Dunedin Hospital, said known risk factors for cardiovascular disease included smoking, diabetes, high cholesterol and high blood pressure.
Treatment was beneficial where people were known to have severe obstructive sleep apnoea, but it remained unclear whether mild or moderate forms of the condition were independent risk factors for cardiovascular disease, including heart attack and stroke.
"There will be huge interest in the results of the study," Prof Taylor said.
Sleep apnoea is present in up to half of people who are considered to be at high cardiovascular risk because of factors such as increased weight or blood pressure, researchers say.
The international study is being led in Australia by researchers from the Adelaide Institute for Sleep Health and the George Institute for Global Health.
Australian researchers said the study could result in a completely new medical approach to the prevention of cardiovascular disease.
• Further volunteers can contact the Otago unit at Dunedin Hospital or via www.savetrial.org.
Obstructive sleep apnoea
• A condition where relaxation of throat muscles causes a person to stop breathing for several seconds at a time during sleep.
• This often causes loud snoring and can also lead to sleepiness and poor concentration.
