Anticoagulation with vitamin K antagonists such as warfarin has historically been used for the long term management of patients with thromboembolic disease. However, these agents have a slow onset of action which requires bridging therapy with heparin and its analogues, which are available only in parenteral route. To overcome these limitations, new oral anticoagulants such as factor Xa inhibitors and direct thrombin inhibitors have been developed. The aim of this article is to systematically review the phase 3 clinical trials of new oral anticoagulants in common medical conditions.
We searched PubMed (Medline) from January 2007 to February 2013 using “Oral anticoagulants”, “New oral anticoagulants”, “Randomized controlled trial”, “Novel anticoagulants”, “Apixaban”, “Rivaroxaban”, “Edoxaban”, “Dabigatran etexilate”, “Dabigatran” and a combination of the above terms. The available evidence from the phase 3 RCTs was summarized on the basis of individual drug and the medical conditions categorized into “atrial fibrillation”, “acute coronary syndrome”, “orthopedic surgery”, “venous thromboembolism” and “medically ill patients”.
Apixaban, rivaroxaban and dabigatran have been found to be either non-inferior or superior to enoxaparin in prophylaxis of venous thromboembolism in knee and hip replacement with similar bleeding risk, superior to warfarin for stroke prevention in atrial fibrillation with significant reduction in the risk of major bleeding, non-inferior to aspirin for reducing cardiovascular death and stroke in acute coronary syndrome with significant increase in the risk of major bleed. Rivaroxaban and dabigatran are also superior to the conventional agents in the management of symptomatic venous thromboembolism. However, compared to enoxaparin, apixaban and rivaroxaban use lead to significantly increased bleeding risk in medically ill patients. Additional studies evaluating the specific reversal agents of these new drugs for the management of life-threatening bleeding or other adverse effects are necessary.
Considering their pharmacological properties, their efficacy and bleeding complications, the new oral agents offer a net favourable clinical profile in orthopedic surgery, atrial fibrillation, acute coronary syndrome and increase the risk of bleeding in critically ill patients. Further studies are necessary to determine the long term safety and to identify the specific reversal agents of these new drugs.
Vitamin K antagonists; Oral anticoagulants; Apixaban; Rivaroxaban; Dabigatran; Orthopedic surgery; Knee replacement; Hip replacement; Acute coronary syndrome; Atrial fibrillation; Venous thromboembolism; Critically ill patients; Systematic review
The incidence of venous thromboembolic disease (VTED) is estimated to be, on average, 1–2 cases per 1,000 individuals per year worldwide. There are few data concerning the incidence rate (IR) of VTED in the Argentinean population at large.
Our aim was to estimate the IR of VTED at the Italian Hospital Medical Care Program (IHMCP) in Buenos Aires, the most populous city in Argentina.
This prospective cohort study evaluated all consecutive incident cases of pulmonary thromboembolism (PTE) and deep vein thrombosis (DVT) confirmed in patients over the age of 17 who were members of the IHMCP from June 2006 to May 2012. Any patient who had an initial confirmed VTED episode and was a member of the IHMCP at the time of diagnosis was considered an incident case.
There were 1,138 cases of VTED for 687,871 person-years of follow-up. The crude IR of VTED was 1.65 (95% CI: 1.56 to 1.75) per 1,000 person-years. The highest IR was found in subjects >80 years old (5.92 per 1,000 person years; 95% CI: 5.41 to 6.49).
The IRs adjusted to the population of the city of Buenos Aires were 0.90 (95% CI: 0.84 to 0.95) for VTED, 0.71 (95% CI: 0.66 to 0.76) for DVT, and 0.34 (95% CI: 0.31 to 0.37) for PTE.
VTED is a common health problem with a high IR in members of the IHMCP, especially the elderly. This is the first paper to report prospectively the cumulative incidence of VTED in Latin America.
