Sleep Apnea May Boost Risk of Sudden Cardiac Death

Study findings bolster suspected link between sleep disorder and heart-related death

By Kathleen Doheny

HealthDay Reporter

TUESDAY, June 11 (HealthDay News) -- Sleep apnea raises the risk of sudden cardiac death, according to a long-term study that strengthens a link doctors have suspected.

"The presence and severity of sleep apnea are associated with a significantly increased risk of sudden cardiac death," said study leader Dr. Apoor Gami, a cardiac electrophysiologist at Midwest Heart Specialists-Advocate Medical Group in Elmhurst, Ill.

The new research is published online June 11 in the Journal of the American College of Cardiology.

Sleep apnea -- in which a person stops breathing frequently during sleep -- affects about 12 million American adults, although many are not diagnosed. The diagnosis is made after sleep tests determine that a person stops breathing for 10 seconds or more at least five times hourly while sleeping.

Some research suggests that sleep apnea is on the rise, in part because of the current obesity epidemic.

Sudden cardiac death kills 450,000 people a year in the United States, according to study background information. It occurs when the heart unexpectedly and suddenly stops beating due to problems with the heart's electrical system. Those problems cause irregular heartbeats. The condition must be treated within minutes if the person is to survive.

Electrophysiologists are cardiologists who treat these heart rhythm problems.

In earlier research, Gami and his team had found that patients with sleep apnea who suffered sudden cardiac death often did so at night, a completely opposite pattern than found in others without sleep apnea who had sudden cardiac death.

"That was the first direct link [found] between sudden cardiac death and sleep apnea," Gami said.

In the new study, the researchers tracked more than 10,000 men and women, average age 53, who were referred for sleep studies at the Mayo Clinic Sleep Disorders Center, mostly due to suspected sleep apnea, from 1987 through 2003. After sleep tests, 78 percent were found to have sleep apnea.

During the follow-up of up to 15 years, they found that 142 had sudden cardiac arrest, either fatal or resuscitated.

Three measures strongly predicted the risk of sudden cardiac death, Gami said. These include being 60 or older, having 20 apnea episodes an hour or having low blood levels of oxygen.

This "oxygen saturation" drops when air doesn't flow into the lungs. "If the lowest oxygen saturation was 78 percent, or less, their risk of [sudden cardiac death] increased by 80 percent," Gami said. In a healthy person, 95 percent to 100 percent is normal.

Having 20 events an hour would be termed moderate sleep apnea, Gami said.

Gami found a link, not a cause-and-effect relationship, between sleep apnea and sudden cardiac death. He can't explain the connection with certainty, but said there are several possible explanations. For example, sleep apnea is related to the type of heart rhythm problem that causes sudden cardiac death, he said.

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Modest Cardiac Benefit From Chelation Therapy Not Enough to OK Use: Experts

New study shows slight effect, but arduous 'leaching' treatment has side effects, doctors say

By E.J. Mundell

HealthDay Reporter

TUESDAY, March 26 (HealthDay News) -- Results from a major trial on controversial chelation therapy for patients with a history of heart attack find a modest benefit from the expensive treatment, but experts conclude there's no clear evidence supporting its use.

Still, "groups that advocate for chelation and groups that oppose chelation will both find comfort in the results," said one expert not connected to the study, Dr. Stephen Green, associate chairman in the department of cardiology at North Shore University Hospital in Manhasset, N.Y.

Chelation therapy involves dozens of arduous infusions conducted over a period of years, aimed at leaching excess metals from the body. Patients typically also receive high doses of vitamins and minerals. The therapy has been offered to heart patients by some clinics across the United States for decades, although its use for this purpose has been considered controversial and it has never received approval as a heart disease treatment from the U.S. Food and Drug Administration.

The results of this latest study are published in the March 27 issue of the Journal of the American Medical Association. Findings from the same study were also presented earlier this month at the annual meeting of the American College of Cardiology (ACC) in San Francisco, and at last fall's annual meeting of the American Heart Association.

Speaking at the ACC meeting on March 10, the study's lead researcher said that the modest benefit noted in the study had not made him any more ready to recommend chelation therapy.

"These findings should stimulate further research, but are not by themselves sufficient to recommend the routine use of chelation therapy and high-dose vitamins in most patients," said Dr. Gervasio Lamas, chief of the Columbia University division of cardiology at Mount Sinai Medical Center, in Miami Beach, Fla.

The trial, which was funded by the U.S. National Institutes of Health, involved more than 1,700 patients from the United States and Canada who had suffered a previous heart attack. Most were already taking standard therapies such as daily aspirin, cholesterol-lowering statins or blood pressure medications.

In the new analysis of the data, the patients were divided into two groups: high-dose vitamin/mineral supplements plus chelation or "dummy" placebo infusions/supplements. Chelation therapy consisted of 40 three-hour sessions with the IV infusions spread over anywhere between 50 and 110 weeks. Doses of vitamins and minerals given were much higher than recommended daily intakes.

After an average follow-up of more than four and a half years, the team did see a slight benefit among the group who took the vitamins/minerals in combination with chelation therapy. Twenty-six percent of people in this group experienced some kind of cardiovascular event such as heart attack, stroke or hospitalization for angina (chest pain) -- less than the 30 percent seen among those who got placebo/placebo therapy only.

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Health Tip: Do I Need a Cardiac Stress Test?

Title: Health Tip: Do I Need a Cardiac Stress Test?
Category: Health News
Created: 3/8/2013 8:35:00 AM
Last Editorial Review: 3/8/2013 12:00:00 AM

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