Women, men with heart failure both benefit from implanted defibrillators

Women with heart failure benefit from implantable cardiac defibrillators as much as men, according to new research in Circulation: Heart Failure, an American Heart Association journal.

"Despite current guidelines recommending that health practitioners consider adding these devices to standard heart failure treatments in both women and men, women with heart failure have been less likely to receive defibrillators. These new data reinforce the existing gender-neutral guidelines," said Emily Zeitler, M.D., lead author of the study and a cardiology and research fellow at the Duke Clinical Research Institute in Durham, North Carolina.

An implantable cardiac defibrillator (ICD) is a small, battery-powered device placed under the skin of the chest to deliver an electrical shock to restore a normal heartbeat if it detects a dangerously abnormal heart rhythm. Patients with heart failure, a condition in which the heart's pumping ability is weakened, are at increased risk to develop dangerous heart rhythms. Previously, randomized controlled trials showed that patients with heart failure live significantly longer if they have an ICD implanted preventatively—before an abnormal heart rhythm occurs. However, because the trials enrolled relatively few women, whether women benefited to the same extent was still an open question.

Using data submitted to Medicare from 264 hospitals included in the Get With the Guidelines-Heart Failure registry, the researchers compared survival in heart failure patients with preventive ICDs or prescribed one (430 women; 859 men) versus matched patients with very similar characteristics but no ICDs. All patients had a reduced ability to pump blood out of the heart. The researchers found:

After 3 years, 40.2 percent of women with ICDs had died, compared with 48.7 percent of women without devices.

After 3 years, 42.9 percent of men with ICDs had died, compared with 52.9 percent of men without devices.

With an ICD, the risk of death was more than 20 percent lower in both men and women after about 3 years.

"Currently, many eligible patients with heart failure are not referred to physicians who can implant the devices. If you have heart failure, ask your doctor whether you might benefit from an ICD in addition to your other therapy," Zeitler said.

Although patients were carefully matched in age, severity of illness, and other treatments being used, this type of study does not have the power of a trial that randomly assigns some patients to receive the devices. However, because the value of ICDs has already been demonstrated, it would be ethically difficult to initiate a trial that denies the treatment to some patients.

"I would encourage patients and providers to enthusiastically pursue good research as participants and enrollers. When we don't equitably enroll women or other important groups in trials, we can be left with less clear answers on how to treat heart disease," Zeitler said.