Sensitivity of the thrombin clotting time and activated partial thromboplastin time to low level of antithrombin III during heparin therapy

Summary. The thrombin clotting time (TCT) has been used at our institution, along with the activated partial thromboplastin time (aPTT), for monitoring heparin therapy. We have observed that, in some patients, a discrepancy develops between the heparin levels predicted by the TCT and the aPTT with the TCT consistently predicting a lower heparin level than the aPTT. An inverse relationship was noted between the functional antithrombin III (AT-III) level and the magnitude of this discrepancy.     

Evaluation of activated partial thromboplastin time (aPTT) reagents for application in biomedical diagnostic device development

Introduction: The most commonly used test for monitoring heparin therapy is the activated partial thromboplastin time (aPTT). The response of available aPTT reagents to heparin varies significantly. The aim of this study was to highlight the differences between aPTT reagents stored in a dried format to select the most suitable formulations to be used for the development of point‐of‐care diagnostic devices used for monitoring of unfractionated heparin dose response. Methods: Ten reagents were analysed in terms of their performance in liquid and in dried form after storage for 24 h and 14 days. Performance was assessed by measurement of the clotting time (CT) as evidenced by the onset of thrombin formation using a chromogenic thrombin substrate in plasma samples activated with these formulations. Results: Reagents in all of the three forms tested (liquid, 24 h and 14 days) resulted in significant shortening of CTs in comparison with the nonactivated plasma CT. Liquids returned more rapid CTs in comparison with dried reagents. Most of the reagents were more sensitive to heparin in dried, rather than in liquid form. Dried reagents based on kaolin as a surface activator were notably more effective in achieving short CT than others, while dried reagents composed of silica and synthetic phospholipids were the most sensitive to heparin. Conclusion: Two reagents, namely aPTT‐SP and SynthASIL both of which are based on synthetic phospholipids and silica, were identified as promising candidates for incorporation into point‐of‐care diagnostic device platforms as dried reagents.     

Comparison between siliconized evacuated glass and plastic blood collection tubes for prothrombin time and activated partial thromboplastin time assay in normal patients, patients on oral anticoagulant therapy and patients with unfractioned heparin therapy

Introduction: The study was designed to evaluate whether there was a statistically significant effect between evacuated glass tubes and plastic tubes on prothrombin time (PT) and activated partial thromboplastin time (aPTT). Methods: Blood samples were drawn into four different tubes from three patient populations—apparently healthy patients, patients on oral anticoagulant therapy with vitamin K antagonists (OAT‐vka) and patients being treated with unfractioned heparin (UFH). Testing was performed on an automated coagulation analyzer, and statistical analysis was achieved using a test of variance (anova ). Results: For normal patients, there were no statistically significant differences for the aPTT test; however, there were statistically significant differences for the PT test. For patients on OAT‐vka, statistically significant differences were clearly observed between the four tube types for the PT test. For patients treated with UFH, there were no statistically significant differences for the aPTT test. Conclusion: The data showed a statistically significant difference between glass and plastic tubes in the normal population only for the PT test, with consequent repercussions for patients on OAT. This means that appropriate care and validation should take place whenever there is a change in tube type.     

Reproducibility and variability of activated clotting time measurements in the cardiac catheterization laboratory.

The objective of this study was to characterize the reproducibility and variability in the measurement to the activated clotting time (ACT) when performed on two different types of instruments, the HemoTec ACT (Medtronic) and the Hemochron 801 (International Technidyne). The ACT has evolved into the most common point-of-care test used in the cardiac catheterization lab to manage patient heparinization. Since the test has not been standardized, different systems frequently produce different results under the same clinical conditions. Duplicate paired ACT tests (n = 885) from 359 patients were performed on both instruments. Prothrombin times (PT) and activated partial thromboplastin times (aPTT) were also determined on subsets of these same samples (PT = 533; aPTT = 487). The performance and relationships between the two tests were determined using a variety of statistical analytical techniques. The average difference between the ACT devices was only 8 sec, yet more than 60% of the measurements varied by more than 10%. Over one-fourth of measurements varied by more than 20%. The reproducibility to the HemoTec instrument was superior to the Hemochron instrument across the entire range of ACTs measured (mean coefficient of variation 2.4% +/- 3.1% vs. 7.2% +/- 6.1% for HemoTec and Hemochron, respectively; P < 0.00001; range = 65-555 sec). The relationship between the two ACTs was nonlinear. In therapeutic ranges used for interventional procedures (200-350 sec), HemoTec and Hemochron ACTs are not comparable to one another. Statistical comparative analysis indicated that the HemoTec ACT has better overall performance.     

