Women are less likely to be diagnosed with heart disease than men, and less likely to get best treatment. Researchers are struggling with old stereotypes to right the balance.
When asked to name the No 1 killer of women, many of us might take a guess and go with cancer. The received wisdom is that we need to be on the alert for breast changes or perhaps gut issues that might be signs of bowel cancer.
In fact, what kills more women than anything – at the rate of eight a day in New Zealand – is heart disease. Much the same as for men.
The way women experience heart disease, though, is not the same as men. And this perception – by people of all genders – that heart disease is a man’s illness is likely to be hurting women.
Susan McIntyre knows how this feels. At 42, fit and healthy, her heart was the last thing on her mind. “I was busy,” she remembers. “I had two young kids. I should have gone to the doctor earlier, but I just thought I had the flu.”
Her doctor thought so, too. Until she didn’t get better. After some follow-up blood tests, the Christchurch teacher received a disturbing phone call. ”My doctor called me on a public holiday and said: ‘You need to go to the hospital. Don’t have a shower, don’t pack a bag, just go to the hospital. Don’t muck around and don’t walk up any stairs. Just go. They’ll be expecting you.’”
For 69% of women who died from heart disease, their first symptom was death.
McIntyre had endocarditis, an infection in her heart. “That was bad enough and scary enough. And then, when I was in hospital having that treated, they scanned my heart and went, ‘Oh dear, this is not looking good.’ Then they found I actually had hypertrophic cardiomyopathy.”
Hypertrophic cardiomyopathy is a genetically linked condition, often with no symptoms, which can cause sudden heart failure. McIntyre’s was probably caused by an inflamed wisdom tooth, which sparked the infection that travelled to her heart, and the thickened wall of the heart muscle created a tiny nick in her mitral valve: enough for the infection to take hold. She considers herself lucky to have a GP who recognised there might be a heart link to her symptoms.
Otherwise, she says, “I might have just gone out for a run one day and never made it back.”
McIntyre had been told in her 20s that she had a heart murmur, but was also told it was unlikely to cause her any problems. Looking back, she says, she should have had this checked when she turned 40, and the underlying issue could have been discovered.
As it was, her troubles didn’t end there. Before the antibiotic treatment for the heart infection could do its work, a piece of the infection “vegetation” broke away and travelled to her brain. She had a stroke. And then another.
“At that point, I couldn’t talk, I couldn’t move, I couldn’t see out of my right eye. I remember the cardiologist holding up a pen and saying, ‘What’s this?’ And I didn’t know what that was.”
During her week in hospital, she recalls, “I would wake up occasionally and see my husband beside the bed, crying, and I’d think, ‘Oh god, it must be quite bad.’”
Against the odds, she made a full recovery. But it was a rough road, and it was a couple of years before she could teach again. “It took a really long time to trust my body again, to be able to do anything. But it’s amazing what you can get through if you know you don’t have a choice.”
McIntyre had a good experience – as much as a near-death experience can be – in the sense her issues were identified and treated in time to save her. In women, hypertrophic cardiomyopathy (HCM) is typically diagnosed six to nine years later than in men, if at all. And women are under-represented in research on the condition.
A study published in the Journal of the American College of Cardiology last month found that once the test for HCM was adjusted for age, sex and size, many more women were diagnosed with the condition. For the past 50 years, the test involved measuring the thickness of the wall of the left ventricle, the heart’s main pumping chamber. If it measured over 15mm, the patient was considered to have HCM. Applying the new thresholds to 43,000 participants in the UK Biobank, there was a more even split between men and women.
System Failure
Ischaemic heart disease, also called coronary artery disease, is the most common heart problem and the No 1 killer of women globally. Women are underdiagnosed, undertreated and under-represented in clinical trials that are meant to come up with treatment and management strategies.
That means treatment guidelines might not work so well for women.
Associate Professor Gerry Devlin, the Heart Foundation’s medical director, gives an example of how this plays out in reality.
“If you look at a woman who presents with a heart attack, they’re less likely to undergo further investigations. They’re less likely, once they do undergo further investigations, to have stenting done [where a tube is inserted into the artery to keep it clear] or bypass surgery done.”
Heart failure is another example, says Devlin. “We know that for women with heart failure, where the heart muscle is not working well, they’re less likely to receive optimal evidence-based medicine than men. So why is that?”
He says people expected to be treated the same at hospitals around New Zealand, “and we don’t fully understand why this isn’t happening”.
University of Auckland heart researcher Carol Bussey says that although the medical and research communities are now recognising that women “are not just slightly smaller men”, treatment for heart disease is still based on research that’s incomplete.
“If you’re a woman and you go in, you don’t necessarily have the symptoms that a man is going to have of a cardiovascular disease. The doctor might not recognise it. They might not believe you.”
She adds many women are told they’re anxious or stressed out when actually they have a physical complaint and the doctor is not applying the right diagnostic criteria.
“Then, if you get treated, you probably get a dose of drug and a type of drug based on data from men, which might not be appropriate.
“Some of the drugs that we give people for cardiac arrhythmias [irregular heartbeat] actually increase the risk of arrhythmia in women. So they’re just not appropriate for everybody.”
Knowledge Gap
What is known about the differences between women’s and men’s hearts?
“Not an awful lot,” says Bussey. “I actually got really angry, the more I read about this, and the more I realised what we didn’t know. It was quite a passionate grant application that ended up going in,” she adds with a smile, in describing what led to her current research project.
She also cites a large 2003 US study of women, which found that for 69% of those who’d died from heart disease, their first symptom was death.
“They had no recognised symptoms, no diagnosis. So nearly 70% of women just died before anyone realised, ‘Oh, she had cardiovascular disease.’ That’s really too late to be identifying that.”
