Nearly Two Thirds of Revascularized Patients Have Asymptomatic Sleep Apnea

Martha Kerr

October 06, 2008

October 6, 2008 (Berlin, Germany) — Swedish investigators say they were surprised to find that a significant number of patients with coronary artery disease (CAD) have obstructive sleep apnea (OSA), but no symptoms.

OSA is thought to be a risk factor for coronary events. However, nearly two thirds of the patients have no symptoms of daytime sleepiness.

Yuksel Peker, MD, from the sleep medicine unit in the department of medicine and cardiology at Skaraborg Hospital, in Skövde, Sweden, reported the current findings of the ongoing Randomized Intervention with CPAP in Coronary Artery Disease and Sleep Apnoea (RICCADSA) trial.

The trial is evaluating the impact of continuous positive airway pressure (CPAP) in 400 revascularized CAD patients who comprise 3 groups: 200 nonsleepy OSA patients randomized to CPAP or non-CPAP; 100 sleepy OSA patients on CPAP; and 100 patients with CAD and without OSA.

The primary end point is the combined rate of new revascularization, myocardial infarction, stroke, and cardiovascular mortality over a 3-year period. Dr. Peker presented the 2-year results of 286 revascularized CAD patients here at the European Respiratory Society 2008 Annual Congress.

OSA was present in 176 (61.6%) patients, 108 (61.4%) of whom had no symptoms of sleep apnea, Dr. Peker announced.

Borderline OSA was observed in 51 (17.8%) patients, and 59 (20.6%) had no OSA.

"We conclude that more than half of the revascularized CAD patients have OSA, which is much higher than previously reported," Dr. Peker told meeting attendees.

RICCADSA will contribute to our understanding of "the impact of CPAP as a nonpharmacological intervention for CAD patients with OSA, regardless of the presence of daytime sleepiness."

The as-yet unpublished findings from a larger group of 730 revascularized patients show that, as of July 31, "the prevalence of sleep apnea is 64% so far, and the majority of those were regarded as nonsleepy," Dr. Peker announced.

"It is noteworthy that 20% of the patients were regarded as a borderline group and were not included in the trial, whereas only 16% were free of sleep apnea," Dr. Peker told the Congress.

"We often don't find out a patient has sleep apnea until after revascularization, when pulse oximetry reveals it," Monica Kraft, MD, professor of medicine in the division of pulmonary, allergy and critical care medicine at Duke University Medical Center, in Durham, North Carolina, told Medscape Pulmonary Medicine during an interview after Dr. Peker's presentation.

"We think sleep apnea promotes atherosclerosis and heart failure," Dr. Kraft continued. "CPAP may help prevent it."

"It makes perfect biologic sense," Dr. Kraft remarked. "It's nice when the data support our hypotheses!"

"As this is an ongoing randomized controlled study of the impact of CPAP treatment on the prognosis of CAD patients with sleep apnea, regardless of daytime sleepiness, over a 3-year period, we do not have the answers yet," Dr. Peker told Medscape Pulmonary Medicine.

"What we noticed during this recruitment period, and now report, is the high prevalence of OSA in this particular group of CAD patients undergoing revascularization. If our results confirm a beneficial effect of CPAP, this will have an important implication for the diagnosis and treatment of these subjects, regardless of daytime symptoms."

"In our cardiac population, one third of the subjects with sleep apnea did not report daytime sleepiness. We would recommend sleep questionnaires to identify the patients who have a highly likelihood of sleep apnea," Dr. Peker advised, "but, as the majority of these subjects do not report symptoms, a portable home-monitoring system of the cardiorespiratory parameters could be a good alternative."

Dr. Peker's study was funded by RestMed, Ltd, but neither he norDr. Kraft have disclosed any relevant financial relationships.

European Respiratory Society (ERS) 2008 Annual Congress: Poster P830. Presented October 5, 2008.

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