Moderate pericardial effusion early after myocardial infarction: left ventricular free wall rupture until proven otherwise.

Pericardial effusion (PE) associated with myocardial infarction (MI) is considered to be associated with anterior ST-segment elevation MI (STEMI), with large infarcts, and when heart failure is present. When PE is associated with cardiac tamponade, it is usually due to cardiac rupture, hemorrhagic pericarditis, or aortic dissection involving the right coronary artery. However, the majority of PE does not cause hemodynamic compromise, and a small to moderate PE may often be viewed as a benign reaction to the MI. In 1986, Galve et al1 demonstrated in a study of 138 consecutive patients with acute MI that 28% of patients had a PE. The study was meticulously performed with repeated echocardiographic evaluations, and there were no cases of cardiac tamponade. However, these data may no longer be valid because the treatment of acute MI has changed dramatically since 1986. In a large study in the modern era of reperfusion from 25 French hospitals including 908 patients with MI, a PE was detected in only 6.6% of the patients.2 Patients had an echocardiogram performed at admission and again at discharge, and 0.8% developed left ventricular free wall rupture (FWR). This incidence of FWR is similar to that of a larger registry that did not search meticulously for rupture.3