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Demographic, clinical and pathological features of sudden deaths due to myocarditis: Results from a state-wide population-based autopsy study
Accepted Manuscript Title: Demographic, Clinical and Pathological Features of Sudden Deaths due to Myocarditis: results from a State-wide Population-Based Autopsy Study Author: Liliang Li Yang Zhang Allen Burke Aimin Xue Ziqin Zhao David Fowler Yiwen Shen Ling Li PII: DOI: Reference:
S0379-0738(16)30569-2 http://dx.doi.org/doi:10.1016/j.forsciint.2016.12.037 FSI 8715
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FSI
Received date: Revised date: Accepted date:
17-11-2016 26-12-2016 27-12-2016
Please cite this article as: Liliang Li, Yang Zhang, Allen Burke, Aimin Xue, Ziqin Zhao, David Fowler, Yiwen Shen, Ling Li, Demographic, Clinical and Pathological Features of Sudden Deaths due to Myocarditis: results from a State-wide Population-Based Autopsy Study, Forensic Science International http://dx.doi.org/10.1016/j.forsciint.2016.12.037 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Demographic, Clinical and Pathological Features of Sudden Deaths due to Myocarditis: results from a State-wide Population-Based Autopsy Study
Liliang Li1, 3, Yang Zhang2, Allen Burke2, Aimin Xue1, Ziqin Zhao1, David Fowler1, 2,3, Yiwen Shen1*, Ling Li1, 2, 3*
1
Department of Forensic Medicine, School of Basic Medical Sciences, Fudan
University, Shanghai 200032, P. R. China 2
Department of Pathology, University of Maryland School of Medicine, 21201, USA
3
Sino-US Forensic Science Research Center, Collaborative Innovation Center of
Judicial Civilization, Office of the Chief Medical Examiner, Baltimore, Maryland 21223, USA
*Corresponding authors: Dr. Ling Li, Sino-US Forensic Science Research Center, Collaborative Innovation Center of Judicial Civilization, Office of the Chief Medical Examiner. 900 West Baltimore Street, Baltimore, Maryland 21223, USA, telephone: +001 410 333 3260; Fax: +001 410 333 6501; Email: [email protected]) Or Dr. Yiwen Shen, Department of Forensic Medicine, School of Basic Medical Sciences, Fudan University. 138 Yixueyuan Road, Xuhui District, Shanghai 200032, P. R. China (email: [email protected]) 1
Highlights
Sudden deaths from myocarditis are studied over a 10-year period
Demographic, clinical and pathological features are analyzed
The incidence of fatal myocarditis is 0.70% of autopsied sudden deaths
In 17.5% cases, no significant myocyte necrosis is identified
Determination of myocarditis as cause of death remains a challenge to pathologist
ABSTRACT 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 2
histopathologic findings can be subtle and the diagnosis of myocarditis remains difficult.
Keywords: Sudden deaths; Myocarditis; Dilated cardiomyopathy; Certainty of diagnosis
1. Introduction Myocarditis is an inflammatory disease of the heart that can cause sudden and unexpected death in otherwise healthy individuals. A population-based study in reported that the death certificate-based incidence of fatal myocarditis was 0.46 per 100.000 person-years and that myocarditis was recorded to cause 0.47 of in all deaths was 0.47 of 1,000 deaths in the general Finland population from 1970 to 1998 [1]. A review of all deaths from Tokyo from 1958 to 1984 reported that myocarditis was the cause of death in 0.15% of autopsy cases [2]. In a 1996 study from France, 0.8% of sudden deaths were caused by myocarditis [3], and another study in the Southern Ontario between 1969 and 1978 indicated that 2.7% of sudden deaths were caused by viral myocarditis [4]. It has been reported that the incidence of myocarditis in sudden cardiac death was much higher in younger age groups (less than 35 years), with 12% of sudden cardiac deaths attributed to myocarditis in in young Australians [5] and 34.7% in a Chinese autopsy case study [6]. Myocarditis has been considered a common cause of dilated cardiomyopathy (DCM), which is defined by the presence of ventricular dilatation and ventricular systolic dysfunction [7,8]; however, the mechanism of myocarditis progression to DCM remains to be elucidated. In the forensic autopsy, ventricular dilatation is common in deaths due to myocarditis, especially in subacute and chronic myocarditis [2]. Identification of the association between myocarditis and DCM could contribute to a better understanding of the pathophysiology of myocarditis and its progression to DCM. Various degrees of certainty exist in defining the cause of a sudden death event [6]. Davies et al first introduced using probability in determining whether a pathologic 3
finding might account for sudden death by describing coronary artery lesions in 1999 [9]. A grading method for the certainty of diagnosis in sudden cardiac deaths was suggested by a European guideline in 2008 [10] and modified by other researchers in 2014 [6]. In the grading methods, the degree of certainty of diagnosis is classified as certain, highly probable and uncertain, and in the setting of probable and uncertain categories, further consideration of other pathologic findings is needed. Despite wide reports of the incidence of myocarditis and grading certainty in sudden unexpected death, no recent study has focused specifically on myocarditis. There are limited available data covering death scene investigation findings and certification of myocarditis as direct cause of death [11]. To our best knowledge, a systemic study of myocarditis as cause of death in forensic autopsy population has not been reported in the recent literature. This study aimed to provide updated statistical data of the incidence of myocarditis, to consider certainty of diagnosis of myocarditis as cause of death, and to better understand potential risk factors for progression of myocarditis to DCM in a state-wide medical examiner system in the United States. 2. Subjects and Methods 2.1. Setting The State of Maryland consists of 23 counties and a Baltimore city, with a population of 5,773,552 according to the 2014 U.S. Census. The Office of the Chief Medical Examiner (OCME) is a state-wide medical examiner system that is responsible for conducting death investigations and certifying the cause and manner of all nonnatural deaths, including homicides, suicides, accidents, and deaths that are sudden unexpected in the State of Maryland. The autopsy procedures/protocols at the OCME have been consistent for the past 20 years. All sudden unexpected deaths investigated by the OCME, which require autopsy examination, are subject to comprehensive evaluation involving death scene investigation, reviewing medical history, autopsy examination and toxicology analysis. The death scene investigation report included essential information such as demographics, related medical history, and circumstances surrounding deaths. 4
