Myopericarditis versus viral or idiopathic acute pericarditis

To investigate the relative incidence, clinical presentation and prognosis of myopericarditis among patients with idiopathic or viral acute pericarditis.

Prospective observational clinical cohort study.

Two general hospitals from an urban area of 220 000 inhabitants.

274 consecutive cases of idiopathic or viral acute pericarditis between January 2001 and June 2005.

Relative prevalence of myopericarditis. Clinical features at presentation including echocardiographic data (ejection fraction (EF), wall motion score index (WMSI)) and follow-up data at 12 months including complications, results of echocardiography, electrocardiography and treadmill testing.

Myopericarditis was recorded in 40/274 (14.6%) consecutive patients. At presentation, the following clinical features were independently associated with myopericarditis: arrhythmias (odds ratio (OR) = 17.6, 95% confidence interval (CI) 5.7 to 54.1; p<0.001), male gender (OR = 6.4, 95% CI 2.3 to 18.4; p = 0.01), age <40 years (OR = 6.1, 95% CI 2.2 to 16.9; p = 0.01), ST elevation (OR = 5.4, 95% CI 1.4 to 20.5; p = 0.013) and a recent febrile syndrome (OR = 2.8, 95% CI 1.1 to 7.7; p = 0.044). After 12 months' follow-up an increase of EF (basal EF 49.6 (5.1)% vs 12-month EF 59.1 (4.6)%; p<0.001) and decrease of WMSI (basal WMSI 1.19 (0.27) vs 12-month WMSI 1.02 (0.09); p<0.001) were recorded in patients with myopericarditis, with a normalisation of echocardiography, electrocardiography and treadmill testing in 98% of cases. Use of heparin or other anticoagulants (OR = 1.1, 95% CI 0.3 to 3.5; p = 0.918) and myopericarditis (OR = 2.3, 95% CI 0.7 to 7.6; p = 0.187) was not associated with an increased risk of cardiac tamponade or recurrences.

Myopericarditis is relatively common and shows a benign evolution also in spontaneous cases not related to vaccination.