Myocarditis after COVID-19 mRNA vaccines

Long-term imaging analysis of a myocarditis case: Utilizing strain with echocardiography and cardiovascular magnetic resonance findings

Herein, we report a case of myocarditis in a 27-year-old male with long-term follow-up using longitudinal peak systolic strain (LPSS) measurements with transthoracic echocardiography (TTE) and late gadolinium enhancement (LGE) in cardiovascular magnetic resonance imaging (CMR). On admission, a predominant decrease was observed in the LPSS in the posterolateral segments of the TTE. After a period of two weeks, the values of the LPSS observed in the posterolateral segments were still slightly reduced, which is consistent with the LGE results in CMR. After a duration of 16 months, an improvement was noted in the LPSS and LGE results in all the segments. Moreover, a time-phase discrepancy was observed in the segmental longitudinal strain curve for a period of two weeks from the onset of myocarditis. However, an improvement in the discrepancy was detected after 16 months.

Learning objective

Longitudinal peak systolic strain (LPSS) on transthoracic echocardiography (TTE) has predominantly focused on diagnosing the acute phase of myocarditis. Herein, LPSS was evaluated not only in the acute phase but also in the chronic phase. Furthermore, the relationship between the results of segmental LPSS and late gadolinium enhancement was documented. We would like to emphasize the usefulness of LPSS on TTE both for identifying myocarditis and as a tool for the long-term follow-up of patients.

Cardiac and Neurological Complications Post COVID-19 Vaccination: A Systematic Review of Case Reports and Case Series

Following mass vaccinations for the control of the COVID-19 epidemic, a spectrum of cardiac and neurological disorders was reported among vaccinated individuals. This study examined the range of complications documented and factors related to their occurrence. Three electronic databases were searched for case reports and case series with descriptions of cardiac and/or neurological complications in COVID-19 vaccine recipients. A total of 698 vaccinees were included in this review, of which 259 (37.1%) had cardiac and 439 (62.9%) had neurological complications. Inflammatory conditions were the commonest among the cardiac complications; while polyneuropathy, demyelinating diseases and cerebrovascular disorders were the more common neurological complications. The mean age of those with cardiac complications (33.8 years) was much younger than those with neurological complications (49.7 years). There was no notable difference in the gender distribution between these two groups of vaccine recipients. mRNA vaccines (all brands) were associated with almost 90.0% of the cardiac complications, whereas viral vector vaccines were associated with slightly over half (52.6%) of the neurological complications. With regard to the dose, cardiac complications were more common after the second (69.1%), whereas neurological complications were more common after the first dose (63.6%). The majority of the cases had an uncomplicated clinical course. Nevertheless, 5.9% of cases with neurological complications and 2.5% of those with cardiac complications were fatal, underscoring the significance of the consistent surveillance and vigilant monitoring of vaccinated individuals to mitigate these occurrences.

Myocarditis post-SARS-CoV-2 vaccination: a systematic review

Variable clinical criteria taken by medical professionals across the world for myocarditis following coronavirus disease 2019 (COVID-19) vaccination along with wide variation in treatment necessitates understanding and reviewing the same. A systematic review was conducted to elucidate the clinical findings, laboratory parameters, treatment and outcomes of individuals with myocarditis after COVID-19 vaccination after registering with PROSPERO. Electronic databases including MEDLINE, EMBASE, PubMed, LitCovid, Scopus, ScienceDirect, Cochrane Library, Google Scholar and Web of Science were searched. A total of 85 articles encompassing 2184 patients were analysed. It was a predominantly male (73.4%) and young population (mean age: 25.5 ± 14.2 years) with most having taken an mRNA-based vaccine (99.4%). The mean duration from vaccination to symptom onset was 4.01 ± 6.99 days. Chest pain (90.1%), dyspnoea (25.7%) and fever (11.9%) were the most common symptoms. Only 2.3% had comorbidities. CRP was elevated in 83.3% and cardiac troponin in 97.6% patients. An abnormal ECG was reported in 979/1313 (74.6%) patients with ST-segment elevation being most common (34.9%). Echocardiographic data were available for 1243 patients (56.9%), of whom 288 (23.2%) had reduced left ventricular ejection fraction. Non-steroidal antiinflammatory drugs (76.5%), steroids (14.1%) followed by colchicine (7.3%) were used for treatment. Only 6 patients died among 1317 of whom data were available. Myocarditis following COVID-19 vaccination is often mild, seen more commonly in young healthy males and is followed by rapid recovery with conservative treatment. The emergence of this adverse event calls for harmonizing case definitions and definite treatment guidelines, which require wider research.

Cardiovascular complications of COVID-19 vaccines: A review of case-report and case-series studies

BACKGROUND

There are multiple reviews on cardiovascular aspects of COVID-19 disease on cardiovascular system in different population but there is lack of evidence about cardiovascular adverse effects of COVID vaccines.

OBJECTIVES

The purpose of this study was to compare the cardiac complications of COVID19 vaccines, based on vaccine type (mRNA, vector-based, and inactivated vaccines).

METHODS

A systematic search was performed covering PubMed for English case-reports and case-series studies, and finally 100 studies were included.

RESULTS

Myocarditis (with overall rate around 1.62%) was shown to be the most common post-COVID19 immunization cardiac event. More than 90% of post-COVID19 vaccination myocarditis occurred after receiving mRNA vaccines (Moderna & Pfizer-BioNTech), but the report of this event was less in the case of vector-based vaccinations and/or inactivated vaccines. Myocarditis was reported more commonly in men and following the second dose of the immunization. Takotsubo cardiomyopathy (TTC) was reported after mRNA (more commonly) and vector-based vaccinations, with no case report after inactivated vaccines. When mRNA and vector-based vaccinations were used instead of inactivated vaccines, a greater frequency of vaccine-induced thrombotic thrombocytopenia (VITT) and pulmonary emboli (PE) was reported. Myocardial infarction/cardiac arrest was recorded in those beyond the age of 75 years.

CONCLUSION

The personal and public health benefits of COVID-19 vaccination much outweigh the minor cardiac risks. Reporting bias, regarding more available mRNA vaccines in developed countries, may conflict these results.

Cardiac MRI Findings in COVID-19 Vaccine-Related Myocarditis: A Pooled Analysis of 468 Patients

Understanding the pattern and severity of myocarditis caused by the coronavirus disease 2019 (COVID-19) vaccine is imperative for improving the care of the patients, and cardiac evaluation by MRI plays a key role in this regard. Our systematic review and meta-analysis aimed to summarize cardiac MRI findings in COVID-19 vaccine-related myocarditis. We performed a comprehensive systematic review of literature in PubMed, Scopus, and Google Scholar databases using key terms covering COVID-19 vaccine, myocarditis, and cardiac MRI. Individual-level patient data (IPD) and aggregated-level data (AD) studies were pooled through a two-stage analysis method. For this purpose, all IPD were first gathered into a single data set and reduced to AD, and then this AD (from IPD studies) was pooled with existing AD (from the AD studies) using fixed/random effect models. I² was used to assess the degree of heterogeneity, and the prespecified level of statistical significance (P value for heterogeneity) was <0.1. Based on meta-analysis of 102 studies (n = 468 patients), 79% (95% confidence interval [CI]: 54%-97%) of patients fulfilled Lake Louise criteria (LLC) for diagnosis of myocarditis. Cardiac MRI abnormalities included elevated T2 in 72% (95% CI: 50%-90%), myocardial late gadolinium enhancement (LGE) in 93% (95% CI: 83%-99%; nearly all with a subepicardial and/or midwall pattern), impaired left ventricular ejection fraction (LVEF) (<50%) in 4% (95% CI: 1.0%-9.0%). Moreover, elevated T1 and extracellular volume fraction (ECV) (>30), reported only by some IPD studies, were detected in 74.5% (76/102) and 32% (16/50) of patients, respectively. In conclusion, our findings may suggest that over two-thirds of patients with clinically suspected myocarditis following COVID-19 vaccination meet the LLC. COVID-19 vaccine-associated myocarditis may show a similar pattern compared to other acute myocarditis entities. Notably, preserved LVEF is probably a common finding in these patients. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 3.

