Platelet-To-Lymphocyte Ratio Across Acute Coronary Syndrome Subtypes: Association and Discriminative Performance in Myocardial Infarction

Abstract

Background: The platelet-to-lymphocyte ratio (PLR) is an inexpensive haematological index that reflects both thrombotic and inflammatory activity, yet whether it differs across the clinical spectrum of acute coronary syndrome (ACS) remains uncertain.Methods: This single-centre retrospective cross-sectional study included 235 adults admitted with ACS to a tertiary referral hospital in Makassar, Indonesia. PLR was calculated from the first complete blood count obtained on arrival. Differences among unstable angina pectoris (UAP), non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) were assessed with the Kruskal-Wallis test and Dunn-Bonferroni post hoc comparisons, multivariable binary and multinomial logistic regression, and receiver operating characteristic analysis.Results: Mean age was 58.49 ± 10.75 years and 77.0% of participants were male; STEMI accounted for 53.2% of cases, while UAP and NSTEMI each accounted for 23.4%. Median PLR differed significantly across subtypes (UAP 130.5, NSTEMI 170.0 and STEMI 162.9; p = 0.002), being higher in both infarction phenotypes than in UAP but not differing between NSTEMI and STEMI. Each 50-unit increase in PLR was independently associated with myocardial infarction rather than UAP (adjusted odds ratio 1.40, 95% confidence interval 1.12-1.76; p = 0.004), with adjusted odds ratios of 1.35 for NSTEMI versus UAP and 1.43 for STEMI versus UAP. Discrimination of myocardial infarction from UAP was modest (area under the curve 0.655, 95% confidence interval 0.574-0.733).Conclusions: PLR is higher in myocardial infarction than in UAP but does not distinguish NSTEMI from STEMI, supporting its use as a low-cost adjunctive haematological index rather than a stand-alone diagnostic discriminator.