Epidemiology; Incidence; Pulmonary embolism; Venous thromboembolism; Venous thrombosis
New oral anticoagulants (NOAC) are approved for several indications for prophylaxis and treatment of venous thromboembolism and for prevention of embolism in atrial fibrillation at fixed daily doses without need of laboratory guided dose adjustment. Due to their low molecular weight of about 500 to 600 Dalton and their hydrophilicity free anticoagulant is excreted immediately through glomerular filtration into the urine. Impairment of renal function may increase the plasma concentration of the anticoagulants and lowered creatinine clearance is a declared contraindication. In contrast to the initial aim of development the anticoagulant effect is required to be determined in special clinical situations. Several specific and non-specific assays using plasma samples are currently undergoing standardization. As all NOACs are excreted into the urine, specific assays were developed for this matrix to determine them quantitatively of qualitatively. Urine samples can be easily and repetitively obtained avoiding problems and risks associated with blood sampling. The qualitative assay can be performed as a point of care test (POC) also by the patient by judging the different colours for the absence or presence of the drugs with the naked eye. The test is rapid (results available within 15 min), sensitive, specific and accurate and does not require a purified NOAC as control. The tests may be a tool for clinicians who need to know for treatment decisions if a NOAC is on board or not. As the tests are specific for oral direct thrombin inhibitors and for oral direct factor Xa inhibitors, the indication does not interfere with other qualitative POC test in development using clotting systems. The test may be indicated for patients at acute hospitalization, before surgery or central nervous system puncture anaesthesia, if fibrinolytic therapy is indicated, acute deterioration of renal function, and for control of adherence to therapy.
Oral anticoagulant; Dabigatran; Rivaroxaban; Apixaban; Renal function; Anticoagulation; Urine; Coagulation assay; Monitoring; Compliance
Atrial fibrillation (AF) is the most common form of heart arrhythmia and a leading cause of stroke and systemic embolism. Chronic anticoagulation is recommended for preventing those complications. Our study aimed to compare the cost/utility (CU) of three main anticoagulation options: 1) standard warfarin dosing (SD-W) 2) warfarin dosage under the guidance of CYP2C9 and VKORC1 genotyping (GT-W) and 3) dabigatran 150 mg twice a day.
A Markov state transition model was built to simulate the expected C/U of dabigatran, SD-W and GT-W anticoagulation therapy for the prevention of stroke and systemic thromboembolism in patients with atrial fibrillation over a period of 5 years under the perspective of the public health care system. Model inputs were derived from extensive literature search and government’s data bases. Outcomes considered were the number of total major events (thromboembolic and hemorrhagic events), total costs in Canadian dollars (1CAD$ = 1$US), total quality-adjusted life years (QALYs), costs/QALYs and incremental costs/QALYs gained (ICUR).
Raw base case results show that SD-W has the lowest C/U ratio. However, the dabigatran option might be considered as an alternative, as its cost per additional QALY gained compared to SD-W is CAD $ 4 765, i.e. less than 50 000, the ICUR threshold generally accepted to adopt an intervention. At the same threshold, GT-W doesn’t appear to be an alternative to SD-W. Our results were robust to one-way and multi-way sensitivity analyses.
SD-W has the lowest C/U ratio among the 3 options. However, dabigatran might be considered as an alternative. GT-W is not C/U and should not currently be recommended for the routine anticoagulotherapy management of AF patients.
Atrial fibrillation; Simulation; Cost-utility; Dabigatran etexilate; Warfarin; Anticoagulation; CYP2C9; VKORC1
Direct oral anticoagulants that target a single coagulation factor have been developed as an alternative to standard therapies with heparin and/or vitamin K antagonists. The purpose of this study was to derive non-inferiority margins suitable for randomised clinical studies designed to evaluate these agents for the treatment of venous thromboembolism (VTE).
We performed a systematic review to derive non-inferiority margins suitable for use in studies evaluating direct oral anticoagulants for the treatment of VTE. A PubMed search identified publications that evaluated current standard treatment versus placebo, ‘no treatment’ or ‘less intensive treatment’ in patients with symptomatic deep vein thrombosis (DVT) and/or pulmonary embolism (PE). Publications were eligible if they had a randomised study design, included patients with symptomatic DVT and/or PE, used objective diagnostic methods to document the index event and reported objectively confirmed symptomatic recurrent VTE.
