How is Acute Pericarditis Diagnosed and Treated?

Case

A 32-year-old female with no significant past medical history is evaluated for sharp, left-sided chest pain for five days. Her pain is intermittent, worse with deep inspiration and in the supine position. She denies any shortness of breath. Her temperature is 100.8ºF, but otherwise her vital signs are normal. The physical exam and chest radiograph are unremarkable, but an electrocardiogram shows diffuse ST-segment elevations. The initial troponin is mildly elevated at 0.35 ng/ml.

Could this patient have acute pericarditis? If so, how should she be managed?

Background

Pericarditis is the most common pericardial disease encountered by hospitalists. As many as 5% of chest pain cases unattributable to myocardial infarction (MI) are diagnosed with pericarditis.1 In immunocompetent individuals, as many as 90% of acute pericarditis cases are viral or idiopathic in etiology.^1,2 Human immunodeficiency virus (HIV) and tuberculosis are common culprits in developing countries and immunocompromised hosts.³ Other specific etiologies of acute pericarditis include autoimmune diseases, neoplasms, chest irradiation, trauma, and metabolic disturbances (e.g. uremia). An etiologic classification of acute pericarditis is shown in Table 2 (p. 16).

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Figure 1. Echocardiographic evidence of right atrial and right ventricular diastolic collapse due to large pericardial effusion suggestive of tamponadeRA: right atrium; RV: right ventricle; LA: left atrium; LV: left ventricle; Eff: pericardial effusion compressing RA and RV.

Pericarditis primarily is a clinical diagnosis. Most patients present with chest pain.⁴ A pericardial friction rub may or may not be heard (sensitivity 16% to 85%), but when present is nearly 100% specific for pericarditis.^2,5 Diffuse ST-segment elevation on electrocardiogram (EKG) is present in 60% to 90% of cases, but it can be difficult to differentiate from ST-segment elevations in acute MI.^4,6

Uncomplicated acute pericarditis often is treated successfully as an outpatient.⁴ However, patients with high-risk features (see Table 1, right) should be hospitalized for identification and treatment of specific underlying etiology and for monitoring of complications, such as tamponade.⁷

Our patient has features consistent with pericarditis. In the following sections, we will review the diagnosis and treatment of acute pericarditis.

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Table 1. High-risk features of acute pericarditis and criteria for hospitalization

Review of the Data

How is acute pericarditis diagnosed?

Acute pericarditis is a clinical diagnosis supported by EKG and echocardiogram. At least two of the following four criteria must be present for the diagnosis: pleuritic chest pain, pericardial rub, diffuse ST-segment elevation on EKG, and pericardial effusion.⁸

History. Patients may report fever (46% in one small study of 69 patients) or a recent history of respiratory or gastrointestinal infection (40%).5 Most patients will report pleuritic chest pain. Typically, the pain is improved when sitting up and leaning forward, and gets worse when lying supine.4 Pain might radiate to the trapezius muscle ridge due to the common phrenic nerve innervation of pericardium and trapezius.⁹ However, pain might be minimal or absent in patients with uremic, neoplastic, tuberculous, or post-irradiation pericarditis.

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Figure 2. EKG in acute pericarditis showing diffuse ST-segment elevations

Physical exam. A pericardial friction rub is nearly 100% specific for a pericarditis diagnosis, but sensitivity can vary (16% to 85%) depending on the frequency of auscultation and underlying etiology.^2,5 It is thought to be caused by friction between the parietal and visceral layers of inflamed pericardium. A pericardial rub classically is described as a superficial, high-pitched, scratchy, or squeaking sound best heard with the diaphragm of the stethoscope at the lower left sternal border with the patient leaning forward.