Death Caused by Myocarditis in Wayne County, Michigan

Myocarditis following COVID-19 vaccination: incidence, mechanisms, and clinical considerations

INTRODUCTION

Vaccines have demonstrated protection against the morbidity and mortality of COVID-19, but concerns regarding the rare side effect of acute myocarditis have stymied immunization efforts. This review aims to describe the incidence and theorized mechanisms of COVID vaccine-associated myocarditis and review relevant principles for management of vaccine-associated myocarditis.

AREAS COVERED

Epidemiologic studies of myocarditis after COVID vaccination are reviewed, which show an incidence of approximately 20-30 per million patients. The vast majority of these cases are seen with mRNA vaccines especially in male patients under 30 years of age. Mechanisms are largely theoretical, but molecular mimicry and dysregulated innate immune reactions have been proposed. While studies suggest that this subtype of myocarditis is mild and self-limited, long-term evidence is lacking. Principles of myocarditis treatment and surveillance are outlined as they apply to COVID vaccine-associated myocarditis.

EXPERT OPINION

COVID vaccine-associated myocarditis is rare but well described in certain at-risk groups. Better understanding of its pathogenesis is key to mitigating this complication and advancing vaccination efforts. Risk-benefit analyses demonstrate that individual- and population-level benefits of vaccination exceed the risks of this rare and mild form of myocarditis.

Sudden cardiac death caused by myocarditis in persons aged 1-49 years: a nationwide study of 14 294 deaths in Denmark

Myocarditis is associated with an increased risk of sudden cardiac death (SCD) in the young. However, information on nationwide burden of SCD caused by myocarditis (SCD-myocarditis) is sparse. For this study all deaths among persons in Denmark aged 1–35 years in 2000–2009 and 36–49 years in 2007–2009 (27.1 million person-years) were included. Autopsy reports, death certificates, discharge summaries, and nationwide registries were used to identify all cases of SCD-myocarditis. In the 10-year study period, there were 14 294 deaths, of which we identified 1 363 (10%) SCD. Among autopsied SCD (n = 753, 55%), cause of death was myocarditis in 42 (6%) cases corresponding to an SCD-myocarditis incidence of 0.16 (95%CI: 0.11–0.21) per 100 000 person-years. Males had significantly higher incidence rates of SCD-myocarditis compared to females with an incidence rate ratio of 2.2 (95%CI: 1.1–4.1). Myocarditis was not registered as cause of death in any of the non-autopsied SCD (n = 610, 45%). In conclusion, after nationwide unselected inclusion of 14 294 deaths, we found that 6% of all autopsied SCD was caused by myocarditis. No cases of SCD-myocarditis were reported in the non-autopsied SCD, which could reflect underdiagnosing of myocarditis in non-autopsied SCD. Furthermore, our data suggest a female protection towards SCD-myocarditis.

When is myocarditis indeed the cause of death?

Attribution of death to myocarditis continues to be a controversial issue in forensic pathology, despite the existence of established histopathological criteria as well as complementary investigations. The aim of the study was two-fold: (a) to retrospectively analyse the data obtained from a series of clinical and forensic autopsies in order to assess the number of cases with death attributed to myocarditis, and (b) to reevaluate these cases in order to assess how properly the histopathological diagnosis of myocarditis conformed to established criteria and therefore how accurately these were used on the basis of all postmortem investigation findings to conclude the cause of death. 2474 clinical and forensic autopsies were taken into consideration. Myocarditis was recorded as the official, underlying cause of death in 48 cases. Of those, 8 cases were considered to accurately conform to the histopathological Dallas criteria for the presence of myocarditis and could therefore be classified as cases of fatal myocarditis. In 19 out of 48 cases, description of focal myocarditis was considered to accurately fulfill the histopathological Dallas criteria for the presence of myocarditis. However, data provided by histological analysis and virology testing result reevaluation allowed alternative causes of death to be speculated. In another 21 out of 48 cases, description of focal myocardial inflammation was considered to inaccurately meet the histopathological Dallas criteria for the presence of myocarditis. The findings of our own study appear to be in agreement with previous observations in similar study groups and highlight that since myocarditis may occur in association with many diseases, a great deal of evidence is required before settling on categorical conclusions.

