Prior simvastatin treatment is associated with reduced thrombin generation and platelet activation in patients with acute ST-segment elevation myocardial infarction

Background

It has been reported that statin therapy produces additional effects including impaired activation of blood coagulation. It is not clear whether statins can affect hemostasis in patients with acute coronary syndrome. The aim of this study was to investigate the effect of prior statin treatment on thrombin generation and platelet activation in patients with ST-segment elevation myocardial infarction (STEMI).

Methods

We studied 53 consecutive STEMI patients admitted within 12 hours of pain onset, including 19 treated with simvastatin (40 mg/d) (simvastatin group) at least one month prior to STEMI, and 34 not receiving any statins (no-statin group) on admission. Thrombin-antithrombin (TAT) complexes generation and soluble CD40 ligand (sCD40L) release were determined in 60-second blood samples collected at the site of microvascular injury.

Results

There were no significant intergroup differences with respect to clinical and laboratory variables, including plasma TAT and sCD40L levels, except lower total cholesterol and low-density lipoprotein cholesterol in the simvastatin group. The mean maximum rate of TAT generation was 47.5% lower (p = 0.0002) and sCD40L release 33.3% lower (p = 0.0006) in the simvastatin group. Total amounts of TAT (p < 0.0001) and sCD40L (p = 0.002) collected within 5 minutes of bleeding were lower in simvastatin-pretreated patients. By multivariate regression analysis, variables describing local TAT and sCD40L profiles in the whole group were independently associated with simvastatin pretreatment (p < 0.0001), but not with cholesterol, platelet count or troponin levels.

Conclusions

Prior simvastatin use is associated with lower thrombin generation and platelet activation following vascular injury in the early phase of STEMI.     

Residual platelet reactivity is an independent predictor of myocardial injury in acute myocardial infarction patients on antiaggregant therapy

In this study we sought to evaluate if platelet function measured after percutaneous coronary intervention (PCI) affects the severity of myocardial infarction (MI), measured by markers of cardiac necrosis. We measured platelet function by both a point-of-care assay (PFA-100) and platelet-rich plasma aggregation by two agonists (arachidonic acid -AA- and 2 and 10 microM ADP) in 367 patients with MI after PCI (200 patients on dual antiplatelet agents - group A- and 167 on dual antiplatelet agents plus GpIIb/IIIa inhibitors - group B). One hundred twenty-one (32.9%) patients were found to have a residual platelet reactivity (RPR) by PFA (CT/EPI <203 sec): 74/200 (37%) in group A and 47/167 (28.1%) in group B (p = 0.07). In 129 (35.1%) patients we found a RPR by AA-PA: 80/200 (40%) in group A and 49/167 (29.3%) in group B (p < 0.05). Seventeen out of 367 (4.6%) were found to have a RPR by ADP2-PA [15/200 (7.5%) in group A and 2/167 (1.2%) in group B; p < 0.005] and 88/367 (23.9%) by ADP10-PA [64/200 (32%) in group A and 24/167 (14.4%) in group B, p < 0.0001]. CK-MB and cTnI mean peak values were significantly higher in the first tertile of CT/ADP and CT/EPI distribution with respect to the other tertiles and they were significantly higher in patients with RPR by CT/EPI in both group A and group B patients. CK-MB and cTnI peak values were significantly higher in the third tertile of AA-PA, ADP 2 microM-PA and ADP 10 microM-PA distribution with respect to the other tertiles and were significantly higher in patients with RPR by AA-PA and by ADP 10-PA in both group A and group B patients. Multivariate analysis revealed platelet function as an independent predictor of CK-MB and cTnI peak values in both groups of patients independently of clinical, laboratory ad procedural parameters. In conclusion, we found that the severity of MI in patients with MI undergoing primary PCI is influenced by a persistent platelet activation on multiple antiplatelet therapy.     

