Feb. 7, 2011 -- An implantable device that packs a one-two punch against heart failure seems to be more effective in women than men, according to a new study.
Once reserved only for the sickest heart failure patients, cardiac resynchronization therapy with a defibrillator consists of a device with two functions.
The device provides cardiac resynchronization therapy by generating small electrical impulses that coordinate the action of the right and left heart ventricles so that they work together more effectively. The defibrillator function senses dangerous heart rhythm abnormalities and provides an electrical shock to restore the heart back to a normal rhythm.
Women in the study who received this therapy had a 70% reduction in heart failure events and a 72% reduced risk of dying from any cause. By contrast, men showed a 35% reduction of heart failure events, the study shows.
The study is published in the Journal of the American College of Cardiology.
“We did find unexpectedly that women did spectacularly better than men,” says study researcher Arthur J. Moss, MD, professor of medicine at the University of Rochester Medical Center in New York.
Heart failure occurs when the heartdoes not pump blood efficiently enough to meet the body's needs. More women with heart failure in the study had a condition called "dyssynchrony." In this condition, both ventricles do not contract simultaneously. The result is an abnormal heart rhythm that is treated with the study device.
More women have dyssynchrony than men, and women also have smaller hearts than men. These factors may explain why women did so much better with the cardiac resynchronization therapy with defibrillator than men, Moss says. “Resynchronization therapy does better in patients with smaller hearts.”
Zayd Eldadah, MD, director of Cardiac Arrhythmia Research and Electrophysiology Laboratories at Washington Hospital Center in Washington, D.C., explains the therapy to patients this way: “Think of the heart as a water balloon, and the goal is to expel all its contents into the body,” he says. “The best way to accomplish this is to put one hand on each side and squeeze at the same time.”
This is exactly how cardiac resynchronization therapy with defibrillator works. “It is a very potent way to improve the way the heart contracts,” Eldadah says.
“Resynchronizing the heart improves survival, and this study show us that women may do better than their male counterparts,” he says. “This is not an iron clad open-and-shut case.”
Studying the Gender Gap
To flesh out any gender differences, “there needs to be a study of men and women where both sexes have the same degrees of failure and other parameters and the only difference is their gender,” Eldadah says.
This study, as a whole, shows that this therapy “is a very effective and lifesaving even in people who don’t look so bad, and we should be using it in people who aren’t so sick,” he says.
“That is important because we are putting a device in, and this is invasive, so you usually try to reserve it for those patients who are the sickest,” says George Sopko, MD, a senior cardiologistat National Heart, Lung, and Blood Institute in Bethesda, Md.
Exactly when to intervene in people with early heart failure is not yet known, he says. “It should be cost-effective because we can prevent very expensive hospitalizations and certainly save lives.”
Ranjit Suri, MD, the director of the Electrophysiology Service and Cardiac Arrhythmia Center at Lenox Hill Hospital in New York, says that “we have known that people with advanced heart failure benefit, but what we have not known is that even people with early deterioration will benefit and that the magnitude of the benefit in women is greater than in men.”