Myocarditis developing after COVID-19 vaccination resolves with in 6 months: JACC

Several case reports have suggested a small risk of myocarditis linked with the mRNA vaccines, especially in young men, and the risk tends to be a little higher with the Moderna vaccine. Cardiac imaging showed these cases resembled "classical" myocarditis and tended to be mild. Data has been published indicating that myocarditis following vaccination does resolve without clinical consequences, with these studies showing a rise in LVEF and resolution of LGE on cardiac MR.

The first series included nine male patients (mean age 22 years) who developed myocarditis after receiving their second Pfizer/BioNTech or Moderna vaccine dose. Yash Patel, Warren Alpert Medical School at Brown University, Providence, RI, and colleagues observed a complete resolution of late gadolinium enhancement (LGE) on cardiac MRI in one patient and resolving, although persistent, LGE in the remaining eight patients.

All cases had resolution of myocardial edema after 3 to 6 months on the repeat cardiac MRI, which implies that the active inflammation is gone. None of the patients had any adverse cardiovascular outcomes. Also, there was no repeat myocarditis, no heart failure, no hospitalizations, and no repeat myocarditis.

The second report consisted of seven male patients (mean age 30 years) who developed myocarditis after receiving either a first or second Pfizer/BioNTech vaccine. The research team led by Arthur Shiyovich, Rabin Medical Center, Tel Aviv, Israel, showed that absolute LGE declined in all patients over time and was entirely resolved in one person after a median follow-up of 212 days. Left ventricular ejection fraction increased in five of the seven patients, and there were no adverse cardiovascular events, including arrhythmias, hospital readmissions, or mortality.

The follow-up study, which included seven patients undergoing MRI after a median of more than seven months, showed a statistically significant improvement in LVEF between the two MR studies (56.8% to 59.4%). Also, there was a decline in LGE between MR scans, with all patients showing signs of improvement or resolution.

In the US study, nine patients were diagnosed with myocarditis following vaccination with Pfizer/BioNTech (n = 7) or Moderna (n = 2) vaccine. They underwent a follow-up cardiac MR scan a median of 94 days after diagnosis. The team led by Patel noted MR evidence of myocardial recovery and no clinical events. Also, there were signs that some mild abnormalities persisted, as seen by measures of global circumferential strain and global longitudinal strain.

Lead authors from both studies agreed that the mRNA vaccination-related myocarditis was very similar to classic myocarditis, with similar LGE scar patterns.

References:

1) Patel YR, Shah NR, Lombardi K, et al. Follow-up cardiovascular magnetic resonance findings in patients with COVID-19 vaccination-associated acute myocarditis. J Am Coll Cardiol Img. 2022;Epub ahead of print.

2) Shiyovich A, Plakht Y, Witberg G, et al. Myocarditis following COVID-19 vaccination: a follow-up magnetic resonance imaging study. J Am Coll Cardiol Img. 2022;Epub ahead of print.