BACKGROUND: Post-stroke myocardial injury is a potentially preventable complication after acute ischemic stroke. Therefore, identifying modifiable variables, such as nutritional status, is crucial for reducing the risk of post-stroke myocardial injury. This study aimed to investigate the association between malnutrition risk on admission, as evaluated by the Geriatric Nutritional Risk Index (GNRI), and post-stroke myocardial injury in elderly patients with first‑ever ischemic stroke. METHODS: We conducted this study using the GNRI score to evaluate the nutritional status of older patients with first‑ever ischemic stroke. The primary outcome of interest was post-stroke myocardial injury. Restricted cubic spline (RCS) was executed to assess the dose-effect relationship between the GNRI score and post-stroke myocardial injury. The correlation of malnutrition risk identified by GNRI score for post-stroke myocardial injury was examined using multivariate logistic regression analysis. To balance the potential confounders and verify the robustness of the results, propensity score matching (PSM) was further conducted. RESULTS: Based on the GNRI score, 30.8% of patients were at moderate to severe risk of malnutrition. The overall incidence of post-stroke myocardial injury was 33.2%. The adjusted RCS analysis revealed a negative dose-response relationship between the GNRI score and post-stroke myocardial injury (P for non-linearity = 0.536). After adjusting for confounders, moderate to severe malnutrition risk, as evaluated by the GNRI score, was substantially associated with an increased risk of post-stroke myocardial injury (OR: 3.25
95% CI: 1.93-5.48
P <
0.002). Following PSM adjustment, the association between the GNRI score and post-stroke myocardial injury remained significantly robust (OR: 4.28
95% CI: 2.34-7.83
P <
0.002). CONCLUSION: Malnutrition risk on admission is associated with higher risk of post-stroke myocardial injury among elderly patients with first‑ever ischemic stroke. Early screening for malnutrition risk is crucial in the management of patients with first‑ever ischemic stroke.