High‐dose unfractionated heparin therapy in a pregnant patient with antiphospholipid syndrome: a case report

A case of a 37‐year‐old pregnant patient with antiphospholipid syndrome (APS), who has a medical history of both thrombosis and recurrent fetal loss, is presented. She was treated with predonisolone and fixed‐dose unfractionated heparin (UFH) infusion, followed by plasmaphereses and fixed‐dose low‐molecular‐weight heparin infusion during her fourth pregnancy. Unfortunately, this treatment did not have beneficial effects, resulting in intrauterine growth restriction and finally neonatal death. Continuous intravenous UFH infusion and low‐dose aspirin were administrated under the monitoring of the activated partial thromboplastin time to achieve a target level of 120 s during her fifth pregnancy. A healthy baby weighing 1818 g at birth was delivered by Cesarean section at the 34th week of pregnancy. High‐dose UFH infusion may be considered to be one of the preferable options to manage pregnant patients with refractory APS.     

Abnormally short activated partial thromboplastin time values are associated with increased risk of recurrence of venous thromboembolism after oral anticoagulation withdrawal

This study prospectively evaluated the relationship between activated partial thromboplastin time (aPTT) and risk of venous thromboembolism (VTE) recurrence after oral anticoagulant (OA) withdrawal in patients with a previous unprovoked VTE event. Six hundred twenty-eight patients (331 males; median age: 67 years) were followed after OA interruption (mean follow-up = 22 months). Three to four weeks from OA discontinuation patients were given a complete thrombophilic work-out, including aPTT (automated aPTT). Recurrent symptomatic VTE events (objectively documented) occurred in 71/628 (11.3%, 6.8/100 person-years) patients. The VTE recurrence rate was 17.5% and 7.5% in patients with aPTT in the lower (ratio < or =0.90) and in the upper (ratio >1.05) quartiles. The recurrence risk was more than twofold higher in patients with ratio < or =0.90 versus those of the reference category [Relative risk (RR): 2.38 (95% confidence interval (CI): 1.18-4.78)]. As expected, the increase in recurrence risk disappeared after adjustment for factor VIII, IX and XI levels [RR: 1.74 (95%CI: 0.43-2.76)]. In contrast, the risk was persistently increased in patients with a ratio < or =0.90 [RR: 2.07 (95%CI: 1.02-4.18)] after adjustment for age, gender and d-dimer level. The aPTT predictive value was independent of the presence of inherited thrombophilic alterations. In conclusion, abnormally short aPTT values are associated with a significantly increased risk of VTE recurrence.     

活化部分凝血活酶时间与急性ST段抬高心肌梗死血栓负荷的相关性

目的探讨急性心肌梗死患者的活化部分凝血活酶时间(aPTT)与冠状动脉内血栓负荷之间的关系。方法收集2011年1月至2013年12月首都医科大学附属北京友谊医院急诊住院的急性ST段抬高心肌梗死(STEMI)患者424例,且均在6 h内接受了直接经皮冠状动脉介入(PCI)治疗。根据冠状动脉造影及介入治疗术中情况,将患者分为高血栓负荷组(199例)和低血栓负荷组(225例)。所有患者均在急诊就诊时测量基线的血液学指标和血栓负荷状态。采用SPSS 19.0统计学软件对数据进行处理,组间多因素分析采用logistic分析。结果高血栓负荷组与低血栓负荷组平均年龄[(59.4±11.7)和(61.9±11.8)岁]、aPTT[(24.9±3.2)和(26.6±4.0) s]、凝血酶原时间(PT)[(11.3±0.8)和(11.5±1.0)s]、左回旋支(LCX)比例[9.5%(19/199)和18.0%(40/225)]、男性比例[84.3%(168/199)和74.3%(167/225)]、白细胞计数[(10.0±3.1)×10~9和(9.3±3.1)×10~9/L]、右冠状动脉(RCA)比例[45.2%(90/199)和29.8%(68/225)]比较,差异均有统计学意义(均P0.05)。2组吸烟状况、用药、既往患有高血压及糖尿病比例、肝肾功能、电解质、PTA、AT-Ⅲ、FBG等指标比较,差异均无统计学意义(均P0.05)。组间多因素logistic分析结果显示,aPTT(OR=1.175,95%CI 1.102～1.252)和RCA(OR=2.783,95%CI 1.409～5.497)为高血栓负荷的独立预测因子(P0.01)。aPTT的受试者工作特征曲线下面积为0.660(95%CI 0.608～0.711,P0.001)。结果提示,排除高血栓负荷的aPTT的最佳临界值为26.05(灵敏度为53.5%,特异度为72.6%)。结论急性ST段抬高型心肌梗死患者急诊就诊时缩短的aPTT值与PCI治疗时所见的高血栓负荷相关。     

