A shortened activated partial thromboplastin time is associated with the risk of venous thromboembolism

Hypercoagulability due to high coagulation factors XI, VIII, IX, II, and fibrinogen is recognized as a risk factor of venous thromboembolism (VTE). These factors are cumulatively explored by the activated partial thromboplastin time (APTT). To test the hypothesis that a short APTT increases the risk of VTE, a case-control study was carried out in 605 patients referred for thrombophilia testing after documented VTE and in 1290 controls. Median APTT ratio (coagulation time of test-to-reference plasma) values were 0.97 (range: 0.75-1.41) for patients and 1.00 (range: 0.72-1.33) for controls (P < .001). In patients who had an APTT ratio smaller than the fifth percentile of the distribution in controls, the odds ratio (OR) for VTE was 2.4 (95% confidence interval [CI]: 1.7-3.6) and was independent of inherited thrombophilic abnormalities. Further statistical analyses in 193 patients and 259 controls for whom factor VIII (FVIII) levels were available showed a decrease of the OR from 2.7 (95% CI: 1.4-5.3) to 2.1 (95% CI: 1.0-4.2), indicating that the risk was only partially mediated by high FVIII levels. In conclusion, hypercoagulability detected by a shortened APTT is independently associated with VTE. This inexpensive and simple test should be considered in the evaluation of the risk of VTE.     

Increased incidence of venous thrombosis in patients with shortened activated partial thromboplastin times and low ratios for activated protein C resistance

A cohort of 69 hospital patients with shortened activated partial thromboplastin time (APTT) were prospectively identified and were further investigated for resistance to activated protein C (APC). This was quantified by APTT-based and Russel viper venom time (RVVT)-based methods. The prevalence of objectively confirmed venous thromboembolism (VTE) in this cohort was 19% (13/69). Of these 69 patients, 28 also had low APC resistance ratios and the incidence of VTE among these patients (group 1) was 36% (10/28). This was significantly higher (P=0.003) than that in the remaining 41 patients (group 2) with shortened APTT and normal APC resistance (7%, 3/41). DNA analysis confirmed 13 of the group 1 patients were FV Leiden positive. The incidence of VTE in the FV Leiden group (group 1a, n=13) was 38% (5/13) and in the group whose abnormal resistance to APC was independent of FV Leiden (group 1b, n=15) was 33% (5/15). These results suggest that a shortened APTT, coexisting with a low APC resistance ratio, regardless of FV Leiden carriership status, is a marker for VTE. Increased resistance to the anticoagulant activity of APC is multifactorial as reflected by evidence of abnormal resistance differing in the two assays.     

Prolonged activated partial thromboplastin time in pregnancy: a brief report

BACKGROUND: Limited data are available regarding causes of prolonged activated partial thromboplastin time (aPTT) in otherwise normal pregnancies. We retrospectively evaluated clinical data of pregnant women in whom an elevated aPTT was noted on routine prenatal testing. Our intent was to identify various causes of prolonged aPTT and to evaluate whether the pregnancies were adversely affected. METHODS: A retrospective review of medical records of 36 pregnant patients with a prolonged aPTT as the sole abnormal coagulation test seen in the outpatient department of a tertiary care hospital over a period of 4 years. RESULTS: Patients' median age was 26 (range, 19-41) years and median duration of gestation period was 19 (range, 8-38) weeks. Fifteen patients were primigravida. Of 36 patients, repeated aPTT values were normal in 24 (67%) patients, whereas 12 (33%) patients had persistently elevated aPTT values. Factor XI deficiency was found in 5 patients, lupus anticoagulant in 3 patients, elevated anticardiolipin antibody in 2 patients, and low von Willebrand Factor level in 1 patient. Overall, 23 patients delivered. No patients experienced excessive bleeding or thromboembolism. CONCLUSION: Factor XI deficiency and antiphospholipid antibody were 2 major abnormalities identified in patients with prolonged aPTT. These coagulopathies were not associated with excessive bleeding or thromboembolism. Repeat normal aPTT in approximately 2 thirds of patients suggests that proper sample collection and processing are important for coagulation assays to avoid erroneous clotting times.     

The activated partial thromboplastin time in early diagnosis of myocardial infarction.