Fourteen publications were included in the analysis. Recurrent VTE occurred in 25 (1.5%) out of 1715 patients who received current standard of care and in 157 (9.2%) out of 1711 patients who received placebo, ‘no treatment’ or ‘less intensive treatment’, for an odds ratio of 0.18 (95% confidence interval, 0.14−0.25; test for heterogeneity, p=0.87). In order to preserve 50% or 75% of the established treatment effect using a linear scale, the corresponding thresholds for non-inferiority equalled 2.50 and 1.75, respectively.
This systematic review and statistical approach determined non-inferiority margins suitable for use in studies of direct oral anticoagulants for the treatment of DVT and/or PE.
Non-inferiority margin; Oral anticoagulants; Venous thromboembolism
Microplate-based thrombin generation test (TGT) is widely used as clinical measure of global hemostatic potential and it becomes a useful tool for control of drug potency and quality by drug manufactures. However, the convenience of the microtiter plate technology can be deceiving: microplate assays are prone to location-based variability in different parts of the microtiter plate.
In this report, we evaluated the well-to-well consistency of the TGT variant specifically applied to the quantitative detection of the thrombogenic substances in the immune globulin product. We also studied the utility of previously described microplate layout designs in the TGT experiment.
Location of the sample on the microplate (location effect) contributes to the variability of TGT measurements. Use of manual pipetting techniques and applications of the TGT to the evaluation of procoagulant enzymatic substances are especially sensitive. The effects were not sensitive to temperature or choice of microplate reader. Smallest location effects were observed with automated dispenser-based calibrated thrombogram instrument. Even for an automated instrument, the use of calibration curve resulted in up to 30% bias in thrombogenic potency assignment.
Use of symmetrical version of the strip-plot layout was demonstrated to help to minimize location artifacts even under the worst-case conditions. Strip-plot layouts are required for quantitative thrombin-generation based bioassays used in the biotechnological field.
Thrombin generation test; Location effects; Immunoglobulin; Thrombogenicity
Research into new anticoagulants for preventing and treating thromboembolic disorders has focused on targeting single enzymes in the coagulation cascade, particularly Factor Xa and thrombin, inhibition of which greatly decreases thrombin generation. Based on the results of phase III clinical trials, rivaroxaban, a direct Factor Xa inhibitor, has been approved in many countries for the management of several thromboembolic disorders. Owing to its predictable pharmacokinetic and pharmacodynamic characteristics, fixed-dose regimens are used without the need for routine coagulation monitoring. In situations where assessment of rivaroxaban exposure may be helpful, anti-Factor Xa chromogenic assays (in tandem with standard calibration curves generated with the use of rivaroxaban calibrators and controls) could be used. It is important to note that test results will be affected by the timing of blood sampling after rivaroxaban intake. In addition, the anti-Factor Xa method measures the drug concentration and not the intensity of the drug’s anticoagulant activity, and a higher than expected rivaroxaban plasma level does not necessarily indicate an increased risk of bleeding complications. Therefore, clinicians need to consider test results in relation to the pharmacokinetics of rivaroxaban and other patient risk factors associated with bleeding.
Factor Xa; Laboratory assessment; Rivaroxaban
Results of clotting tests used to measure the effect of old and new antithrombotic drugs can be expressed in different ways and this is considered as one of the sources of variability to explain the differences of results obtained for the same patient plasma when tested in different laboratories. This is particularly important for patient on vitamin K antagonists and led to the development of the international normalized ratio system of results reporting in this setting. Although standardization of results expression for the tests meant to measure the anticoagulant effect of new oral anticoagulants (NOA) is presently not perceived as an issue, it may become crucially important at the time when test-specific cut off values will be available to help assessing the risk of bleeding in individual patients who are on over-dosage. Effort should therefore be made to harmonize as much as possible results obtained in different laboratories using the same method, but different reagents. This article is aimed at discussing different options of results reporting of tests for NOA and their merits/pitfalls.
