Trending Clinical Topic: Myocarditis

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Myocarditis has been an ongoing concern during the pandemic as it has been associated with COVID-19 infection and, to a much lesser extent, vaccination. New studies that help clarify the two links have resulted in this week’s hottest clinical topic. According to the Centers for Disease Control and Prevention (CDC), myocarditis after mRNA vaccination occurs after 70 out of 1 million doses given in boys aged 16 to 17, who are most at risk. A new review of data from 26 pediatric medical centers in the United States and Canada has provided reassuring information about those affected (see infographic).

The study was published in Traffic and found that symptoms began a median of 2 days (range, 0-22 days) after vaccine administration. Chest pain was the most common symptom (99.3%). Fever was present in 30.9% of patients and shortness of breath was reported in 27.3%. “These data suggest that most cases of suspected COVID-19 vaccine-related myocarditis in people younger than 21 are mild and resolve rapidly,” corresponding author Dongngan Truong, MD, said in a statement.

F. Perry Wilson, MD, MSCE, found the data rather encouraging. He pointed to “a rhythmic band of a 15-second series of unsustained V-tach in a 17-year-old youth” and reduced echocardiology function in 20% of the youths included as signs of some concern. Yet, concludes Wilson, “we must resist the urge to compare the effects of the vaccine to the effects of no vaccine. Given the contagiousness of SARS-CoV-2, we must compare the effects of the vaccine to the effects of the COVID itself.”

The CDC found that patients with COVID-19 have nearly 16 times the risk of myocarditis. The cardiac manifestations of COVID go well beyond myocarditis. In a recent review, the researchers state that clinicians “should be aware of some of the changes reported on the ECG, such as abnormal QRS axis in nearly 20% of patients, conduction abnormalities in about 20%, atrioventricular block in approximately 2.5% and premature beats in almost 10% of patients.” More than 9% of patients admitted with COVID-19 infection suffer from arrhythmias, mainly atrial fibrillation. The authors recommend a baseline and follow-up ECG for QTc interval monitoring in hospitalized patients.

Given the myriad of heart problems associated with SARS-CoV-2 infection, the news that myocarditis associated with mRNA vaccination is usually mild and resolves quickly in the rare cases that it occurs was good news. The results continue to tip the scales in favor of vaccination and resulted in this week’s hottest clinical topic.

Learn more about myocarditis.

Jessica C. Bell