Acute myopericarditis after administration of mRNA vaccines against the SARS-CoV-2 virus

Dear Editor:

Different vaccines have been developed within the last year to prevent COVID-19.¹ Of these, two types have been marketed in Spain: messenger RNA (BNT162b2 mRNA [Pfizer-BioNTech] and mRNA-1273 [Moderna]) and others composed of recombinant adenovirus (Janssen Ad26.COV2.S [Johnson and Johnson] and Vaxzervria [AstraZeneca]).² Adverse reactions associated with their use have been frequently documented, with most of them being mild and transient in nature (mainly puncture site pain, fever and myalgia).³ However, in recent months, potentially more serious adverse reactions such as myocarditis and acute pericarditis⁴ have been described in association with the use of mRNA vaccines. These complications occur especially in adolescent and young adult males, 24−72 h after administration of the second dose of the vaccine and are generally associated with a benign clinical course and a favourable progression with a low case fatality rate. Different pathophysiological mechanisms have been suggested to cause this myocardial/pericardial damage, with the most widespread theory being the activation of inflammatory cascades that infiltrate the myocardium and pericardium due to the mRNA being misinterpreted as an antigen by the innate immune system of genetically susceptible individuals.⁵

We report 3 cases of acute myopericarditis treated in our site after the administration of mRNA vaccines against COVID-19. The main characteristics of the patients (Table 1) included an age between 20 and 25 years and onset of typical symptoms of pericarditis and fever 48−96 h after inoculation of the second vaccine dose. In all cases the initial ECG showed the generalised concave ST-segment elevation characteristic of acute pericarditis, significant mobilisation of ultra-sensitive troponin I (US TpI) (range 347–32. 456 ng/dl; normal < 18 ng/dl) and elevated C-reactive protein (range 4.4–5.0 mg/l; normal < 0.05). Active COVID-19 infection and other viral infections common in acute myopericarditis were ruled out. In all 3 cases the progression during admission was favourable, with no arrhythmic or haemodynamic complications, cessation of pain and fever on initiation of non-steroidal anti-inflammatory treatment and peak US TpI at 48 h from the onset of pain. The echocardiogram in the 3 cases was unremarkable, with normal global and segmental contractility and no pericardial effusion. At one month follow-up, after completing the course of NSAID therapy, all 3 patients were still asymptomatic and had normal systolic function by echocardiography.

Table 1.

Baseline characteristics and biochemical, electrocardiographic and echocardiographic data of patients on admission and at one month of follow-up.

		Case 1	Case 2	Case 3
Age (years)		20	20	25
Sex		Female	Male	Male
Vaccine		Pfizer	Pfizer	Moderna
Past COVID-19 infection		No	No	No
Supplementary tests
CRP (mg/l) (normal < 0.5)	Admission	4.2	4.8	5.0
	At one month	0.5	0	0.1
Peak US TpI (ng/dl) (normal < 18)	Admission	341	28.575	31.988
ECG	Admission	Sinus rhythm at 60 bpm Narrow QRS, no ST segment or T wave changes	Sinus rhythm at 70 bpm Normal PR. Narrow QRS. Generalized concave ST-segment elevation of 3 mm, except aVR. Accompanying positive spiked T-waves	Sinus rhythm at 50 bpm. Narrow QRS Inferior, lateral, and high lateral concave ST-segment elevation. Negative T-waves in V1-V2
	At one month	Normal, no change	Sinus rhythm at 90 bpm Narrow QRS. Isodiphasic T-waves in V3-V6 and aVL	Sinus rhythm at 76 bpm Negative Ts in V5-V6 and aVL
TTE	Admission	Non-dilated LV. Normal EF without segmental contractility abnormalities. No pericardial effusion	Non-dilated LV. Normal EF without segmental contractility abnormalities. No pericardial effusion	Non-dilated LV. Normal EF without segmental contractility abnormalities. No pericardial effusion
	At one month	Without changes	Without changes	Without changes
Chest X-ray	Admission	No pathological findings	No pathological findings	No pathological findings
SARS-CoV-2 PCR	Admission	Negative	Negative	Negative

ECG: electrocardiogram; TTE: transthoracic echocardiogram; EF: ejection fraction; bpm: beats per minute; mg/l: milligram/litre; ng/dl: nanogram/decilitre; CRP: C-reactive protein; US TpI: ultrasensitive troponin; LV: left ventricle.

Acute myopericarditis is a rare but increasingly well-known complication in patients who have received COVID-19 mRNA vaccines. In the US, an incidence of between 50.5 and 62.8 cases per million second doses of mRNA vaccine has been reported.³ In our area, the number of mRNA vaccines administered in the population aged between 15 and 30 years has been 15,593, so the incidence would be 192 cases per million doses. On the other hand, the presentation and clinical progression of previously reported cases of myopericarditis is similar to that described in our patients, generally with a benign clinical course and excellent response to anti-inflammatory treatment.⁴ A diagnostic limitation in our series was the lack of cardiac magnetic resonance imaging, mainly because of the prognostic implications of quantifying the extent of inflammation. Therefore, clinicians should consider this diagnosis in all patients presenting with chest pain after administration of the second dose of COVID mRNA vaccine, especially in young males.⁴

Funding

This paper has not received any type of funding.

Conflict of interests

None.