Platelet/Lymphocyte Ratio and Risk of In-Hospital Mortality in Patients with ST-Elevated Myocardial Infarction - A Prospective Observational Study from KIMS, Hubli, Karnataka

BACKGROUND Cardiovascular disease is a significant health problem in India with an estimate 3.7 million deaths each year. Mechanisms of myocardial ischemia include inflammation, endothelial dysfunction, platelet aggregation and coagulation. Acute coronary syndrome occurs due to rupture of atherosclerotic plaque. Platelets play a role in both development and rupture of the atherosclerotic plaque. Lymphocytes play a role in chronic inflammation of atherosclerosis. Lower lymphocyte count has increased mortality after acute myocardial infarction. METHODS The study was conducted in Department of General Medicine, Karnataka Institute of Medical Sciences, Hubli from February 2019 to December 2020. It is a prospective observational study. Patients aged ≥ 18 years with ST-elevated myocardial infarction (STEMI) were included in the study. Total 156 cases were selected based on inclusion and exclusion criteria. Cardiovascular events during the in-hospital period were noted. The study population was divided into tertiles based on the platelet-lymphocyte ratio (PLR) values. The low PLR group (n = 104) was defined as having values in the lower 2 tertiles (PLR ≤ 148.4) and the high PLR group (n = 52) was defined as having values in the highest tertile (PLR > 148.4). A ‘P’ value < 0.05 was considered statistically significant. RESULTS Out of 156 patients, 103 (66 %) were males and 53 (34 %) cases were female. Mean age group was 59 ± 10 years. Percentage of patients who underwent thrombolysis was higher in high PLR group (65.38 % vs. 48.07 %, P = 0.041). Death rate was higher in high PLR group (28.84 % vs. 8.65 %, P = 0.001). PLR > 148.4 was found to be an independent predictor of in-hospital cardiovascular mortality in multivariate analyses (hazard ratio: 13.222 (2.113-21.749) P = 0.006 with 95 % confidence interval). Receiver operating curve (ROC) analyses, a PLR value of 148.4 for in-hospital mortality rate had sensitivity of 62.5 % and a specificity of 72 % (area under the curve = 0.627, 95% confidence interval 0.485 – 0.769). CONCLUSIONS In our study, higher PLR had significant association with in-hospital mortality in patients with STEMI. KEYWORDS ST Elevation Myocardial Infarction (STEMI), Platelet/Lymphocyte Ratio (PLR), Ischemic Heart Disease (IHD)