New oral anticoagulants (NOACs) have been introduced to improve anticoagulant therapy worldwide, but safe implementation may require additional measures. First, optimization of dose adjustment based on therapeutic levels of the drug may be more appropriate than fixed dose therapy. The development and implementation in quantitative laboratory assays will enable further dose optimization. Second, non-adherence to medication is a potential threat to the safe use of NOACs. Since cardiovascular medication may not be optimally used in about 50% of patients, procedures to improve adherence are imperative, also for NOAC therapy and in particular in elderly patients.
New oral anticoagulants; Adherence; Vitamin K antagonists; Laboratory assays
Unlike traditional anticoagulants, the more recently developed agents rivaroxaban, dabigatran and apixaban target specific factors in the coagulation cascade to attenuate thrombosis. Rivaroxaban and apixaban directly inhibit Factor Xa, whereas dabigatran directly inhibits thrombin. All three drugs exhibit predictable pharmacokinetic and pharmacodynamic characteristics that allow for fixed oral doses in a variety of settings. The population pharmacokinetics of rivaroxaban, and also dabigatran, have been evaluated in a series of models using patient data from phase II and III clinical studies. These models point towards a consistent pharmacokinetic and pharmacodynamic profile, even when extreme demographic factors are taken into account, meaning that doses rarely need to be adjusted. The exception is in certain patients with renal impairment, for whom pharmacokinetic modelling provided the rationale for reduced doses as part of some regimens. Although not routinely required, the ability to measure plasma concentrations of these agents could be advantageous in emergency situations, such as overdose. Specific pharmacokinetic and pharmacodynamic characteristics must be taken into account when selecting an appropriate assay for monitoring. The anti-Factor Xa chromogenic assays now available are likely to provide the most appropriate means of determining plasma concentrations of rivaroxaban and apixaban, and specific assays for dabigatran are in development.
Rivaroxaban; Population Pharmacokinetics; Dabigatran; Apixaban; Coagulation Monitoring
Heparin Induced Thrombocytopenia (HIT) is caused by antibodies that recognize platelet factor 4 (PF4) associated with polyanionic glycosaminoglycan drugs or displayed on vascular cell membranes. These antibodies are elicited by multimolecular complexes that can occur when heparin is administered in clinical settings associated with abundant PF4. Heparin binding alters native PF4 and elicits immune recognition and response. While the presence of heparin is integral to immunogenesis, the HIT antibody binding site is within PF4. Thus HIT antibodies develop and function to cause thrombocytopenia and/or thrombosis only in the presence of PF4. Future emphasis on understanding the biology, turnover and regulation of PF4 may lead to insights into the prevention and treatment of HIT.
Heparin Induced Thrombocytopenia (HIT); Platelet Factor 4 (PF4); Heparin
While the assessment of analytical precision within medical laboratories has received much attention in scientific enquiry, the degree of as well as the sources causing variation between them remains incompletely understood. In this study, we quantified the variance components when performing coagulation tests with identical analytical platforms in different laboratories and computed intraclass correlations coefficients (ICC) for each coagulation test.
Data from eight laboratories measuring fibrinogen twice in twenty healthy subjects with one out of 3 different platforms and single measurements of prothrombin time (PT), and coagulation factors II, V, VII, VIII, IX, X, XI and XIII were analysed. By platform, the variance components of (i) the subjects, (ii) the laboratory and the technician and (iii) the total variance were obtained for fibrinogen as well as (i) and (iii) for the remaining factors using ANOVA.
The variability for fibrinogen measurements within a laboratory ranged from 0.02 to 0.04, the variability between laboratories ranged from 0.006 to 0.097. The ICC for fibrinogen ranged from 0.37 to 0.66 and from 0.19 to 0.80 for PT between the platforms. For the remaining factors the ICC’s ranged from 0.04 (FII) to 0.93 (FVIII).
Variance components that could be attributed to technicians or laboratory procedures were substantial, led to disappointingly low intraclass correlation coefficients for several factors and were pronounced for some of the platforms. Our findings call for sustained efforts to raise the level of standardization of structures and procedures involved in the quantification of coagulation factors.