Mild hyperhomocysteinemia is associated with a decreased fibrinolytic activity in patients after ST-elevation myocardial infarction

BACKGROUND: Elevated homocysteine (Hcy) levels have been associated with increased risk for cardiovascular disease and it has been shown that hyperhomocysteinemia is associated with increased levels of t-PA antigen in individuals without evidence for coronary artery disease (CAD). The aim of this study was to examine if Hcy plasma levels are associated with plasma levels of fibrinolytic factors in patients with CAD and a history of acute myocardial infarction. METHODS: We measured in 56 patients with CAD, 1 month after their first ST-elevation myocardial infarction, plasma levels of Hcy, the fibrinolytic parameters tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-type-1 (PAI-1), and t-PA-PAI-1 complexes. RESULTS: Hcy plasma levels inversely correlated with t-PA activity (r=-0.303, p<0.05). Patients with mild hyperhomocysteinemia (Hcy>15 micromol/L, n=8) showed significantly lower plasma levels of t-PA activity (p<0.05). Regression analysis revealed that out of cardiovascular risk factors and medical treatment only Hcy was significantly associated with t-PA activity. CONCLUSIONS: Patients with CAD after a first myocardial infarction and hyperhomocysteinemia show a reduced t-PA activity independently from cardiovascular risk factors and medical treatment. Homocysteine lowering therapies may increase fibrinolytic activity and thereby may help to avoid atherothrombotic events in patients with CAD after a first myocardial infarction.     

Effects of G-CSF on systemic inflammation, coagulation and platelet activation in patients with acute myocardial infarction

Introduction

In the prospective, randomised, double-blind, placebo-controlled Regenerate Vital Myocardium by Vigorous Activation of Bone Marrow Stem Cells (REVIVAL)-2 trial patients with acute myocardial infarction (AMI) and successful mechanical reperfusion received granulocyte-colony stimulating factor (G-CSF, 10 μg/kg KG s.c.) or placebo for 5 days. Aim of this substudy was to assess the impact of G-CSF on systemic inflammatory and procoagulant responses and platelet activation.

Methods and Results

Before and five days after G-CSF (n = 56) or placebo (n = 58) circulating cytokine concentrations of interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-12 and Tumor-Necrosis Factor-α (TNF-α? were measured. Prothrombin fragment F1 + 2 and Tissue Factor activity served as a measure for activated coagulation. Platelet activation was characterized by cell surface expression of the activated fibrinogen receptor (PAC-1), P-selectin and CD40L by flow cytometry. Administration of G-CSF was associated with elevated TNF-α and CRP?concentrations compared to the placebo group after 5 days. Other cytokines (IL-1ß, IL-6, IL-8, IL-10, IL-12) were comparable after treatment with G-SCF or placebo. Similarly, circulating prothrombin fragments F1 + 2, TF activity and platelet activation did not differ in both groups.

Conclusion

Treatment with G-CSF in patients with AMI was associated with enhanced proinflammatory TNF-α and CRP levels but no activation of coagulation.     

Inhibition of ADP-induced platelet aggregation by dipyrone in patients with acute myocardial infarction

ADP induced platelet aggregation was investigated in 48 patients within three days of the first signs of acute myocardial (AMI). Thirty six of them received 1 gram of dipyrone. Twelve patients who did not receive dipyrone served as controls. Platelet aggregation was found severely inhibited in 11 patients who had received dipyrone up to 12 hours before investigation and moderately inhibited among 25 patients who were given the drug 12-24 hours prior to the investigation. All the patients with AMI who did not receive dipyrone, exhibited a state of hyperaggregability evidenced by the presence of a second phase of aggregation even with 0.5 microM ADP. The inhibitory activity of dipyrone on the second phase of platelet aggregation resembles that of other non steroidal anti-inflammatory drugs.     

Exercise-induced platelet activation in myocardial infarction survivors with normal coronary arteriogram

