Objective: Tricuspid annular movement and velocities before and after thrombolytic therapy were investigated for the detection of right ventricular (RV) involvement in RCA (right coronary artery)-related acute inferior myocardial infarction (IMI). Methods: Patients with RCA-related acute IMI were evaluated for this pilot prospective cohort study. Annular movement was measured by TAPSE (tricuspid annular plane systolic excursion), and annular velocities were measured by tissue Doppler echocardiography. Data collected before and after thrombolysis and angiography. Diagnosis of RV myocardial infarction (RVMI) was defined by co-presence of electrocardiographic and angiographic criteria. Chi-square and Student’s t-tests were used in statistical analysis. Results: Thirty-one patients were included. Before thrombolysis, annular velocities and TAPSE were found significantly higher in patients without RVMI than in patients with RVMI. Comparison of tricuspid systolic velocity (Sa) and movement before and after thrombolytic therapy in patients without RVMI revealed no significant difference (21.6±2.1 mm vs. 21.8±2.0 mm p>0.05 and 136.1±8.8 mm/s vs. 137.5±9.0 mm/s p>0.05, for TAPSE and Sa respectively). Contrarily, in patients with RVMI, TAPSE and systolic velocity increased significantly after thrombolysis compared with pre-thrombolysis (16.2±2.0 mm vs. 17.6±1.8 mm p=0.001 and 110.0±12.6 mm/s vs. 113.08±12.7 mm/s p=0.027 for TAPSE and Sa respectively). Diastolic velocities did not change significantly after thrombolysis in patients with RVMI. Conclusion: Tricuspid annular movement and velocity measurement by echocardiography may contribute to echocardiographic diagnosis of RV involvement in RCA-related IMI. Patients without RVMI have significantly higher annular velocities and TAPSE than in patients with RVMI before thrombolysis. Only in IMI patients with RVMI, significant increases in TAPSE and Sa were observed after thrombolysis.