Inter-rater variability; Intraclass correlation coefficient; Reproducibility of testing; Test validity
Giant left atrium is a condition characterized by huge enlargement of the left atrium with a diameter exceeding 65mm. It is most commonly associated with long standing rheumatic mitral valve disease. We present a 45-year-old female patient with rheumatic mitral stenosis associated with giant left atrium occupied by an 11 × 10 × 5 cm thrombus weighing 500 gms. The patient underwent successful mitral valve replacement and thrombectomy through an inverted T-shaped biatrial incision.
Giant left atrium; Left atrial thrombus; Thrombectomy; Mitral valve replacement
Deep Vein Thrombosis (DVT) is an important cause of morbidity and is the first cause of maternal death after delivery in Western Nations. The risk of venous thromboembolism is present throughout the pregnancy and is maximal during postpartum, especially after twin delivery. Many of the signs and symptoms of DVT overlap those of a normal pregnancy causing difficulty for diagnosis.
We report the case of a 33 year-old woman transferred to our Department one week after caesarean section for twin delivery. She presented with severe abdominal pain, fever, abdominal distension and shortness of breath. She had no personal or family history of thromboembolism. Computerized Tomography Scan revealed right ovarian vein thrombosis, left renal vein thrombosis extending up to the Inferior Vena Cava and pulmonary embolism with bilateral pleural effusion. Caval filter was positioned and anticoagulation therapy associated with antibiotics was instituted. Pancreatitis showed up two days after and was promptly treated. Three months after discharge the caval filter was removed and oral anticoagulation was stopped. During a 12-months follow-up, she remained stable and symptom free.
Ovarian vein thrombosis is rare but recognition of signs and symptoms is fundamental to start adequate therapy and avoid potential serious sequelae. The risk for maternal postpartum ovarian vein thrombosis is increased by caesarean section delivery of twins. Such patients should be closely monitored. We illustrated how an underestimated condition can lead to massive complications.
Twin delivery; Postpartum ovarian vein thrombosis; Pulmonary emboli
Early treatment of disseminated intravascular coagulation (DIC) can be associated with improved patient outcomes. The Japanese Ministry of Health and Welfare (JMHW) and the International Society on Thrombosis and Haemostasis (ISTH) criteria are the most specific for diagnosis of septic DIC. The revised Japanese Association for Acute Medicine (JAAM) criteria are able to diagnose sepsis-induced DIC in the early stage. Recombinant human soluble thrombomodulin (rhTM) has recently been used for treating DIC. Previous studies have shown a benefit of using rhTM for D,IC diagnosed by the JMHW or ISTH criteria, but not the JAAM criteria. The purpose of this study was to sequentially evaluate coagulation biomarkers and the DIC score after giving rhTM treatment to patients with sepsis-induced DIC diagnosed according to the JAAM criteria.
We performed a retrospective cohort study. Critically ill patients were included if diagnosed with sepsis-induced DIC according to the JAAM criteria. They were either treated without rhTM (control group) or with rhTM (treatment group). The primary outcome was the DIC score on day 7. The secondary outcome was 28-day mortality from the start of DIC treatment. Changes in the results of coagulation tests were assessed over time from the start of treatment to day 7.
Twelve and 23 patients were assigned to the treatment and control groups, respectively. The DIC score on day 7 was significantly higher in the treatment group (3.3 ± 1.4) than in the control group (4.9 ± 1.8, p < 0.05). Estimated survival showed lower in treatment group than control group. There was significant difference between the control group and the treatment group (p < 0.05). The D-dimer level on day 7 was significantly lower in the treatment group (7.5 ± 4.1 μg/mL) than in the control group (30.9 ± 33.6 μg/mL, p < 0.05). Life-threatening bleeding did not occur. Our results indicated that rhTM improved sepsis-induced DIC and mortality.
Recombinant human soluble thrombomodulin may improve sepsis-induced DIC diagnosed according to the JAAM criteria without an increased bleeding risk.
Disseminated intravascular coagulation; Sepsis; Thrombomodulin; Intensive care unit; Critically ill patient; Anticoagulant; Multiple organ failure; DIC score; JAAM
Previous animal studies by us and others have indicated that catheter-administered plasmin or its des-kringle derivatives may be more appropriate alternatives to plasminogen activators for treating thrombolytic diseases, since it has a very short serum half-life and therefore does not result in hemorrhaging. We have previously produced recombinant miniPlasmin (mPlasmin) that was proven suitable for treating peripheral arterial occlusion in animal models. However, our previous results showed that non-specific cleavage at position K698 of mPlasmin during activation hindered the further development of this promising therapeutic candidate. In order to minimize or eliminate the non-specific cleavage problem, we performed saturation mutagenesis at the K698 position to develop a mutant form of mPlasmin for thrombolytic therapy.
We changed K698 to 16 other amino acids, with preferred E. coli codons. Each of these mutants were expressed in E. coli as inclusion bodies and then refolded, purified, and subsequently characterized by detailed kinetic assays/experiments/studies which identified highly active mutants devoid of non-specific cleavage.
Activation studies indicated that at those conditions in which the wild type enzyme is cut at the non-specific position K698, the active mutants can be activated without being cleaved at this position.
From the above results, we selected two mutants, K698Q and K698N, as our lead candidates for further thrombolytic drug developments. The selected mutants are potentially better therapeutic candidates for thrombolytic therapy.
Plasminogen (-fragments); Thrombolysis/thrombolytic agents; Deep vein thrombosis; Drug design; Drug development
The aim of the present study was to compare circulating levels of selected prothrombotic markers in patients suffering acute myocardial infarction (AMI) with and without left ventricular (LV) thrombus.
One hundred patients with AMI treated with PCI on the LAD and dual antiplatelet therapy were included. LV thrombus formation was detected by echocardiography and/or MRI in 15 patients. Fasting blood samples were drawn 4–5 days (baseline), 6–7 days, 8–9 days, 2–3 weeks and 3 months after the AMI for determination of haemostatic markers.
We found higher levels of soluble tissue factor (TF) and D-dimer in the LV thrombus group 4–5 days, 8–9 days and 3 months (only TF) after the AMI compared to the patients without thrombus formation (p<0.05). Patients with TF in the upper quartile at baseline had significantly higher risk for LV thrombus (OR 4.2; 95% CI 1.2 -14.5; p=0.02, adjusted for infarct size).
The levels of prothrombin fragment 1+2 (F1+2) and endogenous thrombin potential (ETP) were significantly lower in the thrombus group after 8–9 days (only ETP), 2–3 weeks and 3 months. The levels of plasminogen activator inhibitor 1 activity and tissue plasminogen activator antigen did not differ between the groups.
In the acute phase of AMI, we found higher levels of TF and D-dimer in the LV thrombus group, indicating hypercoagulability of possible importance for the generation of mural thrombus. Lower levels of F1+2, ETP and D-dimer in the thrombus group late during follow-up are probably induced by the initiated anticoagulation therapy.
Acute myocardial infarction; Haemostatic markers; Inflammation; Left ventricular thrombus formation
Effective treatment of venous thromboembolism (VTE) strikes a balance between prevention of recurrence and bleeding complications. The current standard of care is heparin followed by a vitamin K antagonist such as warfarin. However, this option is not without its limitations, as the anticoagulant effect of warfarin is associated with high inter- and intra-patient variability and patients must be regularly monitored to ensure that anticoagulation is within the narrow target therapeutic range. Several novel oral anticoagulant agents are in the advanced stages of development for VTE treatment, some of which are given after an initial period of heparin treatment, in line with current practice, while others switch from high to low doses after the initial phase of treatment. In this review we assess the critical considerations for treating VTE in light of emerging clinical data for new oral agents and discuss the merits of novel treatment regimens for patients who have experienced an episode of deep vein thrombosis or pulmonary embolism.
Venous thromboembolism; Anticoagulants; Vitamin K antagonists; Heparin; Recurrence; Bleeding
Low Frequency Vibro-Percussion (LFVP) assists clearance of thrombi in catheter systems and when applied to the heart and timed to diastole is known to enhance coronary flow. However LFVP on a clotted coronary like vessel given engagement over a chest wall sized barrier (to resemble non-invasive heart attack therapy) requires study.
