Background: RV infarction and microrvascular obstruction (MVO) in AMI are predictors of poor clinical outcome independent of infarct size.The aim of study is to investigate the incidence of RV infarction in inferior wall ST-segment myocardial infarction (STEMI) and evaluate the morphologic features assessed by cardiac magnetic resonance(CMR) imaging. Methods: The study included total 22 patients with inferior wall ST-segment elevation myocardial infarction (STEMI) who underwent primary PCI.We investigate LV microvascular obstruction (MVO),RV infarction assessed by delayed hyperenhancement (DHE),RV MVO,and classified patients into different subgroups.We also measured CRP and compared the CRP level between patients with RV infarction (Group 1) and patients without RV infarction (Group 2).Results: Patients with inferior wall STEMI were classified into different subgroups (Table).Sixteen patients showed RV infarction proven by CMR. CRP levels in group 2 were relatively low.In contrast,CRP levels in group 1 were broadly distributed and different from group 2 (p<0.05, U=32, z= -1.99). We found two patients with RV MVO in group 1, and one patients with RV MVO showed significant high CRP level compared with others. Conclusions: RV infarction assessed by CMR is relatively common in inferior wall STEMI and inferior wall STEMI showed different patterns of morphology in CMR according to LV MVO, RV infarction and RV MVO. CRP level may be a factor reflecting the existence of RV infarction, but more data needed. We need more detailed evaluation of RV infarction, especially RV MVO.