Runners and blood clots

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I’ve mentioned my experience with venous thromboembolism (VTE) - that is, blood clots - and in response, I’ve received countless questions about the risks specific to runners, the symptoms to watch for, and the recovery process.

Tuesday, October 13, was World Thrombosis Day, and in honour of everyone who has asked questions, I put together a Q&A with Dr. Gary E. Raskob, Dean of the College of Public Health and Regents Professor of Epidemiology and Medicine at the University of Oklahoma Health Sciences Center. Raskob is also Chair of the World Thrombosis Day Steering Committee.

Q: What is thrombosis?

The formation of a blood clot in the artery (arterial thrombosis) or vein (venous thrombosis). Worldwide, one in four people die from causes related to thrombosis. It is a common underlying cause of the world’s three leading cardiovascular killers:

  • Heart attack
  • Stroke (ischemic)
  • Venous thromboembolism (VTE)

VTE refers collectively to deep vein thrombosis (DVT) and pulmonary embolism (PE). Deep vein thrombosis refers to a blood clot that forms in a deep vein, usually in the leg. Pulmonary embolism refers to a blood clot that breaks loose and travels to the lungs, a condition that can often be fatal.

Q: Why was World Thrombosis Day started?

Public awareness of VTE is significantly lower than conditions associated with less death and disability.

  • Nearly three in four adults do not know what a DVT feels or looks like and 80 percent do not know what a PE feels or looks like.
  • More than half of adults don’t know that blood clots can be prevented.
  • There is also low awareness of major risk factors for blood clots (hospitalisation, surgery, cancer).

World Thrombosis Day exists to increase public awareness and understanding of thrombosis, including risk factors and signs/symptoms, and to empower patients to proactively reduce their risk. There are 250 partners in 65 countries with 500+ educational events planned.

Q: What are the risk factors?

Known risk factors include:

  • Hospital admission
  • Surgery
  • Age (60+)
  • Personal or family history of blood clots
  • Reduced mobility
  • Cancer/chemotherapy
  • Oestrogen-based medication (like oral contraceptives or hormone replacement therapy)
  • Pregnancy or recent birth
  • Obesity
  • Smoking

VTE is a risk for adults over 60, especially those who are going into surgery with general anaesthesia (for 30+ minutes) for things like hip or knee replacement, abdominal thoracic surgery, or bowel surgery.

Patients who enter the hospital for two to five days for an infectious condition should receive some sort of anti-clotting medication.

If an older parent has a chronic condition (like heart disease or lung issues) and is admitted to the hospital, it’s critical that they ask for a VTE risk assessment and get appropriate prevention.

Coach Jenny says: I had a blood clot develop after a long flight that involved sitting for longer than 12 hours. I was dehydrated when boarding, had a glass of wine, and fell asleep with my legs crossed. I have a friend that developed a clot after completing an Ironman and taking a 10-hour flight. Post-race trauma and swelling can create risks for developing blood clots when flying or driving for long periods of time, especially if you have a genetic disposition.

Q: How can we better protect ourselves from VTE?

Sixty percent of all VTEs occur during or within 90 days of hospitalisation, making it a leading preventable cause of hospital death (ahead of infection and pneumonia). Hospitalisation is an opportune access point for prevention.

Be an active partner in your health. Ask your medical professional about your blood-clot risk and insist on a VTE risk assessment. The doctor evaluates the presence or absence of the different risk factors for VTE, your medical history and whether the reason you’re hospitalised poses a high risk of VTE. 

Coach Jenny says: After getting my second clot, I had a genetic test done and found out I have two genetic blood clotting disorders, Factor V and Prothrombin II. It changed my life in knowing my risk is much higher because of these genes. I use blood thinners and compression socks on every flight and long drives, and I make sure to move every 30 minutes. I also used thinners after my recent wrist surgery while immobile and in recovery.

Q: What are the signs and symptoms of deep vein thrombosis and pulmonary embolism?

The symptoms of DVT include swelling in the foot, ankle or leg; pain or tenderness, often starting in the calf; redness or noticeable discolouration; and warmth on the affected area.

The symptoms of PE include unexplained shortness of breath or rapid breathing; chest pain, especially breathing in; rapid heart rate; and light headedness, faintness, or palpitations.

If you have any of these symptoms, go to the doctor or the emergency room immediately. Ask for appropriate imaging tests (ultrasound of vein for DVT, CT scan for PE).

Q: When is it safe to exercise after a blood clot?

Any individual patient will need to discuss that with their physician. The general practice is to get people up and moving in the ambulatory setting as soon as that can be tolerated. Exercise within reason is okay but again, every person’s individual situation is different, so talk to your doctor.

There won't be major restrictions to standard exercise such as jogging. If you are training for a high/competitive level event or a contact sport, the situation might be different, especially if you’re on blood thinning medications, which can cause a risk of bleeding.

Q: When a clot occurs, how is it treated, and how does it resolve itself in the body?

For most patients, a VTE is treated using anticlotting medications known as anticoagulants, which inhibit further clotting and the growth of the clot. There are enzymes in our blood that work to dissolve clots, and by giving anticoagulants, the growth of the clot is inhibited and the balance tipped in favor of the enzymes being able to break down the clot. In DVT, usually a new layer of blood vessel cells or lining grows over the clot and flow in the vein is restored. It is not known for sure exactly how long it takes so the clot won’t break and travel.

Coach Jenny says: Awareness is key to prevention. The more personal stories I hear, the more I learn about the risks for active people like you and me. Find out how obstacle racer Marie-Victoire Cumming developed a clot, what her symptoms were, and the medication that likely caused it here. Elite runner Kim Smith has also suffered from clots.

Please share this column with your family and friends. I used to think that my running life made me immune to VTE, but I was wrong.  Let’s get the word out together.