For long-term survival after heart surgery: Sex matters

September 3, 2019

Last year, research established heart failure-associated deaths and hospitalizations are higher in women than in men. Today, new research from the University of Ottawa Heart Institute (UOHI) suggests women are also faring worse than men when it comes to their chances of long-term survival after major heart surgery.

Dr. Louise Sun is the director of Team Soleil at UOHI, a research program based on heart failure and long-term outcomes after cardiovascular interventions.

“There exists a significant association between female sex and long-term mortality after a patient undergoes a heart procedure,” said Dr. Louise Sun, a staff anesthesiologist in the Division of Cardiac Anesthesiology and clinician scientist at the UOHI. “More specifically, our study found women experience higher rates of death than men after having a bypass procedure, and combined bypass/mitral valve surgery.”

Dr. Louise Sun is the principal investigator behind Sex Differences in Long-Term Survival After Major Cardiac Surgery: A Population-Based Cohort Study, recently published in the Journal of the American Heart Association. 

Using population-based data from the Institute for Clinical Evaluative Sciences, and CorHealth Ontario, Dr. Sun and her team observed a sample of more than 72,000 Ontario residents over 40-years-old, who underwent a bypass, valve, or combined bypass and valve procedure in Ontario, Canada, between 2008 to 2016.

Overall, these real-world data revealed three (3) principal findings:

  1. The long-term age-standardized mortality rate was lowest in patients who had an isolated bypass procedure. It was highest in those who had bypass combined with reconstruction of multiple valves.
  2. Women who required any procedure involving coronary revascularization, especially those who had bypass or bypass combined with a mitral valve procedure, had higher age-standardized mortality rate than men.
  3. For those who had an isolated mitral valve procedure: Men were more likely to outlive women after mitral valve repair. Conversely, women were more likely to outlive men after mitral valve replacement.

[...] our study found women experience higher rates of death than men after having a bypass procedure, and combined bypass/mitral valve surgery.

- Dr. Louise Sun, staff anesthesiologist, UOHI

The analysis by Dr. Sun's team suggests that more attention should be paid to women with a history of heart attacks and diabetes, and men with a history of chronic obstructive pulmonary disease and depression, as based on the study findings, these patients have a higher risk of death after cardiac surgery.

“Further efforts to educate both physicians and patients in the early recognition of acute presentation of cardiac disease is also needed.”

According to Sun, this is especially true for the diagnosis and timely referral of women with coronary artery disease. Sun notes of those included in the study who had an isolated bypass surgery, only 20% are female.


Dr. Sun was featured in CBC's All in a Day with Alan Neal.

Listen to the interview »

“We know women present much differently than men for coronary artery disease,” said Sun. “When compared to men, women who present for a bypass surgery are older, have a smaller body surface area, are more likely to need an urgent or emergent operation, and have a greater burden of comorbid conditions such as diabetes, hypertension, heart failure, cerebrovascular disease and anemia.”

True, it is well-documented women with cardiac disease often experience a delay in diagnosis and treatment when compared to men, a reality Dr. Sun says leads to more advanced disease at the time of surgery and puts women at increased risk of death after undergoing a major cardiac operation.

Dr. Sun says future research to evaluate the effectiveness of the current risk prediction models used to assess patients undergoing cardiac surgery is a necessary next step to improve patient care.

“Most patients presenting for surgery today are men, and the risk prediction models are primarily derived from male data,” said Sun. “In this era of personalized medicine, we should be able to calculate risk in men and women separately.”