Blood clots: The most common misconception is that they are not urgent (2024)

Oct 17 2022

6 minute read

It is estimated that 100,000 Canadians are affected by venous thromboembolism (VTE) — a type of blood clot that starts in the leg or pelvis and eventually travels to the lungs. The number of deaths caused by VTE is significant: 10,000 a year, which is more than deaths caused by motor vehicle accidents, breast cancer and HIV combined.

Blood clots can happen to anyone, and they may be triggered most often by a cancer diagnosis — blood clots are the second leading cause of death among cancer patients after tumour progression. But there are other risk factors as well, including age, surgery, hospitalization, contraceptive use and in some cases, severe COVID-19 infection. Signs of a blood clot can vary, but most often, symptoms include chest pain, shortness of breath, light-headedness and leg tenderness and swelling.

In a recent survey by Thrombosis Canada, 86 per cent of respondents revealed that they are aware that blood clots can be fatal, but less than one third appear to be concerned about them. This laid back attitude may prevent people from getting the help they need at an earlier stage of the disease, when complications and long-term symptoms could be avoided.

Dr. Marc Carrier, president of Thrombosis Canada and hematologist at The Ottawa Hospital sat down with Healthing to talk about blood clots, share his advice about how to avoid long-term complications, and his thoughts on whether there is a cure on the horizon.

This interview has been edited for length and clarity.

What makes blood clots so dangerous?

One in four people will die from a blood clot. Deep vein thrombosis usually affects lower limbs, but it can eventually travel to the lungs and cause pulmonary embolism. Once we have a diagnosis, urgent treatment is needed to avoid further travelling of clots to the lungs, which, over time, can be fatal.

What are the common misconceptions or assumptions about blood clots?

People sometimes assume that it’s not urgent or that they don’t need to seek medical attention. There is a perception that if it’s not in their head or in their heart, that they’ll be fine, but it should be understood that blood clots are a medical emergency.

What are the consequences of delaying treatment?

The bigger the clot burden (the size of the clot), the more likely a patient is to have chronic symptoms and potential complications. For example, pulmonary embolism is usually described as pain in the chest that is worse with deep breathing, a sudden new shortness of breath that doesn’t go away with rest, and some people may also feel light-headed. If we find the clot early, the likelihood that all the symptoms will get better over time is very high. But if a patient waits until they have a much bigger clot burden on the lungs, they may have additional complications or long-term symptoms, it could impact their exercise capacity and they may have lingering symptoms that affect their overall quality of life.

It’s also worth mentioning that one-third of patients with a significant clot burden have residual symptoms three years after their initial diagnosis. If we can get people to be aware of the symptoms and seek medical attention sooner, we can get an early diagnosis, start them on blood thinners to resolve the clot and prevent the clot from forming and travelling, which can make the condition worse over time.

Who is most at risk?

As we get older, the likelihood of having a blood clot increases. There is not a whole lot of gender difference other than often, females may use birth control pills, or they may be on hormone replacement therapy, both of which may be associated with higher risk of blood clots. Sometimes, blood clots run in families, but generally, people should be aware of the major risk factors a cancer diagnosis, surgery, hospitalization as well as COVID-19 infection.

Did COVID help to generate more public awareness about the signs and symptoms of thrombosis?

It created a lot of noise, and it became a hot topic. Thrombosis Canada hosted many webinars for health-care professionals, and for people living with thrombosis — we also brought in experts who could accurately answer questions from the community. It certainly led to more public awareness, but that said, a recent survey about at-risk populations highlights how much more work we still have to do.

After tumour progression, thrombosis is the second leading cause of death in cancer patients and yet many still don’t know the symptoms. This is very problematic because cancer patients will have scans to determine the staging of the disease and we’ll often see the blood clots on the scans. After a discussion with the patient, we’ll find out that they’ve been having symptoms, such as shortness of breath, which they attributed to chemotherapy and cancer. There is still a lot more work to do to raise awareness in high-risk populations — if they are not aware of the underlying risks, the general population is even less likely to be aware.

How do we change that?

We need a multi-factored approach. Accreditation Canada — the accreditation body in health care — is now asking hospitals to have an official thrombosis policy, to document how physicians are putting patients on small-dose blood thinners during hospitalization for medical illness or surgery. It forces health-care providers to address thrombosis risks and make decisions.

We also need awareness and education for health-care providers, including pharmacists, and we need to engage advocacy groups. In the general population, thrombosis is also underrecognized and people tend to wait for a while before seeking medical attention. Overall, the general prevalence of the disease is not very common, but there is a certain time in life where you’re more likely to have blood clots. Creating awareness is important because it can lead to a faster diagnosis and there are treatments that help people avoid complications.

What are the common complaints you hear from patients?

Some patients have had a few encounters with different health-care providers who did not attribute their symptoms to a blood clot. Most people are surprised about how well-tolerated and easy treatment is, but it does take time for patients to feel better. Some have long-term, chronic symptoms, which could have been avoided had they not waited so long to seek medical attention.

What does the future look like for people with thrombosis?

Not that long ago, someone with new thrombosis had to do self-injections, they would require hospitalization for the first few days, and blood work every few days for the first two weeks. Now, the majority of thrombosis patients can be treated in an outpatient setting with tablets. In the last ten years, that’s a huge shift — transitioning from mostly hospital-based infusion therapy to outpatient-based tablet therapy — and as research is ongoing, from a treatment point of view, we’re aiming to know exactly which tablet at which dose to treat patients long-term so that clots don’t recur.

From a prevention point of view, we have clinical trials looking at if small-dose blood thinners are safe and effective for cancer patients, for those who may need a catheter and for people who require surgery. Hopefully, over time, we can prevent clots from happening. And for those who have it, we can tailor it into regulation so that there is no morbidity or mortality associated with blood clots.

Is there a cure on the horizon?

Canada is the leader in thrombosis research and there are two major research hubs at the University of Ottawa and at McMaster University. This is where most of the clinical trials are done, and that data is used around the world. A lot of the current research focuses on comparing different blood thinners, but it’s also looking at whether we can add an anti-cholesterol medication which may lead to less blood clots.

There are new blood thinners on the horizon as well, such as Factor XI inhibitors, which seem to be associated with an even less risk of bleeding, which from a safety perspective, is even better than the existing blood thinners we have access to.

How do we reduce the risk of thrombosis?

Be mindful of the symptoms and understand the risks and benefits of every decision. In some cases, putting a patient on small-dose blood thinners can be beneficial. I would advise people to seek help and speak with their health-care provider. There are great resources available throughThrombosis Canada. There is also CanVECTOR, the research network in Canada for thrombosis. They have a patient platform for people who want to be engaged and know more about the disease.

Maja Begovic is a Toronto-based writer.

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