The effect of the BNT162b2 vaccine on antinuclear antibody and antiphospholipid antibody levels

The Food and Drug Administration (FDA) approved the first SARS-CoV-2 mRNA vaccine (Pfizer-BioNTech) in December 2020. New adverse events have emerged since these vaccines have reached market. Although no clear association between messenger ribonucleic acid (mRNA) vaccines and autoimmunity has emerged, the significance of such an association warrants further exploration. After obtaining consent, a standardized survey on baseline characteristics and other relevant variables was conducted on unvaccinated individuals who were scheduled for vaccination and had not previously contracted COVID-19. Blood samples were collected from participants prior to the first dose, prior to the second dose, and 1 month after the second dose. All collected samples were tested for antinuclear antibody (ANA) titers using indirect immunofluorescence microscopy kits, and antiphospholipid (APS) immunoglobulin M (IgM) and immunoglobulin G (IgG) levels using an enzyme-linked immunoassay (ELISA) technique. ANA titers were positive for 9 participants out of 101 (8.9%) in the first pre-vaccination draw. For the second draw, the number of participants testing positive for ANA decreased to 5 (5%). For the last draw, 6 (5.9%) participants tested positive for ANA titers. One participant tested positive for APS IgM at the first pre-vaccination draw, 2 tested positive at the second draw, and 2 at the third draw. As for APS IgG titers, all participants tested negative in the three draws. McNemar's test for two dependent categorical outcomes was conducted on all variables and did not show a statistical significance. The McNemar test of these two composite variables (i.e., ANA/APS, first draw vs. ANA/APS, second and third draws) did not show statistical significance. The 2-sided exact significance of the McNemar test was 1.0. The Friedman test also showed no significance (p = 0.459). No association was found between BNT162b2 vaccine administration and changes in APS and ANA titers. The benefits of the BNT162b2 vaccine significantly outweigh any possible risk of autoimmune dysregulation considering the current evidence.

Clinical Characteristics of Patients with Myocarditis following COVID-19 mRNA Vaccination: A Systematic Review and Meta-Analysis

COVID-19 mRNA vaccinations have recently been implicated in causing myocarditis. Therefore, the primary aim of this systematic review and meta-analysis was to investigate the clinical characteristics of patients with myocarditis following mRNA vaccination. The secondary aims were to report common imaging and laboratory findings, as well as treatment regimes, in these patients. A literature search was performed from December 2019 to June 2022. Eligible studies reported patients older than 18 years vaccinated with mRNA, a diagnosis of myocarditis, and subsequent outcomes. Pooled mean or proportion were analyzed using a random-effects model. Seventy-five unique studies (patient n = 188, 89.4% male, mean age 18–67 years) were included. Eighty-six patients had Moderna vaccines while one hundred and two patients had Pfizer-BioNTech vaccines. The most common presenting symptoms were chest pain (34.5%), fever (17.1%), myalgia (12.4%), and chills (12.1%). The most common radiologic findings were ST-related changes on an electrocardiogram (58.7%) and hypokinesia on cardiac magnetic resonance imaging or echocardiography (50.7%). Laboratory findings included elevated Troponin I levels (81.7%) and elevated C-reactive protein (71.5%). Seven patients were admitted to the intensive care unit. The most common treatment modality was non-steroid anti-inflammatory drugs (36.6%) followed by colchicine (28.5%). This meta-analysis presents novel evidence to suggest possible myocarditis post mRNA vaccination in certain individuals, especially young male patients. Clinical practice must therefore take appropriate pre-cautionary measures when administrating COVID-19 mRNA vaccinations.

