Myocarditis overview: Difference between revisions
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{{Myocarditis}} | {{Myocarditis}} | ||
{{CMG}} | {{CMG}} {{AE}} [[Varun Kumar]], M.B.B.S. {{Maliha}} {{Homa}} | ||
==Overview== | ==Overview== | ||
Myocarditis is defined as [[inflammation]] of the [[myocardium]]. It may present with [[chest pain]], [[ST segment elevation]], elevated biomarkers of [[myonecrosis]], [[heart failure]], and/ or [[sudden death]]. [[Myocarditis]] can be classified clinicopathologically into fulminant myocarditis, acute myocarditis, chronic active myocarditis, and chronic persistent myocarditis. During either an infection or a [[hypersensitivity reaction]], the inflammatory response may cause [[myonecrosis]] either directly or indirectly as part of an [[autoimmune]] reaction. Life-threatening causes of myocarditis include [[carbon monoxide poisoning]] and [[Dengue fever]]. Common causes of myocarditis include infections, [[Lyme disease]], and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a [[viral]] infection. | Myocarditis is defined as [[inflammation]] of the [[myocardium]]. It may present with [[chest pain]], [[ST segment elevation]], elevated biomarkers of [[myonecrosis]], [[heart failure]], and/ or [[sudden death]]. [[Myocarditis]] can be classified clinicopathologically into fulminant myocarditis, acute myocarditis, chronic active myocarditis, and chronic persistent myocarditis. During either an infection or a [[hypersensitivity reaction]], the inflammatory response may cause [[myonecrosis]] either directly or indirectly as part of an [[autoimmune]] reaction. Life-threatening causes of myocarditis include [[carbon monoxide poisoning]] and [[Dengue fever]]. Common causes of myocarditis include infections, [[Lyme disease]], and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a [[viral]] infection. Myocarditis must be distinguished from [[pericarditis]] and the life threatening condition of [[ST elevation myocardial infarction]]. In young adults, up to 20% of all cases of [[sudden death]] are due to myocarditis. Myocarditis is slightly more frequent among males than females. Myocarditis is usually self limiting and is associated with a good prognosis especially if it is secondary to a [[viral infection]]. Patients rarely develop [[cardiac failure]], [[pulmonary edema]], [[arrhythmias]], or [[cardiogenic shock]]. In some instances, myocarditis may be associated with [[sudden death]]. Patients with fulminant myocarditis have a good long term prognosis if they survive the acute phase of the disease. The prognosis of fulminant myocarditis is better than that of either acute myocarditis or [[giant cell myocarditis]]. The presence of [[left bundle branch block]], [[q waves]], [[AV block]], [[syncope]] and a [[left ventricular ejection fraction]] < 40% are associated with [[sudden death]] and [[cardiac transplantation]]. The physical examination in patients with myocarditis may reveal [[tachycardia]], a [[cardiac gallop]], [[mitral regurgitation]] due to [[left ventricular dilation]], and [[pedal edema]] suggestive of [[cardiac failure]]. A [[pericardial friction rub]] may be noted in presence of concomitant [[pericarditis]], a condition sometimes referred to as [[myopericarditis]]. | ||
==Historical Perspective== | ==Historical Perspective== | ||
Myocarditis was first discovered by Jean Baptiste Senac, a French [[physician]], in 1794. The term myocarditis was introduced by German [[physician]] Joseph Friedrich Sobernheim in 1837. In 1980s, the [[World Health Organization]] and the International Society and Federation of Cardiology were the first to [[differentiate]] between myocarditis and other [[cardiomyopathies]]. The [[Dallas criteria]] was published in 1986 as a [[Guideline (medical)|guideline]] for [[classification]] of myocarditis. | |||
==Classification== | ==Classification== | ||
[[ | Myocarditis can be [[Classification|classified]] based on the [[Causes|causative]], [[histological]], and clinicopathological [[criteria]]. [[Causes|Causative]] [[criteria]] include three main groups, as well as [[infectious]], [[Immune-mediated disease|immune-mediated,]] and [[toxic]] myocarditis. Based on the type of [[Infiltration (medical)|infiltrating]] [[Cells (biology)|cells]] myocarditis divided in [[lymphocytic]], [[eosinophilic]], [[polymorphic]], [[giant cell]] myocarditis, and [[cardiac sarcoidosis]]. [[Acute]], [[fulminant]], [[chronic]] active, and [[Chronic (medicine)|chronic]] persistent are subtypes of clinicopathopogical [[classification]]. | ||
