Sleep-disordered breathing increases cardiovascular risk in ACS patients

By Laura Cowen

Sleep-disordered breathing (SDB) is an important risk factor for major adverse cardiocerebrovascular events (MACCE) among patients with acute coronary syndromes (ACS), Japanese research shows.

Among patients with ACS, those with SDB were more than twice as likely as those without SDB to experience the MACCE composite of death, ACS recurrence, nonfatal stroke or hospital admission for congestive heart failure, Toru Mazaki (Kobe Central Hospital) and co-researchers report.

They say: "It appears that detecting SDB should be included into the routine clinical care of hospitalized patients following ACS events and primary PCI [percutaneous coronary intervention]."

Overnight cardiorespiratory monitoring revealed that 126 (52.3%) of 241 patients with ACS who were successfully treated with primary PCI had SDB, defined as an apnoea-hypopnoea index (AHI) of at least 5 events per hour.

Baseline characteristics were generally similar between the SDB and no-SDB groups, except that the patients with SDB had significantly greater body mass index, worse Thrombolysis in Myocardial Infarction flow before PCI and lower left ventricular ejection fraction (LVEF).

During a median follow-up period of 5.6 years, patients with SDB had a significantly higher incidence of MACCE than those without SDB, at 21.4% versus 7.8%.

And on multivariable analysis, presence of SDB significantly predicted MACCE at a hazard ratio (HR) of 2.28. Increased age also predicted an increased MACCE risk (HR=1.04), whereas higher mean arterial oxyhaemoglobin saturation (HR=0.97) and LVEF (HR=0.95) and use of ß blockers (HR=0.47) or statins (HR=0.37) were associated with a lower risk of MACCE.

"These findings provide insights into the clinical significance of SDB and perhaps its role in the treatment of ACS patients following primary PCI", write Mazaki and co-authors in the Journal of the American Heart Association.

They continue: "Nevertheless, because of the limited awareness of SDB 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 SDB."

The authors conclude: "Randomized clinical trials investigating whether specific treatment for coexisting SDB in ACS patients following PCI would cause an improvement in clinical outcomes will provide further information regarding the importance of detecting SDB in patients following ACS and PCI."

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