Background--The clinical search for indicators of poor prognosis of acute pericarditis may be useful for clinical triage of patients at high risk of specific causal conditions or complications. The aim of the present article is to assess the relationship between clinical features at presentation and specific causes or complications.

Methods and Results--A total of 453 patients aged 17 to 90 years (mean age 52±18 years, 245 men) with acute pericarditis (post-myocardial infarction pericarditis was excluded) were prospectively evaluated from January 1996 to August 2004. A specific cause was found in 76 of 453 patients (16.8%): autoimmune in 33 patients (7.3%), neoplastic in 23 patients (5.1%), tuberculous in 17 patients (3.8%), and purulent in 3 patients (0.7%). In multivariable analysis, women (hazard ratio [HR] 1.67, 95% confidence interval [CI] 1.03 to 2.70; P=0.036) and patients with fever >38°C (HR 3.56, 95% CI 1.82 to 6.95; P<0.001), subacute course (HR 3.97, 95% CI 1.66 to 9.50; P=0.002), large effusion or tamponade (HR 2.15, 95% CI 1.09 to 4.23; P=0.026), and failure of aspirin or of nonsteroidal anti-inflammatory drugs (HR 2.50, 95% CI 1.28 to 4.91; P=0.008) were at increased risk of specific causal conditions. After a mean follow-up of 31 months, complications were detected in 95 patients (21.0%): recurrences in 83 patients (18.3%), tamponade in 14 patients (3.1%), and constriction in 7 patients (1.5%). In multivariable analysis, women (HR 1.65, 95% CI 1.08 to 2.52; P=0.020) and patients with large effusion or tamponade (HR 2.51, 95% CI 1.37 to 4.61; P=0.003) and failure of aspirin or of nonsteroidal anti-inflammatory drugs (HR 5.50, 95% CI 3.56 to 8.51; P<0.001) were at increased risk of complications.

Conclusions--Specific clinical features (fever >38°C, subacute course, large effusion or tamponade, and aspirin or NSAID failure) may be useful to identify higher risk of specific causal conditions and complications.