Differential diagnosis and clinical management of isolated prolonged activated partial thromboplastin time in a patient with Hashimoto thyroiditis-associated thyroid cancer: A case report

Rationale:Patients preparing for surgery may have isolated, prolonged activated partial thromboplastin time (APTT). Cause analysis is warranted in patients who had neither bleeding symptom nor thromboembolic events because isolated prolongation of APTT may lead to unnecessary delayed surgical intervention or invasive procedure, even ineffective plasma infusion treatments. Here, we report a case of Hashimoto thyroiditis-associated thyroid cancer whose APTT was isolated prolonged and discuss the challenges of diagnosis and clinical management of this patient.Patient concerns:A 57-year-old woman was admitted to the hospital due to thyroid cancer. Anticoagulant assay was performed for this patient before surgery, she had normal values for prothrombin time, thrombin time, and fibrinogen, but had isolated prolonged APTT value (20 seconds longer than normal). However, the routine laboratory of the local hospital showed normal APTT and she did not have any abnormal bleeding or thrombotic episodes. Lupus anticoagulant (LA) was strongly positive according to mixing studies and modified dilute Russell viper venom time method, it was responsible for prolonged APTT.Diagnoses:Hashimoto thyroiditis-associated thyroid cancer whose APTT was isolated prolonged.Interventions:The isolated prolongation of APTT in this patient was due to LA. She had no history of anticoagulant medications and no spontaneous bleeding episodes. There should be no specific intervention before thyroidectomy.Outcomes:This thyroid cancer patient had an uneventful surgery and was discharged after a week.Lessons:Prolonged APTT is not considered an absolute indication for plasma infusion therapy in patients with LA. The correct identification of the cause of APTT prolongation is essential for proper treatment of the individuals.     

Influence of factor VIII:C and factor IX activity in plasmas of haemophilic dogs on the activated partial thromboplastin time measured with two commercial reagents

The present study is based on 145 plasma samples with a reduced activity of factor VIII:C (range: 0.009-0.62 IU mL-1) and 28 samples with a reduced factor IX activity (range: 0.035-0.55 IU mL-1). The samples were collected from dogs with haemophilia A (n=22) or haemophilia B (n=3), some of these during substitution therapy. For all samples the activated partial thromboplastin time (APTT) was measured with two commercial reagents containing kaolin as a contact activator. In each case, the deficiency of factor VIII:C or IX was reflected in abnormal results of the APTT. This was true for both reagents. A significant correlation (P < 0.001) was found between factor VIII:C activity and APTT (reagent 1, Pathromtin(R); Spearman's rank correlation coefficient, rS=-0.731, reagent 2, PTT-Reagenz; rS=-0.875) as well as between factor IX activity and APTT (reagent 1, rS=-0.819; reagent 2, rS=-0.955]. In each case, the relationship between coagulation factor activity and APTT could be proven most precisely by geometric regression. The results of this study illustrate the applicability of commercial APTT test kits as a sensitive screening test of factor VIII:C and IX deficiencies in canine plasma.     

Evaluation of the activated partial thromboplastin time assay for clinical monitoring of PEGylated recombinant factor VIII (BAY 94‐9027) for haemophilia A

Patients with haemophilia (PWH) are usually monitored by the one‐stage activated partial thromboplastin time (aPTT) factor VIII (FVIII) assay. Different aPTT activators may affect clotting time (CT) and FVIII:C levels in patients treated with PEGylated FVIII. To evaluate the characteristics of PEGylated FVIII (BAY 94‐9027) in various aPTT clotting assays, and to identify suitable aPTT reagents for monitoring BAY 94‐9027 during the treatment of PWH, BAY 94‐9027 and World Health Organization (WHO) 8th FVIII standards (WHO‐8) were spiked into pooled and individual severe haemophilia A plasma at 1.0, 0.25 and 0.05 IU mL^?1. Five commercial aPTT reagents widely used in clinical laboratories were compared and evaluated for BAY 94‐9027 activity in plasma from PWH. BAY 94‐9027 and WHO‐8 bestowed similar CT and excellent precision when ellagic acid (SynthAFax, Dade Actin, and Cephascreen) aPTT reagents were used. In contrast, BAY 94‐9027 showed significantly prolonged CT and poor precision compared with WHO‐8 using silica aPTT reagents (APTT‐SP and STA PTT 5). Furthermore, free 60‐kDa polyethylene glycol (PEG), used for the conjugation of FVIII, showed a dose‐dependent prolongation of CT in the APTT‐SP assay. There was no effect on the SynthAFax‐APTT, prothrombin time, or FXIa‐initiated thrombin generation assay, demonstrating that the PEG moiety on FVIII has no general effect on the coagulation cascade. In summary, ellagic aPTT reagents (SynthAFax, Dade Actin, and Cephascreen) are most suitable for evaluating potency of BAY 94‐9027 and should be the preferred aPTT reagents used in clinical laboratories for monitoring FVIII activity after infusion of BAY 94‐9027 to PWH.     

