Latest News

Most pediatric myocarditis caused by viruses


AT AAP 2022

– A wide range of factors can cause myocarditis; most often viral infections cause myocarditis in children and teens, according to Ryan Butts, MD, medical director of the pediatric advanced cardiac care program at the University of Texas Southwestern Medical Center and Children’s Health of Texas.

Dr. Butts provided an overview of what pediatricians and other clinicians caring for children and teens should know about myocarditis at the annual meeting of the American Academy of Pediatrics.

The important new things that attendees may want to take away from this for their practice are improved recognition and diagnostic workup for acute viral myocarditis, making sure cardiology follow-up occurs after an admission for the condition, enhanced evaluation of the child before they return to competitive sports, and the availability of written or verbal education for patients relating to COVID vaccine–associated myocarditis, Dr. Butts said.

He also provided a set of key takeaways:

  • Myocarditis is rare.
  • The most common viruses causing myocarditis are always changing.
  • Myocarditis is most common in infants and teenagers but it has different clinical patterns in each population.
  • MRI is becoming the diagnostic tool of choice.
  • IVIG frequently is used but good evidence for the therapy is lacking.
  • Patients may go home on cardiac medications but have good long-term outcomes.
  • Patients must have a 6-month restriction on competitive sports after diagnosis.

Frank Han, MD, a pediatric cardiologist at OSF Medical Center and Children’s Hospital of Illinois in Peoria, said he found the most helpful parts of Dr. Butts’ presentation to be the diagnosis and triage of myocarditis in the major age groups.

“Myocarditis can have variable presentations, and its cause may influence how the myocarditis behaves,” Dr. Han said. Pediatric cardiologists, he said, are uniquely positioned to triage and diagnose myocarditis.

Epidemiology and presentation

Just 0.05% of admissions from 28.6 million U.S. pediatric ED visits every year are for myocarditis, Dr. Butts said. While viruses are the most common cause of myocarditis, bacterial infections and noninfectious causes, including hypersensitivity reactions, systemic disorders, and toxic substances, can also cause the condition. The dominant viruses causing myocarditis have shifted over the years as well. Coxsackie B was the most common cause in the 1980s, but adenovirus became more common in the 1990s and parvovirus B19 in the 2000s. Why some kids develop myocarditis while others don’t is unclear, but the host-immune response to the virus likely plays an important role.

Research has shown two substantial spikes in the incidence of myocarditis children: infants under 2 years old and teens aged 14-19. Although myocarditis refers to any inflammation of myocardium not caused by ischemia, the signs, symptoms, and lab results vary according to patient’s age group. The only constant is that diaphoresis is rare across all ages.

Infants are more likely to show respiratory distress (68%) and an enlarged liver (40%) but can also present with gastrointestinal symptoms (24%). Vomiting without fever or diarrhea should arouse clinical suspicion of myocarditis in infants, although fever and diarrhea can occur.

In young children, who have the lowest incidence, fatigue presents in about one-third, with 20% presenting with chest pain and 20% with hepatomegaly. The most common symptom in teens by far (80%) is chest pain. About one-third also have respiratory distress but gastrointestinal symptoms are less common (20%).

When should a clinician suspect myocarditis in a teen presenting with chest pain? “If the chest pain is reproducible and if you can localize it, they don’t need further evaluation,” Dr. Butts said. “After that, it’s a lot about the history.”

In terms of lab results, ventricular function measured by brain natriuretic peptide is significantly depressed in infants and young children but often near normal in teens. Inflammatory markers (C-reactive protein) tend to be low in infants but elevated in young children and teens. And troponin levels, denoting myocardial injury, are minimal in infants and young children but elevated in teens. Median ejection fraction on echocardiograms, about 55% in normal hearts, will often be low in infants and young children, around 30%-33%, but is near normal (54%) in teens.


Next Article: