Background: In this study, we assessed the prognostic significance of right ventricular free wall longitudinal strain (RVfwLS) in patients with acute inferior wall MI and investigated its association with angiographic characteristics and adverse outcomes. Methods: A prospective observational study was conducted with 200 patients admitted with acute inferior wall MI who underwent primary angioplasty. 2D speckle tracking echocardiography was used to measure the RVfwLS at the time of admission. Angiographic characteristics were collected, and patients were followed up for adverse outcomes until discharge. Categorical data were compared using the χ2 test or Fisher’s exact test. Logistic regression analysis was used to identify adverse cardiovascular outcomes independently associated with RVfwLS. A p-value of <0.05 was considered statistically significant for all analyses. Results: Compared with patients with normal strain (n=88, 44%), patients with diminished strain (n=116, 56%) had significantly lower blood pressure (56.52% versus 43.58%; p=0.03), reduced tissue velocities (93.3% versus 6.7%; p<0.01), elevated jugular venous pressure (58.93% versus 41.07%; p=0.04), and higher right ventricular systolic pressure (52.04% versus 47.96%; p=0.04). Additionally, patients with diminished strain had a higher incidence of triple vessel disease (80% versus 20%; p=0.026) and arrhythmias necessitating inotropic support (66.67% versus 37.33%; p=0.02), as well as a longer hospital stay (78.7% versus 21.3%; p<0.01) compared with patients with normal strain. In multivariate analysis, arrhythmias (p=0.046; OR 2.05; 95% CI [0.93–8.10]) and right heart failure (p=0.035; OR 3.64; 95% CI [1.35–11.53]) were independently associated with RVfwLS. The optimal RVfwLS cut-off value for predicting adverse outcomes was −14.8% (AUC=0.915; 95% CI [0.876–0.954]; p<0.001), with a sensitivity of 81.3% and specificity of 86.8%. Conclusion: RVfwLS can be used to categorise the severity of infarction and predict adverse outcomes.