Diagnostic Considerations
The classic feature of chest pain and dyspnea with pericarditis may be subtle and can be confused with other diagnoses, particularly in elderly individuals. Be careful not to confuse pericarditis with esophageal disorders, costochondritis, or other causes of noncardiac chest pain. Pericarditis may occur after renal transplantation, which may be related to uremia or infections (eg, cytomegalovirus [CMV]). Liver disease has been noted in asymptomatic constrictive pericarditis.
Given an overall lack of specificity of clinical features, diagnostic protocols to determine the etiology for pericarditis have been described. Following specific protocols, several investigators determined a specific etiology in 14-22% of patients. In one study, cardiac tamponade and an unfavorable clinical outcome, with persistence of fever, significant pericardial effusion, or general illness lasting longer than 1 week, was highly associated with finding a specific etiology. See an example under Workup.
Small asymptomatic pericardial effusions in patients with acquired immunodeficiency syndrome (AIDS) may not require diagnostic evaluation. [29] Large symptomatic pericardial effusions should be investigated, because two thirds of such effusions are potentially infections or neoplasms. Tuberculous pericarditis can also occur. [15]
Pleural effusions appear to be common in hospitalized patients with a first episode of acute pericarditis, and they are associated with the intensity of the inflammatory reaction. [30] Thus, investigators caution that pleural effusions do not necessarily indicate a secondary cause of the pericarditis. When they appear bilaterally, the risk of an in-hospital cardiac tamponade is raised but does not impact the risk of pericarditis recurrence over the long term. [30]
Tension pneumothorax may mimic cardiac tamponade. Trauma ultrasonography has limited this misdiagnosis.
Elevated central venous pressure (CVP) may be absent in patients with pericarditis and preexisting hypovolemia.
The diagnosis of chylopericardium is made with the following criteria (class I, level C evidence) [3] :
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Presence of a milky opalescent pericardial effusion
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Triglyceride level over 500 mg/dL
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Cholesterol-to-triglyceride ratio below 1
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Negative cultures
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Lymphocytic predominance (lymphocyte count between a few hundred to several thousand per mL)
Differentiating pericarditis from acute MI
Aside from clues elicited from the history and physical examination, pericarditis can be difficult to distinguish from myocardial infarction (MI) and repolarization in patients who present with chest pain and ST-segment elevation on electrocardiograms (ECGs). The potential misdiagnosis of pericarditis for acute MI has led to unfortunate complications when thrombolytic therapy has been given.
Some ECG findings that may be helpful include the following:
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Repolarization does not progress through stages and is uncommonly associated with PR depression; serial monitoring of ECGs in young patients with chest pain helps differentiate early repolarization from acute pericarditis
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An ST-segment–to–T-wave ratio of 0.25 or more in V6 can distinguish acute pericarditis from early repolarization
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The ST segment in acute MI is usually convex, bowing upward with reciprocal changes, as opposed to concave ST segments without reciprocal changes observed in acute pericarditis and repolarization
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A study by Rossello et al indicated that unlike patients with acute ST-segment elevation MI (STEMI), patients with acute pericarditis do not show prolongation of the QRS complex and shortening of the QT interval in ECG leads with ST-segment elevation [31]
Differential Diagnoses
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Aortic Dissection
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Myocardial Ischemia
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Stage 1 electrocardiograph changes in a patient with acute pericarditis.
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Stage 4 electrocardiograph changes in the same patient as in the previous image, taken approximately 3 months after acute pericardial illness. The patient remained symptom free despite continued T-wave inversion.
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Chest radiographs revealing markedly enlarged cardiac silhouette and normal-appearing lung parenchyma in prepericardiocentesis (A) and postpericardiocentesis (B). Courtesy of Zhi Zhou, MD.
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Recording of aortic pressure showing pulsus paradoxus. During inspiration, systolic pressure declines 20 mm Hg. Courtesy of Zhi Zhou, MD.
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This ultrasonogram demonstrates a normal subcostal 4-chamber view of the heart. The pericardium is brightly reflective (echogenic or white in appearance). LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle. Part B courtesy of Wikimedia Commons/Patrick J Lynch and C Carl Jaffe.
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H&E stain, medium power magnification showing a rheumatoid nodule in rheumatoid pericarditis, composed of histiocytes and scattered multinucleated giant cells (lower right) surrounding necroinflammatory debris (upper left).
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Pap stain, high power magnification of adenocarcinoma metastatic to the pericardium on pericardiocentesis with the red arrow showing a normal mesothelial cell and the black arrowhead showing adenocarcinoma.