Myocarditis Following COVID-19 Vaccination: Cardiac Imaging Findings in 118 Studies

We reviewed the reported imaging findings of myocarditis in the literature following COVID-19 vaccination on cardiac imaging by a literature search in online databases, including Scopus, Medline (PubMed), Web of Science, Embase (Elsevier), and Google Scholar. In total, 532 cases of myocarditis after COVID-19 vaccination were reported (462, 86.8% men and 70, 13.2% women, age range 12 to 80) with the following distribution: Pfizer-BioNTech: 367 (69%), Moderna: 137 (25.8%), AstraZeneca: 12 (2.3%), Janssen/Johnson & Johnson: 6 (1.1%), COVAXIN: 1 (0.1%), and unknown mRNA vaccine: 9 (1.7%). The distribution of patients receiving vaccine dosage was investigated. On cardiac MR Imaging, late intravenous gadolinium enhancement (LGE) was observed mainly in the epicardial/subepicardial segments (90.8%, 318 of 350 enhancing segments), with the dominance of inferolateral segment and inferior walls. Pericardial effusion was reported in 13.1% of cases. The vast majority of patients (94%, 500 of 532) were discharged from the hospital except for 4 (0.7%) cases. Post-COVID-19 myocarditis was most commonly reported in symptomatic men after the second or third dose, with CMRI findings including LGE in 90.8% of inferior and inferolateral epicardial/subepicardial segments. Most cases were self-limited.

Side Effects Related to BNT162b2 and CoronaVac Vaccine Requiring Emergency Department Visit

Background  Currently, the most effective method in the fight against coronavirus disease 2019 (COVID-19) is vaccination against the disease. However, there are hesitations among society concerning the safety and side effects of COVID-19 vaccines. We aimed to determine the observed side effects that require an emergency room visit after taking the BNT162b2 and CoronaVac vaccines.

Methods  This prospective observational study was conducted with patients who presented to the emergency department due to vaccine-related complications after COVID-19 vaccination. The patients' symptoms at the time of presentation, time from vaccination to the onset of symptoms, and dose of the vaccine administered were determined. In addition, the demographic characteristics of the patients, whether they had a history of COVID-19 infection, and their vital signs at the time of presentation were recorded. The variables were compared according to the type of vaccine administered.

Results  The study included 182 patients who presented to the emergency department over a 6-month period. It was determined that 166 of these patients (91.2%) had received the BNT162b2 vaccine and 16 (8.8%) had received the CoronaVac vaccine. The majority of the patients did not have a history of COVID-19 infection (70.3%), and most presented to the hospital with complications after the second dose (61%). The onset of vaccine-related symptoms was mostly within 1 to 12 hours (39%). The majority of patients (97.8%) were discharged from the emergency department. The most common symptoms after vaccination were fatigue ( n  = 70), followed by muscle/joint pain ( n  = 52), headache ( n  = 33), and fever ( n  = 32). The rate of dizziness was found to be statistically significantly higher in the CoronaVac vaccine group than in the BNT162b2 vaccine group ( p  = 0.008). There was no statistically significant difference between the two vaccine groups in relation to the remaining symptoms ( p  > 0.005).

Conclusion  There were no serious complications related to the BNT162b2 or CoronaVac vaccine. The most common symptom after both vaccines was fatigue; therefore, the BNT162b2 and CoronaVac vaccines can be safely administered.

Signaling COVID-19 Vaccine Adverse Events

Introduction

Statistical signal detection is a crucial tool for rapidly identifying potential risks associated with pharmaceutical products. The unprecedented environment created by the coronavirus disease 2019 (COVID-19) pandemic for vaccine surveillance predisposes commonly applied signal detection methodologies to a statistical issue called the masking effect, in which signals for a vaccine of interest are hidden by the presence of other reported vaccines. This masking effect may in turn limit or delay our understanding of the risks associated with new and established vaccines.

