Introduction: Acute myocardial infarction (AMI) remains as one of major contributors to cardiovascular mortality worldwide. While Killip class and GRACE score are established tools for assessing AMI severity, evidence regarding prognostic potential of hematologic inflammatory markers, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) remains limited, particularly in Southeast Asia. This study aimed to see the correlation between NLR and PLR with Killip classification, GRACE score, and in-hospital mortality in AMI patients.

Methods: This retrospective study included 47 AMI patients admitted to the Intensive Cardiovascular Care Unit of Universitas Sebelas Maret Hospital between September 2024 and June 2025. Data on clinical and laboratory parameters were extracted from medical records. NLR and PLR were calculated from complete blood count values. Killip class and GRACE score were assessed at admission. Statistical analyses included correlation tests, regression models, and outcome comparisons.

Results: Higher NLR and PLR values were significantly associated with increasing Killip class (ρ = 0.897 and ρ = 0.921, respectively) and GRACE score (p < 0.001). PLR was independent predictor of Killip class (p = 0.020), while only troponin I was independently associated with in-hospital mortality (p = 0.040). The GRACE score regression model showed excellent explanatory power (R² = 0.919), with NLR, PLR, and clinical variables contributing significantly.

Conclusion: NLR and PLR are significantly correlated with AMI severity and risk scores. PLR may serve as a simple adjunctive marker for early clinical stratification in AMI.