acute myocardial infarction ( ami ) results from total coronary artery occlusion , usually due to thrombus formation on complicated atherosclerotic plaque . the patients with ami have higher mortality rates , especially during the first 30 days . platelets play an important role in development , destabilization , and rupture of the atherosclerotic plaque , as well as in formation of platelet - fibrin plug at the complicated atherosclerotic plaque . platelet count is associated with increased risk of ami and short- and long - term mortality after ami [ 58 ] . lymphocytes play a dominant role in chronic inflammation of atherosclerosis , and lower lymphocyte count is associated with increased cardiovascular risk and mortality in ami . platelet / lymphocyte ratio ( plr ) has been reported as a novel marker of long - term mortality in patients with non - st - elevated ami . in the present study , we tested the hypothesis that plr is associated with in - hospital cardiovascular mortality in patients with st - elevated ami ( stemi ) . records of patients with ami who were admitted to the coronary care unit between january 2009 and november 2011 were evaluated retrospectively . we consecutively evaluated 645 patients who were diagnosed with stemi and excluded 4 patients with intracranial hemorrhage because of the intra - venous thrombolytic treatment ( streptokinase , tissue plasminogen activator , or tenecteplase ) and 5 patients without eligible laboratory results . a diagnosis of stemi was defined as > 30 minutes of continuous typical chest pain and st - segment elevation 2 mm in 2 contiguous electrocardiography leads within 12 hours of symptom onset or within up to 18 hours if there was evidence of continuing ischemia or hemodynamic instability . from medical records , we obtained demographic information , cardiovascular history and risk factors for coronary artery disease ( cad ) , and treatment received during the in - hospital period . patients who had been treated with antihypertensive drugs or those whose baseline blood pressure exceeded 140/90 mmhg were diagnosed with hypertension ( ht ) . diabetes mellitus ( dm ) was defined as fasting blood sugar level above 126 mg / dl or the use of anti - diabetic medications . the admission glomerular filtration rate ( gfr ) was estimated by the simplified mdrd ( modification of diet in renal disease ) equation . renal failure was defined as a glomerular filtration rate ( gfr ) < 60 ml / min / m . ventricular tachycardia or ventricular fibrillation were defined at least 24 hours after the beginning of the symptoms , advanced heart failure was defined as killip classification 2 , and cardiovascular death was defined as death due to ami , heart failure , or arrhythmia . complete blood counts and biochemical values were evaluated retrospectively from blood samples obtained by antecubital vein puncture upon admission to the emergency department . total and differential leukocyte counts were determined with the beckmancoulterlh 780device ( beckman coulter ireland inc . the high plr group ( n=212 ) was defined as having values in the highest tertile ( plr > 144 ) , and the low plr group ( n=424 ) was defined as having values in the lower 2 tertiles ( plr 144 ) . quantitative variables are expressed as the mean value sd or median ( interquartile range ) , and qualitative variables are expressed as percentages ( % ) . a comparison of parametric values between high and low plr groups was performed using the t test or the mann - whitney u - test . categorical variables were compared by the likelihood - ratio  test or fisher s exact test . a backward stepwise multivariate logistic regression analysis , which included variables with p<0.1 , age 70 , female sex , renal failure ( gfr < 60 ml / min / m ) , time of chest pain , not receiving thrombolytic treatment , nlr>4.1 , and plr>144 were entered into the model . all statistical studies were carried out with the spss program ( version 17.0 , spss , chicago , il , usa ) . records of patients with ami who were admitted to the coronary care unit between january 2009 and november 2011 were evaluated retrospectively . we consecutively evaluated 645 patients who were diagnosed with stemi and excluded 4 patients with intracranial hemorrhage because of the intra - venous thrombolytic treatment ( streptokinase , tissue plasminogen activator , or tenecteplase ) and 5 patients without eligible laboratory results . a diagnosis of stemi was defined as > 30 minutes of continuous typical chest pain and st - segment elevation 2 mm in 2 contiguous electrocardiography