Quantifying the benefit-risk trade-off for individual patients in a clinical trial: principles and antithrombotic case study

BACKGROUND

A treatment's overall favorable benefit-risk profile does not imply that every individual patient will benefit from the treatment.

OBJECTIVES

To describe a statistical methodology for quantifying the benefit-risk trade-off in individual patients.

METHODS

The method requires a large randomized controlled trial containing a primary efficacy outcome and a primary safety outcome, for instance, the Thrombin Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events-Thrombolysis in Myocardial Infarction 50 placebo-controlled trial of vorapaxar in 17 779 patients following myocardial infarction. Multivariate regression models predict each individual patient's risk of ischemic events (benefit) and major bleeding events (harm) based on their profile. Hence, each patient's predicted benefit from vorapaxar (reduction in ischemic events) and predicted risk (increase in bleeding events) were estimated. The relative importance of ischemic and bleeding events based on links to all-cause mortality was quantified, although the limitations of such weightings are noted.

RESULTS

Overall results demonstrated both clear benefit and harm from vorapaxar. Substantial interindividual variation in both benefit and risk facilitated distinguishing patients with a favorable benefit-risk trade-off from those who did not. Such findings were applied to recommend vorapaxar in as many as 98.3% of patients in which a favorable mortality-weighted benefit-risk trade-off was present, in 77.2% of patients with ischemic benefit 20% greater than bleeding risk, or in as few as 45.5% of patients if an annual decrease in ischemic risk of ≥0.5% was also required.

CONCLUSION

While overall randomized controlled trials of treatment benefit vs risk are valuable, models determining each individual patient's estimated absolute benefit and risk provide more useful insight regarding patient-specific benefit-risk trade-offs to better enable personalized therapeutic decision-making.

Hemorrhage induced by antithrombotic agents: new insights from a real-world pharmacovigilance study

BACKGROUND

Hemorrhage represents the most common and serious side effect of antithrombotic agents. Many studies have compared the risk of bleeding between different antithrombotic agents, but analysis of time-to-onset for hemorrhage induced by these drugs is yet sparse.

METHODS

We conducted a retrospective study based on the adverse drug reaction reports on antithrombotic agents collected by the Henan Adverse Drug Reaction Monitoring Center. We assessed the reporting odds ratio to determine the disproportionate reporting signals for bleeding and the Weibull shape parameter was used to evaluate the time-to-onset data.

RESULTS

In the signal detection, crude low molecular weight heparin-hemorrhage was found as a positive signal. The hemorrhage for most antithrombotic agents was random failure profiles. In particular, the hazard of hemorrhage decreased over time for warfarin and clopidogrel and increased for alteplase, nadroparin, and dipyridamole.

CONCLUSION

We found that the risk of bleeding in patients taking Crude low molecular weight heparins was significantly higher compared to other antithrombotic agents, but with a small magnificence, which may be attributed to the severely irrational use of this medication under improper management. Statistics in days, results showed that the risk of bleeding decreased over time for warfarin and clopidogrel and increased for alteplase, nadroparin, and dipyridamole.

A Prospective Observational Study on Gastric Endoscopic Submucosal Dissection under Continuous Administration of Antithrombotic Agents

Background: This study aimed to assess the completion rate and postoperative bleeding incidence of endoscopic submucosal dissection (ESD) for gastric tumors under continuous antithrombotic therapy. Methods: A prospective observational study was conducted including 88 patients with 100 gastric lesions who underwent gastric endoscopic submucosal dissection (ESD) and received continuous antithrombotic therapy. Additionally, retrospective data on gastric ESD in 479 patients with 534 lesions who did not receive antithrombotic therapy were collected for comparison. Results: The en bloc resection rates (100% in the continuous antithrombotic therapy group vs. 100% in the non-antithrombotic therapy group) and complete resection rates (97.0% vs. 96.3%, respectively) were high and comparable between the groups. No significant differences were found in the specimen size or procedure time. Perforation rates were low (0% vs. 2.3%, respectively) and were not significantly different between the groups. However, postoperative bleeding occurred significantly more frequently in the continuous antithrombotic therapy group (10.2% vs. 4.2%, respectively) than in the non-antithrombotic therapy group. The subgroup analysis revealed a higher incidence of postoperative bleeding in patients receiving thienopyridine derivatives. Conclusions: Continuous administration of antithrombotic agents, especially thienopyridines, increased the risk of postprocedural hemorrhage following gastric ESD. These findings support the need for careful consideration of pharamcological management before ESD, aligning with the current guidelines.

