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Why sex differences in cardiovascular disease matter

Doctor using a stethoscope on a patientShare on Pinterest
A special issue of the journal Circulation looks at sex differences in heart disease. Maskot/Getty Images
  • The annual Go Red for Women issue of Circulation explores some of the unique challenges that females with heart disease face.
  • One of the studies published in the special issue reveals that females are less likely to survive after a cardiac arrest in the community.
  • Research Goes Red, a new American Heart Association (AHA) campaign, aims to encourage more female patients to take part in clinical trials.

Sex and gender exist on spectrums. For the purposes of this article, we use “male” and “female” to refer to a person’s sex assigned at birth.

Cardiovascular disease (CVD) is the leading cause of death among females in the United States, according to the Centers for Disease Control and Prevention (CDC).

While the incidence of CVD in females is usually lower than in males, research also suggests that females tend to have a higher mortality rate and worse prognosis following an acute cardiovascular event.

Every February, the AHA journal Circulation publishes a special issue that aims to redress some of these sex disparities. This year will be its fifth Go Red for Women issue.

“By publishing some of the best science on cardiovascular disease in women, our hope is that this issue of Circulationwill catalyze the conduct of transformative and disruptive research in this area,” said the journal’s Editor-in-Chief Dr. Joseph A. Hill.

Dr. Hill is chief of cardiology at UT Southwestern Medical Center and director of the Harry S. Moss Heart Center, both in Dallas, TX.

A study in this year’s special issue highlights the challenges for doctors trying to remedy the poorer cardiovascular outcomes among females compared with males.

The researchers found that among individuals who were resuscitated following a cardiac arrest in the community, 22.5% of females, compared with 36.3% of males, survived until discharge from the hospital.

This disparity was greatest among patients who were judged to have a better prognosis after admission to the hospital.

On a more positive note, the special issue also features research that suggests the gap may be narrowing in some areas.

Between 2008 and 2017, one study tracked 770,408 females and 700,477 males in the U.S. in the 12 months after they had a myocardial infarction (MI).

The researchers found that rates of recurrent MI, coronary heart disease events, hospitalization for heart failure, and all-cause mortality declined considerably in this study population.

There were larger relative reductions in these events for females than for males.

Another study discovered that an anticoagulant drug called edoxaban had a clear safety advantage for females with atrial fibrillation, which involves an irregular, often abnormally fast heart rate.

Compared with warfarin, which is the standard anticoagulant treatment, high doses of edoxaban were associated with a lower risk of stroke and bleeding in females than in males.

There was also good news from researchers studying outcomes for females following surgery for atrial fibrillation.

Previous, less rigorous studies had suggested that females were more likely than males to experience complications from a surgery known as catheter ablation.

The new study randomized 2,204 patients with atrial fibrillation, 37% of whom were females, to receive either catheter ablation or drug therapy to control their heart rhythm.

The researchers found no clinically significant sex difference in the risks of surgery. In addition, both males and females were less likely to experience a recurrence of atrial fibrillation if they had the surgery, compared with drug therapy.

A study published in last year’s special issue revealed that between 2010 and 2017, out of 862,652 adults who took part in cardiovascular trials, only 38.2% were females.

An article in the February 2021 issue of the AHA journal Stroke focuses on problems with recruiting sufficient numbers of females to partake in clinical trials. The authors write:

“The underrepresentation of [females] in clinical trials is a commonly recognized and seemingly intractable problem in many different areas of clinical medicine. Discrepancies in the enrollment of [females] in clinical trials raises concerns about the generalizability of trial evidence, as well as the potential for reduced access and utilization of new therapies in [females].”

Among the possible reasons for lower participation in trials, the authors cite female patients’ attitudes and belief, “resulting in less interest and more refusals in [females].”

To help redress the imbalance, the AHA have launched a public awareness campaign called Research Goes Red in collaboration with Verily Life Sciences. The campaign aims to empower more females to take part in cardiovascular clinical trials.

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