There are several variants of constrictive pericarditis: Chronic constrictive pericarditis, usually requiring pericardiectomy as definitive treatment Subacute (early stage) constrictive pericarditis, developing weeks to months after an inciting injury and managed initially with medical therapy Transient constrictive pericarditis (typically subacute), is that which resolves spontaneously or after medical therapy Effusive-constrictive pericarditis characterized by pericardial constriction involving the visceral pericardium with significant pericardial effusion sometimes requiring treatment for cardiac tamponade Etiology of Pericarditis Acute pericarditis may result from infection, autoimmune or inflammatory disorders, uremia, trauma, myocardial infarction (MI), cancer, radiation therapy, or certain drugs (see table Causes of Acute Pericarditis).