2.2. Case selection This was a retrospective review of all autopsied cases of sudden death due to myocarditis investigated by the OCME in the State of Maryland over a 10-year period from January 1, 2005 through December 31, 2014. Cases were selected with the following criteria: (1) sudden and unexpected deaths; (2) autopsied cases with complete records, including death scene investigation report and available medical records, autopsy report, toxicology report, and (3) myocarditis was the primary cause of death. 2.3. Characterization of myocarditis Myocarditis was sub-categorized as lymphocytic, eosinophilic, neutrophilic, and giant cell based on the type of predominant inflammatory cell infiltration. For the purpose of this study, the extent of inflammatory cell infiltration in the myocardium was classified under the microscopic examination into focal (≤3 areas of lesion with more than 10 inflammatory cell infiltration); Multiple focal (3 to 10 independent areas of more than 10 inflammatory cell infiltration); and diffuse (inflammatory cell infiltration scattered over the sections). 2.4. Subgrouping of the cases based on pathological findings Group 1-exclusive myocarditis without other remarkable autopsy findings; Group 2- myocarditis with macroscopic ventricular dilatation; Group 3-myocarditis with macroscopic dilatation and other findings; Group 4-myocarditis with other findings but without dilatation. 2.5. Grading of the certainty of diagnosis The grading method by Basso et al [10] and the supplementary method by Wang et al [6] have been used to classify the diagnostic certainty of myocarditis as certain, highly probable, and uncertain. We modified the grading system as following: (1) Certain: diffuse inflammatory cell infiltrates with myocyte necrosis or conduction system involvement; (2) Highly probable: multifocal inflammatory cell infiltrates, with myocyte necrosis, with or without conduction system involvement; (3) Uncertain: focal inflammatory cell infiltrate with or without significant myocyte necrosis. 2.6. Death evaluation 5
The following information was extracted for each case: (a) demographic data, including age, race, and gender; (b) investigation report, including the circumstances of death and known medical history prior to death. (c) autopsy findings; (d) toxicology report; and (e) postmortem virology testing results, including Influenza viruses, Parainfluenza virus 1, 2, 3, Adenovirus, Respiratory syncytial virus, Coxsackievirus and Enterovirus results, using real-time polymerase chain reaction (RT-PCR). 2.7. Statistical analysis Percentages in tables were calculated in each column unless otherwise indicated. Statistical analysis was performed using the Chi-square or Fisher’s exact tests to compare proportions, and the Student’s t-test (for two groups) or one-way ANOVA (for 3 or over groups) to compare means of continuous variables by SPSS 16.0 (Chicago, IL, USA). The Chi-square was used for categorical variables and ANOVA for continuous variables. Homogeneity of variance was tested before statistical analysis and the multiple testing correction (Bonferroni) was performed if required by chosen post-hoc test.
The ANOVA post-hoc test was used for individual group-wise
comparisons. After the one-way ANOVA, the Bonferroni’s tests were then performed for post-hoc comparison when appropriate. A difference was considered significant with a p value <0.05. 3. Results 3.1. Epidemiological profile The Office of Medical Examiner (OCME) is responsible for medico-legal investigation of all sudden unexpected deaths (SUDs) in the State of Maryland. Between January 1, 2005 and December 31, 2014, a total of 62,130 SUDs were investigated by the OCME in Maryland. Of the 62,130 SUDs, 14733 cases were autopsied (23.7%). The cause of death was certified as myocarditis in 103 cases, which was 0.17% of the total SUDs and 0.70% of the autopsied SUDs. Most of the cases were reported in 2005 (total 22 cases, 41 cases per 10,000 natural deaths) (Figure 1A). The number of death due to myocarditis occurred more frequently in the summer and winter seasons (Figure 1B). 6
Among the 103 recorded cases, 58 were male and 45 were female (male: female=1.3:1); 37 were African American and 51 were Caucasian. Mean age at death was 31±17 years with a median age of 30 years. More deaths occurred in age groups under 30 years (n=24 for <18 years of age and n=26 for 18-29 years of age). Incidence of myocarditis decreased after the age of 40-49 years. Death from myocarditis also showed sex-dependent differences among different age groups. In males, most cases occurred between age of 18-29 years, after which incidence decreased with aging. In females, most cases occurred prior to the age of 18 years, followed by a bell-shaped distribution with a peak in the age of 40-49 year group (Figure 2). 3.2. Circumstances of death A total of 73 patients was pronounced dead at their residence (Table 1). Nineteen patients died in emergency rooms or hospitals, and the remaining 11 died in public places, including in vehicles or at the gym. Forty-five deaths were witnessed. The individuals were witnessed suddenly collapsed. The other 58 deaths were unwitnessed, 17 of which occurred within 1 hour from the time when they were
last seen alive, 32
deaths occurred within 6 to 12 hours and 4 were within 24 hours from the time when they were last seen alive. The other 3 individuals were found dead more than 24 hours from the time when they were last seen alive. The postmortem interval (PMI) was estimated based on the time of last seen alive to the time of the autopsy. Of the 103 cases, 95 had PMI less than 24 hours, 6 cases had PMI between 24 hours and 48 hours, and 2 cases had PMI more than 48 hours. The PMI ranged from 9 hours to 56 hours with mean PMI of 18 hours. There was no evidence of decomposition or tissue autolysis noted at time of autopsy. Conditions surrounding death were recorded in 66 cases, with 34 deaths occurring during sleeping or resting. Twenty-six deaths occurred during normal daily 7
activity such as walking, working or watching TV. Four deaths occurred during exertion, such as exercising at the gym or heavy physical work, and 2 deaths were associated with emotional stress. A history of recent travel was recorded in 6 cases. Of the 103 cases, 86 (83.5%) individuals reported chest pain, nausea, or palpitations during a time period less than 1 day to more than 2 weeks prior to their deaths. None of the patients sought medical attention. 3.3. Pathological findings Systematic case review showed that 64 cases of myocarditis were associated with other pathological findings, such as ventricular dilatation (41 cases), mild coronary stenosis (18 cases) and mottled myocardial appearance (16 cases). Macroscopic myocardial scarring/ fibrosis was seen in 11 cases. Myocardial bridge and pericardial effusion were each seen in 7 cases (Table 2). Cardiomegaly was diagnosed if the heart weight is >95% confidence interval for body height and weight based on previously published literature [12,13]. Of the 103 cases, 27 (26.2%) showed enlarged heart, among which 24 were adults and 3 were juveniles. The percentage of cardiomegaly in adults was significantly higher than that in juveniles (p=0.03). Of the 41 cardiomegaly cases, 11 had significant ventricular dilatation. Histologically, lymphocytic myocarditis was most common type, 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%) (Figure 3A). Involvement of the cardiac conduction system was seen in 3 cases (2.9%). 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 in lymphocytic and neutrophilic subtypes were significantly higher than those rates in eosinophilic subtype (p=0.02). 8
