Myocarditis
Myocarditis is inflammation of the myocardium, most often postviral or immune-mediated, presenting across a spectrum from a mild chest-pain syndrome mimicking myocardial infarction to fulminant heart failure and arrhythmia. Diagnosis relies on cardiac MRI (or biopsy for severe or refractory cases), and treatment is supportive heart-failure care, with cause-specific immunosuppression for giant cell, checkpoint-inhibitor, and autoimmune myocarditis.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
Definition: myocarditis is inflammation of the myocardium, most commonly from viral infection or immune-mediated processes.
- Epidemiology
A significant cause of sudden death and dilated cardiomyopathy in young adults.
- Risk factors
Recent viral infection (a preceding flu-like or gastrointestinal illness).
- Pathophysiology
Direct and immune-mediated injury: viral infection or an immune trigger causes myocyte injury and an inflammatory infiltrate.
- Clinical features
Chest pain: often pleuritic or ACS-like, sometimes with concurrent pericarditis (myopericarditis).
- Differential diagnosis
Acute myocardial infarction: ACS with a troponin rise, distinguished by obstructive coronary disease on angiography rather than the clean coronaries of myocarditis (STEMI).
- Diagnosis
Establish with cardiac MRI meeting inflammation criteria, reserving biopsy for severe or unexplained cases: the diagnostic basis is a compatible clinical syndrome (troponin rise, ECG changes…
- Management
First, supportive heart-failure and arrhythmia care: guideline-directed therapy for reduced ejection fraction (ACE inhibitor/ARB or sacubitril-valsartan, a beta-blocker such as metoprolol 25 mg PO…
- Complications
Fulminant heart failure and cardiogenic shock.
- Prognosis
Most cases recover with supportive care. Fulminant myocarditis can be survivable with aggressive support, but giant cell myocarditis has a poor prognosis without immunosuppression and often transplantation.
- Prevention
Avoid exercise during the acute phase and for 3 to 6 months to reduce arrhythmia and worsening injury.
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Dilated cardiomyopathy
Dilated cardiomyopathy is left ventricular (often biventricular) dilation with systolic dysfunction not explained by loading conditions or coronary disease, from genetic, viral, toxic, or peripartum causes, presenting as heart failure with reduced ejection fraction. Diagnosis is by echocardiography with a workup for reversible causes, and treatment is guideline-directed heart-failure therapy with device therapy for high-risk patients.
- Acute heart failure
Acute heart failure is the rapid onset or worsening of heart failure symptoms requiring urgent therapy, most often pulmonary congestion from a precipitant such as ischemia, arrhythmia, or nonadherence. Management is oxygen, intravenous diuretics, and vasodilators for the congested-but-perfused patient, with inotropes or support for the hypoperfused patient.
- Acute pericarditis
Acute pericarditis is inflammation of the pericardium, most often viral or idiopathic, presenting with pleuritic chest pain relieved by sitting forward, a pericardial friction rub, and diffuse ST elevation with PR depression. Treatment is an NSAID plus colchicine, and the main hazards are effusion, tamponade, and recurrence.
- ST-elevation myocardial infarction (STEMI)
ST-elevation myocardial infarction is acute transmural myocardial ischemia from complete coronary occlusion, diagnosed by ischemic symptoms with diagnostic ST-segment elevation and a rising troponin. It is a time-critical emergency in which immediate reperfusion, primary PCI within 90 minutes or fibrinolysis when PCI is unavailable, plus antiplatelet and anticoagulant therapy, determines survival.
- MINOCA (myocardial infarction with nonobstructive coronary arteries)
MINOCA is myocardial infarction with nonobstructive coronary arteries, defined by infarction criteria but less than 50 percent stenosis on angiography, requiring a search for the underlying mechanism such as plaque disruption, coronary spasm, spontaneous dissection, microvascular dysfunction, or embolism. Diagnosis pairs the infarction criteria with angiography and often cardiac MRI and intracoronary imaging, and treatment targets the identified cause.
- Pulmonary embolism
Pulmonary embolism is thrombus, usually from a lower-extremity deep vein thrombosis, obstructing the pulmonary arterial circulation and causing V/Q mismatch, right ventricular strain, and hypoxemia. Diagnosis follows Wells criteria (with PERC in low-risk patients) to sequence D-dimer, CT pulmonary angiography, and V/Q scanning, and management is risk-stratified anticoagulation escalating to thrombolysis or embolectomy for hemodynamic instability.