BACKGROUND This was a retrospective study conducted at a rural referral center in East Java, Indonesia, to evaluate the association between the platelet-to-lymphocyte ratio (PLR) on hospital admission and the incidence of new symptomatic heart failure (HF) within 6 months in patients with acute coronary syndrome (ACS). MATERIAL AND METHODS The study population consisted of all ACS patients who were hospitalized between 1 January and 31 December 2018 at a non-percutaneous coronary intervention-capable secondary referral hospital and came for a routine follow-up until 6 months afterwards. The diagnosis of new symptomatic HF was based on International Classification of Diseases 10th revision code I50.9. RESULTS From 126 hospitalized patients, 92 patients were included in the analysis. The incidence rate of new symptomatic HF at 6 months was 70.65%. High PLR upon initial admission was significantly associated with new symptomatic HF incidence (odds ratio=1.70, P<0.001). PLR was also able to discriminate new symptomatic HF incidence at 6 months with area under the curve of 0.83 (P=0.001). Multivariate Cox regression analysis showed that PLR was an independent predictor for new symptomatic HF incidence (hazard ratio=4.5, P=0.001). CONCLUSIONS In a rural center in Indonesia, the PLR was independently correlated with the onset of new symptomatic HF in patients with ACS 6 months after hospital admission. The PLR may be a supplementary biomarker for clinical outcomes in patients with ACS for use in resource-limited regions.