麻豆传媒

Sleep-disordered breathing is associated with long-term elevations in cardiovascular risk, a single-center study following bare-metal stent recipients found.

Over a median of 5.6 years after a successful bare-metal stent procedure, the composite of all-cause death, recurrent acute coronary syndrome (ACS), nonfatal stroke, and hospital admission for congestive heart failure occurred more often in patients with sleep-disordered breathing (21.4% versus 7.8% for those without, P=0.006).

The condition was an as well (hazard ratio 2.28, 95% CI 1.06-4.92), Toru Mazaki, MD, of Kobe Central Hospital in Japan, and colleagues reported online in the .

"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 [percutaneous coronary intervention] patients," Mazaki stated in a .

"It appears that detecting sleep-disordered breathing should be included into the routine clinical care of hospitalized patients following ACS events and primary PCI," he and his colleagues concluded. "Because of the limited awareness of sleep-disordered breathing among cardiologists caring for hospitalized patients following ACS and limited access to and the relatively high cost of in-laboratory polysomnography, only a minority of ACS patients benefit from the identification of sleep-disordered breathing."

Mazaki's group used a portable cardiorespiratory monitoring device -- not a fully-equipped sleep lab -- to determine which patients had sleep-disordered breathing, defined as an apnea-hypopnea index greater than five events per hour.

"It should be noted that portable cardiorespiratory monitoring, which provides a readily available and inexpensive means of detecting sleep-disordered breathing, has a prognostic impact on long-term clinical outcomes," they commented. "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 (e.g., sleep or respiratory specialists)."

, of Singapore's National University Heart Centre, agreed. He told 麻豆传媒: "Clinicians should be more aware of sleep-disordered breathing as a cardiovascular risk factor and prognostic markers in patients undergoing PCI. Using portable diagnostic devices, screening for sleep-disordered breathing could be done easily at a low cost."

"Moreover, weight reduction and continuous positive airway pressure therapy are effective treatments for sleep-disordered breathing," said Lee, who was not involved in Mazaki's study but has in a registry.

The investigation included 241 patients, half of whom (52.3%) had sleep-disordered breathing. All participants had ACS and had been successfully treated with primary PCI -- by way of bare-metal stenting -- between 2005 and 2008. For the study, they were held for overnight sleep monitoring over several days.

Baseline characteristics showed that patients with sleep-disordered breathing had a higher body mass index at baseline (25.9 kg/m² versus 24.3 kg/m², P=0.0006), a lower left ventricular ejection fraction (53% versus 58%, P=0.002), and more cases of no-flow prior to PCI (76% versus 58%, P=0.017).

The effect on adverse events "was not different across subgroups," the researchers noted.

As for the study's limitations, the authors cited their small sample size and the single-center, observational nature of the study that produced these and other potential confounding variables.

The group additionally acknowledged that the results may have been different if they had access to a full polysomnography lab. Without including of recipients of drug-eluting stents, they also wondered if the effect of sleep-disordered breathing holds up in the current drug-eluting stent era.

As a potential mechanism for how abnormal breathing can affect cardiac outcomes, Mazaki and colleagues cited a prior study linking sleep-disordered breathing and a larger infarct area in PCI patients to acute myocardial infarction.

"There has been ample evidence showing sleep-disordered breathing is a risk factor for cardiovascular diseases including coronary disease. PCI is a marker of high coronary plaque burden and indicator of future coronary events," Lee concluded.

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