AHA Study Assesses Risk of Pericarditis and Myocarditis Associated with COVID-19 Vaccines

At the American Heart Association (AHA) 2020 Scientific Sessions, much of the discussion related to COVID-19 among cardiologists concerned the apparent risk of blood clots associated with contracting SARS-CoV-2. Fast forward to AHA 2021 Scientific Sessions and the conversation related to COVID-19 among cardiologists has shifted to discussions around the potential risk of myocarditis and pericarditis associated with the COVID-19 vaccines.

Results of a study from the Intermountain Heart Institute, which assessed rates of pericarditis or myocarditis per 10 million patient-days for vaccinated patients compared to unvaccinated patients, indicate the rate of acute pericarditis was 4.49 times greater in vaccinated patients than unvaccinated patients, but investigators noted this risk was lower than risk inferred by contracting COVID-19.

With an interest in describing the risk of pericarditis among patients who have received the COVID-19 vaccine, investigators designed their study to compare rates among vaccinated and unvaccinated patients from December 15, 2020, to June 15, 2021. A total of 1.7 million Intermountain Healthcare patients were considered eligible for inclusion in the investigators’ analyses, which included 914,611 vaccinated patients and 780,878 unvaccinated patients.

From these patient groups, investigators identified 67 instances of inflammatory heart disease, including 21 among vaccinated patients and 46 among unvaccinated patients. The cases of inflammatory heart disease among vaccinated patients included 10 cases of pericarditis, 21 of myocarditis, and 9 of myopericarditis. The cases of inflammatory heart disease included 18 cases of pericarditis, 16 cases of myocarditis, and 12 cases of myopericarditis.

For the purpose of analysis, pericarditis was defined by at least 2 of the following criteria: chest pain, EKG changes, pericardial effusion, and pericardial rub. The investigators designed analysis to assess rates of pericarditis per 10 million patient days and also designed a case-crossover analysis with 4 control dates for each pericarditis case.

When assessing the rate of acute pericarditis, myocardial injury, or myocarditis per 10 million patient-days was 3.11 for vaccinated patients and 1.91 per 10 million patient-days among unvaccinated patients. Upon analysis, investigators determined the rate of acute pericarditis, myocardial injury, or myocarditis in vaccinated patients was 1.64 times higher compared to unvaccinated patients (95% CI, 0.95-2.71; P=.07). When restricting this to a 30-day post-vaccination window, this rate increased to 2.05 (95% CI, 1.17-3.48; P=.01). In case-crossover analyses, results indicated the odds of experiencing post-vaccine inflammatory heart disease was significantly higher than the unvaccinated interval for both the 30- and 60-day windows (60-day OR, 4.36; 30-day OR, 4.18; [P for both <.0001]).

For more on the results of this study and the topic, Practical Cardiology reached out to study investigator Viet Le, PA-C, a physician assistant at Intermountain Healthcare, and that conversation is the subject of the following AHA 2021 House Call.

This study, “A Small but Significant Increased Incidence of Acute Pericarditis Identified After Vaccination for SARS-CoV-2,” was presented at AHA 2021.