Duke University Medical Center Researchers say that implantable cardioverter-defibrillators (ICDs) reduce the risk of death from sudden cardiac arrest (SCA) among patients with heart failure, and the devices work without significantly altering a person's quality of life.

The conclusions result from the longest and most comprehensive study to date of ICD use to prevent SCA. It is hoped that the findings will alleviate physician and patient concerns over the ICD side effects.

"Basically, we wanted to find out if ICD therapy improves longevity but only at the cost of worse quality of life," says Dr. Daniel Mark, a cardiologist at Duke and the lead author of the study appearing in the September 4 issue of the New England Journal of Medicine.
ICDs both monitor arrhythmia in the heart beat and if necessary, deliver a jolt of electricity to restore normal rhythm. Because such shocks can be painful and disturbing, anticipating a shock may incur anxiety.

Mark and colleagues prospectively studied 2521 patients enrolled from 1997 to 2001 in the Sudden Cardiac Death in Heart Failure Trial. The participants received state-of-the-art medical therapy for heart failure. Patients were randomly assigned to receive an ICD, or the anti-arrhythmia drug amiodarone, or an amiodarone placebo.

Researchers interviewed each participant four times over a 30-month period to assess disease status, physical and social activity levels, psychological well-being, and ability to perform routine daily tasks.

Participants of all groups had essentially the same scores on psychological well-being at the beginning of the study. However, patients with the ICDs actually had somewhat higher quality of life scores at three and 12 months, when compared to those in the other groups.

"Interestingly, we found that patients who happened to experience a shock from the ICD within 30 days before their quality of life interview reported a significant decline in their assessment of their overall physical and emotional health," says Mark. "And those who were shocked within two months reported much the same, but with a somewhat diminished magnitude. But after one year, in comparing the 100 who had been shocked with the 638 who were not shocked, we found no significant differences in measures reflecting overall satisfaction with their quality of life."

The study found that patients in all groups enjoyed a good quality of life even while coping with significant heart failure, reporting that they experienced only a small number of days when they had to stay in bed or felt they lacked energy for regular activities. Eighty-six percent said they were able to drive a car, 92 percent said they could manage their finances independently and 27 percent said they were still employed outside the home. Having an ICD did not appear to have any adverse effect upon these activities.

"Medical intervention almost always brings about unintended consequences. We began examining these patients when ICDs were still relatively new and, until now, we were not entirely sure that in using a device to prolong life we weren't causing additional problems in the process. We are now happy to report that we found no evidence of that in this large trial. ICD users, on the whole, appear satisfied with the benefits and the consequences of defibrillator therapy," says Mark.

The study was funded by the National Heart, Lung, and Blood Institute.

These findings provide a balance to results of another study in the same NEJM issue that call into question the safety of ICDs. Read about it at:
https://www.dotmed.com/news/story/6901/

Adapted by a press release from Duke University Medical Center.

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