(Table 3). Of the 103 cases, 18 cases showed only focal inflammatory cell infiltrate without significant myocyte necrosis. The locations of focal myocarditis findings were as follows: left ventricular myocardium (6 cases); right ventricular myocardium (5 cases); ventricular septum (4 cases); and left and right ventricular myocardium (3 cases. Based on macroscopic examination, 39 cases had other cardiac findings: 41 cases with significant ventricular dilatation, of which 25 cases with mild coronary atherosclerosis and/or myocardial bridge, and 23 cases did not have ventricular dilatation but with mild coronary atherosclerosis and/or myocardial bridge. Table 4 shows the macroscopic findings and comparisons with other general characteristics. 3.4. Diagnostic certainty Based on our modified method, 48 cases were assigned as certain, 37 as highly probable and 18 as uncertain (Figure 4). Statistical analysis showed there was no significant difference among the three subgroups with regard to the assessed categories (Table 5). 4. Discussion Although myocarditis is usually a mild disease with a favorable outcome, it may sometimes cause sudden death. The incidence of death due to myocarditis has been previously reported in a range from 0.047-34.7%, with younger patients disproportionately represented among all the deaths [1-5]. In the USA, the incidence of myocarditis in forensic autopsy population was 0.6% in the State of Indiana from 1987 to 1991 [14]. In Wayne County, the State of Michigan, the incidence was reported as 1.3% from 1996 to 2004 [15]. In our study, the incidence of myocarditis as a cause of sudden death was 0.17% of all natural deaths in our forensic autopsy population from 2005 to 2014. In this study, males were more than females (male: female=1.3:1), which is consistent with other reports [1,6,16]. In contrast to coronary artery disease, which 9
predisposes more elderly patients to sudden deaths, fatal myocarditis was more prevalent in younger population, with age less than 30 years. Patients with myocarditis may experience nonspecific prodromal symptoms before their fatal cardiac event. Of the 103 cases of myocarditis, over 80% of individuals reported prodromal symptoms, such as chest pain, nausea and/or palpitation, often one or two weeks prior to death, indicating that acute and subacute phases predisposed myocarditis patients to sudden death [17]. None of the patients sought medical attention. Consistent with a previous report [6], myocarditis-induced sudden death usually occurs during normal daily actives or at sleep, not related to emotional stress or physical exertion. Increased heart weight was observed in 26% of cases in our study, which was significantly lower than reported rate in autopsy studies, ranging from 50% to 65% [18-20]. It has been reported that African American patients with myocarditis have a significantly higher rate of increased heart weight [21], but other study indicated that heart weight has no significant correlation with myocarditis [22]. Investigators have speculated for decades on the possibility that myocarditis is a common forerunner of ‘idiopathic’ dilated cardiomyopathy [23]. Accumulating data has revealed an important inflammatory component in the pathogenesis of DCM, and there is growing evidence that myocarditis and DCM are closely related [23-25]. Myocarditis can be induced by a number of viruses and represents a significant cause of death especially in young individuals. Among the viruses, the most cited are enteroviruses (especially coxsackievirus), adenovirus, parvovirus B19, human herpesvirus 6, human cytomegalovirus, Epstein–Barr virus, and hepatitis virus. Following infection, patients may develop lymphocytic, eosinophilic, or giant cell/granulomatous myocardial inflammation [26]. The availability of endomyocardial biopsies has brought renewed attention to the importance of persistent virus in chronic myocarditis and dilated cardiomyopathy and clinically, viral genomic analysis in endomyocardial biopsies is proving of value in determining cause and deciding future [26,27]. Our study revealed that 103 patients who died from myocarditis were clinically undiagnosed. Of the 103 patients, 41 (39.8%) had significant ventricular 10
dilatation. Postmortem diagnosis of cardiomegaly can be established by the measurements of heart weight and body height and weight. Cardiomegaly is diagnosed if the heart weight is >95% confidence interval for body height and weight [12,13]. Of the 41 cases with ventricular dilatation, 11 individuals also had cardiomegaly. Viral genomic analysis of autopsied myocarditis’ heart may shed light on the relationship of myocarditis and DCM. 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. A consensus statement was presented in 1987 with histopathologic definition for diagnosis [28, 29]. According to these Dallas criteria [29], the histopathologic diagnosis of myocarditis is based on necrosis or degeneration of the myocytes not characteristic of an ischemic event and an adjacent inflammatory infiltrate, while borderline myocarditis requires a less intense inflammatory infiltrate and no light microscopic evidence of myocyte destruction. Previous studies indicated that myocarditis is overdiagnosed on routine autopsies, particularly in patients who have died suddenly or are found dead, with only 32% of death certificate-based myocarditis judged as meeting the Dallas criteria on histopathologic reanalysis [1,30]. Focal myocardial inflammatory infiltration with or without significant myocyte necrosis had been used as cause of sudden death by forensic pathologists if complete autopsy and toxicological analysis was negative. In the present study, microscopic examination revealed myocyte necrosis in 69 of 103 cases (67.0%). Histological sampling limitation and variation in expert interpretation may explain the lock of myocyte necrosis in certain cases. In summary, myocarditis may cause sudden death. In cases of sudden unexpected death, especially sudden death in young people, forensic pathologists should consider myocarditis as possible cause. Representative sections from anterior, lateral, and posterior wall of atria and ventricles, and sections from ventricular septum should be submitted for microscopic examination. Postmortem diagnosis of borderline myocarditis (focal myocardial inflammatory infiltrate with no obvious microscopic evidence of myocyte destruction) may be used as cause of sudden death in 11
conjunction with clinical presentation, death scene findings and complete autopsy examination including comprehensive toxicological testing. Acknowledgements The authors want to thank Dr. Jennifer Bynum from Johns Hopkins Pathology Department for her assistance in manuscript preparation. This study was supported by the Key Projects of National Natural Science Foundation of China (No. 81430047) and the China Postdoctoral Science Foundation (No. 2016M601507). Dr. Liliang Li acknowledges the financial support from the State Scholarship Fund of China Scholarship Council (No.: 201306100058) for his visit to the University of Maryland School of Medicine and Office of the Chief Medical Examiner, Baltimore, MD, USA where data collection and slides review were performed. This project was in part supported by the Collaborative Innovation Center of Judicial Civilization, China University of Political Science and Law.