We do know that alongside the universal heart disease risk factors such as high cholesterol, high blood pressure, diabetes, obesity and smoking, women also have some sex-specific risk factors that put them at higher risk of heart disease – things most women aren’t even aware of. They include things like premature menopause; gestational diabetes; preterm delivery; polycystic ovary syndrome and hypertensive disorders (pre-eclampsia) in pregnancy.
On top of that are under-recognised risks – psychosocial factors such as abuse and intimate partner violence, socio-economic deprivation and poor health literacy.
Nikki Earle, a senior research fellow in heart health at the university, says these factors often aren’t on doctors’ radars. “Currently, the cardiovascular risk assessment models that are done when you go to your GP don’t take any of these factors into account.”
Treatment Inequity
To compound the issue further, women often experience different heart symptoms to men. That’s the case for angina and stroke, and in heart attacks, women are less likely to present with crushing chest pain and more likely to show up with anxiety, shortness of breath, upset stomach, pain in the shoulder, back or arm, or unusual tiredness and weakness.
Men are more likely to experience blockages in their large arteries, whereas women are more likely to have non-obstructive disease and to have disease in their smaller blood vessels.
“And the treatments for that are not as well established as for the obstructive disease that affects men,” says Earle.
Her work is aimed at addressing some of this inequity. Her study focusing on women aims to better understand how heart attacks differ by sex, and to identify risk markers for subsequent events that are specific to women.
The risk assessment models when you go to your GP don’t take these under-recognised factors into account.
With a background in cardiac genetics, Earle says it’s been “really eye-opening and quite shocking” to learn how little research has been done on both sex differences and on women specifically when it comes to heart disease.
“I got into it by looking at the big national hospitalisation data sets in New Zealand. We published a study last year that looked at more than 60,000 people who had been admitted to hospital with their first heart attack.”
Women on average have their first heart attack seven years later than men. But after menopause, their risk is heightened because of the loss of the heart-protective effect of oestrogen.
But, notes Earle, when you compare the outcomes for men and women all the way up to age 75, women actually have far worse outcomes. And the situation is even more dire for Māori and Pasifika women.
“More women die or are readmitted to hospital for cardiovascular causes than men. And that’s particularly bad for younger women [aged under 55] compared with younger men. The rest of our research is trying to unpick why this is.”
Things have not moved fast in addressing this and other blanks in the research. Bussey is having to take a step back with her work to fill in the gaps in the data before she can get into the really deep investigations she wants to do on the interaction between the nervous system and the heart in women. “I found that in trying to design those studies, I didn’t have the basic information to even design the study,” she says. “And so I’ve had to request to take a step backwards and do the basic stuff again in females, while looking at their hormonal cycles, so that then I know how to design the study.
“But most funders don’t want to fund that because they want to progress forward to a new drug. They don’t want to step back and redo in females what we already know in males.”
International Drive
Bussey and Earle have benefited from a research fund that’s specifically aimed at reducing inequities in heart health, including those experienced by women. The Heart Foundation – as a member of the Global Cardiovascular Research Funders Forum founded in 2018 – is part of this project.
The forum is a collaboration between 11 major international funders of cardiovascular clinical research with the goal of speeding up progress in preventing, diagnosing and treating the world’s biggest killers. At the end of the five-year research challenge, Devlin hopes there will be more understanding of women’s heart health.
“We’re trying to improve care for women presenting with suspected and diagnosed cardiac problems,” he says.
“There’s a misconception that heart disease affects only men. I think it is something that we do urgently need to correct, not just in New Zealand, but around the world. We’ve actually got to do better here.”
Earle says her goal is simple: to improve outcomes for women, “especially young women who are often juggling career and family and who then have a heart attack out of the blue. At the moment, their outcomes are so much worse than men. And it’s not fair.”
As for Susan McIntyre, a decade on from her big health scare, she encourages other women to speak up and be proactive about their health.
“If I knew [back then] what I know now, I would have had a full health check at 40. And, of course, that’s a privilege to be able to consider … but if you can, that’s what I’d do.
“And don’t be scared to go to the doctor; don’t just put up with stuff. Because you just don’t know.”
The Gender Pain Gap
One of the reasons for women faring worse when they have heart issues is gender bias.
It’s well established from research that women’s pain is more likely to be minimised or dismissed by health professionals; that includes when the pain is from life-threatening causes.
A University of Maryland study in 2001 found while women experience and report more frequent and greater bouts of pain, they are less likely than men to get effective treatment. Authors Diane Hoffmann and Anita Tarzian concluded there were gender-based biases about women’s pain experiences.
The evidence for heart disease shows women are less likely than men to have positive treatment outcomes for chronic conditions such as angina and musculoskeletal pain. A 2018 British Medical Journal study found that in England and Wales, the poorer-quality care women received compared with men after a heart attack was to blame for 8243 preventable deaths from 2003-13.
With heart attacks, researcher Nikki Earle says women’s different biology and gender bias are at play.
“Bias is both in women not recognising they could be having a heart attack – so they delay in seeking care – and then delays when they get to hospital: delays in treatment and the lower use of guideline-recommended therapies.”
A Canadian study showed doctors were four times more likely to recommend a knee replacement for a man than a woman with the same knee injury. Women with endometriosis – and often in severe pain – take an average of nine years to receive a diagnosis.
Gender stereotypes inform unconscious bias in doctors, too. That includes the belief that women have more tolerance to pain because it’s built into menstruation and childbirth, and that women’s pain is more likely to be psychologically driven – “all in her head”.
A small study by University of Rhode Island researcher Karen Calderone found women were half as likely as men to receive painkillers after coronary bypass surgery because their complaints were not taken as seriously.
Some studies have also found that women in pain are more likely than men to be prescribed sedatives rather than pain medication.