The Extent of Pericardial Involvement as documented by Cardiac Magnetic Resonance Imaging in Patients with ST-Elevation Myocardial Infarction

Background: The clinical diagnosis of peri-myocardial infarction pericarditis declined dramatically in the era of primary PCI and novel antiplatelet agents. However, recent data documents the presence of pericardial effusion in substantial proportion of acute myocardial infarction patients.

Methods: We prospectively evaluated 187 consecutive patients, without known prior coronary disease, who underwent Primary PCI for STEMI. All patients underwent cardiac MRI (CMR) 5±1 day post admission. CMR was performed using a 1.5 T (n=101) and 3 T (n=86). Delayed enhancement (DE) and microvascular obstruction (MVO) were quantified as % of the LV mass. DE was also qualitatively assessed for the degree of transmurality. Involved segments (according to the AHA segments model) were identified for both DE and MVO. Pericardial enhancement on DE images was considered as CMR evidence of pericarditis. The presence of pericardial effusion was documented. Pericarditis extent was expressed as the number of enhanced pericardial segments.

Results: Clinical diagnosis of pericarditis was documented only in three patients (1%). Pericardial effusion was documented in 94 patients (50%), and Enhancement of the pericardium on DE images was documented in 127 patients (68%). Pericardial involvement was significantly associated with the % of DE (P=0.007) and MVO (p=0.04 ). DE transmurallity (per segment) correlated with pericardial involvement both for extent and location. Additional parameters associated with CMR pericarditis included Pain to balloon (p=0.07) and maximal CRP level (p=0.015).

Conclusions : In contrast to the low clinical diagnosis of pericarditis, CMR documented pericardial involvement in more than 58% of STEMI patients. This pericardial involvement significantly correlated with the extent transmuraliy and location of the myocardial damage.