Cardiac manifestations after COVID-19 jabs: When do they arise and who are at risk?

Cardiac manifestations, such as acute myocardial infarction (AMI) and myocarditis, after vaccination for the coronavirus disease 2019 (COVID-19) are more common in men, according to a recent Singapore study. AMI is more likely to arise after the first shot, while myocarditis becomes more common after the second dose.

“Despite recent emerging literature supporting the temporal association between cardiac manifestations and vaccination, these findings are to be interpreted with caution as causality cannot be deduced,” the researchers said.

“Nonetheless, health authorities must maintain vigilance through continued monitoring of serious COVID-19 vaccine side-effects, with the Dengvaxia controversy in the Philippines serving as a reminder,” they added.

Thirty patients participated in the study, all of whom had onset of cardiac manifestations within 14 days following COVID-19 vaccination. A systematic review of 16 studies from PubMed, LitCovid, MedRxiv, Embase, and Research Square was also performed.

Combining participants from the study cohort and from the systematic review yielded a cumulative sample of 77 patients, 35 (median age 65 years, 80 percent men) of whom had AMI and 42 (median age 21 years, 91 percent men) had myocarditis. Participants were predominantly men, and those who developed AMI were markedly older than their myocarditis counterparts, pointing to a potential age and sex bias of such postvaccination cardiac manifestations. [QJM 2021;doi:10.1093/qjmed/hcab252]

In terms of timing, AMI seemed to develop sooner, with symptoms manifesting a median of 1 day after vaccination; in comparison, myocarditis arose after a median of 3 days. Moreover, majority of AMI patients developed symptoms after the first dose, whereas 83 percent of myocarditis patients manifested symptoms after the second jab.

Among AMI patients who underwent coronary angiography, 60 percent were also subjected to percutaneous coronary intervention, with the left anterior descending artery emerging as the most common culprit. In the myocarditis group, 76 percent was found to have late gadolinium enhancements.

Treatment approach varied across all patients and depended largely on the underlying pathology. Myocarditis patients often received colchicine nonsteroidal anti-inflammatory drugs, while AMI was commonly treated with beta-blockers, antiplatelet therapy, or statins.

Though still insufficiently explored, several hypotheses could explain the onset of postvaccination AMI. An autoimmune response against the platelets could lead to a prothrombic state, for instance, or the stress from the jab could trigger demand ischaemia, culminating in a cardiovascular event. Myocarditis, on the other hand, is likely to have a distinct pathophysiology, though an autoimmune response has also been postulated. [N Engl J Med 2021;384:2092-2101; Cureus 2021;13:e13651-e; Cell Mol Immunol 2018;15:586-594]

“This pooled analysis of patients presenting with cardiac manifestations following the COVID-19 vaccination highlights the differences between myocarditis and AMI presentations in temporal association with the COVID-19 vaccination,” the researchers said.

“Population-based studies might help elucidate if myocarditis and AMI rates are higher in the vaccination era compared to prepandemic times. For now, COVID-19 vaccines remain the cornerstone in our fight against the contagion,” they added.