Objective

The aim is to investigate the problem of masking in the context of COVID-19 vaccine signal detection, assessing its impact, extent, and root causes.

Methods

Based on data underlying the Vaccine Adverse Event Reporting System, three commonly applied statistical signal detection methodologies, and a more advanced regression-based methodology, we investigate the temporal evolution of signals corresponding to five largely recognized adverse events and two potentially new adverse events.

Results

The results demonstrate that signals of adverse events related to COVID-19 vaccines may be undetected or delayed due to masking when generated by methodologies currently utilized by pharmacovigilance organizations, and that a class of advanced methodologies can partially alleviate the problem. The results indicate that while masking is rare relative to all possible statistical associations, it is much more likely to occur in COVID-19 vaccine signaling, and that its extent, direction, impact, and roots are not static, but rather changing in accordance with the changing nature of data.

Conclusions

Masking is an addressable problem that merits careful consideration, especially in situations such as COVID-19 vaccine safety surveillance and other emergency use authorization products.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-022-01186-z.

Myocarditis after COVID-19 mRNA vaccination: A systematic review of case reports and case series

Background

The coronavirus disease of 2019 (COVID‐19) is a global pandemic with over 266 million cases and 5 million deaths worldwide. Anti‐COVID‐19 vaccinations have had exceptional success in subduing the incidence, prevalence, and disease severity of COVID‐19, but rare cases of myocarditis have been reported after COVID‐19 vaccinations.

Hypothesis

Myocarditis occurring after COVID‐19 mRNA vaccinations have distinguishable clinical characteristics. They usually have a favorable prognosis.

Methods

We performed a systematic literature search on PUBMED and MEDLINE database from inception to December 5, 2021. Studies were analyzed based on predetermined eligibility criteria.

Results

A total of 57 studies containing 275 cases of COVID‐19 vaccine‐associated myocarditis were catalogued. Mean age was 26.7 years and male to female ratio was 14:1. For 86.9% of patients, myocarditis occurred after the second dose. Average time to onset and length of hospitalization were 3.7 and 3.9 days, respectively. Prognosis was largely benign, but there was a 1.1% reported mortality. Chest pain (95.2%), elevation of troponin (100%), and ST elevation on electrocardiography (68.5%) were common. Nonsteroidal anti‐inflammatory drugs (81.4%) were the most used medication, followed by colchicine (33.1%).

Conclusions

Patients with COVID‐19 vaccine‐associated myocarditis are usually younger males presenting with chest pain 3–4 days after receiving their second dose of COVID vaccine. Diagnosis is made by exclusion of all other etiologies. Given significant population benefit from COVID‐19 vaccination, physicians should continue to encourage vaccination while remaining vigilant of the very rare occurrence of myocarditis following COVID‐19 vaccination.

Global reports of myocarditis following COVID-19 vaccination: A systematic review and meta-analysis

BACKGROUND AND AIMS

Recent media reports of myocarditis after receiving COVID-19 vaccines, particularly the messenger RNA (mRNA) vaccines, are causing public concern. This review summarizes information from published case series and case reports, emphasizing patient and disease characteristics, investigation, and clinical outcomes, to provide a comprehensive picture of the condition.

METHODS

A systematic literature search of PubMed and Google scholar was conducted from inception to April 27, 2022. Individuals who develop myocarditis after receiving the COVID-19 vaccine, regardless of the type of vaccine and dose, were included in the study.

RESULTS

Sixty-two studies, including 218 cases, participated in the current systematic review. The median age was 29.2 years; 92.2% were male and 7.8% were female. 72.4% of patients received the Pfizer-BioNTech (BNT162b2) vaccine, 23.8% of patients received the Moderna COVID-19 Vaccine (mRNA-1273), and the rest of the 3.5% received other types of COVID-19 vaccine. Furthermore, most myocarditis cases (82.1%) occurred after the second vaccine dose, after a median time interval of 3.5 days. The most frequently reported symptoms were chest pain, myalgia/body aches and fever. Troponin levels were consistently elevated in 98.6% of patients. The admission ECG was abnormal in 88.5% of cases, and the left LVEF was lower than 50% in 21.5% of cases. Most patients (92.6%) resolved symptoms and recovered, and only three patients died.

