September 4, 2008

Defibrillators Increase Death Risk

New research noted that heart failure patients were far more likely to die within four years after their defibrillator zapped the heart into beating normally, compared with those who got no shock.

If their defibrillator triggers, experts said patients should promptly tell their doctors, who should then check to see if their patients' condition has worsened.

"We need to think about everything else we possibly could do to make them as healthy as they can be," said the study's lead author, Dr. Jeanne Poole of the University of Washington.

The report is published in Thursday's New England Journal of Medicine, along with another study that found having an implanted defibrillator does not affect one's quality of life.

About 234,800 North American patients have defibrillators. The devices cost between $25,000 and $35,000 and are about the size of a stopwatch. They are designed to correct dangerously high or erratic heartbeats in the lower, pumping chambers of the heart.

Previous studies noted that defibrillators cut the risk of death by 23 percent. The new reports come from that same study of 2,500 heart failure patients.

The government paid for reports that show how a defibrillator prolongs "survival in patients with heart failure, with relatively little compromise in the quality of life," wrote Drs. Jeff Healey and Stuart Connolly of McMaster University in Hamilton, Ontario.

But they both noted,  "It is somewhat disturbing to realize that actually receiving a shock is such an important predictor of death."

In the study, about a third of the 811 patients with defibrillators were shocked during nearly four years of follow-up.

Data recorded by the devices shows the shock corrected a life-threatening irregularity or was maybe even inappropriately fired by another problem, such as an abnormal rhythm in the heart's upper chambers.

However, researchers found patients who needed a shock were more than five times more likely to die over the next four years than those who didn't receive a shock. Even people who didn't seem to need a shock but got one had double the risk of dying.

Dr. N.A. Mark Estes, president of the Heart Rhythm Society, said the defibrillators used in this particular study are a generation-old. He said the newer devices could often correct a high heartbeat through painless pacing techniques, before a shock would be needed.

"The frequency of shocks would be considerably less with contemporary devices," said Estes, of Tufts Medical Center in Boston.

"We found no evidence that the patients who got the defibrillator were feeling any worse for having received that therapy," said Dr. Daniel Mark, lead author of the study from Duke University Medical Center.

A heart patient at Duke, John McKinnon, said he was at first uneasy to get a defibrillator for a couple of years but has had no concerns since.

Months ago, the 65-year-old pastor got a shock to his heart, which he described as a strong kick. Since the shock, he has had a procedure to treat an abnormal heartbeat.

"I'm getting my energy back, doing some walking, getting some exercise," said McKinnon.


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