Pleural effusions in acute idiopathic pericarditis and postcardiac injury syndrome

Pleural effusions are frequent in the context of acute idiopathic pericarditis and following pericardiotomy, but they have seldom been characterized. This review summarizes their most relevant clinical features.

In acute idiopathic pericarditis, pleural effusions tend to be left-sided and, if bilateral, they are usually larger on the left. Less than 5% are unilateral right-sided. About 90% of the effusions occupy less than one-third of the hemithorax, and 99% meet Light's exudative criteria with a predominance of lymphocytes in three fourths of the cases. Although postcardiac injury syndrome (PCIS)-related effusions share similar characteristics, they present some differential features: more than 15% are unilateral on the right (except for Dressler syndrome), one-fourth opacify half or more of the hemithorax, and nearly two thirds are bloody. The combination of nonsteroidal anti-inflammatory drugs and colchicine, along with therapeutic thoracenteses for moderate-to-large effusions, is the mainstay treatment approach. The postoperative use of colchicine is also a reasonable option for preventing PCIS in patients who have undergone cardiac surgery.

Pleural effusions because of pericardial diseases remain a clinical diagnosis. If unilateral right-sided, massive, or transudative effusions are seen, an alternative diagnosis to acute pericarditis should be considered.