Among people who suffer moderate to severe carbon monoxide poisoning, more than a third will develop cardiovascular symptoms, new research indicates.

Previous studies investigating carbon monoxide poisoning have focused primarily on the neurologic impact. To look into the effects on the heart, Dr. Timothy D. Henry, from the Minneapolis Heart Institute Foundation, and colleagues reviewed the cases of 230 patients poisoned by carbon monoxide who were treated at one medical center between 1994 and 2002.

Most of the patients were male, and their average age was 47 years. All of the subjects were treated in a high-pressure (hyperbaric) oxygen chamber.

Overall, 37 percent of the patients had evidence of injury to the myocardium - that is, the muscle layer of the heart - the investigators report in the Journal of the American College of Cardiology.

Only 16 percent of the patients in the study had a normal electrocardiogram reading.

“Further study is needed to determine the long-term clinical significance of the myocardial injury as well as the efficacy of hyperbaric oxygen as adjunctive therapy for patients with myocardial injury resulting from CO poisoning,” the investigators conclude.

SOURCE: Journal of the American College of Cardiology, May 3, 2005.