==Pathophysiology== | ==Pathophysiology== | ||
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==Causes== | ==Causes== | ||
Life-threatening causes of myocarditis include [[carbon monoxide poisoning]] and [[Dengue fever]]. Common causes of myocarditis include infections such as [[Lyme disease]] and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a [[viral]] infection. | Life-threatening causes of myocarditis include [[carbon monoxide poisoning]] and [[Dengue fever]]. Common causes of myocarditis include infections such as [[Lyme disease]] and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a [[viral]] infection. | ||
==Differentiating Myocarditis from other Diseases== | ==Differentiating Myocarditis from other Diseases== | ||
Myocarditis must be distinguished from [[pericarditis]] and the life threatening condition of [[ST elevation myocardial infarction]]. | Myocarditis must be distinguished from [[pericarditis]] and the life threatening condition of [[ST elevation myocardial infarction]]. | ||
==Risk factors== | |||
There are no established [[risk factors]] for myocarditis. | |||
==Screening== | |||
There is insufficient [[evidence]] to recommend routine [[screening]] for myocarditis. | |||
==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
The [[incidence]] of myocarditis is approximately 10 to 20 per 100,000 [[patients]] worldwide. It commonly affects younger individuals. Yong [[males]] are slightly more commonly affected by myocarditis than [[females]]. There is no [[racial]] predilection to myocarditis. [[Viral infections]] especially [[coxsackie B]] and [[enterovirus]] are the most common cause of myocarditis in [[Developed country|developed countries]]. While, In South America, [[Chagas' disease]] (caused by ''[[Trypanosoma cruzi]]'') is the main cause of myocarditis. | |||
==Natural History, Complications and Prognosis== | ==Natural History, Complications and Prognosis== | ||
Myocarditis is usually self limiting and is associated with a good prognosis especially if it is secondary to a [[viral infection]]. Patients rarely develop [[cardiac failure]], [[pulmonary edema]], [[arrhythmias]] or [[cardiogenic shock]]. In some instances, myocarditis may be associated with [[sudden death]]. Patients with fulminant myocarditis have a good long term prognosis if they survive the acute phase of the disease. | Myocarditis is usually self limiting and is associated with a good [[prognosis]] especially if it is [[secondary]] to a [[viral infection]]. [[Patients]] [[Rare|rarely]] [[Development|develop]] [[cardiac failure]], [[pulmonary edema]], [[arrhythmias]], or [[cardiogenic shock]]. In some instances, myocarditis may be associated with [[sudden death]]. Patients with fulminant myocarditis have a good long term [[prognosis]] if they survive the [[acute]] phase of the [[disease]]. The [[prognosis]] of fulminant myocarditis is better than that of either [[acute]] myocarditis or [[giant cell myocarditis]]. The presence of [[syncope]], [[pulmonary hypertension]], [[Ventricular dysfunction|biventricular dysfunction]], [[left bundle branch block]], [[q waves]], [[AV block]], and a [[left ventricular ejection fraction]] < 40% are associated with [[sudden death]] and [[cardiac transplantation]]. [[Complications]] of myocarditis include [[chronic]] [[dilated cardiomyopathy]], [[heart block]], [[congestive heart failure]], [[pericarditis]], [[ventricular dysfunction]], [[arrythmia]]s, and [[sudden cardiac death]]. | ||
==Diagnosis== | ==Diagnosis== | ||
===History and Symptoms=== | ===History and Symptoms=== | ||
Myocarditis should be suspected in a [[patient]] with [[acute]] [[decompensation]] of [[Cardiac function curve|cardiac function]] who is at low risk of [[ischemic heart disease]]. A [[History and Physical examination|history]] of a recent (within the preceding 2-4 weeks) [[viral]] [[illness]] is often elicited in a large [[number]] of [[patients]] with myocarditis. [[Cardiac]] specific [[symptoms]] may become apparent usually in the [[subacute]] [[virus]]-clearing [[Phase (matter)|phase]]. In myocarditis due to [[drug hypersensitivity]], [[patients]] may give a [[History and Physical examination|history]] of ingesting an offending [[drug]]. In [[fulminant]] myocarditis, [[patients]] present with the abrupt onset of [[flu]]-like [[symptoms]] and the abrupt onset of [[heart failure]] [[symptoms]]. In [[chronic]] and [[acute]] myocarditis, the onset of [[symptoms]] may be more insidious. Common [[symptoms]] of myocarditis include [[chest pain]], [[pedal edema]], [[palpitation]]s, [[fever]], and [[joint pain]]s. | |||