CONCLUSION

These findings may help public health policy to consider myocarditis in the context of the benefits of COVID-19 vaccination.

What Should We Do after the COVID-19 Vaccination? Vaccine-Associated Diseases and Precautionary Measures against Adverse Reactions

COVID-19 vaccines have been used to counteract the global COVID-19 pandemic. While these are effective, adverse reactions have been reported, such as injection-site pain, muscle ache, fever, palpitation, and chest discomfort. The release of inflammatory cytokines, such as interleukin (IL)-6 and IL-1β, is a potential mechanism for post-vaccine side-effects. Chest discomfort after the vaccination, including myocarditis and acute coronary syndrome, is a particularly serious adverse reaction. It is important to be familiar with the differential diagnoses of chest discomfort and organ-specific diseases associated with COVID-19 vaccines as the preparation for booster shots and vaccinations among children aged 5–11 years begins. High-intensity exercise, alcohol, tobacco smoking, and baths promote inflammatory cytokines, such as IL-6, which may exacerbate the adverse reactions after vaccination. Japanese data show that deaths during baths are the most common for several days after mRNA vaccination. Additionally, alcohol and tobacco smoking were identified as predictive factors of lower antibody titers after vaccination. In this review, we aimed to provide a few recommendations to prevent vaccine-associated disease.

Cardiovascular Complications of COVID-19 Vaccines

Coronavirus disease 2019 (COVID-19) has become a global public health catastrophe. Vaccination against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is proven to be the most effective measure to suppress the pandemic. With the widespread application of the four vaccines, namely, ChAdOx1, Ad26.COV2.S, BNT162b2, and mRNA-1273.2, several adverse effects have been reported. The most serious type of complication is cardiovascularly related, including myocarditis, immune thrombocytopenia (ITP), cerebral sinus venous thrombosis, among others. All these adverse events undermine the health of the vaccinees and affect the administration of the vaccines. As the distribution of COVID-19 vaccines is surrounded by suspicion and rumors, it is essential to provide the public with accurate reports from trusted experts and journals. Monitoring the safety of COVID-19 vaccines is an important and ongoing process that is also urgent. Thus, we summarized the cardiovascular complications of the major types of COVID-19 vaccines, including mRNA vaccines, which are now generally considered to be innovative vaccines, and the future for vaccination against COVID-19, in addition to the underlying pathogenesis and potential therapeutics.

Lymphohistiocytic Myocarditis Possibly Due to Moderna mRNA-1273 Vaccine

OBJECTIVES

Despite the clear benefits of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in mitigating the impact of the coronavirus disease 2019 pandemic, there are emerging reports of postvaccination myocarditis, the majority of which are diagnosed based on the clinical and radiologic findings without biopsy confirmation. We report a case of biopsy-confirmed lymphohistiocytic myocarditis after Moderna mRNA-1273 vaccination.

METHODS

We describe a case of a previously healthy 45-year-old woman who had palpitations, exercise intolerance, and syncope 1 week after her first mRNA-1273 vaccine dose. Laboratory tests and cardiac imaging were compatible with myocarditis. Given her unusual clinical presentation, an endomyocardial biopsy was performed to exclude other potential etiologies.

RESULTS

The endomyocardial biopsy specimen showed patchy endocardial and intramyocardial lymphohistiocytic infiltrates with scattered eosinophils and focal myocyte injury. CD3 and CD68 immunostains confirmed the lymphocytic and histiocytic nature of the infiltrate, respectively. A focal histiocytic collection suggestive of an ill-defined granuloma was present. The histologic and immunohistochemical findings of a lymphohistiocytic myocarditis were highly suggestive of a postvaccination hypersensitivity reaction.