Demographic, clinical and pathological features of sudden deaths due to myocarditis: Results from a state-wide population-based autopsy study

Causes of sudden cardiac deaths have been widely reported with limited data focused specifically on myocarditis. A retrospective review of cases from the Office of the Chief Medical Examiner (OCME), State of Maryland yielded a total of 103 sudden unexpected deaths (SUDs) due to myocarditis (0.17% of all SUDs and 0.70% of autopsied SUDs) from 2005 through 2014. Most deaths occurred in patients <30 years of age with a male:female ratio 1.3:1. Of the 103 cases, 45 (43.7%) patients were witnessed collapsed. Four deaths occurred during exertion, such as exercising at the gym or performing heavy physical work, and 2 deaths were associated with emotional stress. The common cardiac macroscopic findings included ventricular dilatation (39.8%), mild coronary stenosis (17.5%), mottled myocardial appearance (15.5%), and myocardial fibrosis (10.7%). The histological classification of myocarditis was based on the predominant type of inflammatory cell infiltration. In our study group, lymphocytic myocarditis was most common, accounting for 56 cases (54.4%), followed by neutrophilic (32 cases, 31.7%), eosinophilic (13 cases, 12.6%) and giant cell type (2 cases, 1.9%). Microscopic examination revealed myocyte necrosis in 69 cases (67.0%) and interstitial or perivascular fibrosis in 48 cases (46.6%). The percentage of myocyte necrosis was 75.0% (42/58 cases) in lymphocytic, 65.6% (21/31 cases) in neutrophilic, 30.8% (4/13 cases) in eosinophilic, and 100% (2/2 cases) in giant cell myocarditis. Determination of myocarditis as cause of death continues to present a major challenge to forensic pathologists, because histopathologic findings can be subtle and the diagnosis of myocarditis remains difficult.

Phosphorylated Myosin Light Chain 2 (p-MLC2) as a Molecular Marker of Antemortem Coronary Artery Spasm

Background

It is not uncommon that only mild coronary artery stenosis is grossly revealed after a system autopsy. While coronary artery spasm (CAS) is the suspected mechanism of these deaths, no specific biomarker has been identified to suggest antemortem CAS.

Material/Methods

To evaluate the potential of using phosphorylated myosin light chain 2 (p-MLC2) as a diagnostic marker of antemortem CAS, human vascular smooth muscle cells (VSMCs) were cultured and treated with common vasoconstrictors, including prostaglandins F2α (PGF2α), acetylcholine (ACh), and 5-hydroxy tryptamine (5-HT). The p-MLC2 level was examined in the cultured cells using Western blot analysis and in a rat model of spasm provocation tests using immunohistochemistry (IHC). Effects of increased p-MLC2 level on VSMCs contractile activities were assessed in vitro using confocal immunofluorescence assay. Four fatal cases with known antemortem CAS were collected and subject to p-MLC2 detection.

Results

The p-MLC2 was significantly increased in VSMCs after treatments with vasoconstrictors and in the spasm provocation tests. Myofilament was well-organized and densely stained in VSMCs with high p-MLC2 level, but disarrayed in VSMCs with low p-MLC2 level. Three of the 4 autopsied cases showed strongly positive staining of p-MLC2 at the stenosed coronary segment and the adjacent interstitial small arteries. The fourth case was autopsied at the 6th day after death and showed negative-to-mild positive staining of p-MLC2.

Conclusions

p-MLC2 might be a useful marker for diagnosis of antemortem CAS. Autopsy should be performed as soon as possible to collect coronary arteries for detection of p-MLC2.

