New analysis has turned up no evidence that the devices, which are used to detect and then correct abnormal heart rhythms, actually lowered the risk of death among patients that are female, despite the fact that this is considered routine therapy for all patients that suffer from heart failure.

Dr. Christian Machado, who is the senior author of a paper appearing in the September 14 issue of the Archives of Internal Medicine, said, “We do know of the benefits of defibrillators when used as primary prevention. We just do not know how much women benefit from this therapy.”

Yet according to an accompanying editorial, approximately 30 percent of people that are getting implantable cardioverter-defibrillators, which are also called ICDs, are female. Machado, who is also the director of electrophysiology at Providence Hospital Heart Institute, in Southfield, Michigan, stated that there are even guidelines which support the practice.

ICDs are intended to prevent sudden cardiac death in patients that suffer from heart failure, who have a higher risk for this kind of event, and while the clinical trials do support this practice, the trials tend to be biased towards males. Research of medical literature databases turned up only five relevant randomized clinical trials between the years of 1950 and 2008. The trials involved a total of 934 females and 3,810 males, which is a clear indication that females are underrepresented in this type of study, even though females make up approximately half of the 5.3 million Americans who suffer from heart failure. None of these studies on their own showed any survival rate advantage for females having an implanted defibrillator, nor did the combined data show any benefit for females. However, there was a reduction in death rates for males in each of the trials, as well as when the results were put together.

Machado said, “We need to find a way to study more women in order to be able to identify what subgroups truly benefit from this therapy.” However, this could be very difficult. Given that the current guidelines recommend the use of the ICDs, it would be unethical to propose a trial that randomized some women to go without an ICD, explained Machado. He speculated that the reasons for females deriving different or less benefit from the ICDs could range from may different anatomy to hormonal factors to how female’s bodies use calcium.

Source: HealthNews