Clinical features including fever >38°C, subacute course, large effusion or tamponade, and NSAID failure indicate a poor prognosis and higher risk of complications in acute pericarditis.
Specific clinical features (fever >38 degrees 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.
Imazio et al. (2007) studied this question.