leads within 12 hours of symptom onset or within up to 18 hours if there was evidence of continuing ischemia or hemodynamic instability . from medical records , we obtained demographic information , cardiovascular history and risk factors for coronary artery disease ( cad ) , and treatment received during the in - hospital period . patients who had been treated with antihypertensive drugs or those whose baseline blood pressure exceeded 140/90 mmhg were diagnosed with hypertension ( ht ) . diabetes mellitus ( dm ) was defined as fasting blood sugar level above 126 mg / dl or the use of anti - diabetic medications . the admission glomerular filtration rate ( gfr ) was estimated by the simplified mdrd ( modification of diet in renal disease ) equation . renal failure was defined as a glomerular filtration rate ( gfr ) < 60 ml / min / m . ventricular tachycardia or ventricular fibrillation were defined at least 24 hours after the beginning of the symptoms , advanced heart failure was defined as killip classification 2 , and cardiovascular death was defined as death due to ami , heart failure , or arrhythmia . complete blood counts and biochemical values were evaluated retrospectively from blood samples obtained by antecubital vein puncture upon admission to the emergency department . total and differential leukocyte counts were determined with the beckmancoulterlh 780device ( beckman coulter ireland inc . the high plr group ( n=212 ) was defined as having values in the highest tertile ( plr > 144 ) , and the low plr group ( n=424 ) was defined as having values in the lower 2 tertiles ( plr 144 ) . quantitative variables are expressed as the mean value sd or median ( interquartile range ) , and qualitative variables are expressed as percentages ( % ) . a comparison of parametric values between high and low plr groups was performed using the t test or the mann - whitney u - test . categorical variables were compared by the likelihood - ratio  test or fisher s exact test . a backward stepwise multivariate logistic regression analysis , which included variables with p<0.1 , was performed to identify independent predictors of in - hospital cardiovascular mortality . age 70 , female sex , renal failure ( gfr < 60 ml / min / m ) , time of chest pain , not receiving thrombolytic treatment , nlr>4.1 , and plr>144 were entered into the model . all statistical studies were carried out with the spss program ( version 17.0 , spss , chicago , il , usa ) . a total of 636 patients ( 505 men and 131 women ) were enrolled into the present study . no differences were found between the groups regarding thrombolytic and other treatments received during the in - hospital period . tobacco use , ht , dm , and chd history were not significantly different between the groups . the rate of male patients ratio was lower in the high plr group ( 73% vs. 82.8% , p=0.004 ) . the patients in the high plr group were older ( 63.712.1 vs. 61.412.0 , p=0.022 ) . baseline platelet and neutrophil levels were significantly higher in the high plr group than in the low plr group ( 9.6 [ 3.225.1]10/mm 
 vs. 7.3 [ 2.218.4]10/mm , p<0.001 ; 245 [ 121779]10/mm 
 vs. 215 [ 43419]10/mm , p=0.001 ) , whereas the baseline lymphocyte level was significantly lower in the high plr group than in the low plr group ( 1 , 2 [ 0.43.7]10/mm 
 vs. 2.4 [ 0.69.1]10/mm , p=0.001 ) . neutrophil - to - lymphocyte ratio ( nlr ) was higher in high plr group ( p<0.001 ) ( table 2 ) . the high plr group had a significantly higher incidence of in - hospital cardiovascular mortality than the low plr group ( 12.7% vs. 5.9% , p=0.003 ) . advanced heart failure ( killip class 2 ) was more frequent in patients with high plr values ( 18.9% vs. 12.3% , p=0.026 ) . independent predictors of in - hospital cardiovascular mortality were determined by backward stepwise multivariate logistic regression . chest pain duration more than 6 hours , female sex , not receiving thrombolytic treatment , renal failure , age 70 years , nlr > 4.1 , and plr > 144 were found to be associated with increased in - hospital cardiovascular mortality in a logistic regression analysis ( table 4 ) . plr > 144 was found to be an independent predictor of in - hospital cardiovascular mortality in multivariate analyses ( hazard ratio : 2.16 , 95% confidence interval : 1.164.0 , p=0.014 ) . an plr value of 144 was determined as an effective cut - off point in stemi of in - hospital mortality , with a sensitivity of 51% and a specificity of 69% ( area under the curve=0.59 , 95% confidence interval 0.500.67 ) ( figure 1 ) . in this study we show