Intracoronary thrombosis is fundamental to the pathogenesis of acute myocardial infarction (MI), yet few studies have examined the diagnostic value of routine coagulability markers, such as the activated partial thromboplastin time (aPTT), in patients with chest pain. We hypothesized that the initiation of thrombosis early in MI would shorten the aPTT, and conducted a retrospective cohort study of patients admitted with a diagnosis of chest pain through the emergency department of one community hospital between 1 January and 30 August 1998. Patients were diagnosed as MI positive or negative based on World Health Organization (WHO) criteria. The aPTT obtained on arrival (prior to anticoagulation therapy) was retrieved from the electronic medical record. Of 120 eligible patients (49% female, mean age 63.7 years), 27 (23%) were diagnosed with MI. Patients with an aPTT control (RR = 2.83, 95% confidence interval 1.15 to 6.96, P = 0.013). A shortened aPTT (相似文献   

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。     

Diagnostic uses of the activated partial thromboplastin time and prothrombin time

The activated partial thromboplastin time (APTT) and prothrombin time (PT) have three principal uses. In screening for coagulation disorders (or increased risk of postoperative hemorrhage), the tests add no information to the preoperative care of patients without clinical findings indicative of increased bleeding risk. Furthermore, the prevalence of asymptomatic congenital coagulopathies is so low that false-positive test results greatly outnumber true-positive results. Thus, clinicians may use clinical assessment to screen and should reserve coagulation tests to investigate patients with abnormal findings. In evaluating abnormal bleeding, these tests are sufficiently sensitive that if both are negative, further investigation of the coagulation system is obviated. If one or both tests are positive, the pattern of results directs further attention to limited segments of the coagulation sequence. In monitoring anticoagulation therapy, the APTT and PT tests appear to contribute to the safety and effectiveness of heparin and warfarin therapies, respectively.     

Measurement of a newly developed thrombomodulin addition activated partial thromboplastin time assay in patients with deep venous thrombosis.

We developed a simple assay using rabbit thrombomodulin (TM) based on an activated partial thromboplastin time method, which detected the response to TM in plasma coagulation. We call it thrombomodulin addition clotting time (TACT). The anticoagulant response to TM was calculated by dividing the clotting time with TM by the clotting time with buffer solution. Results were expressed as TACT ratio, which indicates the degree of inhibition of plasma clotting by TM. Using this assay, we measured the TACT ratio in 80 patients with deep-vein thrombosis (DVT) and in 126 controls matched to the patients according to age and sex. A significant difference in the TACT ratio was observed between patients with DVT (mean 1.874) and controls (mean 1.956) (p < 0.001). Twenty- three patients (29%) had TACT ratios below the 10th percentile (1.757) of distribution of control subjects (odds ratio: 3.5; 95% confidence interval (CI): 1.7-7.2). After excluding subjects with a deficiency of protein C, protein S and antithrombin III, we found an odds ratio for DVT of 3.4 (95% CI: 1.6-7.2). These data suggest that natural anticoagulant deficiencies do not influence the TACT ratio, and our case-control study may show that the plasma of patients with DVT has a low response to TM.     

Laboratory controls of heparin therapy with thrombin time, partial thromboplastin time and activated recalcification time

For the laboratory control of a heparin therapy thrombin time, partial thromboplastin time and activated recalcification time are used. On account of distinct differences in the heparin sensitivity of these reactions an indication-related application is necessary. The ability of evidence and the possibility of establishing test-specific therapeutic regions are restricted by differences caused by reagents, individual variability and influence by accompanying haemostasiological changes. The own approach, taking into consideration the so-called heparin resistance, it presented.     

Relationship between activated partial thromboplastin time,heparin and potassium levels

We performed a meta-analysis of five randomized, placebo-controlled trials to characterize the impact of plant sterols/stanols on plasma lipids in patients with type 2 diabetes. Upon meta-analysis, plant sterols/stanols significantly reduced total and LDL cholesterol, with a trend towards improvement in HDL. No beneficial effect on triglycerides was apparent.     

Thrombolytic fibrin specificity influences activated partial thromboplastin time prolongation in vitro.

Despite limited comparative data, guidelines suggest the same concomitant unfractionated heparin (UFH) dose for all fibrin-specific thrombolytic agents in acute myocardial infarction. Since a supratherapeutic activated partial thromboplastin time (aPTT) correlates with adverse outcomes, clarifying effects of various agents on aPTT are needed. The present in vitro study evaluated the influence of alteplase (rt-PA), reteplase (r-PA), and tenecteplase (TNK) on aPTT prolongation. Blood samples from healthy volunteers (n = 12) were treated with equipotent concentrations of rt-PA, r-PA, and TNK, with and without UFH. Samples of each treatment group were incubated at 37 degrees C; aPTT and fibrinogen activity were measured after 4 h. Mean aPTT values for rt-PA alone and r-PA alone were prolonged versus those of TNK alone (P = 0.001 for both). Combined with UFH, rt-PA and r-PA increased the aPTT versus UFH alone (P < 0.05 for both). Interestingly, TNK + UFH reduced the aPTT versus UFH alone (P < 0.001). A negative correlation existed between fibrinogen activity and aPTT for all treatments, except TNK alone. The present investigation illustrates that an agent with maximal fibrin specificity (TNK) has minimal effect on the aPTT, while agents with less fibrin specificity are more likely to prolong the aPTT, with and without UFH present.