Platelet activation may participate in the pathophysiology of myocardial infarction occurring in patients with normal coronary arteriogram. We investigated this possibility in a series of 9 such patients (group A) during a standardized bicycle exercise test as myocardial infarction had occurred in all of them during or soon after strong physical exercise. Twelve patients with effort-induced angina and coronary atherosclerosis (group B) and eleven healthy subjects (group C) served as test groups. Peripheral venous blood was collected by separate venipuncture before, at peak exercise and during recovery. As a sensitive index of activation, the shape of the circulating platelets was examined with a phase contrast microscope after instantaneous fixation of the whole blood. The percentage of non strictly disc-shaped platelets with one or more thin pseudopods was determined. Simultaneously, the plasma levels of platelet factor 4 (PF4) and of beta-thromboglobulin (beta-TG) were measured. At rest, there was no significant difference in the platelet morphology nor in the plasma levels of platelet specific proteins between the three groups. During exercise, a significant change in platelet shape occurred in group A and B patients and not in the healthy subjects. This platelet activation was not related to myocardial ischemia since it occurred to a similar extent in group B patients who developed electrocardiographic changes and in group A patients who did not. There was no detectable release of platelet proteins during exercise in any group.     

急性脑梗死患者的血小板活化、聚集状态及其临床意义

目的 探讨急性脑梗死患者的血小板活化、聚集状态及其临床意义.方法 97例急性脑梗死患者按梗死体积和卒中类型分别分为小体积和中-大体积脑梗死亚组,大动脉粥样硬化性卒中(LAA)和小动脉闭塞性卒中(SAO)亚组.在脑梗死患者发病48 h内(治疗前)和病程第12 d,采用全血流式细胞术检测血小板CD62P表达,用比浊法检测花生四烯酸、二磷酸腺苷诱导的血小板最大聚集率(MARAA,MARADP);并与正常对照者(n=99)比较.结果 脑梗死组发病48 h内血小板CD62P表达水平和MARAA、MARADP显著高于正常对照组(P＜0.05 ～0.01),且发病第12 d比发病48 h内明显降低(均P＜0.01).中-大体积脑梗死亚组、LAA亚组的血小板CD62P表达和MARAA、MARADp分别显著高于小体积脑梗死亚组和SAO亚组(均P＜0.01).结论 急性脑梗死患者发病后血小板活化、聚集程度增高,脑梗死体积大、大血管病变的患者增高更明显.观察急性脑梗死患者的血小板活化、聚集状态,有助于对其病情的判断.     

急性心肌梗死患者静脉溶栓治疗65例急诊护理

目的 评价急诊经静脉rt-PA溶栓治疗急性心肌梗死的护理效果.方法 对65例急性心肌梗死急诊溶栓患者进行溶栓前后护理,以及正确的康复锻炼与出院指导.结果 65例患者通过急诊静脉溶栓后,大部分患者血管再灌通良好.参加早期锻炼的患者平均住院天数与并发症发生率明显下降.结论 急诊静脉溶栓是一种重建冠脉灌注非常有效的方法.正确的全程护理及出院注意事项是提高患者生存质量的保证.     

Warmer outdoor temperature is associated with task-related increased BOLD activation in patients with multiple sclerosis

Patients with multiple sclerosis (MS) demonstrate worse cognition on warmer days. Here, we examine the neurophysiology underlying this temperature-cognition relationship. The association between task-related BOLD fMRI activation and outdoor temperature was investigated in 28 MS patients who demonstrated worse cognitive function on warmer days. In MS patients, warmer outdoor temperature was associated with greater BOLD activation during performance of a simple sustained attention task. The brain areas that showed greater activation on warmer days (p?=?.01) were regions that have been shown to be more activated by MS patients during task performance: frontal, dorsolateral prefrontal, and parietal cortex. The relationship between outdoor temperature and cerebral activation was absent in healthy controls. The purpose of this study was to identify the neurophysiological basis for worse cognition among MS patients on warmer days. We show here that MS patients activate task-related brain regions more on warmer days. Increased brain activation required by MS patients on warmer days to perform a simple task may signify neural inefficiency.     

Evidence of increased platelet reactivity in the first six months after acute ST segment elevation myocardial infarction

Introduction

Platelets play a crucial role in the pathogenesis of acute coronary syndromes. Accordingly, previous studies showed increased platelet reactivity on admission in these patients. In this study we assessed platelet reactivity at short-medium term follow-up in patients with ST-segment elevation acute myocardial infarction (STEMI).