Diagnosis of myocarditis: Current state and future perspectives

Myocarditis, i.e. inflammation of the myocardium, is one of the leading causes of sudden cardiac death (SCD) and dilated cardiomyopathy (DCM) in young adults, and is an important cause of symptoms such as chest pain, dyspnea and palpitations. The pathophysiological process of disease progression leading to DCM involves an ongoing inflammation as a result of a viral-induced auto-immune response or a persisting viral infection. It is therefore crucial to detect the disease early in its course and prevent persisting inflammation that may lead to DCM and end-stage heart failure. Because of the highly variable clinical presentation, ranging from mild symptoms to severe heart failure, and the limited available diagnostic tools, the evaluation of patients with suspected myocarditis represents an important clinical dilemma in cardiology. New approaches for the diagnosis of myocarditis are needed in order to improve recognition, to help unravel its pathophysiology, and to develop new therapeutic strategies to treat the disease. In this review, we give a comprehensive overview of the current diagnostic strategies for patients with suspected myocarditis, and demonstrate several new techniques that may help to improve the diagnostic work-up.

The presence of enterovirus, adenovirus, and parvovirus B19 in myocardial tissue samples from autopsies: an evaluation of their frequencies in deceased individuals with myocarditis and in non-inflamed control hearts

PURPOSE

Multiple viruses have been detected in cardiac tissue, but their role in causing myocarditis remains controversial. Viral diagnostics are increasingly used in forensic medicine, but the interpretation of the results can sometimes be challenging. In this study, we examined the prevalence of adenovirus, enterovirus, and parvovirus B19 (PVB) in myocardial autopsy samples from myocarditis related deaths and in non-inflamed control hearts in an effort to clarify their significance as the causes of myocarditis in a forensic material.

METHODS

We collected all autopsy cases diagnosed with myocarditis from 1992 to 2010. Eighty-four suicidal deaths with morphologically normal hearts served as controls. Polymerase chain reaction was used for the detection of the viral genomes (adenovirus, enterovirus, and PVB) in myocardial tissue specimens. The distinction between acute and persistent PVB infection was made by the serological determination of PVB-specific immunoglobulins M and G.

RESULTS

PVB was detected in 33 of 112 (29 %) myocarditis cases and 37 of 84 (44 %) control cases. All of the samples were negative for the presence of adenovirus and enterovirus. Serological evidence of an acute PVB infection, determined by the presence of immunoglobulin M, was only present in one case. In the remaining cases, PVB was considered to be a bystander with no or limited association to myocardial inflammation.

CONCLUSION

In this study, adenovirus, enterovirus, and PVB were found to be rare causes of myocarditis. The detection of PVB in myocardial autopsy samples most likely represents a persistent infection with no or limited association with myocardial inflammation. The forensic investigation of myocardial inflammation demands a thorough examination, including special attention to non-viral causes and requires a multidisciplinary approach.

The effects of gender and age on occurrence of clinically suspected myocarditis in adulthood

OBJECTIVE

To study the effects of gender and age on occurrence of myocarditis.

DESIGN

Nationwide, multicentre registry study in Finland.

SETTING

All medical hospital admissions (n=1 698 397) of patients aged ≥ 16 years during 9.5 years in 29 hospitals.

PATIENTS

3198 myocarditis patients.

RESULTS

Myocarditis was more common in men (76.61%; 95% CI 75.11% to 78.05%) than in women (23.39%; 95% CI 21.95% to 24.89%, p<0.0001). Median age of patients was 33 years (IQR 23-50 years). Male patients were significantly younger than females (mean age 34.1 ± SD 15.1 vs 49.0 ± 18.7 years, p<0.0001). In men, occurrence was highest at 16-20 yrs of age, with a linear decline to elderliness (r=-0.95, p<0.0001). By contrast, myocarditis affected women more evenly at all ages with highest occurrence at the age of 56-60 years. Myocarditis caused 0.19% (95% CI 0.18% to 0.19%) of all medical admissions, and 0.48% (95% CI 0.46% to 0.49%) of admissions due to cardiovascular reasons with an inverse logarithmic association with age (r=-0.97, p<0.0001). Admissions were more commonly caused by myocarditis in men (risk ratio 3.11; 95% CI 2.87 to 3.38, p<0.0001).

CONCLUSIONS

Men are significantly more susceptible to myocarditis than women. Young men are especially at risk for acquiring myocarditis, while women are affected most commonly at the postmenopausal age. The proportion of hospital admissions caused by myocarditis has an inverse, logarithmic association with age.