===Physical Examination=== | ===Physical Examination=== | ||
There are no specific findings for myocarditis. [[Patients]] with myocarditis usually show [[signs]] of [[cardiac dysfunction]] and underlying [[diseases]]. The [[physical examination]] in [[patients]] with myocarditis may reveal [[tachycardia]], a [[cardiac gallop]], [[mitral regurgitation]] due to [[left ventricular dilation]], and [[pedal edema]] suggestive of [[cardiac failure]]. A [[pericardial friction rub]] may be noted in presence of concomitant [[pericarditis]], a condition sometimes referred to as [[myopericarditis]]. | |||
===Laboratory Findings=== | ===Laboratory Findings=== | ||
[[Laboratory|Laboratory findings]] consistent with the [[diagnosis]] of myocarditis include [[Elevation|elevated]] [[Marker|markers]] of [[myonecrosis]], [[inflammatory]] [[Marker|markers]], and other [[biomarkers]]. [[Marker|Markers]] of [[myonecrosis]] include [[creatine kinase]] ([[CK-MB]]), [[Troponin|cardiac troponin]] I ([[cTnI]]) or T ([[cTnT]]), [[lactate dehydrogenase]] ([[LDH]]), [[alanine transaminase]] ([[ALT]]), and [[aspartate transaminase]] ([[AST]]). [[Elevation|Elevated]] levels of [[C-reactive protein]] and [[erythrocyte sedimentation rate]] ([[ESR]]), and [[leukocytosis]] are suggestive of myocarditis. [[Serologic]] [[Marker|markers]] such as [[Fas]], [[Fas ligand]], [[interleukin-10]] or antimyosin [[autoantibodies]] are of [[prognostic]] value in myocarditis. Other [[Autoantibodies|auto-antibodies]] such as [[ANA]] and [[rheumatoid factor]] may also be detected. | |||
===Electrocardiogram=== | ===Electrocardiogram=== | ||
The presence of [[ST segment elevation]] in patients with [[myocarditis]] can mimic [[pericarditis]] and [[myocardial infarction]]. [[Arrhythmias]] and [[heart block]] may also be observed in myocarditis patients. Myocarditis can be distinguished from [[pericarditis]] by the presence of [[PR]] | The presence of [[ST segment elevation]] in patients with [[myocarditis]] can mimic [[pericarditis]] and [[myocardial infarction]]. [[Arrhythmias]] and [[heart block]] may also be observed in myocarditis [[patients]]. Myocarditis can be distinguished from [[pericarditis]] by the presence of [[PR depression]] in the [[patient]] with [[pericarditis]]. | ||
===Endomyocardial Biopsy=== | ===Endomyocardial Biopsy=== | ||
[[Endomyocardial biopsy]] remains the gold standard test to evaluate for the presence of and to subclassify the type of myocarditis. A small tissue sample of the [[endocardium]] and [[myocardium]] is obtained via right sided cardiac catheterization. The sample is then evaluated by a pathologist using [[immunochemistry]] and special staining techniques as necessary. Histopathological features include abundant [[edema]] in the myocardial [[interstitium]] and an inflammatory infiltrate which is rich in [[lymphocyte]]s and [[macrophage]]s. Focal destruction of [[myocytes]] as a result of the inflammatory process results in [[left ventricular dysfunction]]. | [[Endomyocardial biopsy]] remains the gold standard test to evaluate for the presence of and to subclassify the type of myocarditis. A small tissue sample of the [[endocardium]] and [[myocardium]] is obtained via right sided cardiac catheterization. The sample is then evaluated by a pathologist using [[immunochemistry]] and special staining techniques as necessary. Histopathological features include abundant [[edema]] in the myocardial [[interstitium]] and an inflammatory infiltrate which is rich in [[lymphocyte]]s and [[macrophage]]s. Focal destruction of [[myocytes]] as a result of the inflammatory process results in [[left ventricular dysfunction]]. [[Endomyocardial biopsy]] is recommended when the results would identify an underlying disease that is amenable to therapy. Routine performance of [[endomyocardial biopsy]] is not recommended in all patients with myocarditis. | ||
