Background: The aim of this study was to assess the prevalence of pericardial effusion in acute myocardial infarction and the different prognosis associated with distinct patterns of pericardial effusion (anechoic/hypoechoic vs hyperechoic effusion).
Methods: Five hundred eighty-five consecutive patients admitted to the Coronary Care Unit for acute myocardial infarction were initially considered. Forty of them were excluded due to a technically poor acoustic window. The remaining 545 patients were studied by two-dimensional echocardiography at admission, before discharge (after an average of 9 days in the Coronary Care Unit) and whenever there was an important change in the clinical status (chest pain, lipothymia or syncope, hemodynamic deterioration with systolic blood pressure < 90 mmHg, cardiac arrest).
Results: Pericardial effusion was found in 51 patients (9%). Three distinct textural patterns of pericardial effusion were noted on the basis of the echogenic properties: 1) anechoic or hypoechoic pericardial effusion was frequent (30 patients), mild or moderate and generally benign; 2) hyperechoic type "A" effusion pattern was rare (2 patients) and associated with fever, leukocytosis and pericardial rubs; 3) hyperechoic type "B" was frequent (19 patients), large and always associated with major complications (all cases cardiac tamponade and/or death).
Conclusions: Pericardial effusion is not an uncommon finding in serial echo evaluation of patients with acute myocardial infarction, especially when infarction is anterior, extensive and Q wave. Echocardiographically detected pericardial effusion shows different textural patterns with hypoanechoic effusion more frequent, limited and prognostically benign than hyperechoic effusion larger and often associated with adverse events.