Randomized Secondary Prevention Trials in Participants With Symptomatic Intracranial Atherosclerotic Stenosis

Intracranial atherosclerotic stenosis is a prevalent cause of ischemic stroke worldwide. Its association with silent cerebral infarcts and its contribution to cognitive impairment and dementia emphasize the critical need for disease prevention and effective management strategies. Despite extensive research on secondary stroke prevention treatment over the past several decades, intracranial atherosclerotic stenosis continues to exhibit a notably higher recurrent stroke rate compared with other causes. This review focuses on randomized secondary prevention trials involving antithrombotic therapy, endovascular treatment, open surgical therapy, and remote ischemic conditioning. It aims to provide an insightful overview of the major findings from each trial and their implications for future research efforts.

Bleeding events in thrombotic antiphospholipid syndrome: prevalence, severity, and associated damage accrual

Background

Life-long anticoagulation increases bleeding risk in patients with antiphospholipid syndrome (APS). The Damage Index for Antiphospholipid Syndrome does not include bleeding events in damage accrual.

Objectives

We aimed to characterize the prevalence, severity, and damage associated with bleeding events in patients with APS.

Methods

This was a single-center retrospective analysis of patients with thrombotic APS (2006 Sydney criteria). Bleeding events were reviewed up to 43 years and classified according to the ISTH definitions into 2 groups: 1) major bleedings and 2) nonmajor bleedings (minor bleedings and clinically relevant nonmajor bleedings). Damage events were recorded as bleeding events a) resulting in permanent (>6 months) decrease in organ function and b) complicated by total/partial organ resection.

Results

Among 197 patients (2412 patient-years [PYs] of follow-up), all of whom had been exposed to antithrombotic therapy, 40.6% experienced 167 bleedings (6.9 events per 100 PYs), of whom 61.3% had nonmajor bleedings (77.2% of bleedings: 42.6% minor, 57.4% clinically relevant nonmajor) and 38.8% had major bleedings (22.8% of bleedings; 1.6 events per 100 PYs). Soft/connective tissue was affected in 44.3% of bleedings, and 94.6% were nonmajor bleedings. Central nervous system was affected in 20.9% of bleedings, and 62.9% were major bleedings. Bleeding events were spontaneous in 90.4% of cases, and thrombocytopenia was likely involved in 62.2% of bleedings. Damage occurred in 11.4% of bleedings and affected 7.6% of patients. Most of the damage was associated with central nervous system events (8.4% of all bleedings).

Conclusion

Approximately 40% of patients experienced at least 1 bleeding, and almost 8% of patients were left with organ damage not recognized by the current version of the Damage Index for Antiphospholipid Syndrome.

Management of Coronary Artery Disease in Older Adults: Recent Advances and Gaps in Evidence

Coronary artery disease (CAD) is highly prevalent in older adults, yet its management remains challenging. Treatment choices are made complex by the frailty burden of older patients, a high prevalence of comorbidities and body composition abnormalities (e.g., sarcopenia), the complexity of coronary anatomy, and the frequent presence of multivessel disease, as well as the coexistence of major ischemic and bleeding risk factors. Recent randomized clinical trials and epidemiological studies have provided new data on optimal management of complex patients with CAD. However, frail older adults are still underrepresented in the literature. This narrative review aims to highlight the importance of assessing frailty as an aid to guide therapeutic decision-making and tailor CAD management to the specific needs of older adults, taking into account age-related pharmacokinetic and pharmacodynamic changes, polypharmacy, and potential drug interactions. We also discuss gaps in the evidence and offer perspectives on how best in the future to optimize the global strategy of CAD management in older adults.

An update on novel therapies for treating patients with arterial thrombosis

INTRODUCTION

Antithrombotic therapy field is undergoing rapid and significant changes during the past decade. In addition to new therapeutic strategies with existing targets, investigators are exploring the potential use of new targets to address unmet needs to treat patients with arterial diseases.

AREAS COVERED

We aim to provide an update on and a comprehensive review of the antithrombic agents that are being explored in patients with arterial diseases. We discuss latest developments with respect to upstream antiplatelet agents, and collagen and thrombin pathway inhibitors. We searched PubMed databases for English language articles using keywords: antiplatelet agents, thrombin pathway inhibitors, collagen receptors, arterial disease.

EXPERT OPINION

Despite implementation of potent P2Y12 inhibitors, there are numerous unmet needs in the treatment of arterial diseases including ceiling effect of currently available antiplatelet agents along with and an elevated risk of bleeding. The latter observations encouraged investigators to explore new targets that can attenuate the generation of platelet-fibrin clot formation and subsequent ischemic event occurrences with minimal effect on bleeding. These targets include collagen receptors on platelets and thrombin generation including FXa, FXIa, and FXIIa. In addition, investigators are studying novel antiplatelet agents/strategies to facilitate upstream therapy in high-risk patients.

A multicenter prospective study of the treatment and outcome of patients with gastroduodenal peptic ulcer bleeding in Japan

Gastroduodenal peptic ulcers are the main cause of nonvariceal upper gastrointestinal bleeding (UGIB). We believe that recent advances in endoscopic techniques and devices for diagnosing upper gastrointestinal tract tumors have advanced hemostasis for UGIB. However, few prospective multicenter studies have examined how these changes affect the prognosis. This prospective study included 246 patients with gastroduodenal peptic ulcers treated at 14 participating facilities. The primary endpoint was in-hospital mortality within 4 weeks, and the secondary endpoints required intervention and refractory bleeding. Subsequently, risk factors affecting these outcomes were examined using various clinical items. Furthermore, the usefulness of the risk stratification using the Glasgow-Blatchford score, rockall score and AIMS65 based on data from the day of the first urgent endoscopy were examined in 205 cases in which all items were complete there are two periods. Thirteen (5%) patients died within 4 weeks; and only 2 died from bleeding. Significant risk factors for poor outcomes were older age and severe comorbidities. Hemostasis was required in 177 (72%) cases, with 20 cases of refractory bleeding (2 due to unsuccessful endoscopic treatment and 18 due to rebleeding). Soft coagulation was the first choice for endoscopic hemostasis in 57% of the cases and was selected in more than 70% of the cases where combined use was required. Rockall score and AIMS65 predicted mortality equally, and Glasgow-Blatchford score was the most useful in predicting the requirement for intervention. All scores predicted refractory bleeding similarly. Although endoscopic hemostasis for UGIB due to peptic ulcer had a favorable outcome, old age and severe comorbidities were risk factors for poor prognosis. We recommend that patients with UGIB should undergo early risk stratification using a risk scoring system.

Antithrombotics increase bleeding after endoscopic submucosal dissection for gastric cancer: Nationwide propensity score analysis

OBJECTIVES

Post-operative bleeding is the most common adverse event in endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). Patients taking antithrombotic agents has increased. We evaluated the influence of antithrombotic agents on delayed bleeding in ESD for EGC.

METHODS

This was a post hoc analysis of nationwide, multicenter, retrospective cohort study in Japan. Altogether, 11,452 patients who underwent ESD for EGC in 33 institutions between November 2013 and October 2016 were enrolled. The primary outcome was the incidence of delayed bleeding in patients with or without antithrombotic agents. The secondary outcome was the incidence of delayed bleeding in those who took each antithrombotic agent and the cessation status of its use compared with each matched pair of patients. We used propensity matching and inverse probability of treatment weighting (IPTW) analyses.

RESULTS

There were 1353 matched pairs of patients. The incidence of delayed bleeding was 2.8% and 10.7% in those without and with antithrombotic agents, respectively (odds ratio [OR] 4.15, 95% confidence interval [CI] 2.88-5.99; P < 0.001). The IPTW analysis showed similar results (OR 4.21, 95% CI 3.48-5.08; P < 0.001). Antiplatelets, anticoagulants, and their combination increased such incidence. Heparin bridging therapy had high OR (8.80), and the continuation (OR 3.46) and cessation (OR 2.95) of antithrombotic agent use had similar risk.

CONCLUSIONS

Antithrombotic agents increased the incidence of delayed bleeding in patients who underwent ESD for EGC. Continuing antithrombotics may be more appropriate than heparin bridging therapy.

