Sleep Apnea Predictive of Poorer Outcomes After PCI in ACS Patients

Breathing problems that interrupt sleep may be an important sign that patients who have had acute coronary syndromes are at risk for poor outcomes after PCI. 

“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 (Kobe Central Hospital, Kobe, Japan), in a press release.

In a paper published online June 15, 2016, ahead of print in the Journal of the American Heart Association, Mazaki and colleagues conclude that recognition of sleep-disordered breathing should be included in the routine clinical care of hospitalized patients following ACS and primary PCI.

In an email to TCTMD, Nieca Goldberg, MD (NYU Langone Medical Center, New York, NY), who was not involved in the study, agreed that cardiologists need to be more aware of patients who have these conditions.

“Patients need to report symptoms of fatigue, falling asleep during the day, and being awakened at night from sleep,” she said. “The doctors need to ask the patients of these symptoms and have an evaluation for sleep apnea.”

More MACCE, Death Noted

For the study, Mazaki and colleagues looked at 241 hospitalized ACS patients who had undergone successful PCI between January 2005 and December 2008 at a single center. All patients underwent an overnight sleep study in which airflow and snoring were monitored. Just over half of the group (52.3%) were found to have sleep-disordered breathing.

During an average follow up of 5.6 years, 21.4% of those with sleep-disordered breathing experienced major cardiocerebrovascular events (MACCE) versus 7.8% who had no breathing issues during sleep (P = 0.006). Additionally, more than three times as many patients with sleep-disordered breathing died over follow-up, and more than eight times as many were admitted for congestive heart failure.

Cumulative event-free survival was lower when sleep-disordered breathing was present than when it was not (log-rank P = 0.006). Multivariable analyses confirmed that having sleep-disordered breathing more than doubled the risk of MACCE (HR 2.28, 95% CI 1.06-4.92).

Easy, Portable Monitoring

Although the reasons why sleep-disordered breathing worsen prognosis in ACS patients are not clear, Mazuki and colleagues say some data have suggested that the condition causes a larger infarct area and impaired healing after PCI, which could explain the cause and effect, particularly the increased risk for hospital admission for heart failure. Furthermore, they say data in CAD patients showing a lower incidence of cardiac death in conjunction with treatment for the sleep-disordered breathing strengthens the suggestion that the two are causally related.

Importantly, the researchers note that detecting sleep-disordered breathing is not as difficult as some may think. In fact, they used portable monitoring devices, not a fully-equipped sleep lab.

“In the present study, we specifically evaluated whether we could identify patients at high risk for the incidence of MACCE by using a simple modality for determining the long-term clinical outcome, as we need a simple, inexpensive, feasible, and sensitive and specific tool for identifying [sleep-disordered breathing], even in this patient population, and for identification of risk factors by cardiologists themselves and not by other specialists (eg, sleep or respiratory specialists),” they write.

To TCTMD, Goldberg said cardiologists should consider that even patients who have not had ACS but who have stable angina or have had an elective PCI should be evaluated for sleep-disordered breathing problems, too, since they are associated with high blood pressure, elevated glucose, and arrhythmia.