===Chest X Ray=== | ===Chest X Ray=== | ||
Findings on chest x-ray suggestive of myocarditis include cardiomegaly, pericardial thickening in presence of [[pericarditis]], [[pulmonary edema]], and [[pleural effusion]]. | Findings on [[Chest X-ray|chest x-ray]] suggestive of myocarditis include [[cardiomegaly]], [[Cephalization on chest x-ray|cephalization]] of the [[pulmonary vessels]] and, [[Kerley B lines|Kerley B-lines]] in presence of [[heart failure]] [[pericardial]] thickening in presence of [[pericarditis]], [[pulmonary edema]], and [[pleural effusion]]. | ||
===Echocardiography=== | |||
[[Echocardiography]] in patients with [[myocarditis]] allows for serial assessment of left ventricular dysfunction and can be used to distinguish fulminant (non-dilated [[hypocontractile left ventricle]] with thick [[interventricular septum]]) from acute myocarditis (dilated [[hypocontractile left ventricle]] with normal [[interventricular septum]]). Echocardiography may be helpful in the diagnosis of myocarditis. Findings on an echocardiography suggestive of myocarditis include wall [[Motion (physics)|motion]] [[abnormalities]], [[Systolic dysfunction|systolic]] and [[diastolic dysfunction]], changes in [[image]] texture, [[pericardial effusion]], and functional [[regurgitation]] through the [[Atrioventricular valves|AV valves]]. | |||
===CT scan=== | |||
[[Cardiac]] [[CT scan]] may be helpful in the [[diagnosis]] of myocarditis. [[Cardiac]] [[CT scan]] can be used in [[diagnosis]] of [[acute myocarditis]] ( [[Epicardium|subepicardial]] late [[iodine]] enhancement), [[Exclusion criteria|exclusion]] of [[Acute coronary syndromes|acute coronary syndrome]] by [[CT angiography]], and alternative [[diagnostic]] tool in [[patients]] with [[CMR]] [[contraindications]]. | |||
===MRI=== | ===MRI=== | ||
[[Cardiac MRI]] findings associated with [[myocarditis]] include [[myocardial inflammation]], [[myocardial edema]], [[capillary leak]], and [[reduced left ventricular function]]. While the | [[Cardiac]] [[MRI]] is indicated in [[patients]] with new or persisting [[symptoms]] of [[chest pain]] and [[congestive heart failure]], who have [[evidence]] of [[significant]] [[myocardial injury]], in the absence of or in whom there is a low suspicion of coronary [[Atherosclerosis|atherosclerosis.]] [[Cardiac MRI]] findings associated with [[myocarditis]] include [[myocardial inflammation]], [[myocardial edema]], [[capillary leak]], and [[reduced left ventricular function]]. While the [[CMR]] pattern of [[gadolinium]] hyperenhancement in [[ST segment elevation myocardial infarction]] is transmural and extends from the [[endocardium]] to the [[epicardium]], the patchy, non-segmental hyperenhancement pattern in [[myocarditis]] in contrast involves the [[epicardium]] and spares the [[Endocardium|subendocardium]]. [[CMR]] has a [[sensitivity]] of 76%, [[specificity]] of 95.5%, and overall [[diagnostic]] [[accuracy]] of 85% when any-two of the following three sequences are used, focal and global T2 signal [[intensity]], [[myocardial]] global relative enhancement, and delayed [[gadolinium]] enhancement. | ||
=== | ===Other Imaging Findings=== | ||
[[ | [[Coronary angiography]] may be helpful in excluding either [[myocardial ischemia]] or [[MI|infarction]] as the cause of [[ST segment elevation]], elevated [[cardiac biomarkers]], or [[left ventricular dysfunction]]. [[Nuclear]] [[imaging]] may be useful in [[diagnosis]] of [[cardiac sarcoidosis]]. | ||
===Other | ===Other Diagnostic Findings=== | ||
==Treatment== | ==Treatment== | ||
===Medical Therapy=== | ===Medical Therapy=== | ||
Symptomatic treatment is the mainstay of therapy for patients with | [[Symptomatic]] [[Therapy|treatment]] is the mainstay of [[therapy]] for [[patients]] with [[viral myocarditis]]. Supportive [[therapy]] includes [[diuretic]]s and [[inotrope]]s for [[left ventricular failure]]. [[ACE inhibitor]] [[therapy]] may aid in left [[ventricular remodeling]]. Among patients with [[fulminant myocarditis]], placement of either an [[intra-aortic balloon pump]] or a [[left ventricular assist device]] may be necessary as bridge to [[recovery]]. Administration of [[antimicrobial]] [[therapy]] is recommended for [[bacterial myocarditis]]. [[Immunosuppressive therapy]] may be effective in the management of [[giant cell myocarditis]], [[autoimmune myocarditis]], and [[eosinophilic myocarditis]]. In [[patients]] with [[arrythmias]], [[Therapy|treatment]] should be initiated only if [[arrhythmias]] are [[symptomatic]] or sustained. [[Myocarditis]] [[patients]] presenting with [[Electrical conduction system of the heart|conduction]] abnormalities, particularly [[Mobitz II|Mobitz type II]] and [[complete heart block]] require temporary [[pacemaker]] usually during the [[acute]] phase. | ||
