Platelet-To-Lymphocyte Ratio Across Acute Coronary Syndrome Subtypes: Association and Discriminative Performance in Myocardial Infarction Platelet-to-lymphocyte ratio across ACS subtypes

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.