Myocarditis at Post-Mortem Examination: A Forensic Perspective

Myocarditis is an uncommon cause of death but its myriad clinical presentations, young target population, diverse etiologies and potential to cause sudden unexpected death warrant its review. Myocarditis has been defined as myocardial necrosis and/or degeneration in the presence of an inflammatory infiltrate adjacent to the damaged myocytes. The type of predominant inflammatory cell present may assist with elucidating its pathoetiology. Ancillary testing as an adjunct to routine histopathological examination, such as immunohistochemical or immunofluorescence staining or detection of viral nucleic acid are of debatable diagnostic use in either the biopsy or autopsy setting. Myocarditis may clinically and/or histologically mimic other disease entities such as acute or organizing myocardial infarction, or hematological malignancy. There are no macroscopic pathognomonic features suggestive of myocarditis, thus in cases of unexplained sudden death it is vital to sample the heart extensively to rule out myocarditis. It is important to recognize that myocarditis may be an incidental finding in an autopsy. To attribute the cause of death to myocarditis, all relevant case findings including scene investigation, autopsy and ancillary testing including toxicology should be assessed.

What is Sudden Cardiac Death?

Sudden cardiac death (SCD) is a rapid, unexpected death due to cardiac causes. The differential diagnosis includes diseases from all four structural divisions of the heart: the blood vessels, myocardium, valves, and conduction system. Although ischemic heart disease is a common cause of SCD, acute myocardial infarcts and/or coronary thromboses are not always detected and are not required to make the diagnosis of death due to atherosclerotic coronary disease. Some people die suddenly from heart disease with a grossly and microscopically normal heart. Molecular analysis of some of these autopsy-negative, sudden unexplained deaths (SUD) may detect putative cardiac channel mutations.

There are three SCD scenarios that are of particular interest to forensic pathologists: sudden cardiac deaths in young athletes, during criminal altercations (homicide by heart attack), and in other hostile environments. In young athletes, most sudden deaths involve cardiac disease and include cardiomyopathies, congenital coronary artery anomalies, myocarditis, and channelopathies. One must, however, consider other causes in these deaths (e.g., commotio cordis, hyperthermia, sickle cell trait). Homicide-by-heart-attack deaths are those in which the cause of death is an acute exacerbation of underlying cardiac disease, however, the manner is homicide because a criminal act triggered the lethal pathologic cascade. A sudden cardiac arrest may occur in hostile locations with resultant trauma (e.g., while driving a motor vehicle). When the event occurs in the bathtub or other body of water, the question of whether the person died naturally from heart disease or unnaturally from trauma (e.g., drowning) often arises. One should not be mislead by the initial physical surroundings of the death (i.e., in a motor vehicle collision, or swimming pool) and fail to distinguish a natural sudden death from an accidental one.

Cardiovascular magnetic resonance of myocarditis

Within the past decade, cardiovascular magnetic resonance (CMR) imaging has led to unprecedented growth in our understanding of myocarditis. From what began as a diagnostic tool for assessing ventricular function, CMR has transitioned into visualizing changes that occur in myocardial tissue during inflammation, including edema, hyperemia/inflammation, and fibrosis. In terms of research applications, the entire spectrum ranging from subclinical to fulminant myocarditis can be visualized, as well as unmasking myocarditis from other cardiomyopathies. The impact of CMR in clinical applications is best exemplified by recent findings demonstrating that CMR is a leading diagnostic tool and may perhaps even be the method of choice for establishing a diagnosis of myocarditis in Germany. With the advent of an International Consensus Group on Cardiovascular Magnetic Resonance in Myocarditis and large-scale multicenter registries on CMR-based visualization of myocarditis, further advances aimed at improving clinical decision making and guiding patient therapy are expected.

Acute myocarditis-related complete atrioventricular block---an accidental finding in an acute appendicitis patient

We report a 20-year-old male patient with preoperatively undiagnosed myocarditis, who received general anesthesia for laparoscopic appendectomy. Because of arrhythmia, a cardiologist was consulted postoperatively. The 12-lead electrocardiogram showed complete atrioventricular block and the echocardiogram showed global hypokinesia of the left ventricle with impaired contractility, a left ejection fraction of 37%, and a dilated right heart. Subsequently, a permanent pacemaker was implanted and the patient was discharged from hospital without any complications.