that high plr at admission to hospital is an independent predictor of early cardiovascular mortality in patients with ami . older age , renal failure , and not treated with thrombolytic treatment are other independent predictors of mortality . to our knowledge this is the first study to investigate the relationship between plr and mortality in stemi . atherosclerotic cad is still the most common cause of mortality and morbidity in developed countries . activated platelets precipitate to produce inflammatory substances from endothelial cells and leucocytes that cause monocyte adhesion and transmigration , and thereby increase the inflammatory process and progression of atherosclerotic plaque . furthermore , these activated adhesion molecules and chemokines increase the activation of leucocytes , and produce reactive oxygen molecules and matrix metalloproteinase that cause plaque destabilization in atherosclerotic plaque . ami usually occurs as a result of coronary artery occlusion due to complication of an atherosclerotic plaque . platelets play a dominant role in pathogenesis of acute coronary syndromes by formation of platelet - fibrin complexes . platelet count was found to be associated with development of ami and presence of cad . gary et al . concluded that higher platelet volume may change blood viscosity and increase inflammation . healy et al . reported that expression of cd-49 and plasma myeloid protein in platelets is increased in patients with st - elevated mi . in addition , it was found that platelet count is associated with short- and long - term mortality in patients with st - elevated and non - st - elevated ami , and unstable angina pectoris [ 2022 ] . showed a relationship between platelet count and mortality in patients with recurrent ami in the first year after primary percutaneous intervention . in addition , fibrinogen levels and platelet counts are positively correlated and related to inflammation in ami patients . these findings suggest that platelets are one of the most important components of cad and cardiovascular events . lymphocytes are an important part of chronic inflammation in the atherosclerotic process . in ami , lymphocytes infiltrate to the ischemic and reperfused myocardium and express interleukin-10 , which may play a significant role in transmigration of mononuclear cells , and induce the expression of tissue inhibitor of metalloproteinase-1 . recent studies showed that higher plr is related to presence of cad and is correlated with c - reactive protein and fibrinogen levels . reported that plr above 170 is an independent predictor of long - term mortality in non - st - elevated ami patients . in our study , we found that high plr ( above 144 ) is an independent predictor of in - hospital mortality in patients with stemi who received thrombolytic treatment . complications of ami , including heart failure , shock , and ventricular rupture , are more frequent in older ami patients . in the present study , neutrophils may cause plaque rupture as a result of stimulating the release of proteolytic enzymes , superoxide radicals , and arachidonic acid derivates , and exacerbates the inflammatory condition . microvascular obstruction due to neutrophil - platelet plug , vasoconstriction due to thromboxanes , and vasoactive molecules may cause no - reflow and cause further myocardial injury . these high inflammatory processes appear to be responsible for high rates of heart failure and mortality . nlr was higher in the high plr group and was strongly related to cardiovascular mortality in our population , in line with results of previous studies . in multivariate analyses , we found that nlr was not an independent predictor and that plr is an independent predictor of mortality . patient long - term survival and cardiac conditions could not be assessed because the patient records and the coronary angiography results of patients were not known . anti - platelet treatment before ami is an important factor affecting in - hospital mortality , but our data were not able to demonstrate previous antiplatelet use . ami is the most important cause of mortality ( especially in the first month ) and morbidity worldwide . this study showed that high plr is an independent predictor of in - hospital cardiovascular mortality in patients with stemi . complete blood count analysis is a routine and inexpensive method that may be useful for the identification of high - risk patients . plr and other inflammatory markers and clinical findings might be helpful in identifying high - risk patients and treatment strategies .