'Idiopathic' pericarditis--the clinician's challenge [nothing is idiopathic]

Reports on the aetiologic distribution of acute pericarditis vary significantly from study to study. We attempted to summarise reports on incidence of different aetiologies of pericarditis and explain the variable range of reported frequencies of different aetiologies. The literature between 1978 and 2005 was reviewed for comparative incidence of acute pericarditis. Reports of more than 50 subjects were included. The most common cause of pericarditis was 'idiopathic' pericarditis (mean: 26.1%), followed by neoplastic diseases (mean: 25.6%) and iatrogenic pericarditis (mean: 16.3%). Each mean had a wide range of 95% confidence interval. In summary, the clinician is confronted by a huge dispersion of reported frequencies of pericarditis aetiologies as a consequence of multiple factors. Recognising specific rare causes of pericarditis, often essential for early diagnosis and successful treatment, means coping with that aetiologic dispersion and its implied probabilities.