Hospitalization is not necessary in most cases
Consider admission for:
Patients likely to have a specific cause (i.e. uremia, malignancy)
Subacute onset over weeks
Fever >100.4
Large effusion (echo-free space>20mm)
Cardiac tamponade
Immunosupressed
Anticoagulant use
Failure to respond to NSAIDs (>7dy)
Elevated cardiac enzymes (suggesting myopericarditis)
Trauma
Patients likely to have a specific cause (i.e. uremia, malignancy)
Subacute onset over weeks
Fever >100.4
Large effusion (echo-free space>20mm)
Cardiac tamponade
Immunosupressed
Anticoagulant use
Failure to respond to NSAIDs (>7dy)
Elevated cardiac enzymes (suggesting myopericarditis)
Trauma
Pericarditis
Cardiac
Constrictive pericarditis
ST-segment elevation myocardial infarction 
Myocarditis 
Post-MI 
Myocarditis
Previous MI with recurrent ischemia in same area