Acute pericarditis in the United States is usually idiopathic and presumed to be viral. A history and laboratory tests, a chest radiograph, and an echocardiogram are used in evaluation. Treatment usually includes an NSAID and colchicine. The latest Clinical Practice review, on this topic, comes from Dr. Martin LeWinter, at the University of Vermont Medical Center.
In developed countries, roughly 80 to 90% of cases of acute pericarditis are idiopathic; that is, no specific cause is identified after routine evaluation. It is assumed that these cases are viral. The remaining 10 to 20% of cases are most commonly associated with post-cardiac injury syndromes, connective-tissue diseases (especially systemic lupus erythematosus), or cancer.
•How does acute pericarditis present clinically, and what are the diagnostic criteria?
Chest pain is the presenting symptom in virtually all patients for whom a diagnosis of pericarditis would be considered. Although the differential diagnosis of chest pain is extensive, certain features point strongly to pericarditis, especially pleuritic pain that is relieved by sitting forward and that radiates to the trapezius ridge (the latter feature is virtually pathognomonic). Many patients have premonitory symptoms suggestive of a viral illness, and an abrup onset is not unusual. Sinus tachycardia and low-grade fever are also common. The diagnosis of acute pericarditis is established when a patient has at least two of the following symptoms or signs: chest pain consistent with pericarditis, pericardial friction rub, typical ECG changes, or a pericardial effusion of more than trivial size. Because the rub and ECG findings may be transient, frequent auscultation and ECG recordings can be helpful in establishing the diagnosis.
• What is the general approach when acute pericarditis is suspected or confirmed?
Appropriate tests include a complete blood count with a differential count, a high-sensitivity test of C-reactive protein, measurements of troponin I or T and serum creatinine, and liver-function tests. A chest radiograph should always be obtained, and findings should be normal unless there is a large pericardial effusion or an associated pulmonary disorder. An echocardiogram is routinely indicated for patients with suspected or confirmed pericarditis. The most important rationale is detection of a pericardial effusion, which can cause or threaten to cause cardiac tamponade without enlarging the cardiac silhouette on a chest radiograph.
Morning Report Questions
Q: What is the treatment for acute pericarditis?
A: Nonsteroidal antiinflammatory drugs (NSAIDs) have long been the mainstay of the initial treatment of acute pericarditis. The most commonly used agents are ibuprofen (600 to 800 mg every 6 to 8 hours), indomethacin (25 to 50 mg every 8 hours), and aspirin (2 to 4g daily in divided doses). Patients receiving these drugs should also receive a proton pump inhibitor for gastric protection. On the basis of observational data from a relatively small number of patients with recurrent pericarditis, the European Society of Cardiology concluded in its 2004 guidelines that there was sufficient evidence to recommend colchicine combined with an NSAID for initial treatment of a first bout of pericarditis. More recently, evidence from the Investigation on Colchicine for Acute Pericarditis (ICAP) randomized clinical trial, involving patients with a first episode of pericarditis, strongly supported this recommendation. The optimal duration of treatment is uncertain. For colchicine, a 3-month course is reasonable on the basis of results from the ICAP trial. The usual duration of NSAID treatment, supported by expert opinion, is 1 to 2 weeks, with the actual duration driven by clinical response.
Q: What clinical course can be expected for most patients diagnosed with acute pericarditis?
A: In 70 to 90% of patients, acute idiopathic pericarditis is self-limited, responds promptly to initial treatment, and completely resolves. In a small number of patients, probably less than 5%, the condition does not respond satisfactorily to initial treatment, and in 10 to 30% of patients, recurrences develop after a satisfactory initial response. Most patients have only one or two recurrences, but a small fraction (probably less than 5% of the total population with acute pericarditis) have multiple recurrences with considerable disability. Ultimately, recurrences cease in the majority of cases.