DALLAS, June 15, 2016 -- People who have had percutaneous coronary intervention (PCI), also known as angioplasty, for acute coronary syndrome could be at higher risk of death, heart failure, heart attack and stroke if they have sleep-disordered breathing, such as sleep apnea, according to new research in Journal of the American Heart Association, the Open Access Journal of the American Heart Association/American Stroke Association.

Acute coronary syndrome, is an umbrella term for conditions in which the blood supplied to the heart is suddenly blocked. Doctors reopen blocked arteries by threading a catheter through the femoral artery in the groin or the radial artery in the wrist in a procedure called PCI or angioplasty.

"Sleep-disordered breathing, which includes snoring and sleep apnea, has long been recognized as an important risk factor for heart disease. However, there is limited awareness of sleep-disordered breathing among cardiologists who care for PCI patients," said Toru Mazaki, MD, study author and chief physician of the Department of Cardiology, Kobe Central Hospital, Kobe, Japan.

Researchers studied 241 patients (average age 64) with acute coronary syndrome, who were in the hospital after successful PCI. Researchers monitored patients' breathing overnight and followed the patients' health for an average 5.6 years, tracking deaths, strokes, recurrent acute coronary syndromes and hospital admissions for heart failure.

They found:

• 52.3% had sleep-disordered breathing.

• 21.4% of those with sleep-disordered breathing had major cardiovascular events.

• Only 7.8% of those without sleep disordered breathing had major cardiovascular events.

In the entire study group, the cumulative event-free survival was significantly lower in patients with sleep-disordered breathing than in those without it.

"Our findings suggest that sleep-disordered breathing is an important risk factor for stroke, heart failure and more after PCI for acute coronary syndrome," Mazaki said. "Doctors and patients should consider sleep studies post-PCI to rule out sleep-disordered breathing or take necessary precautions to restore healthy breathing during sleep."

The study was relatively small and conducted at one center. Researchers detected sleep-disordered breathing using the simple method of portable cardiorespiratory monitoring, rather than a fully equipped sleep lab.

Researchers suggest that detecting sleep-disordered breathing should be included into the routine clinical care of hospitalized patients following acute coronary events and angioplasty.

"It may not be feasible for all patients to undergo a fully-equipped sleep study following acute coronary syndrome," Mazaki said. "Randomized clinical trials with a larger number of patients will provide further information."