Canada Soccer announced on Friday that Alphonso Davies will miss the country's upcoming World Cup qualifiers, hours after his return to Bayern Munich from a bout with COVID-19 was put on hold when testing showed signs of inflammation in his heart muscle, a condition called myocarditis.
Julian Nagelsmann, Bayern's manager, said ultrasound testing indicated Davies' myocarditis wasn't "so dramatic" but would still require time to properly heal.
— Canada Soccer (@CanadaSoccerEN) January 14, 2022
Myocarditis enlarges and weakens the heart, can create scar tissue, and forces the heart to work harder to circulate blood and oxygen throughout the body. This type of inflammation can have wide-ranging effects -- including fatigue, shortness of breath, heart palpitations and chest pain -- though the vast majority of myocarditis cases overall are both mild and temporary.
Severe cases of myocarditis, though, can be permanently damaging and lead to heart failure, heart attacks, arrhythmias or even sudden cardiac death. In athletes, myocarditis has been implicated in a significant portion of sudden cardiac death cases, up to 22 per cent, though a fatal outcome is still exceedingly unlikely overall.
Bayern said last week that Davies had tested positive for COVID-19 and was feeling well while isolating at home. It is not known at this time if he has been experiencing symptoms related to the inflammation.
Often, the exact cause of a case of myocarditis isn't determined. However, viruses like SARS-Cov-2, the one that causes COVID-19, are commonly associated with the condition.
Medical literature on Covid-induced myocarditis in elite athletes is still emerging, given the small real-world sample sizes available to examine due to the relative scarcity of athletes like Davies, and has been largely centred on prevalence of the condition and helping to craft return-to-play guidelines as opposed to charting long-term impacts.
One study, published in 2021, looked at 145 student-athletes from the University of Wisconsin who were recovering from Covid asymptomatically or with mild to moderate symptoms. Of these athletes, only two, or roughly 1.4 per cent, showed evidence of myocarditis.
This finding was largely reflected in a May 2021 cohort study, a type of research that examines a group of people at different intervals over a prolonged period of time, examining 1,597 competitive United States collegiate athletes which found 37 of them -- 2.3 per cent -- were diagnosed with clinical and subclinical myocarditis.
Studies like these have helped inform a general belief that persistent myocarditis affects one to five per cent of athletes who contract COVID-19, making Davies developing the condition an extremely rare outcome of his infection.
Typically, if athletes are diagnosed with myocarditis, they are taken out of play for at least three months to give the heart a chance to heal, according to Nature, one of the foremost scientific journals in the world.
Canada's men’s team has six matches remaining in the Concacaf Final Round of FIFA World Cup Qualifiers, with upcoming games in Honduras (Jan. 27), at home to the U.S. in Hamilton (Jan. 30) and in El Salvador (Feb. 2).
The Canadian men, bidding to qualify for the World Cup for only the second time ever, currently top the final round of qualifying in CONCACAF with a 4-0-4 record. They have six games remaining.
Come March, the top three teams in the eight-team round robin will represent North and Central America and the Caribbean at Qatar 2022. The fourth-place team will take on an Oceania country in an intercontinental playoff to see who joins them.