Pericarditis after Myocardial Infarction

A 61-year-old man with no previous history of coronary artery disease presented with an acute ST-elevation myocardial infarction (MI). He was promptly taken for cardiac catheterization and stenting of an occluded obtuse marginal artery. He received abciximab during the procedure and for the next 12 hours. He tolerated the procedure without immediate complication; however, post-catheterization echocardiography revealed pericarditis, with a moderate-sized pericardial effusion. During the next few days, serial echocardiograms revealed enlargement of the pericardial effusion. Given that there were concerns about arterial perforation or perhaps free wall rupture, cardiac magnetic resonance imaging was performed (Figs. 1–4 ^1,2).

Fig. 1 Cine balanced Fast Field Echo (FFE) magnetic resonance image of the left ventricle (2-chamber, long-axis view) reveals a moderate-sized pericardial effusion. Black arrows denote visceral pericardium overlying epicardial fat. White arrows point to parietal pericardium.

Real-time motion image is available at texasheartinstitute.org/nemeth303.html. Note “swirling” within the effusion secondary to hemorrhage.

Fig. 2 Cine balanced Fast Field Echo (FFE) magnetic resonance image (short-axis view). Arrows point to pericardial effusion that completely surrounds the heart.

Real-time motion image is available at texasheartinstitute.org/nemeth303.html. Note the diastolic collapse of the right ventricular outflow tract, a finding specific for tamponade. ¹

Fig. 3 Cine T1-Rho magnetic resonance image (oblique 4-chamber view) shows acute myocardial injury as areas of higher signal intensity (lateral wall of left ventricle). The dark band within the infarcted territory is microvascular obstruction (arrow), a finding associated with increased cardiovascular complications. ²

Real-time motion image is available at texasheartinstitute.org/nemeth303.html.

Fig. 4 Delayed-enhancement “scar” magnetic resonance imaging (short-axis view) shows normal viable myocardium as dark black and nonviable myocardium (scar) as bright white. Again, the dark band within the bright white infarcted area is microvascular obstruction (arrows).

Discussion

Pericardial effusions are found in 15% to 28% of patients presenting with a 1st myocardial infarction. ^3,4 Effusions do not alter the overall prognosis but are associated with a higher morbidity and mortality rate, in part because they occur more frequently with larger MIs that tend to be transmural. ⁵ A recent study of 1,646 patients with a first MI found that patients with early small pericardial effusions are more likely to develop late moderate-to-severe effusions. Two-thirds of those patients with moderate-to-severe effusions developed tamponade or free wall rupture. ⁵

Our patient had an early effusion and, within 3 days after MI, had a moderate-to-severe effusion with tamponade. He underwent pericardiocentesis that yielded 500 cc of bloody pericardial fluid, with immediate hemodynamic improvement. The remainder of his hospital course was uneventful.