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.

Clinical Pearls

•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.

Figure 1. Typical Electrocardiogram in a Patient with Acute Pericarditis.

• 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.

Figure 2. Suggested Initial Approach for a Patient Presenting with Chest Pain Suggestive of Acute Pericarditis.

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.

In a trial involving smokers who called the New Zealand national quitline, cytisine (a partial agonist of the nicotinic acetylcholine receptor) was superior to nicotine-replacement therapy in helping smokers quit. Nausea and sleep disorders were more frequent with cytisine.

Four systematic reviews report cytisine to be superior to placebo for short-term and long-term smoking abstinence. No trials have compared cytisine with nicotine-replacement therapy; a pragmatic, open-label, noninferiority trial conducted in New Zealand investigated whether cytisine was at least as effective as nicotine-replacement therapy.

Clinical Pearls

•What is cytisine?

Cytisine is a plant-based alkaloid found in members of the Leguminosae family. Like varenicline, cytisine is a partial agonist of nicotinic acetylcholine receptors (nAChRs), with an affinity for the alpha4beta2 receptor subtype, and a half-life of 4.8 hours. Cytisine remains relatively unknown outside Eastern Europe despite calls for licensing worldwide because of its proven benefits, low cost as compared with other cessation medications (cytisine, $20 to $30 for 25 days; nicotine-replacement therapy, $112 to $685 for 8 to 10 weeks; varenicline, $474 to $501 for 12 weeks), and low cost per quality-adjusted-life-year.

•Is cytisine as effective as nicotine-replacement therapy for smoking cessation?

Cytisine was not only noninferior to nicotine-replacement therapy but had superior effectiveness: 1-month continuous abstinence rates were significantly higher in the cytisine group (40%, 264 of 655) than in the nicotine-replacement therapy group (31%, 203 of 655) (risk difference, 9.3 percentage points; 95% confidence interval [CI], 4.2 to 14.5; number needed to treat, 11). The effectiveness of cytisine for continuous abstinence was superior to that of nicotine-replacement therapy at 1 week, 2 months, and 6 months.

Table 2. Continuous Abstinence and 7-Day Point-Prevalence Abstinence According to Treatment Group, According to the Intention-to-Treat Analysis.

Morning Report Questions

Q: Is cytisine equally effective in men and women?

A: Among secondary outcomes, prespecified analyses conducted according to sex showed a significantly higher 1-month continuous abstinence rate with cytisine in women and showed no significant difference (noninferiority) in men (P=0.011 for heterogeneity). The higher quit rate observed in women taking cytisine has not been previously reported in studies of nAChR partial agonists. This finding could be the result of chance (since data were not adjusted for multiplicity) but warrants further investigation, since several reviews of nicotine-replacement therapy have reported lower quit rates in women than in men, possibly as a result of biologic and psychosocial differences.

Q: How do the safety profiles of cytisine and nicotine-replacement therapy compare?

A: Self-reported adverse events occurred more frequently in the cytisine group (288 events reported by 204 participants) than in the nicotine-replacement-therapy group (174 events reported by 134 participants), with an incidence rate ratio of 1.7 (95% CI, 1.4 to 2.0; P<0.001). The majority of adverse events were nonserious and were mild to moderate in severity. The most frequent adverse events in the cytisine group were nausea and vomiting and sleep disorders.