Background Methods Right ventricle (RV) involvement causes acute systolic and diastolic functional alterations in the RV in patients after inferior myocardial infarction (IMI), which may result in an increase in left ventricle (LV) end-diastolic and right atrial (RA) pressure. In our study, we sought to evaluate RA volumes and mechanical functions using real-time three-dimensional echocardiography (RT3DE) in IMI patients with or without RV involvement. Ninety-six consecutive patients with IMI (mean age: 59.7 +/- 10.2 years, 60 female) were included. RV myocardial involvement (RVMI) was defined as the presence of a culprit lesion at the proximal portion of the first RV marginal branch in coronary angiography. The study population was divided into two groups: IMI (58.3%) and IMI + RVMI (41.7%). Patients were evaluated using conventional two-dimensional echocardiography (2DE) and RT3DE. Results Conclusions In RT3DE measurements, IMI + RVMI patients had significantly higher RA phasic volumes and worse conduit mechanical function. A receiver operating characteristic (ROC) curve analysis revealed that an RT3DE RA maximum volume (Vmax) index > 27.9 mL/m(2) was an independent predictor of RV involvement in patients after acute IMI, with a sensitivity of 80.0% and a specificity of 89.3%. Right ventricle involvement may cause an increase in RA phasic volumes and deterioration of conduit function in patients with acute IMI.