A multicenter, randomized study of argatroban versus heparin as adjunct to tissue plasminogen activator (TPA) in acute myocardial infarction: myocardial infarction with Novastan and TPA (MINT) study

OBJECTIVES

This study examined the effect of a small-molecule, direct thrombin inhibitor, argatroban, on reperfusion induced by tissue plasminogen activator (TPA) in patients with acute myocardial infarction (AMI).

BACKGROUND

Thrombin plays a crucial role in thrombosis and thrombolysis. In vitro and in vivo studies have shown that argatroban has advantages over heparin for the inhibition of clot-bound thrombin and for the enhancement of thrombolysis with TPA.

METHODS

One hundred and twenty-five patients with AMI within 6 h were randomized to heparin, low-dose argatroban or high-dose argatroban in addition to TPA. The primary end point was the rate of thrombolysis in myocardial infarction (TIMI) grade 3 flow at 90 min.

RESULTS

TIMI grade 3 flow was achieved in 42.1% of heparin, 56.8% of low-dose argatroban (p = 0.20 vs. heparin) and 58.7% of high-dose argatroban patients (p = 0.13 vs. heparin). In patients presenting after 3 h, TIMI grade 3 flow was significantly more frequent in high-dose argatroban versus heparin patients: 57.1% versus 20.0% (p = 0.03 vs. heparin). Major bleeding was observed in 10.0% of heparin, and in 2.6% and 4.3% of low-dose and high-dose argatroban patients, respectively. The composite of death, recurrent myocardial infarction, cardiogenic shock or congestive heart failure, revascularization and recurrent ischemia at 30 days occurred in 37.5% of heparin, 32.0% of low-dose argatroban and 25.5% of high-dose argatroban patients (p = 0.23).

CONCLUSIONS

Argatroban, as compared with heparin, appears to enhance reperfusion with TPA in patients with AMI, particularly in those patients with delayed presentation. The incidences of major bleeding and adverse clinical outcome were lower in the patients receiving argatroban.     

Sweetener influences plasma concentration of flavonoids in humans after an acute intake of a new (poly)phenol-rich beverage

Background and aimThe overconsumption of sucrose is closely related to sugar-sweetened beverages and one of the main factors associated with the increase of metabolic diseases, such as type 2 diabetes, obesity, and insulin resistance. So, the addition of alternative sweeteners to new fruit-based drinks could contribute to minimizing the incidence or severity of these pathologies. Nevertheless, current knowledge on the influence of these additives on the bioactive compounds present in these beverages is still scarce.new-onset hypertension, but few data were published in Asian. We aimed to investigate the association of lipid profiles with new-onset hypertension in a Chinese community-based non-hypertensive cohort without lipid-lowering treatment (n = 1802).Methods and resultsHence, to contribute to the understanding of this issue, the plasma concentration of phenolic compounds (anthocyanins and flavanones), after the ingestion of a new maqui-citrus-based beverage, supplemented with sucrose (natural high caloric), stevia (natural non-caloric), or sucralose (artificial non-caloric), was evaluated as evidence of their intestinal absorption and metabolism previous to renal excretion. The beverages were ingested by volunteers (n = 20) and the resulting phenolic metabolites in plasma were analyzed by UHPLC-ESI-MS/MS. A total of 13 metabolites were detected: caffeic acid sulfate, caffeic acid glucuronide, 3,4-dihydroxyfenylacetic, 3,4-dihydroxyfenylacetic sulfate. 3,4-dihydroxyfenylacetic acid di-sulfate, 3,4-dihydroxyfenylacetic di-glucuronide, 3,4-dihydroxyfenylacetic glucuronide-sulfate, trans-ferulic acid glucuronide, naringenin glucuronide, vanillic acid, vanillic acid sulfate, vanillic acid glucuronide-sulfate, and vanillic acid di-glucuronide, being recorded their maximum concentration after 30–60 min.ConclusionIn general, sucralose provided the greatest absorption value for most of these metabolites, followed by stevia. Due to this, the present study proposes sucralose and stevia (non-caloric sweeteners) as valuable alternatives to sucrose (high caloric sweetener), to avoid the augmented risk of several metabolic disorders.