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pathology in 2007 consecutive forensic autopsies, Clin. Cardiol. 15 (1992) 760-765. [15] F.J. Diaz, C. Loewe, A. Jackson, Death caused by myocarditis in Wayne County, Michigan: a 9-year retrospective study, Am J Forensic Med Pathol 27 (2006) 300303. [16] J.W. Mason, J.B. O'Connell, A. Herskowitz, N.R. Rose, B.M. McManus, M.E. Billingham, et al., A clinical trial of immunosuppressive therapy for myocarditis. The Myocarditis Treatment Trial Investigators, N Engl J Med 333 (1995) 269-275. [17] M.A. Pettit, A. Koyfman, M. Foran, Myocarditis, Pediatr. Emerg. Care 30 (2014) 832-835, 836-838. [18] P. Fornes, D. Lecomte, G. Nicolas, Sudden out-of-hospital coronary death in patients with no previous cardiac history. An analysis of 221 patients studied at autopsy, J. Forensic Sci. 38 (1993) 1084-1091. [19] F. Tavora, Y. Zhang, M. Zhang, L. Li, M. Ripple, D. Fowler, et al., Cardiomegaly is a common arrhythmogenic substrate in adult sudden cardiac deaths, and is associated with obesity, Pathology 44 (2012) 187-191. [20] M.T. Subirana, J.O. Juan-Babot, T. Puig, J. Lucena, A. Rico, M. Salguero, et al., Specific characteristics of sudden death in a mediterranean Spanish population, Am. J. Cardiol. 107 (2011) 622-627. [21] A.P. Burke, A. Farb, R. Virmani, J. Goodin, J.E. Smialek, Sports-related and non-sports-related sudden cardiac death in young adults, Am. Heart J. 121 (1991) 568-575. [22] M.A. Weber, M.T. Ashworth, R.A. Risdon, M. Malone, M. Burch, N.J. Sebire, Clinicopathological features of paediatric deaths due to myocarditis: an autopsy series, Arch. Dis. Child. 93 (2008) 594-598. [23] J.W. Mason, Myocarditis and dilated cardiomyopathy: an inflammatory link, Cardiovasc. Res. 60 (2003) 5-10. [24] C. Kawai, From myocarditis to cardiomyopathy: mechanisms of inflammation and cell death: learning from the past for the future, Circulation 99 (1999) 1091-1100. [25] R.D. Latham, J.P. Mulrow, R. Virmani, M. Robinowitz, J.M. Moody, Recently diagnosed idiopathic dilated cardiomyopathy: incidence of myocarditis and efficacy 14
of prednisone therapy, Am. Heart J. 117 (1989) 876-882. [26] N.R. Rose, Viral myocarditis, Curr. Opin. Rheumatol. 28 (2016) 383-389. [27] F. Dominguez, U. Kuhl, B. Pieske, P. Garcia-Pavia, C. Tschope, Update on Myocarditis and Inflammatory Cardiomyopathy: Reemergence of Endomyocardial Biopsy, Rev Esp Cardiol (Engl Ed) 69 (2016) 178-187. [28] H.T. Aretz, M.E. Billingham, W.D. Edwards, S.M. Factor, J.T. Fallon, J.J. Fenoglio, et al., Myocarditis. A histopathologic definition and classification, Am J Cardiovasc Pathol 1 (1987) 3-14. [29] H.T. Aretz, Myocarditis: the Dallas criteria, Hum. Pathol. 18 (1987) 619-624. [30] V. Kyto, P. Saukko, E. Lignitz, G. Schwesinger, V. Henn, A. Saraste, et al., Diagnosis and presentation of fatal myocarditis, Hum. Pathol. 36 (2005) 1003-1007.
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Figure legends Figure 1. Case distribution by year (A) and month (B) (n=103).
Figure 2. Case distribution by age and gender (n=103).
Figure 3. The death distribution by histological classification (n=103).
Figure 4. The death distribution by degrees of diagnostic certainty (n=103).
16
17
Table legends Table 1. Circumstances of deaths Categories Location of death Residence ER or hospital Public locations Witnessed death Yes No Activity prior to death Sleeping or resting Normal daily activity Physical exertion Emotional stress Prodrome (chest pain, nausea, or palpitation) Yes No or unknown ER, emergency room.
18
Number
Percentage (%)
73 19 11
70.9 18.4 10.7
45 58
43.7 56.3
34 26 4 2
33.0 25.2 3.9 1.9
86 17
83.5 16.5
Table 2. Macroscopic findings Macroscopic findings Ventricular dilatation Mild coronary stenosis Mottled myocardial appearance Macroscopic scarring/fibrosis Myocardial bridge Pericardial effusion
Number 41 18 16 11 7 7
19
Percentage (%) 39.8 17.5 15.5 10.7 6.8 6.8
Table 3. Association of histological classification with myocyte necrosis and microscopic fibrosis Category Total Lymphocytic Neutrophilic Eosinophilic Giant cell N (%) (n=56) (n=32) (n=13) (n=2) N (%) N (%) N (%) N (%) Myocyte necrosis 69 (100) 42 (75.0) 21 (65.6) 4 (30.8) 2 (100) Fibrosis 48 (100) 29 (51.8) 13 (38.5) 5 (38.5) 1 (50)
20
P value 0.02 0.76
Table 4. Macroscopic findings and comparisons with other general characteristics group 1 group 2 group 3 group 4 P Categories (n=39) (n=16) (n=25) (n=23) value Age (years) 29±17 35±20 34±16 30±16 0.566 a a Male gender, N (%) 15(38.5) 9(56.3) 17(68.0) 17(73.9) 0.023 With prodrome, N (%) 33(84.6) 15(93.8) 17(68.0) 21(91.3) 0.083 2 a a BMI (kg/m ) 23.9±4.9 28.3±6.0 27.8±7.6 25.9±5.7 0.017 a a Heart weight (g) 321±125 382±153 416±138 424±129 0.011 † a, c Cardiomegaly , N (%) 5 (12.8) 6 (37.5) 5 (20.0) 11 (47.8) 0.012 Lymphocytic subtype, N (%) 23(59.0) 7(43.8) 12(48.0) 14(60.9) 0.613 Myocyte necrosis, N (%) 29 (74.4) 8 (50.0) 16 (64.0) 16 (69.6) 0.364 a ,b a, c Microscopic fibrosis, N (%) 8 (20.5) 6 (37.5) 21 (84.0) 13 (56.5) <0.001 Group 1-myocarditis without other cardiac findings Group 2- myocarditis with significant ventricular dilatation Group 3-myocarditis with significant dilatation and other findings (mild coronary atherosclerosis and/or myocardial bridge Group 4-myocarditis with no ventricular dilatation, but with mild coronary atherosclerosis and/or myocardial bridge. a p<0.05 vs. group 1; bp<0.05 vs. group 2; cp<0.05 vs. group 3. BMI, Body Mass Index. † Cardiomegaly is diagnosed if the heart weight is >95% confidence interval for body height and weight [12,13].
21
Table 5. Diagnostic certainty by clinical and histological characteristics Categories Certain Highly Uncertai (n=48) probable n (n=18) (n=37) Age (years) 31±18 29±16 35±16 2 BMI (kg/m ) 25.8±5.4 27.1±6.7 26.5±7.4 Heart weight (g) 375±151 391±138 352±109 † Cardiomegaly , N (%) 14 (29.2) 8 (21.6) 5 (27.8) With prodrome, N (%) 43 (89.6) 28 (75.7) 13 (72.2) Death triggers, N (%) Resting 16 (33.3) 10 (27.0) 8 (44.4) Normal daily activity 13 (27.1) 9 (24.3) 4 (22.2) Under stress 2 (4.2) 4 (10.8) 1 (5.6) Histological type*, N (%) Lymphocytic 23 (47.9) 22 (59.5) 11 (61.1) Neutrophilic 17 (35.4) 9 (24.3) 6 (33.3) Eosinophilic 6 (12.5) 6 (16.2) 1 (5.6) Microscopic fibrosis, N 21 (43.8) 21 (56.8) 6 (33.3) (%) Myocyte necrosis, N (%) 34 (70.8) 21 (56.8) 14 (77.8) † Cardiomegaly was determined based on previously published literatures [12,13]; *Two cases of giant cell myocarditis were not included because of limited cases.