===Surgery=== | |||
[[Cardiac transplantation]] is sometimes required to [[Therapy|treat]] [[refractory]] [[giant cell myocarditis]]. However, the [[condition]] can recur in post-[[transplant]] [[patients]]. | |||
===Primary prevention=== | |||
There are no established measures for the [[primary prevention]] of all types of myocarditis. [[Vaccination]] against [[measles]], [[rubella]], [[mumps]], [[poliomyelitis]], and [[influenza]] could [[Prevention|prevent]] myocarditis [[secondary]] to these [[diseases]]. | |||
=== | ===Secondary prevention=== | ||
[[ | Effective measures for the [[secondary prevention]] of myocarditis include, [[clinical]] evaluation, [[ECG]], and [[echocardiography]]. [[CMR]], [[cardiac]] [[CT scan]], [[Nuclear|nuclear assessment]] in [[patients]] that [[echocardiography]] is undiagnostic. [[Patients]] should udergo [[Cardiac function curve|cardiac function]] assessment at one and six months and yearly after that. | ||
==References== | ==References== | ||
Latest revision as of 16:09, 14 June 2020
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Myocarditis Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Myocarditis overview On the Web |
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American Roentgen Ray Society Images of Myocarditis overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Varun Kumar, M.B.B.S. Maliha Shakil, M.D. [2] Homa Najafi, M.D.[3]
Overview
Myocarditis is defined as inflammation of the myocardium. It may present with chest pain, ST segment elevation, elevated biomarkers of myonecrosis, heart failure, and/ or sudden death. Myocarditis can be classified clinicopathologically into fulminant myocarditis, acute myocarditis, chronic active myocarditis, and chronic persistent myocarditis. During either an infection or a hypersensitivity reaction, the inflammatory response may cause myonecrosis either directly or indirectly as part of an autoimmune reaction. Life-threatening causes of myocarditis include carbon monoxide poisoning and Dengue fever. Common causes of myocarditis include infections, Lyme disease, and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a viral infection. Myocarditis must be distinguished from pericarditis and the life threatening condition of ST elevation myocardial infarction. In young adults, up to 20% of all cases of sudden death are due to myocarditis. Myocarditis is slightly more frequent among males than females. Myocarditis is usually self limiting and is associated with a good prognosis especially if it is secondary to a viral infection. Patients rarely develop cardiac failure, pulmonary edema, arrhythmias, or cardiogenic shock. In some instances, myocarditis may be associated with sudden death. Patients with fulminant myocarditis have a good long term prognosis if they survive the acute phase of the disease. The prognosis of fulminant myocarditis is better than that of either acute myocarditis or giant cell myocarditis. The presence of left bundle branch block, q waves, AV block, syncope and a left ventricular ejection fraction < 40% are associated with sudden death and cardiac transplantation. The physical examination in patients with myocarditis may reveal tachycardia, a cardiac gallop, mitral regurgitation due to left ventricular dilation, and pedal edema suggestive of cardiac failure. A pericardial friction rub may be noted in presence of concomitant pericarditis, a condition sometimes referred to as myopericarditis.
Historical Perspective
Myocarditis was first discovered by Jean Baptiste Senac, a French physician, in 1794. The term myocarditis was introduced by German physician Joseph Friedrich Sobernheim in 1837. In 1980s, the World Health Organization and the International Society and Federation of Cardiology were the first to differentiate between myocarditis and other cardiomyopathies. The Dallas criteria was published in 1986 as a guideline for classification of myocarditis.
