Many people think of DVT and PE as a problem occurring in elderly people, but not in young and apparently healthy individuals. While it is certainly true that they occur more commonly in the elderly and in non-athletic overweight individuals, they can, nevertheless, happen in young, normal weight, and athletic people.
How Commonly do Blood Clots Occur in Athletes?
No studies have determined whether athletes are at increased, the same, or lower risk for developing DVT and PE than non-athletes of same age.
There are several mechanisms by which an athlete may theoretically be prothrombotic and at risk for development of thrombosis. Examples are:
- There may be a disparity between the two systems that balance the clotting process ; either (A) too much activity of the procoagulant system (coagulation proteins, platelets), or (B) too little activity of the fibrinolytic system;
- There is trauma to the blood vessel wall, as may occur after a bone fracture or in thoracic outlet obstruction (see discussion below);
- Venous blood return from the extremities to the heart is impaired, such as when sitting with bent legs in cramped positions for a prolonged period of time;
- Dehydration, use of erythropoietin (EPO), or excessive blood transfusions (blood doping) lead to an increase in hematocrit.
Unfortunately, there are few studies investigating the influence that physical training has on blood clot formation and fibrinolysis. Therefore, the exact net effect of training on this equilibrium is unknown. It is known, for example, that blood levels of coagulation factor VIII increase with exercise and that the elevation persists during recovery. Theoretically, this could lead to an increased risk of thrombosis in athletes. However, data also indicate that the fibrinolytic system is overactive in people who exercise. With this overactivity present, the athlete would be protected from having a blood clot. Yet, the net effect of these changes in the athlete is not known. A detailed scientific discussion of the coagulation issues relevant to exercise and training can be found in reference 1. However, the conclusions are sparse and vague, because of a lack of data and conflicting results from different studies.
Risk Factors for DVT and PE in the Athlete
- General risk factors: The athlete is at risk for DVT and PE for the same reasons as non-athletes. Risk factors, with particular focus on the athlete, are listed in Table 1. Risk factors for DVT and PE in the athlete. A few unique risk factors for DVTs that play a role mostly in the young and the athlete are the following:
- Thoracic Outlet Obstruction
In some individuals an extra (cervical) rib or excess muscle or tendon tissue compresses the subclavian vein (image 1 – red area reflects clot, i.e. DVT, in the subclavian vein). This compression typically gets worse when the arm is lifted up. This obstruction, often combined with repeated trauma to the vein (due to throwing activities or gymnastics maneuvers), may cause a DVT in this area, extending into the arm veins. This is termed “effort thrombosis” or “thoracic outlet obstruction/syndrome.” If the DVT resolves, such as after thrombolytic therapy, resection of the extra rib or the excess tissue may be indicated to increase space in the thoracic outlet.
- May-Thurner Syndrome (detailed discussion here): This is a common congenital anatomic variation that predisposes to DVT in the left leg, because the left common iliac vein is compressed by the overlying main right common iliac artery. This increases the risk of thrombosis at the site of this narrowing, with extension of DVT down into the left leg.
- Congenital Absence or Malformation of the Vena Cava
Congenital abnormalities of the anatomy of the inferior vena cava or pelvic veins can be a cause of DVT in young people. The abnormal anatomy probably leads to disturbed blood flow and an increased risk of thrombosis.
Misdiagnosis or delayed diagnosis
If an athlete develops symptoms of DVT or PE, the diagnosis may be delayed or missed because the athlete is typically young and healthy and DVT and PE are sometimes not considered sufficiently in the differential diagnosis of extremity or respiratory symptoms in the young and healthy. Symptoms may, therefore, be misinterpreted as “muscle tear”, “Charley horse”, “twisted ankle”, or “shin splints” in the case of leg DVT, or a “pulled muscle”, “costochondritis”, “bronchitis”, a “touch of pneumonia”, or “new onset of asthma” in the case of a PE. Of course, such misdiagnosis occurs in non-athletes as well. An assessment of an athlete’s risk factors for venous thromboembolism may be helpful to increase the level of suspicion: is the female athlete on contraceptives? Has there been recent long-distance travel? Does the athlete have a personal or family history of venous thromboembolism? Does he or she have a history of recent major trauma, surgery, hospitalization, or immobility?
Treatment of DVT and PE
Treatment decisions for people affected with venous thromboembolism must always be individualized. Such individual treatment regime is particularly true for young, apparently healthy individuals, such as athletes. In the case of unexplained DVT, testing for an inherited or acquired thrombophilia may be appropriate. When first diagnosed with the DVT, mechanical thrombectomy and fibrinolytic therapy can be considered to dissolve the clot. However, this therapy has not been systematically studied to determine whether it really decreases the risk for the postthrombotic syndrome. A clinical trial, the ATTRACT trial, is presently ongoing (details here). A major question for any patient with DVT or PE is how long anticoagulants should be given. This decision needs to take all risk factors that caused the DVT into consideration, as well as all the implication for the person to be on an anticoagulant. D-dimer testing (on and off warfarin) may be helpful as a supportive indicator of a higher or lower risk of recurrence. Involvement of a thrombosis specialist may be helpful.
