Key result
Moderna booster-associated complete heart block in an elderly patient resolves spontaneously with supportive care.
Why the study?
Myocarditis following COVID-19 vaccination is rare and can involve the cardiac conduction system causing high-grade AV block, but its diagnosis and management remain challenging.
Case Report (n=1)
High-grade AV block is a rare but potentially reversible manifestation of COVID-19 vaccine-associated myocarditis in older adults, emphasizing the need for cardiac MRI diagnosis and conservative monitoring to avoid unnecessary permanent pacing.
Background: Myocarditis has been rarely reported following COVID-19 vaccination, most commonly in younger males. Although a temporal association has been observed, establishing causality in individual cases remains challenging. Myocardial inflammation may involve the cardiac conduction system, rarely resulting in high-grade atrioventricular (AV) block. Importantly, these conduction abnormalities may be transient and resolve as the underlying inflammation improves. Case Summary: We report a rare case of myocarditis following a COVID-19 vaccination in an elderly woman who experienced complete heart block and worsening exertional dyspnea subsequent to receiving a COVID-19 booster. Coronary angiography revealed patent coronary arteries, and magnetic resonance imaging confirmed the presence of myocarditis. Her conduction abnormality progressively resolved without the need for permanent pacing, and she was subsequently discharged in stable condition. Discussion: Myocarditis should be considered as a potentially reversible cause of high-grade AV block. A thorough clinical history and multimodal imaging are essential for diagnosis, as early recognition and appropriate monitoring may allow recovery of AV conduction and avoid unnecessary permanent pacemaker implantation.
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Shrestha et al. (2026) conducted a case report in COVID-19 vaccine-associated myocarditis (n=1). Moderna COVID-19 booster was evaluated. Acute myocarditis following a Moderna COVID-19 booster presented as complete heart block in an elderly woman, resolving spontaneously with supportive care and avoiding permanent pacemaker implantation.
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