One hour old clots (n=16) were dispensed within a flexible segment of Soft-Flo catheter (4 mm lumen), weighted, interfaced with Heparinized Saline (HS), secured atop a curved dampening base, and photographed. A ~4 cm meat slab was placed over the segment and randomized to receive intermittent LFVP (engaged, - disengaged at 1 second intervals), or no LFVP for 20 minutes. HS was pulsed (~120/80 mmHg), with the diastolic phase coordinated to match LFVP delivery. The segment was then re-photographed and aspirated of fluid to determine post clot weight. The trial was then repeated with 0.5 mls of Streptokinase (15,000 IU/100 microlitre) delivered ~ 2 cm upstream from the clot.
LFVP - HS only samples (vs. controls) showed; a) development of clot length fluid channels absent in the control group (p < 0.0002); b) enhanced dissolved clot mixing scores ( 5.0 vs. 0.8, p < 2.8 E – 6); and c) increased percent clot dissolution (23.0% vs. 1.8% respectively, p < 8.5 E-6). LFVP - SK samples had a similar comparative clot disruptive profile, however fluid channels developed faster and percent clot dissolution more than doubled (51.0% vs. 3.0%, p< 9.8 E- 6).
Diastolic timed LFVP (50 Hz) engaged across a chest wall sized barrier enhances clot disruptive effects to an underlying coronary like system.
Vibration; Thrombolysis; STEMI; Reperfusion; Diastole
Dual antiplatelet treatment with aspirin and clopidogrel is the antithrombotic treatment recommended after an acute coronary syndrome and/or coronary artery stenting. The evidence for optimal antiplatelet therapy for patients, in whom long-term treatment oral anticoagulation is mandatory, is however scarce. To evaluate the safety and efficacy of the various antithrombotic strategies adopted in this population, we reviewed the available evidence on the management of patients receiving oral anticoagulation, such as a vitamin-k-antagonists, referred for coronary artery stenting.
Atrial fibrillation is the most frequent indication for oral anticoagulation. The need of starting antiplatelet therapy in this clinical scenario raises concerns about the combination to choose: triple therapy with warfarin, aspirin, and a thienopyridine being the most frequent and advised. The safety of this regimen appeared suboptimal because of an increased risk in hemorrhagic complications. On the other hand, the combination of oral anticoagulation and an antiplatelet agent is suboptimal in preventing thromboembolic events and stent thrombosis; dual antiplatelet therapy may be considered only when a high hemorrhagic risk and low thromboembolic risk are perceived. Indeed, the need for prolonged multiple-drug antithrombotic therapy increases the bleeding risks when drug eluting stents are used.
Since current evidence derives mainly from small, single-center and retrospective studies, large-scale prospective multicenter studies are urgently needed.
Atrial fibrillation; Percutaneous coronary intervention; Stent; Warfarin; Antiplatelet drugs
Hump-nosed pit viper (Genus Hypnale) is a medically important venomous snake in Sri Lanka and Southwestern India which causes significant morbidity and mortality. Envenoming of this snake results in hemostastic dysfunction, thrombotic microangiopathy, acute kidney injury and death. This case describes an authenticated first case of ischemic stroke in a 65 year old male following envenoming by H.hypnale in Sri Lanka.
Venous thromboembolism (VTE) is a leading cause of hospital-related deaths worldwide. However, the proportion of patients at risk of VTE who receive appropriate prophylaxis in Egypt is unknown. The ENDORSE study in Egypt is part of a global initiative to uncover the incidence of high-risk surgical and medical patients and determine what proportion of these patients receive appropriate VTE prophylaxis.
Ten Egyptian hospitals participated in this observational study, enrolling all surgical and medical patients that met the study criteria. This resulted in a cohort of 1,008 patients in acute care facilities who underwent a retrospective chart review. Each patient’s VTE risk status and the presence or absence of appropriate prophylactic care was assessed according to the American College of Chest Physicians (ACCP) guidelines 2004.