22
P value 0.44 0.65 0.62 0.73 0.14 0.43 0.91 0.47 0.47 0.54 0.53 0.23 0.22
S0379-0738(16)30569-2 http://dx.doi.org/doi:10.1016/j.forsciint.2016.12.037 FSI 8715
To appear in:
FSI
Received date: Revised date: Accepted date:
17-11-2016 26-12-2016 27-12-2016
Please cite this article as: Liliang Li, Yang Zhang, Allen Burke, Aimin Xue, Ziqin Zhao, David Fowler, Yiwen Shen, Ling Li, Demographic, Clinical and Pathological Features of Sudden Deaths due to Myocarditis: results from a State-wide Population-Based Autopsy Study, Forensic Science International http://dx.doi.org/10.1016/j.forsciint.2016.12.037 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Demographic, Clinical and Pathological Features of Sudden Deaths due to Myocarditis: results from a State-wide Population-Based Autopsy Study
Liliang Li1, 3, Yang Zhang2, Allen Burke2, Aimin Xue1, Ziqin Zhao1, David Fowler1, 2,3, Yiwen Shen1*, Ling Li1, 2, 3*
1
Department of Forensic Medicine, School of Basic Medical Sciences, Fudan
University, Shanghai 200032, P. R. China 2
Department of Pathology, University of Maryland School of Medicine, 21201, USA
3
Sino-US Forensic Science Research Center, Collaborative Innovation Center of
Judicial Civilization, Office of the Chief Medical Examiner, Baltimore, Maryland 21223, USA
*Corresponding authors: Dr. Ling Li, Sino-US Forensic Science Research Center, Collaborative Innovation Center of Judicial Civilization, Office of the Chief Medical Examiner. 900 West Baltimore Street, Baltimore, Maryland 21223, USA, telephone: +001 410 333 3260; Fax: +001 410 333 6501; Email: [email protected]) Or Dr. Yiwen Shen, Department of Forensic Medicine, School of Basic Medical Sciences, Fudan University. 138 Yixueyuan Road, Xuhui District, Shanghai 200032, P. R. China (email: [email protected]) 1
Highlights
Sudden deaths from myocarditis are studied over a 10-year period
Demographic, clinical and pathological features are analyzed
The incidence of fatal myocarditis is 0.70% of autopsied sudden deaths
In 17.5% cases, no significant myocyte necrosis is identified
Determination of myocarditis as cause of death remains a challenge to pathologist
ABSTRACT 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 2
histopathologic findings can be subtle and the diagnosis of myocarditis remains difficult.
Keywords: Sudden deaths; Myocarditis; Dilated cardiomyopathy; Certainty of diagnosis
1. Introduction Myocarditis is an inflammatory disease of the heart that can cause sudden and unexpected death in otherwise healthy individuals. A population-based study in reported that the death certificate-based incidence of fatal myocarditis was 0.46 per 100.000 person-years and that myocarditis was recorded to cause 0.47 of in all deaths was 0.47 of 1,000 deaths in the general Finland population from 1970 to 1998 [1]. A review of all deaths from Tokyo from 1958 to 1984 reported that myocarditis was the cause of death in 0.15% of autopsy cases [2]. In a 1996 study from France, 0.8% of sudden deaths were caused by myocarditis [3], and another study in the Southern Ontario between 1969 and 1978 indicated that 2.7% of sudden deaths were caused by viral myocarditis [4]. It has been reported that the incidence of myocarditis in sudden cardiac death was much higher in younger age groups (less than 35 years), with 12% of sudden cardiac deaths attributed to myocarditis in in young Australians [5] and 34.7% in a Chinese autopsy case study [6]. Myocarditis has been considered a common cause of dilated cardiomyopathy (DCM), which is defined by the presence of ventricular dilatation and ventricular systolic dysfunction [7,8]; however, the mechanism of myocarditis progression to DCM remains to be elucidated. In the forensic autopsy, ventricular dilatation is common in deaths due to myocarditis, especially in subacute and chronic myocarditis [2]. Identification of the association between myocarditis and DCM could contribute to a better understanding of the pathophysiology of myocarditis and its progression to DCM. Various degrees of certainty exist in defining the cause of a sudden death event [6]. Davies et al first introduced using probability in determining whether a pathologic 3
finding might account for sudden death by describing coronary artery lesions in 1999 [9]. A grading method for the certainty of diagnosis in sudden cardiac deaths was suggested by a European guideline in 2008 [10] and modified by other researchers in 2014 [6]. In the grading methods, the degree of certainty of diagnosis is classified as certain, highly probable and uncertain, and in the setting of probable and uncertain categories, further consideration of other pathologic findings is needed. Despite wide reports of the incidence of myocarditis and grading certainty in sudden unexpected death, no recent study has focused specifically on myocarditis. There are limited available data covering death scene investigation findings and certification of myocarditis as direct cause of death [11]. To our best knowledge, a systemic study of myocarditis as cause of death in forensic autopsy population has not been reported in the recent literature. This study aimed to provide updated statistical data of the incidence of myocarditis, to consider certainty of diagnosis of myocarditis as cause of death, and to better understand potential risk factors for progression of myocarditis to DCM in a state-wide medical examiner system in the United States. 2. Subjects and Methods 2.1. Setting The State of Maryland consists of 23 counties and a Baltimore city, with a population of 5,773,552 according to the 2014 U.S. Census. The Office of the Chief Medical Examiner (OCME) is a state-wide medical examiner system that is responsible for conducting death investigations and certifying the cause and manner of all nonnatural deaths, including homicides, suicides, accidents, and deaths that are sudden unexpected in the State of Maryland. The autopsy procedures/protocols at the OCME have been consistent for the past 20 years. All sudden unexpected deaths investigated by the OCME, which require autopsy examination, are subject to comprehensive evaluation involving death scene investigation, reviewing medical history, autopsy examination and toxicology analysis. The death scene investigation report included essential information such as demographics, related medical history, and circumstances surrounding deaths. 4
2.2. Case selection This was a retrospective review of all autopsied cases of sudden death due to myocarditis investigated by the OCME in the State of Maryland over a 10-year period from January 1, 2005 through December 31, 2014. Cases were selected with the following criteria: (1) sudden and unexpected deaths; (2) autopsied cases with complete records, including death scene investigation report and available medical records, autopsy report, toxicology report, and (3) myocarditis was the primary cause of death. 2.3. Characterization of myocarditis Myocarditis was sub-categorized as lymphocytic, eosinophilic, neutrophilic, and giant cell based on the type of predominant inflammatory cell infiltration. For the purpose of this study, the extent of inflammatory cell infiltration in the myocardium was classified under the microscopic examination into focal (≤3 areas of lesion with more than 10 inflammatory cell infiltration); Multiple focal (3 to 10 independent areas of more than 10 inflammatory cell infiltration); and diffuse (inflammatory cell infiltration scattered over the sections). 2.4. Subgrouping of the cases based on pathological findings Group 1-exclusive myocarditis without other remarkable autopsy findings; Group 2- myocarditis with macroscopic ventricular dilatation; Group 3-myocarditis with macroscopic dilatation and other findings; Group 4-myocarditis with other findings but without dilatation. 2.5. Grading of the certainty of diagnosis The grading method by Basso et al [10] and the supplementary method by Wang et al [6] have been used to classify the diagnostic certainty of myocarditis as certain, highly probable, and uncertain. We modified the grading system as following: (1) Certain: diffuse inflammatory cell infiltrates with myocyte necrosis or conduction system involvement; (2) Highly probable: multifocal inflammatory cell infiltrates, with myocyte necrosis, with or without conduction system involvement; (3) Uncertain: focal inflammatory cell infiltrate with or without significant myocyte necrosis. 2.6. Death evaluation 5
The following information was extracted for each case: (a) demographic data, including age, race, and gender; (b) investigation report, including the circumstances of death and known medical history prior to death. (c) autopsy findings; (d) toxicology report; and (e) postmortem virology testing results, including Influenza viruses, Parainfluenza virus 1, 2, 3, Adenovirus, Respiratory syncytial virus, Coxsackievirus and Enterovirus results, using real-time polymerase chain reaction (RT-PCR). 2.7. Statistical analysis Percentages in tables were calculated in each column unless otherwise indicated. Statistical analysis was performed using the Chi-square or Fisher’s exact tests to compare proportions, and the Student’s t-test (for two groups) or one-way ANOVA (for 3 or over groups) to compare means of continuous variables by SPSS 16.0 (Chicago, IL, USA). The Chi-square was used for categorical variables and ANOVA for continuous variables. Homogeneity of variance was tested before statistical analysis and the multiple testing correction (Bonferroni) was performed if required by chosen post-hoc test.
