Differentiation of Acute Myocarditis and Acute Myocardial Infarction by the Regional Distribution of Myocardial Irreversible Injury Using Cardiovascular Magnetic Resonance Imaging

Background and Objective. In this study, we have sought for differences between cardiovascular magnetic resonance patterns of acute myocarditis and acute myocardial infarction.
Material and Methods. A prospective analysis of 110 consecutive patients was performed. The presence, precise location, and pattern of late gadolinium enhancement (LGE) by cardiovascular magnetic resonance were investigated.
Results. The subendocardial LGE pattern was much more frequent in the myocardial infarction group (76.7%) than myocarditis group (10.0%) (P<0.001). Meanwhile, midmyocardial LGE was much more typical of myocarditis (65.0%) than acute myocardial infarction (1.1%) (P<0.001), and epicardial LGE was also much more typical of myocarditis (55.0%) than acute myocardial infarction (0.0%) (P<0.001). Midmyocardial and epicardial LGE patterns were defined as a nonischemic LGE pattern more typical of myocarditis. Logistic regression analysis revealed that the subendocardial and midmyocardial LGE locations played the greatest role in differentiation between acute myocarditis and acute myocardial infarction. A statistical model based on midmyocardial LGE distribution and age showed a sensitivity of 90% and a specificity of 93.3% in differentiating between acute myocarditis and acute myocardial infarction.
Conclusion. Our findings suggest that in clinical practice, differentiation between acute myocardial infarction and acute myocarditis can be done based on the subendocardial and midmyocardial LGE location. The presence of subendocardial LGE was found to be strongly associated with acute myocardial infarction; meanwhile, the presence of midmyocardial LGE indicated acute myocarditis. However, other clinical factors should also be taken into account when making the final diagnosis.