Pericardial effusion of various sizes is a quite common clinical finding, while its progression to effusive-constrictive pericarditis occurs in about 1.4–14% of cases. Although available evidence on prevalence and prognosis of this rare pericardial syndrome is poor, apparently a considerable proportion of patients conservatively managed has a spontaneous resolution after several weeks.

A 61-year-old female presented to our emergency department reporting fatigue, effort dyspnea and abdominal swelling. The echocardiography showed large pericardial effusion with initial hemodynamic impact, so she underwent a pericardiocentesis with drainage of 800–850cm³ of exudative fluid, on which diagnostic investigations were undertaken: possible viral and bacterial infections, medical conditions, iatrogenic causes, neoplastic and connective tissue diseases were all excluded. Despite empirical therapy with NSAIDs and colchicine, after about one week she had a recurrence of pericardial effusion and progressive development of constriction. Echocardiography performed after a few weeks of anti-inflammatory therapy showed resolution of constriction and PE, with clinical improvement.

If progression of pericardial syndromes to a constrictive form is rarely described in literature, cases of transitory effusive-constrictive phase are even more uncommon, mainly reported during the evolution of pericardial effusion. According to the available data, risk of progression to a constrictive form is very low in case of idiopathic pericardial effusion. We report a case of large idiopathic subacute pericardial effusion, treated with pericardiocentesis and then evolved into an effusive-constrictive pericarditis. A prolonged anti-inflammatory treatment leads to complete resolution of pericardial syndrome without necessity of pericardiectomy.