A tiny device--albeit very expensive device-- that can send a life- saving shock to the heart may have been implanted unnecessarily into "hundreds of thousands of women," according to a study published Monday.
The devices, called implantable cardioverter defibrillators or ICDs, are used to prevent sudden cardiac death in patients with advanced heart failure, meaning that patients who hearts have been damaged by heart attacks or heart disease so that they can no longer efficient pump blood through the body.
Each ICD costs about $30,000 per device and Medicare currently pays for use of the devices in both men and women.
A number of studies have provided evidence that implanting these devices can save live, but the evidence that the devices work was based on trials in which most of the patients were men, and that's what has led some researchers to take a second look.
The analysis published Monday in Archives of Neurology pools data from five ICD trials that tested the devices or optimal medical therapy in 3,810 men and just 934 women.
When Dr. Hamid Ghanbari, of Providence Hospital Heart Institute and Medical Center in Southfield, Mich., analyzed the results in women he found no reduction in "all cause mortality" among women treated with the shock devices.
Reducing that finding to simple numbers, it means that one would need to treat 40 women with ICDs to save a single life, versus treating 12 men with ICDs to save a life.
"The exact reasons for the significant sex differences in ICD implantation rates are not well established, but perhaps some of this disparity is driven by the paucity of data for women in randomized clinical trials of ICD therapy," they wrote.
Dr. Rita F. Redberg, editor of Archives of Internal Medicine, put it this way in an editorial; "ICDs are being implanted in hundreds of thousands of women without substantial evidence of benefit, apparently based on the assumption that, to paraphrase an old saying, 'What's good for the gander is good for the goose.'"
Men, Women React Differently to Heart Attack Treatments
Such reasons, Redberg said, was especially troubling given a recent analysis of data from the National Cardiovascular Data Registry, which "found that women have a 70 percent higher risk of major adverse events after ICD implantation than do men."
Dr. Stephanie Moore, of Massachusetts General Hospital in Boston agreed.
"We need to report data based on gender and reported ethnicity. We cannot treat patients as "all the same". On the contrary, we are all unique and through thoughtful research we can personalize treatment so the goose and gander both have the best," said Moore.
Redberg said the meta-analysis was more evidence that the FDA had dropped the ball by failing to require more sex-specific data on both drugs and devices.
The authors of the study also thought more studies would settle the question.
"The best answer to this problem would be to perform a clinical trial that specially targets women with heart failure to test the hypothesis of whether ICD implantation reduces their overall mortality rate," Ghanbari wrote.
But because current guidelines do not qualify recommendations for use ICDs based on gender and nor does Medicare stipulate a gender criteria for ICDs to treat heart failure, such a prospects for such a trial are slim.
Dr. Alfred A. Bove, a heart failure specialist from Temple University in Philadelphia and president of the American College of Cardiology, disagreed about the prospects for such a study.
In an interview, Bove pointed out that the five trials included in the meta-analysis were not originally designed to answer the gender question, so he cautioned that the results of comparing them should be considered hypothesis-generating.
But given the findings of the new study, Bove said there was no doubt that further research of ICDs in women was needed. Moreover, he said that the current push for comparative-effectiveness research in health care means that "there is now money available for this research."
Doctors Call for More Heart Attack and Gender Difference Studies
Dr. Douglas P. Zipes, professor of medicine at Indiana University School of Medicine's Krannert Institute of Cardiology in Indianapolis and Editor-in-Chief, of HeartRhythm, was also cautious about over-interpreting results of a meta-analysis.
"While unquestionably a woman's heart is different than a man's, nevertheless I would expect a heart in ventricular tachycardia or ventricular fibrillation to respond to appropriate therapy from an ICD regardless of sex," Zipes said when queried by MedPage Today and ABC News.
He said the most likely explanation for a difference, if in fact the difference is "real", the results are true, would be "competing causes of death between the sexes, i.e., women with heart failure are more likely to die of causes other than a ventricular tachyarrhythmia which can be treated by the ICD."
But Zipes with Bove that a prospective trial was needed to "prove or disprove this hypothesis."
However, use of these devices in women has been the exception rather than the rule—Medicare data indicate only 8.6 of every 1,000 women who meet criteria for ICD for primary prevention of sudden cardiac death receive a device within a year of diagnosis versus 32.3 of every 1,000 men with the same diagnosis.
Likewise, according to the American Heart Association's Get With the Guidelines program, "women represented only 27.2 percent of patients of the total population who received ICDs and 37.5 percent of patients who did not."
Yet the gender question does not appear to be simple, according to Boston Scientific spokesperson, David Kinugson, who pointed out that a study recently published in the New England Journal of Medicine showed there was no discernable difference in ICD deaths between men and women.
Still many doctors feel that women, and people from a variety of ethnic backgrounds, need to be included more often in clinical trials.
"There is no doubt that women are underrepresented in clinical trials -- the issues are complicated," said Dr. James B. Young, of the Cleveland Clinic in Ohio. "Many other demographic groups are underrepresented as well."