Posts Tagged ‘Sleep Apnea’

SLEEP APNEA, OBESITY - HIGHER RISK FOR AGRESSIVE HEART DISEASE

Tuesday, November 30th, 2010

Chicago, Ill - November 30, 2010
People with sleep apnea at higher risk for aggressive heart disease.

Joseph Schoepf, M.D
Joseph Schoepf, M.D
Professor of radiology
and medicine and director
of cardiovascular imaging
at the Medical University of
South Carolina in Charleston, S.C.
Photo: muschealth.com

People with obstructive sleep apnea (OSA), a sleep disorder associated with obesity, have more noncalcified or “bad” plaque in their coronary arteries, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA).

“Our study reveals that individuals with obstructive sleep apnea are prone to developing an aggressive form of atherosclerosis that puts them at risk for impaired blood flow and cardiovascular events,” said Uwe Joseph Schoepf, M.D., professor of radiology and medicine and director of cardiovascular imaging at the Medical University of South Carolina in Charleston, S.C.

OSA is caused by obstruction of the upper airway during sleep and is characterized by periodic pauses in breathing, which last for 10 or more seconds. OSA is also commonly associated with snoring.

According to the National Heart, Lung and Blood Institute, millions of Americans have OSA, and approximately half of them are overweight. In the study, 49 obese patients, mean age 61, with OSA and a mean body mass index (BMI) of 33, and 46 obese patients without the disorder (mean age of 60 and mean BMI of 30) underwent coronary CT angiography (cCTA), which provides detailed pictures and information on plaque buildup and narrowing in the vessels. The OSA group included 26 men and 23 women, and the matched control group included 22 men and 24 women.

The imaging revealed that the amount of calcified plaque in the coronary arteries was not significantly different between the two groups, but the overall composition of vessel plaque was notably different.

“Compared to the non OSA group, the patients with OSA had a significantly higher prevalence of noncalcified and mixed plaque,” Dr. Schoepf said.

Noncalcified plaque is considered bad plaque, because it is more vulnerable to rupturing and causing a blood clot, which could lead to a heart attack or other cardiovascular event.

Patients with OSA also had a significantly higher prevalence of vessel narrowing and more extensive vessel involvement. Eightyeight percent of OSA patients had narrowing in at least one vessel, compared to 59 percent of non OSA patients. One third of OSA patients had narrowing in four vessels.

“Coronary CT angiography is an effective way to noninvasively diagnose noncalcified and mixed plaque,” Dr. Schoepf said. “With technological advancements that are lowering the radiation dose required for cCTA, this exam could become a screening tool for obese individuals at increased risk for cardiovascular disease.”

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EVEN MILD SLEEP APNEA INCREASES CARIOVASCULAR RISK

Friday, October 24th, 2008

People with even minimally symptomatic obstructive sleep apnea (OSA) may be at increased risk for cardiovascular disease because of impaired endothelial function and increased arterial stiffness, according to a study from the Oxford Centre for Respiratory Medicine in the UK.

“It was previously known that people with OSA severe enough to affect their daytime alertness and manifest in other ways are at increased risk of cardiovascular disease, but this finding suggests that many more people - some of whom may be completely unaware that they even have OSA - are at risk than previously thought,” said lead author of the study, Malcolm Kohler, M.D.

The study will be published in the first issue for November of the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

“Only one out of approximately five subjects with [clinically defined OSA] complains of excessive daytime sleepiness in population studies,” wrote Geraldo Lorenzi-Filho, M.D., Ph.D. in an editorial in the same issue of the Journal. “[I]t is now recognized that OSA triggers a cascade of biological reactions, including increased sympathetic activity, systemic inflammation, oxidative stress, and metabolic alterations that are potentially harmful to the cardiovascular system.”

To determine the exact nature of some of these effects, Dr. Kohler and colleagues performed a controlled, cross-sectional study to assess differences in endothelial function (often a harbinger for cardiovascular problems to come), arterial stiffness and blood pressure in patients with minimally symptomatic OSA. They compared 64 patients who had proven OSA to matched control subjects without OSA.

Their findings suggested that minimally symptomatic OSA is a cardiovascular risk factor to a degree not previously known.

“In our study, the augmentation index, a measure of central arterial stiffness that independently predicts cardiovascular events in high-risk populations, was significantly higher in patients with minimally symptomatic OSA compared to matched controls,” said Dr. Kohler. “We also found impaired endothelial function as indicated by decreased vascular reactivity of their arteries compared to control subjects without OSA.”

The difference in arterial stiffness between OSA patients and control subjects, Dr. Kohler said was “comparable in size to the effect seen after four weeks’ continuous positive airway pressure (CPAP) therapy in patients with moderate to severe symptomatic OSA.”

This suggests that asymptomatic or minimally symptomatic patients with OSA may enjoy a cardiovascular benefit from CPAP therapy.

Dr.Kohler and colleagues from the Oxford Centre for Respiratory Medicine are currently investigating the effects of 6 month CPAP therapy on arterial stiffness and endothelial function as part of an international randomized controlled trial (Multicentre Obstructive Sleep Apnoea Interventional Cardiovascular Trial; MOSAIC) which will show the impact of CPAP therapy on cardiovascular risk in patients with minimally symptomatic OSA.

Press release - thorcic.org

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