Classification
Myocarditis can be classified based on the causative, histological, and clinicopathological criteria. Causative criteria include three main groups, as well as infectious, immune-mediated, and toxic myocarditis. Based on the type of infiltrating cells myocarditis divided in lymphocytic, eosinophilic, polymorphic, giant cell myocarditis, and cardiac sarcoidosis. Acute, fulminant, chronic active, and chronic persistent are subtypes of clinicopathopogical classification.
Pathophysiology
During either an infection or a hypersensitivity reaction, the inflammatory response may cause myonecrosis either directly or indirectly as part of an autoimmune reaction.
Causes
Life-threatening causes of myocarditis include carbon monoxide poisoning and Dengue fever. Common causes of myocarditis include infections such as Lyme disease and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a viral infection.
Differentiating Myocarditis from other Diseases
Myocarditis must be distinguished from pericarditis and the life threatening condition of ST elevation myocardial infarction.
Risk factors
There are no established risk factors for myocarditis.
Screening
There is insufficient evidence to recommend routine screening for myocarditis.
Epidemiology and Demographics
The incidence of myocarditis is approximately 10 to 20 per 100,000 patients worldwide. It commonly affects younger individuals. Yong males are slightly more commonly affected by myocarditis than females. There is no racial predilection to myocarditis. Viral infections especially coxsackie B and enterovirus are the most common cause of myocarditis in developed countries. While, In South America, Chagas' disease (caused by Trypanosoma cruzi) is the main cause of myocarditis.
Natural History, Complications and Prognosis
Myocarditis is usually self limiting and is associated with a good prognosis especially if it is secondary to a viral infection. Patients rarely develop cardiac failure, pulmonary edema, arrhythmias, or cardiogenic shock. In some instances, myocarditis may be associated with sudden death. Patients with fulminant myocarditis have a good long term prognosis if they survive the acute phase of the disease. The prognosis of fulminant myocarditis is better than that of either acute myocarditis or giant cell myocarditis. The presence of syncope, pulmonary hypertension, biventricular dysfunction, left bundle branch block, q waves, AV block, and a left ventricular ejection fraction < 40% are associated with sudden death and cardiac transplantation. Complications of myocarditis include chronic dilated cardiomyopathy, heart block, congestive heart failure, pericarditis, ventricular dysfunction, arrythmias, and sudden cardiac death.
Diagnosis
History and Symptoms
Myocarditis should be suspected in a patient with acute decompensation of cardiac function who is at low risk of ischemic heart disease. A history of a recent (within the preceding 2-4 weeks) viral illness is often elicited in a large number of patients with myocarditis. Cardiac specific symptoms may become apparent usually in the subacute virus-clearing phase. In myocarditis due to drug hypersensitivity, patients may give a history of ingesting an offending drug. In fulminant myocarditis, patients present with the abrupt onset of flu-like symptoms and the abrupt onset of heart failure symptoms. In chronic and acute myocarditis, the onset of symptoms may be more insidious. Common symptoms of myocarditis include chest pain, pedal edema, palpitations, fever, and joint pains.
Physical Examination
There are no specific findings for myocarditis. Patients with myocarditis usually show signs of cardiac dysfunction and underlying diseases. The physical examination in patients with myocarditis may reveal tachycardia, a cardiac gallop, mitral regurgitation due to left ventricular dilation, and pedal edema suggestive of cardiac failure. A pericardial friction rub may be noted in presence of concomitant pericarditis, a condition sometimes referred to as myopericarditis.
Laboratory Findings
Laboratory findings consistent with the diagnosis of myocarditis include elevated markers of myonecrosis, inflammatory markers, and other biomarkers. Markers of myonecrosis include creatine kinase (CK-MB), cardiac troponin I (cTnI) or T (cTnT), lactate dehydrogenase (LDH), alanine transaminase (ALT), and aspartate transaminase (AST). Elevated levels of C-reactive protein and erythrocyte sedimentation rate (ESR), and leukocytosis are suggestive of myocarditis. Serologic markers such as Fas, Fas ligand, interleukin-10 or antimyosin autoantibodies are of prognostic value in myocarditis. Other auto-antibodies such as ANA and rheumatoid factor may also be detected.
Electrocardiogram
The presence of ST segment elevation in patients with myocarditis can mimic pericarditis and myocardial infarction. Arrhythmias and heart block may also be observed in myocarditis patients. Myocarditis can be distinguished from pericarditis by the presence of PR depression in the patient with pericarditis.