Materials and methods

Fifty-nine patients (58 ± 11 years, 45 men), treated with primary angioplasty, were studied 1 month after STEMI. Thirty-five patients were retested at 6 months. Twenty matched patients with stable coronary artery disease served as controls. Platelet reactivity was assessed by flow cyometry at rest and at peak exercise, with and without adenosine diphosphate (ADP) stimulation, by measuring monocyte-platelet aggregates (MPAs) and glycoprotein IIb/IIIa (CD41) expression in the MPA gate, and CD41 and fibrinogen receptor (PAC-1) expression in the platelet gate.

Results

Compared to controls, basal MPAs and CD41 in the MPA gate were higher in STEMI patients both at 1 month (p = 0.001 and p = 0.002, respectively) and at 6 months (p = 0.03 and p = 0.01, respectively). Basal CD41 and PAC-1 expression was also higher in STEMI patients at the two assessments compared to controls (P < 0.001 for both). Exercise induced a similar increase in platelet reactivity in patients and controls. ADP induced a higher increase in CD41 platelet expression in STEMI patients compared to controls both at 1 and 6 months (P < 0.001).

Conclusion

Platelet reactivity is increased in the first 6 months after STEMI. The persistence of increased platelet reactivity in this time period may play a role in the early recurrence of coronary events after STEMI.     

Dynamics of platelet activation in diabetic and non-diabetic subjects during the course of an acute myocardial infarction

INTRODUCTION: The dynamics of platelet activation during the course of a myocardial infarction is unknown but of great importance in terms of risk assessment and anti-thrombotic therapy. The aim of the present study was sequentially to analyse platelet activation in diabetic and non-diabetic subjects with an acute myocardial infarction. MATERIALS AND METHODS: We used a sensitive laser light scattering technique to assess platelet aggregation as a measure of activation. Measurements were made on the first, second, third and fifth day in-hospital. Two hundred and forty-three patients with an acute myocardial infarction, of whom 48 had diabetes, were included. RESULTS: Platelet activation increased until the third in-hospital day in both diabetic and non-diabetic subjects, despite intense anti-thrombotic therapy. The activation was more pronounced in diabetic subjects from the time of hospital admission. Platelet activation tended to decrease after the third in-hospital day. CONCLUSIONS: We conclude that platelet activation increases rapidly at the onset of a myocardial infarction, despite aggressive anti-thrombotic treatment. The activation is more pronounced in diabetic subjects and tends to decrease within a few days. More targeted and effective anti-platelet therapy has the potential further to reduce cardiac and cerebral ischemic events following myocardial infarction and ongoing clinical trials are addressing this issue.     

瑞舒伐他汀联合氯吡格雷对脑梗死急性期患者血小板活化及聚集状态的影响

目的探讨瑞舒伐他汀联合氯吡格雷对脑梗死急性期患者血小板活化及聚集状态的影响。方法脑梗死急性期患者76例,随机分为2组。对照组给予氯吡格雷治疗,观察组给予瑞舒伐他汀联合氯吡格雷治疗。结果治疗后,观察组神经功能缺损评分及疗效优于对照组,差异具有统计学意义(P0.05)。治疗后,观察组CD63表达水平(0.2±0.1)%,CD62P表达水平(1.4±0.8)%均优于对照组(0.4±0.2)%、(2.6±1.0)%,差异有统计学意义(P0.05)%。治疗后,观察组AA水平(83.8±21.2)%及ADP途径诱导的血小板抑制率(50.0±18.1)%高于对照组的(65.5±21.9)%、(37.2±10.4)%,差异有统计学意义(P0.05)。结论瑞舒伐他汀联合氯吡格雷可有效抑制脑梗死急性期患者血小板活化及聚集,促进神经功能损伤恢复。     

Serial thrombolysis-related changes after thrombolytic therapy with TPA in patients with acute myocardial infarction.

