How pericarditis is diagnosed:
tests, ECG, echocardiogram and cardiac MRI

Article written and reviewed by Dr Luca Moretti

The diagnosis of pericarditis does not depend on a single test. It is established by combining symptoms, clinical examination, electrocardiogram, blood tests and imaging. The 2025 ESC guidelines updated the criteria: a definite clinical diagnosis requires a compatible presentation, such as chest pain, together with more than one additional criterion among a pericardial friction rub, characteristic ECG changes, elevated C-reactive protein, a new or increased pericardial effusion, and signs of pericardial inflammation on cardiac magnetic resonance imaging.
With only one additional criterion the diagnosis is considered possible; chest pain alone, without other findings, is not sufficient to confirm it.

The investigations used most often are:

• medical examination and cardiac auscultation;
• electrocardiogram;
• C-reactive protein and other inflammatory markers;
• troponin to assess possible myocardial involvement;
• echocardiogram to look for effusion and hemodynamic consequences;
• cardiac magnetic resonance imaging in uncertain or complex cases or when myocardial involvement is suspected;
• additional targeted tests when a specific cause is suspected.

Pericarditis may present with very typical features or with subtle findings. The purpose of testing is not only to confirm inflammation of the pericardium, but also to exclude conditions that can present with similar symptoms, determine whether the myocardium is involved, and identify possible complications or specific causes.

What the physician looks for during examination and ECG

The characteristics of the pain are the first element. Pericarditic pain is often sharp, worsens with deep inspiration or when lying down, and may improve when sitting up or leaning forward. Examination may detect a pericardial friction rub, a superficial sound produced by the inflamed surfaces rubbing against each other. It is highly suggestive when present, but it is not constant and may be intermittent.
Blood pressure, heart rate and signs of congestion or hemodynamic compromise also help determine whether complications are present, particularly a large effusion or tamponade.

The electrocardiogram may show PR-segment depression and diffuse ST-segment elevation. These changes are known as characteristic of pericarditis, but they do not occur in every case. The 2025 ESC guidelines also emphasize that the pericardium is electrically silent: ECG changes therefore suggest possible concomitant myocardial involvement and must be interpreted in the context of the entire clinical picture.
This is one reason why the differential diagnosis with myocardial infarction should never rely on a single finding. The guide pericarditis or heart attack examines this issue in more detail.

What blood tests show

C-reactive protein (CRP) is one of the most useful markers because it documents an inflammatory response and can be followed over time. According to the 2025 ESC guidelines, it is elevated in most patients with acute pericarditis, but not in all. A normal CRP therefore does not absolutely exclude the diagnosis, especially if the other findings are convincing.
Erythrocyte sedimentation rate, complete blood count and other parameters may also be assessed depending on the context. Creatinine, kidney function, thyroid tests, and infectious or autoimmune investigations are not requested indiscriminately in every case: the choice depends on the clinical history, risk features and suspicion of a specific cause.

The troponin has a different role. It is not used to measure pericardial inflammation, but myocardial cell injury. If it is elevated in a patient with pericarditis, myocardial involvement such as myopericarditis must therefore be considered, as well as other possible causes of troponin elevation.
Troponin is particularly important because chest pain with elevated troponin also enters the differential diagnosis with an acute coronary syndrome. The value must be interpreted together with symptoms, ECG, its trend over time, echocardiogram and, when appropriate, magnetic resonance imaging.

What the echocardiogram is used for

The transthoracic echocardiogram is the first-line imaging test in pericardial disease. It can show whether a pericardial effusion is present, estimate its size and, above all, determine whether the fluid is interfering with normal cardiac filling. It also allows assessment of chamber size and function and can identify findings suggesting myocardial involvement or constrictive physiology.
However, a normal echocardiogram does not exclude pericarditis. Many patients have no effusion, or only a small rim of fluid. Echocardiography shows fluid and functional consequences well, but it is not the best test for directly characterizing inflammation of the pericardial tissue.

When an effusion is present, its measurement is not the only factor that matters. The speed at which it formed and its effects on cardiac dynamics are also important. Rapid accumulation can be dangerous even without becoming very large, whereas an effusion that develops slowly may be tolerated for longer.
If the echocardiogram shows findings compatible with cardiac tamponade, the problem becomes urgent and assessment focuses on hemodynamic stability and the need for drainage.

When cardiac magnetic resonance imaging is needed

Cardiac magnetic resonance imaging has become central when the diagnosis is unclear or the clinical picture is more complex. It can show pericardial edema and late gadolinium enhancement, which are signs of inflammation and increased vascularity of the tissue. It also allows simultaneous assessment of the myocardium, which is particularly useful when troponin is elevated or there is concern for myopericarditis.
Modern guidelines do not require routine cardiac MRI for every simple episode with a typical presentation that responds to treatment. The test becomes particularly valuable in atypical, persistent or recurrent forms, in uncertain diagnoses, and when it is necessary to distinguish active inflammation from fibrotic sequelae.

Cardiac computed tomography has a more selective role. It is useful for visualizing pericardial calcifications, characterizing some collections or masses, and assessing alternative thoracic diseases. The choice among echocardiography, CT and MRI is therefore not a ranking of tests that are "more or less accurate": each modality answers different questions.
In uncomplicated cases, a good clinical assessment with ECG, blood tests and echocardiography may be sufficient; in complex situations multimodality imaging adds decisive information.

Frequently asked questions about tests for pericarditis

Which tests are needed to diagnose pericarditis?
Generally a clinical examination, ECG, blood tests and an echocardiogram; MRI is used mainly in uncertain or complex cases.
Is the ECG always abnormal?
No. Characteristic changes are not present in all patients and a normal ECG does not exclude the diagnosis.
Is CRP always elevated?
No. It is often elevated and represents an important additional criterion, but it may be normal in a minority of cases.

Does troponin increase in pericarditis?
It may increase when the myocardium is also involved. In that case, myopericarditis and other causes of myocardial injury must be considered.
Is MRI always needed?
No. It is particularly useful when the diagnosis is uncertain, symptoms persist or recur, or myocardial involvement is suspected.