What are the symptoms of viral myocarditis?

Symptoms of Viral Myocarditis

The most common symptoms of viral myocarditis are chest pain, dyspnea, and fever, though presentation ranges from mild nonspecific complaints to fulminant cardiogenic shock. 1, 2

Cardinal Symptoms

Most Common Presentations

• Chest pain occurs in 82-95% of adult patients with acute myocarditis, often mimicking acute coronary syndrome with angina-like quality 2, 1
• Dyspnea presents in 19-49% of cases, ranging from mild exertional breathlessness to acute heart failure 2, 1
• Fever is among the most common symptoms, particularly with COVID-19 myocarditis 1
• Cough frequently accompanies viral myocarditis, especially in respiratory viral infections 1

Additional Cardiac Symptoms

• Palpitations from supraventricular or ventricular arrhythmias are common 1, 3
• Syncope occurs in 5-7% of patients, often related to arrhythmias or hemodynamic compromise 2, 1
• Postexertional fatigue is a characteristic symptom that may persist long-term 1
• Nonspecific chest discomfort beyond typical angina, including pressure sensations 1, 4

Clinical Spectrum and Severity

Mild to Moderate Cases

• Nonspecific symptoms of fatigue and mild shortness of breath without overt heart failure 4, 2
• Symptoms may be subtle enough that patients present with only palpitations or mild chest discomfort 1

Severe Presentations

• Acute congestive heart failure with or without cardiogenic shock can occur 1
• Cardiogenic shock develops in 27% of COVID-19-associated myocarditis cases 1
• Distributive shock from sepsis or hyperinflammatory state occurs in 12% of cases 1
• Sustained ventricular arrhythmias requiring urgent intervention 1
• Advanced atrioventricular block causing bradyarrhythmias 1

Temporal Pattern

Prodromal Phase

• Recent viral illness with gastrointestinal or upper respiratory symptoms often precedes cardiac symptoms by days to weeks 5, 1
• The acute viral phase lasts only 1-3 days, characterized by direct viral myocyte injury 1

Acute Phase Duration

• Symptoms typically evolve over days to weeks during the inflammatory phase 1
• Resolution within 3 months occurs in many cases 1
• Persistence beyond 12 months has been documented, indicating chronic myocarditis 1

Critical Clinical Caveats

Symptom-Severity Discordance

Symptom intensity does not correlate well with left ventricular ejection fraction, cardiac troponin levels, natriuretic peptides, or C-reactive protein. 1, 6 This means:

• Patients may have severely reduced LVEF with minimal symptoms 6
• Conversely, significant symptoms may occur with preserved systolic function 6
• Do not rely on symptom severity alone to gauge disease severity—objective testing is mandatory 6

Asymptomatic Presentations

• Subclinical myocarditis can occur, discovered incidentally on screening (e.g., athletes undergoing cardiac MRI) 1
• These patients may have abnormal ventricular strain patterns without overt symptoms 6

Mimicry of Other Conditions

• ST-elevation myocardial infarction (STEMI) is frequently mimicked, with ST-segment elevations on ECG and elevated troponins 3, 1
• Young patients presenting with "infarct-like" symptoms should raise suspicion for myocarditis, especially with recent viral illness 6, 3

Diagnostic Approach Based on Symptoms

When symptoms suggest cardiac involvement (chest pain/pressure, dyspnea, palpitations, syncope):

• Obtain ECG looking for diffuse T-wave inversion, ST-segment elevation without reciprocal depression, or QRS prolongation 1
• Measure cardiac troponin (preferably high-sensitivity assay) 1
• Perform echocardiography to assess wall motion abnormalities in noncoronary distribution 1
• Consider cardiac MRI if diagnosis remains uncertain, looking for elevated T1/T2 mapping and nonischemic late gadolinium enhancement 1, 6

The absence of specific pathognomonic features combined with the wide spectrum of clinical manifestations makes myocarditis diagnosis particularly challenging—maintain high clinical suspicion in young patients with cardiac symptoms following viral illness. 5, 3