The Changes Of Platelet Parameters In Patients With Coronary Artery Disease And Hypertension And Its Clinical Significance

Objective: The interaction between platelets and artery vein wall is important for atherosclerosis and its complication, myocardial infarction. After rupture of an arteriosclerotic plaque in a coronary artery, platelets play a crucial role in the subsequent thrombus formation, leading to myocardial infarction. Larger platelets are haemostatically more active and are a risk factor for developing coronary thrombosis, leading to myocardial infarction. An increased mean platelet volume (MPV), as an indicator of larger, more reactive platelets, may represent a risk factor for myocardial infarction. Mean platelet volume was higher in acute myocardial infarction (AMI) patients than in those diagnosed with unstable angina pectoris. Mean platelet volume is a predictor of unfavorable outcome in AMI patients. Mean platelet volume is a strong, independent predictor of impaired angiographic reperfusion and six-month mortality in STEMI treated with primary PCI. Some research showed that mean platelet volume did not predict occurrence of myocardial infarction. Previous studies didn't show the influence of hypertension on platelet parameters of patients with coronary heart disease. There were at least 5 days without having aspirin before blood collection in some researches. In this study, we have aimed to search prospectively the value of platelet parameters in patients hospitalized with diagnosis of acute myocardial infarction and unstable angina with hypertension or not. We investigated the prospective value of MPV at random for patients with coronary heart disease on admission and its possibility of being an independent risk factor for acute myocardial infarction simultaneously. We collected blood preparation at random without dealing with the effect of aspirin, only recording it.Methods: All patients were selected from individuals who underwent coronary angiography in our hospital with acute myocardial infarction or acute coronary syndrome or a suspicion of coronary artery disease. The platelet count (PLT), mean platelet volume (MPV), platelet distribution width(PDW) and thrombocytocrit (PCT) were measured. According to the diagnosis of coronary heart disease of WHO, patients were divided into three groups considering the results of coronary arteriongraphy. Thirty-five patients were selected for group one of acute myocardial infarction(AMI). These patients had typical symptom or distinctive change of electrocardiogram. They had coronary artery occlusion or had coronary stenosis with increased creatine kinase and positive troponin. Fifty-two patients were selected for group two of unstable angina pectoris(USAP). These patients had angina pectoris symptom with normal creatine kinase and troponin. They had coronary stenotic lesions of more than 50% in at least one of left anterior descending, circumflex artery, right coronary artery or their chief branches. Twenty-six patients were selected for group three of control group. They had normal coronary arteries or had coronary stenotic lesions of less than 50% with the symptoms of chest pain or cheat discomfort. The three groups were subdivided depending upon having hypertension or not. 2 ml of blood was collected from ulnar vein of enrolled patients at admission, injected into a tube containing EDTA and antigrading. Hemocytes assay were obtained between 1 and 2 hours after venepuncture. Another 5 ml of blood was collected from ulnar vein on the next morning at 6 o'clock, injected into a tube containing heparin as anticoagulation, antigrading and used for the test of hepatic function, renal function and lipid profile. It's not necessary for the patients to stop aspirin before blood collection if he/she has been always taking aspirin.Results: Platelet count was lower in AMI than in USAP (221.85±61.26×109/L vs. 232.65±66.16×109/L, P = 0.4483),without statistically significant difference. MPV was lower in AMI patients than in those diagnosed with USAP (7.50±0.87 fL vs. 7.57±0.70 fL, P = 0.1822), without statistically significant difference. PDW was lower in AMI than in USAP(14.02±2.68 % vs. 14.73±2.41 %, P =0.2039), without statistically significant difference. PCT was lower in AMI than in USAP (0.16±0.05 % vs. 0.17±0.05 %, P = 0.2829), without statistically significant difference. There were no difference compared to the control group, too. PLT is 215.79±54.89×109/L in AMI patients with hypertension and 218.73±61.99×109/L in AMI without hypertension, P≥0.05. MPV is 7.63±1.02 fL and 7.40±0.54 fL respectively, P≥0.05. PLT is 233.03±65.51×109/L in USAP patients with hypertension and 232.33±73.86×109/L in USAP without hypertension, P≥0.05. MPV is 7.66±0.71 fL in USAP patients with hypertension higher than 7.24±0.61 fL of USAP without hypertension, P≥0.05. MPV in AMI group without hypertension is higher than the USAP group, but it is not significant throughout statistic calculation. There were no statistically significant differences among these subgroups. White blood cell (WBC) in acute myocardial infarction was significant higher than it in unstable angina pectoris. The percentage of patients who take aspirin in acute myocardial infarction was significant lower than it in unstable angina pectoris (8.57% vs. 44.23%, P≤0.05 ).Conclusion: There was no difference in the platelet count, Mean platelet volume, platelet distribution width and thrombocytocrit during acute myocardial infarction, unstable angina pectoris and control group in our finding. The clinical value of platelet parameters on admission in coronary heart disease is still uncertain and can't be used for diagnosis of acute myocardial infarction or unstable angina pectoris. The time to detect samples, aspirin, exercise, age and diabetes may make a difference on the result. Platelet parameters can't be a marker of acute myocardial infarction like isoenzymes of creatine kinase and troponin from recent study. Its clinical value of coronary heart disease is undetermined.MPV in AMI group without hypertension is higher than the USAP group, but it is not significant throughout statistic calculation. There were no statistically significant differences among these subgroups. The difference needs more study. The hypertension patients will take antihypertensive agent and take aspirin as a routine at the same time, which prevents the evolution of coronary artery disease. People with other high risk of coronary artery disease, though without hypertension, need to evaluate the danger of coronary artery disease regularly and take aspirin early as primary prevention no matter how old he is. This may decrease myocardial infarction.