Clinical Manifestations and Adverse Cardiovascular Events in Patients with Cardiovascular Symptoms after mRNA Coronavirus Disease 2019 Vaccines.

Purpose: The number of patients presenting with vaccination-related cardiovascular symptoms after receiving mRNA vaccines (mRNA-VRCS) is increasing. We investigated the incidence of vaccine-related adverse events (VAEs), including myocarditis and pericarditis, in patients with mRNA-VRCS after receiving BNT162b2-Pfizer-BioNTech and mRNA-1273-Moderna vaccines.

Materials and methods: We retrospectively collected data on patients presenting with mRNA-VRCS who visited the outpatient clinic of two tertiary medical centers. Clinical characteristics, laboratory findings, echocardiographic findings, and electrocardiographic findings were evaluated. VAE was defined as myocarditis or pericarditis in patients after mRNA vaccination. Clinical outcomes during short-term follow-up, including emergency room (ER) visit, hospitalization, or death, were also assessed among the patients.

Results: A total of 952 patients presenting with mRNA-VRCS were included in this study, with 89.7% receiving Pfizer-BioNTech and 10.3% receiving Moderna vaccines. The mean duration from vaccination to symptom was 5.6±7.5 days. VAEs, including acute myocarditis and acute pericarditis, were confirmed in 11 (1.2%) and 10 (1.1%) patients, respectively. The VAE group showed higher rates of dyspnea, echocardiography changes, and ST-T segment changes. During the short-term follow-up period of 3 months, the VAE group showed a higher hospitalization rate compared to the control group; there was no significant difference in ER visit (p=0.320) or mortality rates (p>0.999).

Conclusion: Amongst the patients who experienced mRNA-VRCS, the total incidence of VAEs, including acute myocarditis and pericarditis, was 2.2%. Patients with VAEs showed higher rates of dyspnea, echocardiographic changes, and ST-T segment changes compared to those without VAEs. With or without the cardiovascular events, the prognosis in patients with mRNA-VRCS was favorable.