This Heart Therapy Benefits Women More

A treatment that helps regulate heartbeats works much better in women then men, though it isn’t offered to women nearly as much, says a study in JAMA Internal Medicine.

Based on a 2010 report from a national implantable defibrillator registry, there were approximately 100,000 cardiac resynchronization therapy defibrillator (CRT-D) installations that year in the United States, and about 28,000 were in women.

CRT-Ds make the two walls of the heart pump at nearly the same time, addressing a problem called left bundle branch block (LBBB).

According to current guidelines, the top recommendation for CRT-D is in patients with a LBBB and a QRS duration of 150 milliseconds or longer. QRS duration is the time for electrical activation of the heart, represented by the large wave on an ECG recording.

CRT-Ds led to a 60% reduction in heart failure or death in women, according to researchers at the Food and Drug Administration. It reduces women’s risk of death alone by 55%.

For men, it’s a different story, reducing the risk of heart failure or death by 26% and death alone by 15%.

In women with a QRS of 130 to 149 milliseconds, CRT-D reduced their risk of heart failure or death by 76%. Men saw no benefit.

“This is important because recent guidelines limit the class I indication [highest recommendation] for CRT-D to patients with LBBB and QRS of 150 milliseconds or longer. While guidelines do give a class IIa to patients with LBBB and a QRS of 120 to 149 milliseconds, the present findings are important to communicate because women are less likely to receive CRT-D than men are,” the study states.

It may simply come down to physiological differences, says David G. Strauss, MD, PhD, the study’s corresponding author.

“The fact that women normally have smaller heart ventricles and shorter QRS duration than men provides an anatomical and physiological explanation for the findings, but the higher rate of nonischemic heart failure in women compared with men may have also contributed,” says Strauss.