Endomyocardial Biopsy
Endomyocardial biopsy remains the gold standard test to evaluate for the presence of and to subclassify the type of myocarditis. A small tissue sample of the endocardium and myocardium is obtained via right sided cardiac catheterization. The sample is then evaluated by a pathologist using immunochemistry and special staining techniques as necessary. Histopathological features include abundant edema in the myocardial interstitium and an inflammatory infiltrate which is rich in lymphocytes and macrophages. Focal destruction of myocytes as a result of the inflammatory process results in left ventricular dysfunction. Endomyocardial biopsy is recommended when the results would identify an underlying disease that is amenable to therapy. Routine performance of endomyocardial biopsy is not recommended in all patients with myocarditis.
Chest X Ray
Findings on chest x-ray suggestive of myocarditis include cardiomegaly, cephalization of the pulmonary vessels and, Kerley B-lines in presence of heart failure pericardial thickening in presence of pericarditis, pulmonary edema, and pleural effusion.
Echocardiography
Echocardiography in patients with myocarditis allows for serial assessment of left ventricular dysfunction and can be used to distinguish fulminant (non-dilated hypocontractile left ventricle with thick interventricular septum) from acute myocarditis (dilated hypocontractile left ventricle with normal interventricular septum). Echocardiography may be helpful in the diagnosis of myocarditis. Findings on an echocardiography suggestive of myocarditis include wall motion abnormalities, systolic and diastolic dysfunction, changes in image texture, pericardial effusion, and functional regurgitation through the AV valves.
CT scan
Cardiac CT scan may be helpful in the diagnosis of myocarditis. Cardiac CT scan can be used in diagnosis of acute myocarditis ( subepicardial late iodine enhancement), exclusion of acute coronary syndrome by CT angiography, and alternative diagnostic tool in patients with CMR contraindications.
MRI
Cardiac MRI is indicated in patients with new or persisting symptoms of chest pain and congestive heart failure, who have evidence of significant myocardial injury, in the absence of or in whom there is a low suspicion of coronary atherosclerosis. Cardiac MRI findings associated with myocarditis include myocardial inflammation, myocardial edema, capillary leak, and reduced left ventricular function. While the CMR pattern of gadolinium hyperenhancement in ST segment elevation myocardial infarction is transmural and extends from the endocardium to the epicardium, the patchy, non-segmental hyperenhancement pattern in myocarditis in contrast involves the epicardium and spares the subendocardium. CMR has a sensitivity of 76%, specificity of 95.5%, and overall diagnostic accuracy of 85% when any-two of the following three sequences are used, focal and global T2 signal intensity, myocardial global relative enhancement, and delayed gadolinium enhancement.
Other Imaging Findings
Coronary angiography may be helpful in excluding either myocardial ischemia or infarction as the cause of ST segment elevation, elevated cardiac biomarkers, or left ventricular dysfunction. Nuclear imaging may be useful in diagnosis of cardiac sarcoidosis.
Other Diagnostic Findings
Treatment
Medical Therapy
Symptomatic treatment is the mainstay of therapy for patients with viral myocarditis. Supportive therapy includes diuretics and inotropes for left ventricular failure. ACE inhibitor therapy may aid in left ventricular remodeling. Among patients with fulminant myocarditis, placement of either an intra-aortic balloon pump or a left ventricular assist device may be necessary as bridge to recovery. Administration of antimicrobial therapy is recommended for bacterial myocarditis. Immunosuppressive therapy may be effective in the management of giant cell myocarditis, autoimmune myocarditis, and eosinophilic myocarditis. In patients with arrythmias, treatment should be initiated only if arrhythmias are symptomatic or sustained. Myocarditis patients presenting with conduction abnormalities, particularly Mobitz type II and complete heart block require temporary pacemaker usually during the acute phase.
Surgery
Cardiac transplantation is sometimes required to treat refractory giant cell myocarditis. However, the condition can recur in post-transplant patients.
Primary prevention
There are no established measures for the primary prevention of all types of myocarditis. Vaccination against measles, rubella, mumps, poliomyelitis, and influenza could prevent myocarditis secondary to these diseases.
Secondary prevention
Effective measures for the secondary prevention of myocarditis include, clinical evaluation, ECG, and echocardiography. CMR, cardiac CT scan, nuclear assessment in patients that echocardiography is undiagnostic. Patients should udergo cardiac function assessment at one and six months and yearly after that.