Myocarditis Associated with COVID19 Vaccination - Echocardiography, Cardiac Tomography and Magnetic Resonance Imaging Findings

Background: Israel achieved early mass vaccination against COVID19 [BioNTech COVID19 (Pfizer) vaccine]. In January 2020, age limit for vaccination was lowered to 16 years. Shortly thereafter, a cluster of patients presented with myocarditis timely related to their second vaccination dose. Futheremore, on July 30th, a third vaccination dose, a "booster shot" of the Pfizer vaccine was approved In Israel with additional patients with clinical picture of myocarditis presenting after receiving their third dose.

Methods: Clinical and radiological work-up of patients hospitalized with myocarditis shortly their 2nd and 3rd vaccination. Imaging included echocardiography, cardiac MR (CMR) and spectral cardiac gated CTA with delayed iodine enhancement phase. The study was approved by our Institutional Review Board.

Results: 12 cases of suspected post-vaccination myocarditis, all involving young (age 20-38 years) patients, 11/12 of male gender. Acute COVID19 infection was excluded. All patients developed chest pain within 3-7 days of their vaccine. ECG was abnormal in 7/12 patients. All had high troponin levels. Echocardiograms showed reduced LVEF in 5 patients and impaired speckled strain in 7. On CMR 11/12 of them fulfilled criteria for myocardial inflammation. The spectral cardiac CT (n=8), ruled out obstructive coronary artery disease, while showing on the delayed scan, (6 minutes post injection), late iodine enhancement in a distribution typical of myocarditis, similar to the late gadolinium enhancement on CMR. Resolution of symptoms without complications and decrease in troponin levels invariably occurred within several days. None suffered from complications (e.g. hemodynamic instability, arrhythmias).

Conclusion: These clusters of patients with similar clinical, laboratory and imaging findings had a clear timeline link to their vaccinations. Spectral cardiac CT showed excellent correlation to CMR by demonstrating a classic myocarditis pattern of late iodine enhancement, in addition to timely non-invasive exclusion of significant coronary disease. Our findings suggest that this complication is benign.