CPAP May Not Prevent Major Cardiovascular Events in OSA and ACS

In patients with acute coronary syndrome and obstructive sleep apnea, treatment with continuous positive airway pressure may not prevent the recurrence of major cardiovascular events.

In patients with acute coronary syndrome (ACS) and obstructive sleep apnea (OSA), treatment with continuous positive airway pressure (CPAP) may not prevent the recurrence of major cardiovascular events, according to study results published in The Lancet Respiratory Medicine.

Between 40% and 60% of patients with coronary artery disease have OSA, with results from previous studies showing that the treatment of OSA using CPAP may lead to improvements in the prognosis of patients with coronary artery disease. However, other studies have shown that CPAP may not be associated with a reduced risk of cardiovascular outcomes or death in patients with OSA. The objective of this study was to evaluate the effect of OSA and CPAP on the clinical evolution and prognosis of ACS.

In this multicenter, open-label study (Impact of Sleep Apnea Syndrome in the Evolution of Acute Coronary Syndrome [ISAACC]; Identifier: NCT01335087), researchers evaluated 2551 nonsleepy patients admitted to hospitals in Spain with symptoms of ACS. During the first 24 to 72 hours after hospital admission, all patients had respiratory polygraphy to diagnose OSA. Patients with OSA were randomly assigned (1:1) to receive either CPAP therapy plus usual care (CPAP group) or usual care alone. A group of patients with ACS without OSA was included as a reference group. All patients were monitored and followed up for ≥1 year, and clinic visits were scheduled for all patients at months 1, 3, 6, 12, 18, 24, 30, and 36 and every year thereafter.

The primary end point was the prevalence of a composite of the first cardiovascular events (cardiovascular death or nonfatal events). Secondary end points included the individual components of the primary composite end point, other composites of cardiovascular events, revascularization procedures, new-onset atrial fibrillation, new-onset diabetes, mortality from any cause, clinical symptoms of OSA, and health-related quality of life.

Results revealed that of the 2551 patients enrolled in the study, 49.55% (n=1264) had OSA and were randomly assigned to either the CPAP group (n=633) or the usual care group (n=631). The median follow-up period was 3.35 years (interquartile range [IQR], 1.50-5.31). The number of patients who experienced a cardiovascular event during the follow-up was similar between the CPAP and usual care groups (98 patients vs 108 patients; hazard ratio [HR], 0.89; 95% CI; IQR, 0.68-1.17; P =.40). 

The mean CPAP adherence was 2.78 hours per night (standard deviation [SD], 2.73) and the median was 2.2 hours per night (IQR, 0.03-5.13). There were 102 patients in the usual care group and 90 patients in the reference group who experienced a cardiovascular event during follow-up (HR, 1.01; 95% CI; IQR, 0.76-1.35; P =.93). CPAP was not shown to have a significant effect on the primary cardiovascular composite end point, the composite of major cardiovascular events, revascularization procedures, all-cause mortality, atrial fibrillation or other arrhythmias, or newly diagnosed diabetes. In the CPAP group, 464 patients (74%) had 1538 serious adverse events, and in the usual care group, 406 patients (65%) had 1764 serious adverse events.

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This study had several limitations. First, the results apply only to nonsleepy patients with OSA. Second, the majority of the patients included in this study were men. Third, the severity of OSA may have been underestimated because the diagnosis was based on respiratory polygraphy. Fourth, patients with ACS could have been given pharmacological treatment such as opioids, which may have influenced sleep study results. Fifth, the beneficial effect of well-conducted CPAP could not be excluded on behalf of low compliance to treatment. Sixth, there were fewer patients screened than initially planned. Last, only white patients were included in this study.

The researchers concluded that in these patients with ACS and OSA, the use of CPAP did not effectively prevent the recurrence of major cardiovascular events and the presence of OSA was not associated with an increased prevalence of cardiovascular events.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Sánchez-de-la-Torre M, Sánchez-de-la-Torre A, Bertran S, et al; on behalf of the Spanish Sleep Network. Effect of obstructive sleep apnoea and its treatment with continuous positive airway pressure on the prevalence of cardiovascular events in patients with acute coronary syndrome (ISAACC study): a randomised controlled trial [published online December 12, 2019]. Lancet Respir Med. doi: 10.1016/S2213-2600(19)30271-1