COVID-19 patients have nearly three times the risk of developing myocarditis compared to those with influenza, with young males and pediatric populations showing the highest rates, according to a recent study.

The retrospective cohort study analyzed health claims data from over 1.12 million adults diagnosed with COVID-19 (2020–2021) and nearly 440,000 adults diagnosed with influenza (2016–2018). The myocarditis rate per 1,000 person-years was 0.73 for COVID-19 patients, compared to 0.24 for influenza patients. In pediatric populations, the rate was 0.53 versus 0.06 per 1,000 person-years, an 8.8-fold higher risk for COVID-19.

Young males aged 18–29 years had the highest myocarditis rates, with 1.16 cases per 1,000 person-years in the COVID-19 group, compared to 0.22 for influenza patients. Adults with preexisting cardiac comorbidities also showed elevated risk. After adjustments for demographic factors and comorbidities, COVID-19 infection was associated with a 2.85-fold increased risk of myocarditis compared to influenza.

Diagnostic evaluations, including electrocardiography, echocardiography, and troponin testing, were frequently performed. While cardiovascular magnetic resonance (CMR) was recommended for non-invasive assessment, only about 25% of patients diagnosed with myocarditis underwent CMR, with contrast-enhanced imaging predominating.

The study, published in Open Heart, highlighted the higher prevalence of cardiovascular comorbidities among COVID-19 patients compared to the influenza cohort. Additionally, the myocarditis rate among COVID-19 patients decreased from 0.82 per 1,000 person-years in 2020 to 0.67 in 2021.

Further research is needed to confirm these associations and assess the underutilization of CMR in routine practice. Full disclosures and limitations can be found in the published study.