Myocarditis differential diagnosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maliha Shakil, M.D. [2] Homa Najafi, M.D.[3]


Myocarditis must be differentiated from other causes of chest pain such as ST elevation myocardial infarction, pericarditis, and unstable angina. Myocarditis must also be differentiated from pulmonary edema and alcoholic cardiomyopathy.

Differential Diagnosis

Differential Diagnosis History and Symptoms Physical Examination Laboratory Findings Imaging Findings
ST Segment Elevation Myocardial Infarction
  • Chest pain with possible radiation to left arm and lower jaw
  • Squeezing, crushing chest pain
  • Sweating
  • Nausea and vomiting
  • Anxious patient in pain with diaphoresis
  • Signs of heart failure may be present
  • Arrhythmia
  • ST elevation, new left bundle branch block, and Q wave on EKG
  • Elevated cardiac biomarkers
  • Either complete or subtotal occlusion of an epicardial coronary artery on coronary angiography
  • Confluent hyperenhancement extending from the endocardium
Non ST Elevation Myocardial Infarction
  • Crushing, left-sided substernal chest pain or pressure that radiates to the neck or left arm
  • Same as ST-elevation MI
  • ST-segment depression or T-wave inversion on EKG
  • Elevated cardiac biomarkers
  • Chest pain relieved by sitting up and leaning forward and worsened by lying down
  • Fever, anxiety, difficulty breathing
  • Pericardial friction rub
  • Signs of cardiac tamponade may be present
  • PR segment depression and electrical alternans on EKG
  • A flask-shaped, enlarged cardiac silhouette on CXR
  • Pericardial thickness of more than 4 mm on MRI
  • Pericardial effusion and cardiac chamber indentation or collapse on echo when cardiac tamponade is present
Pulmonary Edema
  • Hemoptysis
  • Difficulty breathing, wheezing
  • Symptoms of fluid overload if pulmonary edema is chronic
  • Dyspnea, nasal flaring
  • End-inspiratory crackles
  • Third heart sound (S3)
  • Low oxygen saturation on ABG
  • Kerley B lines, increased vascular markings, interstitial edema, and peribronchial cuffing on CXR
  • Patchy alveolar infiltrates on CXR in noncardiogenic edema
Alcoholic Cardiomyopathy
  • History of alcohol abuse
  • Fatigue, weakness, anorexia, palpitations, and shortness of breath on activity
  • Leg swelling and pedal edema
  • Signs of heart failure such as presence of S3 and S4 heart sounds, pedal edema, and jugular venous distension
  • Signs of alcoholic liver disease may be present
  • Elevated MCV and MCHC on CBC
  • Elevated LDH, AST, ALT, creatine kinase, gammaglutamyl transpeptidase, malic dehydrogenase, and alpha-hydroxybutyric dehydrogenase
  • Q waves and non specific ST and T wave changes on EKG
  • Cardiomegaly, pulmonary congestion, and pleural effusions on CXR
  • Left ventricular dilatation on echo

Differentiating Myocarditis from ST Segment Elevation Myocardial Infarction

Both diseases present with chest pain, elevated cardiac biomarkers, and focal left ventricular dysfunction. There are two studies that can be used to distinguish the two syndromes:

Coronary Angiography

Coronary angiography can be performed to distinguish myocarditis from ST segment elevation myocardial infarction. ST segment elevation myocardial infarction is associated with either complete or subtotal occlusion of an epicardial coronary artery on coronary angiography. When used in conjunction with the findings on coronary angiography, cardiac MRI is useful in establishing the diagnosis of myocarditis.[1]

Cardiac Magnetic Resonance Imaging

Cardiac magnetic resonance imaging is also useful in distinguishing between the two diseases as well. On cardiac MRI, myocarditis is associated with patchy, non-sentimental, hyperenhancement which is confined to the epicardial layer of the myocardium. In contrast, in ST segment elevation myocardial infarction there is confluent hyperenhancement extending from the endocardium in a distribution that mimics the distribution of the epicardial coronary arteries.

Differentiating Myocarditis from Pericarditis

Both diseases present with chest pain and ST segment elevation. The two conditions can be distinguished by the following studies:


While both disorders are associated with ST segment elevation, pericarditis is also associated with PR segment depression.

Cardiac Biomarkers

Myocarditis is associated with elevations of the CK-MB and the troponin, while pericarditis is not. If pericarditis is associated with underlying inflammation of the myocardium, then this is called myopericarditis. If there is concomitant involvement of both the pericardium and myocardium in myopericarditis, then there are elevations of the cardiac biomarkers.


In patients with myocarditis there will be a focal wall motion abnormalities, while these will be absent in patients with pericarditis. There may be a pericardial effusion in the patient with pericarditis, while myocarditis is not associated with a pericardial effusion.


[Disease name] must be differentiated from other diseases that cause [clinical feature 1], [clinical feature 2], and [clinical feature 3], such as [differential dx1], [differential dx2], and [differential dx3].


[Disease name] must be differentiated from [[differential dx1], [differential dx2], and [differential dx3].


  1. Monney PA, Sekhri N, Burchell T, Knight C, Davies C, Deaner A; et al. (2011). "Acute myocarditis presenting as acute coronary syndrome: role of early cardiac magnetic resonance in its diagnosis". Heart. 97 (16): 1312–8. doi:10.1136/hrt.2010.204818. PMID 21106555. Unknown parameter | ignored (help)

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