Viral Myocarditis Diagnosis Criteria

Viral myocarditis is a condition characterized by inflammation of the heart muscle due to a viral infection. Diagnosing this condition involves a combination of clinical evaluation, patient history, laboratory tests, and imaging studies. The diagnostic criteria can be broken down into several key components.

Patient History

One of the primary indicators for viral myocarditis is a recent history of viral infection. This typically occurs within two weeks prior to the onset of cardiac symptoms. Common viral illnesses include upper respiratory infections marked by fever, runny nose, coughing, and phlegm production, as well as gastrointestinal infections that present with symptoms like diarrhea. A documented or reported viral illness within this timeframe significantly increases the likelihood of a viral myocarditis diagnosis.

Cardiac Symptoms

Patients often present with symptoms that indicate myocardial damage or dysfunction. These may include palpitations, chest tightness, shortness of breath, and irregular heartbeats. In more severe cases, symptoms can progress to include signs of heart failure such as fatigue, fluid retention, and reduced exercise tolerance.

Biomarker Testing

Cardiac biomarkers play a crucial role in confirming myocardial injury. Elevated levels of cardiac enzymes such as creatine kinase (CK) and serum creatine kinase MB (CK-MB) are commonly observed. Additionally, increased levels of cardiac troponins—specifically troponin T and troponin I—are strong indicators of heart muscle damage. In severe cases, biomarkers for heart failure, such as brain natriuretic peptide (BNP), may also be elevated. Inflammatory markers like C-reactive protein (CRP) are often increased, reflecting the body's immune response to the infection.

Imaging and Electrocardiographic Findings

Electrocardiogram (ECG) abnormalities are frequently seen in patients with viral myocarditis. These may include arrhythmias or signs of myocardial necrosis. Echocardiography is another essential diagnostic tool. It can reveal regional or global left ventricular dysfunction, such as segmental or diffuse reductions in wall motion. These findings help support the diagnosis and assess the severity of myocardial involvement.