The ANOVA post-hoc test was used for individual group-wise
comparisons. After the one-way ANOVA, the Bonferroni’s tests were then performed for post-hoc comparison when appropriate. A difference was considered significant with a p value <0.05. 3. Results 3.1. Epidemiological profile The Office of Medical Examiner (OCME) is responsible for medico-legal investigation of all sudden unexpected deaths (SUDs) in the State of Maryland. Between January 1, 2005 and December 31, 2014, a total of 62,130 SUDs were investigated by the OCME in Maryland. Of the 62,130 SUDs, 14733 cases were autopsied (23.7%). The cause of death was certified as myocarditis in 103 cases, which was 0.17% of the total SUDs and 0.70% of the autopsied SUDs. Most of the cases were reported in 2005 (total 22 cases, 41 cases per 10,000 natural deaths) (Figure 1A). The number of death due to myocarditis occurred more frequently in the summer and winter seasons (Figure 1B). 6
Among the 103 recorded cases, 58 were male and 45 were female (male: female=1.3:1); 37 were African American and 51 were Caucasian. Mean age at death was 31±17 years with a median age of 30 years. More deaths occurred in age groups under 30 years (n=24 for <18 years of age and n=26 for 18-29 years of age). Incidence of myocarditis decreased after the age of 40-49 years. Death from myocarditis also showed sex-dependent differences among different age groups. In males, most cases occurred between age of 18-29 years, after which incidence decreased with aging. In females, most cases occurred prior to the age of 18 years, followed by a bell-shaped distribution with a peak in the age of 40-49 year group (Figure 2). 3.2. Circumstances of death A total of 73 patients was pronounced dead at their residence (Table 1). Nineteen patients died in emergency rooms or hospitals, and the remaining 11 died in public places, including in vehicles or at the gym. Forty-five deaths were witnessed. The individuals were witnessed suddenly collapsed. The other 58 deaths were unwitnessed, 17 of which occurred within 1 hour from the time when they were
last seen alive, 32
deaths occurred within 6 to 12 hours and 4 were within 24 hours from the time when they were last seen alive. The other 3 individuals were found dead more than 24 hours from the time when they were last seen alive. The postmortem interval (PMI) was estimated based on the time of last seen alive to the time of the autopsy. Of the 103 cases, 95 had PMI less than 24 hours, 6 cases had PMI between 24 hours and 48 hours, and 2 cases had PMI more than 48 hours. The PMI ranged from 9 hours to 56 hours with mean PMI of 18 hours. There was no evidence of decomposition or tissue autolysis noted at time of autopsy. Conditions surrounding death were recorded in 66 cases, with 34 deaths occurring during sleeping or resting. Twenty-six deaths occurred during normal daily 7
activity such as walking, working or watching TV. Four deaths occurred during exertion, such as exercising at the gym or heavy physical work, and 2 deaths were associated with emotional stress. A history of recent travel was recorded in 6 cases. Of the 103 cases, 86 (83.5%) individuals reported chest pain, nausea, or palpitations during a time period less than 1 day to more than 2 weeks prior to their deaths. None of the patients sought medical attention. 3.3. Pathological findings Systematic case review showed that 64 cases of myocarditis were associated with other pathological findings, such as ventricular dilatation (41 cases), mild coronary stenosis (18 cases) and mottled myocardial appearance (16 cases). Macroscopic myocardial scarring/ fibrosis was seen in 11 cases. Myocardial bridge and pericardial effusion were each seen in 7 cases (Table 2). Cardiomegaly was diagnosed if the heart weight is >95% confidence interval for body height and weight based on previously published literature [12,13]. Of the 103 cases, 27 (26.2%) showed enlarged heart, among which 24 were adults and 3 were juveniles. The percentage of cardiomegaly in adults was significantly higher than that in juveniles (p=0.03). Of the 41 cardiomegaly cases, 11 had significant ventricular dilatation. Histologically, lymphocytic myocarditis was most common type, 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%) (Figure 3A). Involvement of the cardiac conduction system was seen in 3 cases (2.9%). 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 in lymphocytic and neutrophilic subtypes were significantly higher than those rates in eosinophilic subtype (p=0.02). 8
(Table 3). Of the 103 cases, 18 cases showed only focal inflammatory cell infiltrate without significant myocyte necrosis. The locations of focal myocarditis findings were as follows: left ventricular myocardium (6 cases); right ventricular myocardium (5 cases); ventricular septum (4 cases); and left and right ventricular myocardium (3 cases. Based on macroscopic examination, 39 cases had other cardiac findings: 41 cases with significant ventricular dilatation, of which 25 cases with mild coronary atherosclerosis and/or myocardial bridge, and 23 cases did not have ventricular dilatation but with mild coronary atherosclerosis and/or myocardial bridge. Table 4 shows the macroscopic findings and comparisons with other general characteristics. 3.4. Diagnostic certainty Based on our modified method, 48 cases were assigned as certain, 37 as highly probable and 18 as uncertain (Figure 4). Statistical analysis showed there was no significant difference among the three subgroups with regard to the assessed categories (Table 5). 4. Discussion Although myocarditis is usually a mild disease with a favorable outcome, it may sometimes cause sudden death. The incidence of death due to myocarditis has been previously reported in a range from 0.047-34.7%, with younger patients disproportionately represented among all the deaths [1-5]. In the USA, the incidence of myocarditis in forensic autopsy population was 0.6% in the State of Indiana from 1987 to 1991 [14]. In Wayne County, the State of Michigan, the incidence was reported as 1.3% from 1996 to 2004 [15]. In our study, the incidence of myocarditis as a cause of sudden death was 0.17% of all natural deaths in our forensic autopsy population from 2005 to 2014. In this study, males were more than females (male: female=1.3:1), which is consistent with other reports [1,6,16]. In contrast to coronary artery disease, which 9
