There are several inherent differences to the physical make up of a woman’s heart versus that of a man. For starters, a man’s heart is physically larger, weighing up to 60 grams more than a woman’s heart on average.  Functionally there are differences, too. Arteries which feed a women’s heart with rich, oxygenated blood typically have smaller openings than men, causing women to be more prone to blood clots and plaque blockages, and making certain types of heart surgeries riskier for women. A woman’s heart valves are typically floppier than those of men as well. As a result, women are more likely to suffer diastolic dysfunction, a stiffening of the heart muscles between beats which can ultimately lead to heart failure, a functional disorder which affects one in five people and accounts for 35% of total female cardiovascular mortality.

For women, these numbers can be quite unsettling to say the least. That’s why researchers at the University of Ottawa Heart Institute are hopeful new research will help women to better understand these statistics in the coming years. Though science has led to many important advances in the management of heart failure in the past decade, much is still to be learned, especially where ambulatory patients diagnosed with heart failure are concerned.

“Detailed sex-specific outcomes are scarce in hospitalized cohorts and are unavailable in ambulatory patients,” writes Dr. Louise Sun, a clinician investigator in the Division of Cardiac Anesthesiology at the University of Ottawa Heart Institute, and the principal investigator of a new study published in the Canadian Medical Association Journal, titled Sex Differences in Outcomes of Heart Failure in an Ambulatory, Population-Based Cohort from 2009-2013. “An in-depth understanding of these sex differences may help to increase awareness and lead to clinical trials to identify optimal monitoring and treatment strategies in both women and men.” The results of Dr. Sun et al’s study were published July 16.

Dr. Louise Sun of the University of Ottawa Heart Institute
Dr. Louise Sun is a staff anesthesiologist at the UOHI and an Assistant Professor at the Department of Anesthesiology and School of Epidemiology, Public Health and Preventative Medicine, at the University of Ottawa.

The research team, which consists mostly of female investigators, sought to examine more closely the sex differences in heart failure incidence, mortality rates, hospitalizations and comorbidities in all Ontario residents who were diagnosed with heart failure in an ambulatory setting over five years between April 1, 2009 and March 31, 2014. Included in the study were men and women over 40 years of age, who were newly diagnosed with heart failure in an ambulatory setting – meaning not an inpatient receiving treatment for their disease at the hospital. It found of a total of 90,707 patients with incident ambulatory heart failure, just under half (47%) were women. These women were also noted to be older, frailer and have different comorbidities such as hypertension, chronic pulmonary disease, hypothyroidism, metastatic malignancy, dementia and depression when compared to men, who were more likely to have atrial fibrillation, myocardial infarction, valvular disease, peripheral arterial disease, diabetes, renal and liver disease.

Dr. Lisa Mielniczuk of the University of Ottawa Heart Institute
Dr. Lisa Mielniczuk, the study’s co-principal investigaor, is an Associate Professor of Medicine at the University of Ottawa and a Cardiologist and Clinician Investigator at the UOHI.

“This study highlights the achievements of the Women’s Heart Health Team at the University of Ottawa Heart Institute and underscores the importance of further work investigating the gender discrepancies in care delivery, access and outcomes. Such studies are ongoing by our research team,” said Dr. Lisa Mielniczuk, the study’s co-principal investigator.

The study also found heart failure-associated deaths and hospitalizations remain higher in women than in men. Specifically, the age-standardized female mortality rate was 89 deaths per 1,000 new heart failure cases in 2009 and 85 deaths per 1,000 in 2013, versus male mortality rates of 88 per 1,000 new heart failure cases in 2009 and 83 per 1,000 in 2013. Conversely, the rates of incident heart failure hospitalizations decreased in men and increased in women.

“This work reveals that heart failure-associated morbidity and mortality remain high especially in women in this current era,” writes Dr. Sun. “These findings introduce the need for further research to focus on sex differences in health-seeking behaviour, medical therapy and response to therapy to improve outcomes in women.”

Dr. Sun wishes to acknowledge and honour the memory of her mentor and friend, Dr. Jack Tu, who passed away during the preparation of this manuscript for publication. Dr. Sun and her team vow to keep Dr. Tu’s legacy alive in their hearts and in future pursuits of better population health, policy and services through population-based cardiovascular research programs.

See more on The Beat.