People who suffer from breathing disorders like sleep apnea are usually at higher risk for cardiovascular disease, but researchers from Technion-Israel Institute of Technology found that some heart attack patients may actually benefit from mild to moderate sleep-disordered breathing.
Dr Lena Lavie and her colleagues believe the findings could help predict which patients are at a greater health risk after a heart attack, and may even suggest ways to rebuild damaged heart tissue.
Sleep-disordered breathing is characterised by cycles of apnea-induced hypoxia, where the sleeper experiences a temporary drop in oxygen levels.
It occurs in about 5 to 10 per cent of the general adult population, but is extremely common in patients with cardiovascular diseases - somewhere between 40-60 per cent.
Many studies have shown that sleep apnea is a risk factor for everything from high blood pressure to chronic heart failure, Lavie noted.
The study reported in the American Journal of Respiratory and Critical Care Medicine wanted to find out if sleep disordered breathing is associated with cardiovascular disease, then why people who suffer from breathing disorders in sleep seem to do as well as healthy sleepers after a heart attack.
Researchers looked for clues to this puzzle in 40 male patients - a mix of healthy sleepers and those with sleep disordered breathing, who had had a heart attack just a few days earlier.
Blood samples drawn from these patients revealed that the sleep disordered breathing patients had markedly higher levels of endothelial progenitor cells (EPCs), which give rise to new blood vessels and repair the injured heart, than the healthy sleepers.
They also had higher levels of other growth-promoting proteins and immune cells that stimulate blood vessel production.
The Technion researchers were able to trigger a similar increase in vessel-building activity in vascular cells taken from a second set of twelve healthy men and women, by withholding oxygen from the cells for short periods.
"Indeed, our results point at the possibility that inducing mild-moderate intermittent hypoxia may have beneficial effects," Lavie said in an American Technion Society statement.
