How Frequent and Dangerous is COVID-19 Myocarditis?

Paul Thompson, MD

I searched PubMed on January 19, 2021, using the terms “COVID” and “athletes” and got 675 hits. I repeated the search 6 days later and got 704 hits. When I added the term “cardiac”, I got 47 hits on January 20th and 71 hits on a search performed on January 25th.

That is an amazing number of publications on COVID-19 in athletes and an amazing increase in the number of publications in just a week. There must be a lot of assistant medical school professors headed to the associate professor level thanks to COVID-19 publications! But I am concerned that so many publications produced so quickly means that either new data are being produced rapidly or that the issues with COVID-19 in athletes are not settled.

I think the latter is most likely because many of the citations on COVID-19 in athletes are essentially opinion pieces. For example, in my latest cardiac search, the words consensus, considerations, game plan, or recommendations appeared in the title of 6 of the first 10 cited articles. So, what do we know?

Among 419 patients hospitalized in Wuhan, 19.7% had cardiac troponin (cTn) I values >99th percentile suggesting myocardial involvement. These patients had a worse prognosis.¹

Among 100 German patients studied by cardiac magnetic resonance imaging (cMRI) 64-92 days after their COVID-19 diagnosis, 78 had abnormal cMRI finding.² These included 71 and 60 patients with cMRI elevations of T1 and T2 values, respectively, 32 with late gadolinium enhancement (LGE) suggestive of myocardial scarring, and 22 with evidence of pericardial involvement. HsTnT values were detected in 71 at the time of their cMRI.

The Sports Medicine community is concerned because myocarditis was the 3rd leading cause of sudden cardiac death (SCD) (after hypertrophic cardiomyopathy and anomalous coronary arteries) in Barry Maron’s collection of SCD in high school and college athletes. Myocarditis was responsible for 6% of the 1046 SCDs.³

There are at least 3 studies that have looked at myocarditis using cMRI in athletes after COVID-19 infection. Among 26 Ohio State athletes studied 11-53 days after COVID diagnosis, none have ECG, echocardiographic or cTnI abnormalities on the day of imaging, but 12 (46%) had cMRI evidence of a myocardial scar and 2 met criteria for myocarditis (13%).⁴ This study had no control group.

In a study from Vanderbilt University, researchers compared cMRI results in 59 of their athletes studied 10-162 days post COVID-19 diagnosis with 60 not infected athletic and 29 healthy non-athletic controls. The athletes had experienced no (22%) or mild (78%) COVID symptoms.⁵ Only 2 of the athletes (3%) had cMRI evidence of myocarditis, but two additional athletes had pericarditis or a new drop in their left ventricular ejection fraction. Moreover, there were mild increases in cMRI T1 and T2 values suggestive of myocardial involvement in 39% of the COVID athletes, 13% of the athletic controls, and 8% of the healthy normal subjects. This study was criticized for its small sample size.

In another study, clinicians from the U of Wisconsin performed a retrospective review of cMRI studies from 145 athletes consecutive athletes who had no (16%) mild (49%) moderated (28%) or undocumented (7%) symptoms.⁶ None were hospitalized. The athletes were studied 11-194 days after diagnosis. Only 2 athletes (1.4%) had findings of myocarditis. Also, 4 others had cTn elevations without cMRI findings. So do 13, 3, or 1.4% of previously healthy, college athletes develop myocarditis after COVID-19 infection?

We just do not know. Indeed, we know very little about myocarditis in athletes, a point I made in an editorial published at the very start of the epidemic.⁷ That editorial addressed viral myocarditis in general and not COVID-19 myocarditis because it predated the Wuhan cardiac report.

Concern about myocarditis has led some sports cardiology authorities to recommend routine cMRI screening of all athletes after COVID infection, even constantly asymptomatic athletes, before allowing return to exercise training and sports competition. That’s because these cMRI abnormalities in athletes after COVID raise the concern that many athletes are risk for SCD. But to my knowledge, there has not been a remarkable increase in SCD in athletes during the epidemic. This could be because athletes are not training and competing because COVID-19 myocarditis is not as deadly as we thought or because COVID-19 myocarditis is actually uncommon in athletes.

Some investigators are collecting cMRI results on athletes in an attempt to determine how many have myocardial changes. Such a registry is important, but not the key point. The key point is how many athletes experience SCD during exercise after COVID-19 infection.

What do I think? I think that athletes have a lot of cMRI abnormalities, but similar changes may occur with other viral infections. I suspect that COVID 19 myocarditis is not as dangerous as first suspect, at least not in previously healthy athletes. Such considerations prompted the American College of Cardiology’s Sports and Exercise Subsection to recommend less testing in athletes before return to play unless they were hospitalized, very sick or have ongoing symptoms.⁸ In the interim I fear we are restricting and frightening too many athletes and families. We have to be honest about what we do and do not know. Right now, we know little about myocarditis in athletes, COVID or otherwise.

References:

1. Shi S, Qin M, Shen B, et al. Association of cardiac injury with mortality in hospitalized patients with COVID-19 in wuhan, china. JAMA Cardiol. 2020;5(7):802-810. doi: 10.1001/jamacardio.2020.0950 [doi].

2. Puntmann VO, Carerj ML, Wieters I, et al. Outcomes of cardiovascular magnetic resonance imaging in patients recently recovered from coronavirus disease 2019 (COVID-19). JAMA Cardiol. 2020;5(11):1265-1273. doi: 10.1001/jamacardio.2020.3557 [doi].

3. Maron BJ, Doerer JJ, Haas TS, Tierney DM, Mueller FO. Sudden deaths in young competitive athletes: Analysis of 1866 deaths in the united states, 1980-2006. Circulation. 2009;119(8):1085-1092. doi: 10.1161/CIRCULATIONAHA.108.804617 [doi].

4. Rajpal S, Tong MS, Borchers J, et al. Cardiovascular magnetic resonance findings in competitive athletes recovering from COVID-19 infection. JAMA Cardiol. 2021;6(1):116-118. doi: 10.1001/jamacardio.2020.4916 [doi].

5. Clark DE, Parikh A, Dendy JM, et al. COVID-19 myocardial pathology evaluation in AthleTEs with cardiac magnetic resonance (COMPETE CMR). Circulation. 2020. doi: 10.1161/CIRCULATIONAHA.120.052573 [doi].

6. Starekova J, Bluemke DA, Bradham WS, et al. Evaluation for myocarditis in competitive student athletes recovering from coronavirus disease 2019 with cardiac magnetic resonance imaging. JAMA Cardiol. 2021. doi: 10.1001/jamacardio.2020.7444 [doi].

7. Thompson PD, Dec GW. We need better data on how to manage myocarditis in athletes. Eur J Prev Cardiol. 2020:2047487320915545. doi: 10.1177/2047487320915545 [doi].

8. Kim JH, Levine BD, Phelan D, et al. Coronavirus disease 2019 and the athletic heart: Emerging perspectives on pathology, risks, and return to play. JAMA Cardiol. 2020. doi: 10.1001/jamacardio.2020.5890 [doi].