Athlete-Specific Challenges and Questions
Often, an active individual – be it an athlete or one who remains physically fit through routine training and exercise – is suddenly thrown of his/her path by the clotting incident. A lot of questions are asked by the athlete/patient. Some of them have to do with loss of college scholarships or athletic career implications if long-term anticoagulant therapy is deemed to be the appropriate treatment. Here are a few questions with general responses that might be helpful for the athlete.
A. Can I continue my sport while on anticoagulants?
A solid medical assessment should be made whether the person who has had a DVT or PE can come off anticoagulants or should remain on them. Being on anticoagulants increases the risk of bleeding. Therefore, contact sports and sports with a risk for serious injury, such as football, hockey, basketball, soccer, gymnastics, alpine skiing, or boxing should not be pursued by a person on anticoagulants. However, athletes such as runners, bicyclists or triathletes may be able to continue their sport, but they should adapt their activities to avoid trauma that might put them at risk for bleeding (i.e from such things as bicycle crashes). Individual anticoagulant management treatment plans can also be designed, such as:
- Xarelto (rivaroxaban) is fully active within 3 hours of oral intake; in addition, due to its half-life of 10-12 hours, it is out of the system within 1 1/2 – 2 days after stopping it. This quick on-and-off makes it an attractive anticoagulant option in athletes who consider temporarily interrupting therapy for an athletic activity that puts them at high risk for bleeding. However, I would also take into consideration when counseling the athlete, that bleeding may theoretically occur after the sporting event due to trauma suffered during the event. Thus, restarting anticoagulant therapy may best be delayed for some time after the competition, if one chose this unusual management approach of on/off-anticoagulation with sporting events.
- A decrease in warfarin dose a few days prior to athletic events that might put the person at less risk for bleeding.
- Stopping anticoagulants during the season and accepting a higher risk for thrombosis during that time, but restarting anticoagulants during the off-season.
Finally, an athlete may decide to switch from a high risk bleeding competitive sport to one with a lower risk. Obviously, these are all very individual treatment decisions that should be thoroughly discussed between the patient’s personal physician, a thrombosis specialist, the patient, and the team physician (if the patient is participating in a team sport).
B. How soon after a DVT or PE can I go back to training?
Patients with a DVT may have significant extremity swelling and pain which may improve only slowly over weeks and months. Some residual symptoms may persist long-term. It appears that being highly active one month after a DVT is not detrimental; it may, actually be beneficial and lead to less symptoms of postthrombotic syndrome [ref 2]. This can be used as an argument to encourage individuals to return to physical activity relatively soon after a DVT. Also, wearing individually fitted compression stockings (grade 2; 30-40 mm Hg) decreases the long-term risk for postthrombotic syndrome. No official guidelines exist as to when and how quickly an athlete might return to exercising. Each patient will need an individualized exercise plan (an example is described in reference 3). It seems appropriate to refrain from any athletic activities for the first 10-14 after an acute DVT or PE until the clot is more attached to the blood vessel wall and the risk of having the clot break loose and cause a PE has decreased. To lessen deconditioning during this period of relative inactivity, the athlete may do some strength training – arm and trunk exercises in the case of a leg DVT, leg and trunk exercises in the case of an arm DVT. The athlete may then increase activity between week 2 and 4 and return to pre-clot activity levels by week 4.
C. Psychosocial Implications
Athletes need to appreciate that significant deconditioning can occur after a DVT or PE. Depression can also set in after such a life-changing event. This is not surprising, given that athletes often view themselves as healthy and, from a health point of view, invincible, and now suddenly realize that they are vulnerable, sick, and sometimes even disabled. Patient support structures, including the ability to connect with other athletes who have faced DVTs and PEs, may be helpful in this situation. Also, antidepressants are sometimes indicated in this situation.
How to minimize the risk for clots
Measures that the athlete, and non-athlete, should take to minimize the risk for DVT or PE are listed in Table 2. How to prevent DVT + PE. For the athlete, the most important ones are probably to (a) avoid dehydration, and (b) take breaks when traveling long distances.
- El-Sayed MS et al: Exercise and training effects on blood haemostasis in health and disease: an update. Sports Med2004;34(3):181-200.
- Shrier I, Kahn SR: Effect of physical activity after recent deep venous thrombosis: a cohort study. Medicine and Science in Sports and Exercise 2005;37: 630-634.
- Roberts WO, Christie DM: Return to training and competition after deep venous calf thrombosis. Medicine and Science in Sports and Exercise 1992;24:2-5.
Authors: This blog was written by Dr. Stephan Moll. Input was also provided by Dr. William Roberts and Dr. Edward Libby.
Disclosure: I have consulted for Janssen.
Last updated: March 16th, 2013