Twenty-nine patients with acute myocardial infarction were given recombinant tissue plasminogen activator (tPA) within 6 hr after onset of chest pain (mean: 3.2 hr) with a total dose of 100mg iv drip given within 3hr for thrombolytic therapy. Serial determinations of total FDP, FDP D-Dimer (specific for FbDP), fibrinogen (Fg), PT, APTT, reptilase time (RT), plasminogen, alpha 2-antiplasmin (AAP), euglobulin lysis time (ELT) and antithrombin III (ATIII) were performed before and 1, 2, 4, 6, 12, 24, 48 hr after initiation of tPA injection in the 29 patients in order to evaluate the hemostatic changes after thrombolytic therapy. Decreases of plasminogen, Fg, AAP & ELT were found from 1 hr after therapy and persisted to 24, 12, 24 & 12 hr, respectively, with the maximum decrease usually between 1-4 hr. Increases of FDP, FDP D-dimer, PT, APTT & RT were found from 1, 1, 2, 1 & 1 hr after therapy, respectively, and sustained to 24, 12, 12, 24 & 12 hr, respectively, with maximum increases between 1-4 hr. No significant changes of ATIII were noted during the 48-hr study-period. 4 of these 29 patients (13.79%) had the complication of localized bleeding, 1 of them needed 1 unit of packed red blood cell transfusion. All thrombolysis-related changes recovered within 24 hr after tPA therapy. No parameter we have studied so far could be used for the prediction of the possibility of coronary patency after tPA therapy. But markedly elevated FDP was found to be associated with high risk of bleeding complication. As the coagulation changes persist for 24 hr or longer, careful monitoring of the coagulation tests and close observation of clinical bleeding signs up to 48 hr are necessary in patients treated with tPA.     

Intracranial hemorrhage associated with thrombolytic therapy for elderly patients with acute myocardial infarction: results from the Cooperative Cardiovascular Project

BACKGROUND AND PURPOSE: Intracranial hemorrhage is a serious complication of thrombolytic therapy for acute myocardial infarction, especially among the elderly, but little information exists on estimating risk. Better estimation of risk in individual patients may allow for withholding or using alternate therapies among those at highest risk. METHODS: To quantify the risk and identify predictors of intracranial hemorrhage associated with thrombolytic therapy, we performed a retrospective cohort study using data from medical charts. The study involved nearly all acute-care hospitals in the United States. All Medicare patients discharged with a principal diagnosis of acute myocardial infarction during a 9-month period in 1994 to 1995 were included. The main outcome measure was intracranial hemorrhage among those treated with thrombolytic therapy. RESULTS: The rate of intracranial hemorrhage was 1.43% (455 of 31 732). In a logistic model, age > or =75 years, female, black race, prior stroke, blood pressure > or =160 mm Hg, tissue plasminogen activator (versus other thrombolytic agent), excessive anticoagulation (international normalized ratio > or =4 or prothrombin time > or =24), and below median weight (< or =65 kg for women; < or =80 kg for men) were independent predictors. A risk stratification scale was developed on the basis of these factors: with none or 1 of the factors (n=6651), the rate of intracranial hemorrhage was 0.69%; with 2 factors (n=10 509), 1.02%; with 3 factors (n=9074), 1.63%; with 4 factors (n=4298), 2.49%; and with > or =5 factors (n=1071), 4. 11% (Mantel-Haenszel; P<0.001). CONCLUSIONS: The rate of intracranial hemorrhage in older patients after treatment with thrombolytic therapy exceeds 1%. Readily available factors can identify elderly patients with acute myocardial infarction at high and low risk for intracranial hemorrhage associated with thrombolytic therapy.     

Transient focal ischemia in hyperglycemic rats is associated with increased cerebral infarction

To study whether transient ischemia is influenced by hyperglycemia, the middle cerebral artery was occluded for 5, 10 and 15 min in normo- and hyperglycemic rats. Five-minute ischemia induced minor lesions in both groups. After 10-min ischemia a significant greater infarct volume was found in hyperglycemia compared with normoglycemia (29 +/- 9 mm3 vs 4 +/- 4 mm3, P less than 0.001). Fifteen-minute artery occlusion induced even more damage in both hyper- and normoglycemia (63 +/- 20 mm3 vs 13 +/- 12 mm3, P less than 0.006). The lateral part of striatum was infarcted in all hyperglycemic animals exposed to 10 or 15 min of ischemia. In the same area selective neuronal injury occurred in 6 out of 9 normoglycemic animals. The findings show that hyperglycemia increases brain damage during transient ischemia by conversion of selective neuronal injury into cerebral infarction.