Of the 1,008 patients enrolled, 395 (39.2%) were found to be at high-risk for VTE. Overall, 227 surgical patients were at high-risk, although only 80 (35.2%) received ACCP-recommended prophylaxis. Similarly, 55/268 (32.75%) of high-risk medical patients received appropriate VTE prophylaxis. Low molecular weight heparin was the most commonly used anticoagulant, while mechanical prophylactic use was quite low (1.5%) in high-risk patients.
In Egypt, more than one-third of all patients hospitalized for surgery or acute medical conditions are at high risk for developing VTE. However, only a small fraction of these patients receive appropriate VTE prophylaxis. Corrective measures are necessary for preventing VTE morbidity and mortality in these high risk patients.
Venous thromboembolism; Egypt; Thromboprophylaxis; Risk factors
Postprandial hyperlipidemia and hyperglycemia have been related to cardiovascular events. Among different underlying mechanisms platelet activation seems to be responsible too. No comparable data between various tests in normo- vs. hyperlipidemics before and at different time intervals are available after a fat meal. We aimed to compare 9 of them within the same patients at several time points in postprandial hyperlipidemia.
For some tests baseline values between the groups were significantly different (TXB2, platelet sensitivity, sedimentation and WU-test). However, hyperlipidemia revealed a variable influence on the tests examined. Some of the available tests apparently sensitive to show platelet activation reflect the increase in triglycerides (TG), such as the sedimentation index. ADP-induced platelet aggregatory activity in count adjusted washed isolated platelet samples during postprandial hyperlipidemia indicates mildly enhanced platelet activity, but does not seem to induce significant changes in aggregation. In patients with severe hypertriglyceridemia (> 400 mg/dl fasting) changes in platelet function are more pronounced due to delayed decay and may last up to 16 hours paralleling TG reaching the prevalue. The overwhelming majority of platelet function tests do not significantly respond to postprandial hyperlipidemia. The correlation between the tests applied is poor. For standardization purpose, platelet aggregation tests, aimed to examine proaggregatory capacity in atherosclerosis, should only be performed at the same time of the day after a fasting period > 6 hours. The great variation in preanalytical work-up on comparison of various tests, large number of platelet tests available and their respective potential value are discussed.
At present, the suspicion that platelet function is significantly activated in the postprandial period cannot be supported by any of the tests used. The information provided is valuable to know for which test and group of patients a fasting period of which duration is recommendable.
Postprandial hyperlipidemia; Platelet activity; Platelet aggregation; Platelet count; Atherosclerosis
This is a commentary discussing the article published in Thrombosis Journal by Subramanian et al. [Thrombosis Journal 2012, 10:15].
Computer-assistance and self-monitoring lower the cost and may improve the quality of anticoagulation therapy. The main purpose of this clinical investigation was to use computer-assisted oral anticoagulant therapy to improve the time to reach and the time spent within the therapeutic target range compared to traditional oral anticoagulant therapy by physicians.
54 patients were randomized equally into 3 groups. Patients in two groups used CoaguChek® systems to measure international normalized ratio (INR) values and had dosages of anticoagulation treatment calculated in a computer system by an algorithm specific to each group. The third group received traditional anticoagulation treatment by physicians. The obtained INR values were compared regarding the time to reach, and the time spent within, the therapeutic target range, corresponding to INR values from 2 to 3.
Patients randomized to computer-assisted anticoagulation and the CoaguChek® system reached the therapeutic target range after 8 days compared to 14 days by prescriptions from physicians (p = 0.04). Time spent in the therapeutic target range did not differ between groups. The median INR value measured throughout the study from all patients by CoaguChek® at 2.5 (2.42–2.62) was lower than measured by a hospital-based Clinical and Biochemical Laboratory at 2.6 (2.45–2.76), (p = 0.02).
The therapeutic target range was reached faster by the use of computer-assisted anticoagulation treatment than prescribed by physicians, and the total time spent within the therapeutic target range was similar. Thus computer-assisted oral anticoagulant therapy may reduce the cost of anticoagulation therapy without lowering the quality. INR values measured by CoaguChek® were reliable compared to measurements by a clinical and biochemical laboratory.