People having surgery may be more likely to experience cardiovascular problems afterward when they have a common night-time breathing disorder known as sleep apnoea, a study suggests.
Compared to patients without apnoea, people with severe apnoea were more than twice as likely to die of heart complications or experience serious cardiac events like heart attacks and strokes within 30 days of surgery, researchers report in JAMA.
Previous research suggests that sleep irregularities can increase the risks for a variety of cardiovascular disorders, such as clogged or hardened arteries, high blood pressure, irregular heartbeat, and stroke, as well as metabolic problems like high cholesterol, obesity and diabetes that all contribute to cardiovascular disease.
For the current study, researchers did sleep studies for 1,218 patients before they had surgery for conditions unrelated to heart disease. None of the patients had been previously diagnosed with apnoea – which occurs when breathing repeatedly stops and starts during sleep – but two-thirds of them were found to have the condition based on their sleep study results.
“In patients with severe obstructive sleep apnoea, there are repeated episodes of complete or partial airway obstruction during sleep,” said lead study author Dr Matthew Chan of the Chinese University of Hong Kong.
“Patients having surgery are particularly vulnerable because the surgery and anaesthetics are likely to worsen airway obstruction,” Chan said.
The type of anaesthesia during the surgery didn’t appear to influence the risk of heart complications afterwards. Use of opioids and oxygen therapy after surgery also didn’t appear to impact the risk.
Slightly more than one in 10 patients in the study had severe apnoea, when breathing stopped and started more than 30 times a night.
- The authors identified 1,218 pre-surgical patients newly diagnosed with sleep apnoea and followed them for 30 days after their surgery.
- These surgical patients had a 50% higher risk of complications related to their heart. The authors believe this is due to the sleep apnoea going undiagnosed and untreated.
- On further analysis, patients with severe sleep apnoea were associated with a 14-fold increase in cardiac death, an 80% higher risk of heart injury and an almost 7-fold higher risk of heart failure.
- Since sleep apnoea occurs while you’re asleep, 80% of men and 90% of women with sleep apnoea may not even know they have it.
Like severe apnoea, moderate and mild cases also appeared to increase the risk of cardiac events after surgery. But with the exception of severe apnoea, the increased risk was too small to rule out the possibility that it was due to chance.
The study wasn’t a controlled experiment designed to prove whether or how undiagnosed or untreated apnoea might directly cause heart problems after surgery.
One limitation of the study is the potential for differences in postoperative care to influence the risk for heart complications, the study authors note.
Even so, the results suggest that identifying patients with undiagnosed apnoea prior to surgery may help reduce their risk of cardiac complications afterward, said Dr. Dennis Auckley of Case Western Reserve University and MetroHealth Medical Center in Cleveland, Ohio, who wrote an editorial that was published with the study.
That’s because the recurrent episodes of low oxygen levels that happen with sleep apnoea are associated with increased blood pressure and heart rate and place significant stress on the cardiovascular system, said Auckley.
“When this is happening every time an individual goes to sleep, night after night, it increases their risk for long-term cardiovascular complications (i.e. heart attacks, heart rhythm problems, stroke),” Auckley added.
“It may be that the increased stress of the post-surgery environment, which can temporarily worsen obstructive sleep apnoea and the low oxygen level associated with it, accelerates the development of these bad outcomes in someone at risk for them (e.g. severe untreated obstructive sleep apnoea).”
Source: Reuters Health