Women Do as Well as Men with Implanted Cardiac Devices

Study highlights gender disparity in life-saving treatment


Women receive fewer implantable cardiac devices than do men, yet when they do receive them, their survival is the same or — in some cases — better, a recent study shows.

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The study, led by cardiologist and heart rhythm specialist Niraj Varma, MD, PhD, analyzed information from a database of more than a quarter-million heart patients who received implanted devices from a single manufacturer. The data very likely represents patterns across the United States, Dr. Varma says.

Implantable cardiac devices are used to treat electrical problems in the heart such as arrhythmia, which is an irregular or abnormal heartbeat. Examples include pacemakers and defibrillators.

The study showed that of all the heart patients referred by doctors to receive an implanted cardiac device, only about a third are women.

It’s unclear why women are less likely to be referred for an implanted device. However, older data that suggests women do less well with them may be influencing cardiologists and internists, Dr. Varma says.

Few women enrolled in clinical trials

“Doctors also may exclude many women because many of these guidelines are based on clinical research that studied predominantly male patients,” Dr. Varma says. “Therefore, definitive conclusions about their effect in women are unknown.”

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“It’s astounding,” Dr. Varma says. “These issues haven’t been examined properly because trials have enrolled few women.”

One surprising aspect of the analysis is the revelation that women treated with a special type of implantable device called cardiac resynchronization therapy (CRT) survived about 30 percent longer than men. Other recent scientific studies support those findings, but this is the first study on this scale conducted nationwide to show this.

“I think this story is on its way to maturing, because of some significant contributions in the last 12 months,” Dr. Varma says. It’s unclear exactly why women who received CRT live longer than men. Women do have smaller hearts than men. But Dr. Varma doesn’t think heart size can explain the difference in survival data.

“The kind of heart failure in women may be different,” he says. “Nobody has really looked at this.”

Dr. Varma recently presented the study results at the European Heart Rhythm Association Europace meeting.

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Other work from Cleveland Clinic published by Dr. Varma last year suggested that the rules for selecting candidates for CRT on the basis of the electrocardiogram (ECG) should be different for women – they should be enrolled more readily than men. In follow-up, this notion was supported in an analysis from the FDA.

The guidelines for implantable cardiac devices eventually may change, Dr. Varma says. But typically, the process takes a long time. In the meantime, physicians who are aware of research on women and implantable devices can refer their female heart patients for the devices, if appropriate.

“At the moment, change depends on physicians reading the medical literature and being convinced by others who have changed their practice,” Dr. Varma says.

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