-Tara Hun-Dorris-

After an impressive 4-1 start, ‘Canes veteran goaltender Frederik Andersen was diagnosed with deep vein thrombosis (DVT) and pulmonary embolism (PE) and placed on injured reserve. The words mostly used to explain to the public have been “blood clotting issues.” We know that Andersen has been on anticoagulant medications. But what does all of this mean, and how common are these types of injuries in hockey?

DVT is one manifestation – actually the most common along with PE – of venous thromboembolism (VTE). DVT/PE is not an uncommon condition, especially among older adults. It also frequently occurs in professional athletes, who increase their risk by being prone to injury, requiring surgeries and immobilization periods following injuries, and also routine sitting for long periods in dehydrating conditions, such as air travel.

DVT occurs when a blood clot or “thrombus” forms in a deep vein, typically the leg but these can also occur in the upper body. This blood clot may cause pain or swelling or there may be no noticeable symptoms. PE occurs when the blood clot breaks off and travels to the lung, where it can block blood flow. Symptoms may include shortness of breath, chest pain, fainting, and other symptoms possibly associated with the underlying thrombus: leg pain or swelling, cough that may even be bloody, irregular heartrate, dizziness, fever, or clammy or discolored skin. And this blockage is potentially fatal. Of the 900,000 Americans diagnosed with PE, it is estimated that 10% to 30% die within 1 month, the higher end being those for whom the condition is not diagnosed.

This isn’t said to be dramatic, but PE is a serious condition, and particularly if not diagnosed is likely to be fatal. Fortunately, Andersen was diagnosed promptly and receives what is likely the best medical care in the world, and hence was able to return to practice in only a matter of months.

The most common treatment approach for stable patients with PE are anticoagulation treatments, commonly referred to as “blood thinners.” Common medical practice is to treat patients with PE with anticoagulation therapy for a minimum of three months. None of us our privy to Andersen’s private health details (and nor should we be), but one of the main risks of anticoagulation treatments is that they increase the risk of bleeding. Therefore, it is pretty obvious that collision with an 80 mph puck while on blood thinners (or after treatment when they’re still in the system) would be an astoundingly fatalistic approach to living.

The risk of blood clots in professional athletes, particularly hockey players, is nothing new. SI reported on the issue in 2014 (https://www.si.com/edge/2014/12/16/blood-clots-pose-deadly-threat-to-athletes). In 2017, the Orthopaedeic Journal of Sports Medicine published a retrospective review (that is a look backwards at the data from the past rather than designing a prospective study) of the occurrence of VTE with professional American sports leagues (doi: 10.2310/8000.2011.110408).

Dr. Meghan Bishop and colleagues searched all media and team injury reports of “DVT/PE” available from NHL, MLB, NBA, and NFL players in the public domain. They found 55 VTE events from 1999 through 2016, with the NHL leading with 40% – 22 of the events. That puck moves really fast! Players who experienced VTE lost an average of 6.7 months of play, but the majority were able to return to the sport. Predictors for faster return to play were upper extremity DVT versus lower extremity DVT. One interest factoid the researchers noted in the discussion is that hockey players practice on a rink with temperatures below freezing and numerous other studies have found that DVT has a seasonal pathology and occurs more often in winter months. How or if that seasonality correlates with practicing on a frozen rink in otherwise sunny Carolina has not been determined.

All this to say that what is happening with Andersen is far from unheard of in professional sports. While we’d love to see him back on the ice at puck-drop ahead of and during the playoffs, previous thrombotic events are a major risk factor for recurrent VTE. And previous PE is predictive of likelihood of future PE. So first and foremost we’d like to see Andersen and Canes management do everything they can to ensure his health.