CONCLUSIONS

Myocarditis following SARS-CoV-2 vaccination is a rare adverse event. The findings of a lymphohistiocytic myocarditis with scattered eosinophils and a possible ill-defined granuloma are highly suggestive of a hypersensitivity reaction. The mechanism by which this inflammation occurs remains uncertain. Despite our findings, the benefits of SARS-CoV-2 vaccination far outweigh the risks.

PQQ Supplementation and SARS-CoV-2 Spike Protein-Induced Heart Inflammation

SARS-CoV-2 spike protein-induced heart inflammation may originate from either COVID-19 infection or the administration of COVID-19 mRNA vaccines. As pyrroloquinoline quinone (PQQ) is a scavenger of free radicals, redox cofactor, and antioxidant which supports cognitive and mitochondrial functions, supplementation with PQQ could have a positive effect to reduce heart inflammation after COVID-19 mRNA vaccines. However, there is no evidence yet for this opportunity in the literature. Cellular and animal model results are missing. Similarly, no clinical trials have been conducted. While it is recommended to measure the levels of the cardiac biomarkers before and after COVID-19 vaccination, no recommendation can be made about supplementation with PQQ, which, however, we note has no contraindication.

Cardiac complications following mRNA COVID-19 vaccines: A systematic review of case reports and case series

There have been several local and systemic adverse events associated with mRNA COVID-19 vaccines. Pericarditis, myocarditis and myocardial infarction are examples of cardiac complications related to these vaccines. In this article, we conducted a systematic review of case reports and case series to identify the clinical profile, investigations, and management of reported cardiac complications post-mRNA COVID-19 vaccines. We systematically searched PubMed, Scopus, Web of Science, and Google Scholar, as well as the medRxiv preprint server, with terms including: 'SARS-CoV-2', 'COVID-19', 'messenger RNA vaccine*', 'mRNA-1273 vaccine', 'BNT162 vaccine', 'myocarditis', 'pericarditis', 'stroke' and 'Myocardial Ischemia' up to 25 September 2021. Studies were excluded if they were not case reports or case series, or reported cases from non-mRNA vaccines. Case reports and case series were included that investigated the potential cardiac complications associated with mRNA COVID-19 vaccines. The JBI checklist was used to assess quality and data synthesis was conducted using a qualitative methodology called narrative synthesis. Sixty-nine studies, including 43 case reports and 26 case series, were included. Myocarditis/myopericarditis and pericarditis were the most common adverse events among the 243 reported cardiac complications, post mRNA COVID-19 vaccination. Males with a median age of 21 years had the highest frequency of myocarditis. Almost three quarters (74.4%) of cases with myocarditis had received the BNT162b2 vaccine and 87.7% had received the second dose of the vaccine. Chest pain (96.1%) and fever (38.2%) were the most common presentations. CK-MB, troponin, and NT-proBNP were elevated in 100%, 99.5% and 78.3% of subjects, respectively. ST-segment abnormality was the most common electrocardiogram feature. Cardiac magnetic resonance imaging, which is the gold-standard approach for diagnosing myocarditis, was abnormal in all patients diagnosed with myocarditis. Non-steroidal anti-inflammatory drugs were the most prescribed medication for the management of myocarditis. Apart from inflammatory conditions, some rare cases of Takotsubo cardiomyopathy, myocardial infarction, myocardial infarction with non-obstructive coronary arteries, and isolated tachycardia were also reported following immunisation with mRNA COVID-19 vaccines. We acknowledge that only reviewing case reports and case series studies is one potential limitation of our study. We found that myocarditis was the most commonly reported adverse cardiac event associated with mRNA COVID-19 vaccines, which presented as chest pain with a rise in cardiac biomarkers. Further large-scale observational studies are recommended.