predisposes more elderly patients to sudden deaths, fatal myocarditis was more prevalent in younger population, with age less than 30 years. Patients with myocarditis may experience nonspecific prodromal symptoms before their fatal cardiac event. Of the 103 cases of myocarditis, over 80% of individuals reported prodromal symptoms, such as chest pain, nausea and/or palpitation, often one or two weeks prior to death, indicating that acute and subacute phases predisposed myocarditis patients to sudden death [17]. None of the patients sought medical attention. Consistent with a previous report [6], myocarditis-induced sudden death usually occurs during normal daily actives or at sleep, not related to emotional stress or physical exertion. Increased heart weight was observed in 26% of cases in our study, which was significantly lower than reported rate in autopsy studies, ranging from 50% to 65% [18-20]. It has been reported that African American patients with myocarditis have a significantly higher rate of increased heart weight [21], but other study indicated that heart weight has no significant correlation with myocarditis [22]. Investigators have speculated for decades on the possibility that myocarditis is a common forerunner of ‘idiopathic’ dilated cardiomyopathy [23]. Accumulating data has revealed an important inflammatory component in the pathogenesis of DCM, and there is growing evidence that myocarditis and DCM are closely related [23-25]. Myocarditis can be induced by a number of viruses and represents a significant cause of death especially in young individuals. Among the viruses, the most cited are enteroviruses (especially coxsackievirus), adenovirus, parvovirus B19, human herpesvirus 6, human cytomegalovirus, Epstein–Barr virus, and hepatitis virus. Following infection, patients may develop lymphocytic, eosinophilic, or giant cell/granulomatous myocardial inflammation [26]. The availability of endomyocardial biopsies has brought renewed attention to the importance of persistent virus in chronic myocarditis and dilated cardiomyopathy and clinically, viral genomic analysis in endomyocardial biopsies is proving of value in determining cause and deciding future [26,27]. Our study revealed that 103 patients who died from myocarditis were clinically undiagnosed. Of the 103 patients, 41 (39.8%) had significant ventricular 10
dilatation. Postmortem diagnosis of cardiomegaly can be established by the measurements of heart weight and body height and weight. Cardiomegaly is diagnosed if the heart weight is >95% confidence interval for body height and weight [12,13]. Of the 41 cases with ventricular dilatation, 11 individuals also had cardiomegaly. Viral genomic analysis of autopsied myocarditis’ heart may shed light on the relationship of myocarditis and DCM. 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. A consensus statement was presented in 1987 with histopathologic definition for diagnosis [28, 29]. According to these Dallas criteria [29], the histopathologic diagnosis of myocarditis is based on necrosis or degeneration of the myocytes not characteristic of an ischemic event and an adjacent inflammatory infiltrate, while borderline myocarditis requires a less intense inflammatory infiltrate and no light microscopic evidence of myocyte destruction. Previous studies indicated that myocarditis is overdiagnosed on routine autopsies, particularly in patients who have died suddenly or are found dead, with only 32% of death certificate-based myocarditis judged as meeting the Dallas criteria on histopathologic reanalysis [1,30]. Focal myocardial inflammatory infiltration with or without significant myocyte necrosis had been used as cause of sudden death by forensic pathologists if complete autopsy and toxicological analysis was negative. In the present study, microscopic examination revealed myocyte necrosis in 69 of 103 cases (67.0%). Histological sampling limitation and variation in expert interpretation may explain the lock of myocyte necrosis in certain cases. In summary, myocarditis may cause sudden death. In cases of sudden unexpected death, especially sudden death in young people, forensic pathologists should consider myocarditis as possible cause. Representative sections from anterior, lateral, and posterior wall of atria and ventricles, and sections from ventricular septum should be submitted for microscopic examination. Postmortem diagnosis of borderline myocarditis (focal myocardial inflammatory infiltrate with no obvious microscopic evidence of myocyte destruction) may be used as cause of sudden death in 11
conjunction with clinical presentation, death scene findings and complete autopsy examination including comprehensive toxicological testing. Acknowledgements The authors want to thank Dr. Jennifer Bynum from Johns Hopkins Pathology Department for her assistance in manuscript preparation. This study was supported by the Key Projects of National Natural Science Foundation of China (No. 81430047) and the China Postdoctoral Science Foundation (No. 2016M601507). Dr. Liliang Li acknowledges the financial support from the State Scholarship Fund of China Scholarship Council (No.: 201306100058) for his visit to the University of Maryland School of Medicine and Office of the Chief Medical Examiner, Baltimore, MD, USA where data collection and slides review were performed. This project was in part supported by the Collaborative Innovation Center of Judicial Civilization, China University of Political Science and Law.
