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Common heart abnormality linked to risks

Researchers connect the condition, called an increased PR interval, to a substantially higher risk of erratic heartbeats and need for a pacemaker, as well as risk of death.

June 24, 2009|Thomas H. Maugh II

A common heart abnormality often seen of electrocardiograms that has long been thought to be inconsequential is actually associated with a substantially increased risk of erratic heartbeats or a need for a pacemaker -- and with a modestly increased risk of death, researchers reported today.

Although there is no treatment to forestall such events, the presence of the abnormality should lead to increased monitoring of the patients to detect problems early, the team reported in the Journal of the American Medical Assn.

The abnormality, called an increased PR interval, "is fairly common in healthy people. We see it often in clinical practice and typically assume that it is a benign finding," said Dr. Thomas J. Wang of Massachusetts General Hospital in Boston, the lead author.

But the condition is also seen in people with congenital heart disease and other problems, "so we know that it is not always so benign," Wang said.

The PR interval is the time it takes for an electrical signal emitted by the heart's natural pacemaker to spread from the upper chambers of the heart to the lower chambers. A PR interval of less than 200 microseconds is considered normal.

Wang and his colleagues studied 7,575 individuals enrolled in the multi-decade, government-funded Framingham Heart Study of residents of a Massachusetts town.

The participants had a mean age of 47 when they underwent an electrocardiogram examination in 1968 through 1974, and they were followed through 2007. Over the years, 481 developed erratic heartbeats, 124 required a pacemaker and 1,739 died.

At the beginning of the study, 124 individuals had PR intervals longer than 200 microseconds. They had about twice the risk of atrial fibrillation, about three times the risk of requiring a pacemaker and about a 40% increased risk of death from all causes.

"The [increased] PR interval is a red flag for physicians to be on the alert for these things," said Dr. Albert Waldo of University Hospitals Case Medical Center in Cleveland, who was not involved in the study.

A longer PR interval "might be an early marker for fibrosis and scarring," or other problems, said Dr. John Kennedy of Marina del Rey Hospital, who was also not part of the study.

Patients with a prolonged PR interval "should be looking more closely for signs of problems, such as palpitations, lightheadedness and fatigue," Kennedy added.


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