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pathology in 2007 consecutive forensic autopsies, Clin. Cardiol. 15 (1992) 760-765. [15] F.J. Diaz, C. Loewe, A. Jackson, Death caused by myocarditis in Wayne County, Michigan: a 9-year retrospective study, Am J Forensic Med Pathol 27 (2006) 300303. [16] J.W. Mason, J.B. O'Connell, A. Herskowitz, N.R. Rose, B.M. McManus, M.E. Billingham, et al., A clinical trial of immunosuppressive therapy for myocarditis. The Myocarditis Treatment Trial Investigators, N Engl J Med 333 (1995) 269-275. [17] M.A. Pettit, A. Koyfman, M. Foran, Myocarditis, Pediatr. Emerg. Care 30 (2014) 832-835, 836-838. [18] P. Fornes, D. Lecomte, G. Nicolas, Sudden out-of-hospital coronary death in patients with no previous cardiac history. An analysis of 221 patients studied at autopsy, J. Forensic Sci. 38 (1993) 1084-1091. [19] F. Tavora, Y. Zhang, M. Zhang, L. Li, M. Ripple, D. Fowler, et al., Cardiomegaly is a common arrhythmogenic substrate in adult sudden cardiac deaths, and is associated with obesity, Pathology 44 (2012) 187-191. [20] M.T. Subirana, J.O. Juan-Babot, T. Puig, J. Lucena, A. Rico, M. Salguero, et al., Specific characteristics of sudden death in a mediterranean Spanish population, Am. J. Cardiol. 107 (2011) 622-627. [21] A.P. Burke, A. Farb, R. Virmani, J. Goodin, J.E. Smialek, Sports-related and non-sports-related sudden cardiac death in young adults, Am. Heart J. 121 (1991) 568-575. [22] M.A. Weber, M.T. Ashworth, R.A. Risdon, M. Malone, M. Burch, N.J. Sebire, Clinicopathological features of paediatric deaths due to myocarditis: an autopsy series, Arch. Dis. Child. 93 (2008) 594-598. [23] J.W. Mason, Myocarditis and dilated cardiomyopathy: an inflammatory link, Cardiovasc. Res. 60 (2003) 5-10. [24] C. Kawai, From myocarditis to cardiomyopathy: mechanisms of inflammation and cell death: learning from the past for the future, Circulation 99 (1999) 1091-1100. [25] R.D. Latham, J.P. Mulrow, R. Virmani, M. Robinowitz, J.M. Moody, Recently diagnosed idiopathic dilated cardiomyopathy: incidence of myocarditis and efficacy 14
of prednisone therapy, Am. Heart J. 117 (1989) 876-882. [26] N.R. Rose, Viral myocarditis, Curr. Opin. Rheumatol. 28 (2016) 383-389. [27] F. Dominguez, U. Kuhl, B. Pieske, P. Garcia-Pavia, C. Tschope, Update on Myocarditis and Inflammatory Cardiomyopathy: Reemergence of Endomyocardial Biopsy, Rev Esp Cardiol (Engl Ed) 69 (2016) 178-187. [28] H.T. Aretz, M.E. Billingham, W.D. Edwards, S.M. Factor, J.T. Fallon, J.J. Fenoglio, et al., Myocarditis. A histopathologic definition and classification, Am J Cardiovasc Pathol 1 (1987) 3-14. [29] H.T. Aretz, Myocarditis: the Dallas criteria, Hum. Pathol. 18 (1987) 619-624. [30] V. Kyto, P. Saukko, E. Lignitz, G. Schwesinger, V. Henn, A. Saraste, et al., Diagnosis and presentation of fatal myocarditis, Hum. Pathol. 36 (2005) 1003-1007.
15
Figure legends Figure 1. Case distribution by year (A) and month (B) (n=103).
Figure 2. Case distribution by age and gender (n=103).
Figure 3. The death distribution by histological classification (n=103).
Figure 4. The death distribution by degrees of diagnostic certainty (n=103).
16
17
Table legends Table 1. Circumstances of deaths Categories Location of death Residence ER or hospital Public locations Witnessed death Yes No Activity prior to death Sleeping or resting Normal daily activity Physical exertion Emotional stress Prodrome (chest pain, nausea, or palpitation) Yes No or unknown ER, emergency room.
18
Number
Percentage (%)
73 19 11
70.9 18.4 10.7
45 58
43.7 56.3
34 26 4 2
33.0 25.2 3.9 1.9
86 17
83.5 16.5
Table 2. Macroscopic findings Macroscopic findings Ventricular dilatation Mild coronary stenosis Mottled myocardial appearance Macroscopic scarring/fibrosis Myocardial bridge Pericardial effusion
Number 41 18 16 11 7 7
19
Percentage (%) 39.8 17.5 15.5 10.7 6.8 6.8
Table 3. Association of histological classification with myocyte necrosis and microscopic fibrosis Category Total Lymphocytic Neutrophilic Eosinophilic Giant cell N (%) (n=56) (n=32) (n=13) (n=2) N (%) N (%) N (%) N (%) Myocyte necrosis 69 (100) 42 (75.0) 21 (65.6) 4 (30.8) 2 (100) Fibrosis 48 (100) 29 (51.8) 13 (38.5) 5 (38.5) 1 (50)
20
P value 0.02 0.76
Table 4. Macroscopic findings and comparisons with other general characteristics group 1 group 2 group 3 group 4 P Categories (n=39) (n=16) (n=25) (n=23) value Age (years) 29±17 35±20 34±16 30±16 0.566 a a Male gender, N (%) 15(38.5) 9(56.3) 17(68.0) 17(73.9) 0.023 With prodrome, N (%) 33(84.6) 15(93.8) 17(68.0) 21(91.3) 0.083 2 a a BMI (kg/m ) 23.9±4.9 28.3±6.0 27.8±7.6 25.9±5.7 0.017 a a Heart weight (g) 321±125 382±153 416±138 424±129 0.011 † a, c Cardiomegaly , N (%) 5 (12.8) 6 (37.5) 5 (20.0) 11 (47.8) 0.012 Lymphocytic subtype, N (%) 23(59.0) 7(43.8) 12(48.0) 14(60.9) 0.613 Myocyte necrosis, N (%) 29 (74.4) 8 (50.0) 16 (64.0) 16 (69.6) 0.364 a ,b a, c Microscopic fibrosis, N (%) 8 (20.5) 6 (37.5) 21 (84.0) 13 (56.5) <0.001 Group 1-myocarditis without other cardiac findings Group 2- myocarditis with significant ventricular dilatation Group 3-myocarditis with significant dilatation and other findings (mild coronary atherosclerosis and/or myocardial bridge Group 4-myocarditis with no ventricular dilatation, but with mild coronary atherosclerosis and/or myocardial bridge. a p<0.05 vs. group 1; bp<0.05 vs. group 2; cp<0.05 vs. group 3. BMI, Body Mass Index. † Cardiomegaly is diagnosed if the heart weight is >95% confidence interval for body height and weight [12,13].
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Table 5. Diagnostic certainty by clinical and histological characteristics Categories Certain Highly Uncertai (n=48) probable n (n=18) (n=37) Age (years) 31±18 29±16 35±16 2 BMI (kg/m ) 25.8±5.4 27.1±6.7 26.5±7.4 Heart weight (g) 375±151 391±138 352±109 † Cardiomegaly , N (%) 14 (29.2) 8 (21.6) 5 (27.8) With prodrome, N (%) 43 (89.6) 28 (75.7) 13 (72.2) Death triggers, N (%) Resting 16 (33.3) 10 (27.0) 8 (44.4) Normal daily activity 13 (27.1) 9 (24.3) 4 (22.2) Under stress 2 (4.2) 4 (10.8) 1 (5.6) Histological type*, N (%) Lymphocytic 23 (47.9) 22 (59.5) 11 (61.1) Neutrophilic 17 (35.4) 9 (24.3) 6 (33.3) Eosinophilic 6 (12.5) 6 (16.2) 1 (5.6) Microscopic fibrosis, N 21 (43.8) 21 (56.8) 6 (33.3) (%) Myocyte necrosis, N (%) 34 (70.8) 21 (56.8) 14 (77.8) † Cardiomegaly was determined based on previously published literatures [12,13]; *Two cases of giant cell myocarditis were not included because of limited cases.
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P value 0.44 0.65 0.62 0.73 0.14 0.43 0.91 0.47 0.47 0.54 0.53 0.23 0.22