Antiplatelet Agents Affecting GPCR Signaling Implicated in Tumor Metastasis

Metastasis requires that cancer cells survive in the circulation, colonize distant organs, and grow. Despite platelets being central contributors to hemostasis, leukocyte trafficking during inflammation, and vessel stability maintenance, there is significant evidence to support their essential role in supporting metastasis through different mechanisms. In addition to their direct interaction with cancer cells, thus forming heteroaggregates such as leukocytes, platelets release molecules that are necessary to promote a disseminating phenotype in cancer cells via the induction of an epithelial-mesenchymal-like transition. Therefore, agents that affect platelet activation can potentially restrain these prometastatic mechanisms. Although the primary adhesion of platelets to cancer cells is mainly independent of G protein-mediated signaling, soluble mediators released from platelets, such as ADP, thromboxane (TX) A2, and prostaglandin (PG) E2, act through G protein-coupled receptors (GPCRs) to cause the activation of more additional platelets and drive metastatic signaling pathways in cancer cells. In this review, we examine the contribution of the GPCRs of platelets and cancer cells in the development of cancer metastasis. Finally, the possible use of agents affecting GPCR signaling pathways as antimetastatic agents is discussed.

Risk factors for short-term re-bleeding in patients with colonic diverticular bleeding: a multicenter retrospective study

BACKGROUND AND AIM

Few studies have evaluated risk factors for short-term re-bleeding in patients with colonic diverticular bleeding (CDB). We aimed to reveal risk factors for re-bleeding within a month in patients with CDB.

METHODS

We retrospectively analyzed clinical course of patients with CDB diagnosed at 10 institutions between 2015 and 2019. Risk factors for re-bleeding within a month were assessed by Cox proportional hazards models.

RESULTS

Among 370 patients, 173 (47%) patients had been under the use of antithrombotic agents (ATs) and 34 (9%) experienced re-bleeding within a month. Multivariate analysis revealed that the use of ATs was an independent risk factor for re-bleeding within a month (HR 2.38, 95% CI 1.10-5.50, p = .028). Furthermore, use of multiple ATs and continuation of ATs were found to be independent risk factors for re-bleeding within a month (HR 3.88, 95% CI 1.49-10.00, p = .007 and HR 3.30, 95% CI 1.23-8.63, p = .019, respectively). Two of 370 patients, who discontinued ATs, developed thromboembolic event.

CONCLUSIONS

Use of ATs was an independent risk factor for short-term re-bleeding within a month in patients with CDB. This was especially the case for the use of multiple ATs and continuation of ATs. However, discontinuation of ATs may increase the thromboembolic events those patients.

Endoscopic hand suturing for mucosal defect closure after gastric endoscopic submucosal dissection may reduce the risk of postoperative bleeding in patients receiving antithrombotic therapy

OBJECTIVES

Endoscopic hand suturing (EHS) is expected to decrease the risk of post-endoscopic submucosal dissection (ESD) bleeding by closing mucosal defects. We investigated the efficacy of EHS after gastric ESD in patients with antithrombotic agents.

METHODS

In this prospective single-arm trial, patients taking antithrombotic agents for cardiovascular disease, arrhythmia, cerebrovascular disease and/or peripheral arterial disease and having <3-cm gastric neoplasms were recruited. The mucosal defects after ESD were closed by EHS in which the needle was delivered through an overtube, and the mucosal rim of the defect was continuously sutured in a linear fashion by manipulating the needle grasped with the needle holder, followed by cutting the remnant suture and retrieval of the needle. The primary endpoint was the incidence of postoperative bleeding within 4 weeks after ESD.

RESULTS

Twenty-two lesions in 20 patients (continuing antiplatelet agents in 11, anticoagulant agents in eight, both in one) underwent ESD followed by EHS. All defects (median size, 30 mm; range, 12-51 mm) were completely closed by EHS and remained closed on postoperative day 3. The median number of stitches was six (range, 4-8) and median suturing time was 36 (range, 24-60) min. There were no adverse events during/after EHS or postoperative bleeding.

CONCLUSIONS

Postoperative bleeding was not observed in patients taking antithrombotic agents without perioperative cessation. EHS appears to be useful for prevention of post-gastric ESD bleeding in high-risk patients. (Clinical registration number: UMIN000024184).

First-in-Class Isonipecotamide-Based Thrombin and Cholinesterase Dual Inhibitors with Potential for Alzheimer Disease

Recently, the direct thrombin (thr) inhibitor dabigatran has proven to be beneficial in animal models of Alzheimer’s disease (AD). Aiming at discovering novel multimodal agents addressing thr and AD-related targets, a selection of previously and newly synthesized potent thr and factor Xa (fXa) inhibitors were virtually screened by the Multi-fingerprint Similarity Searching aLgorithm (MuSSeL) web server. The N-phenyl-1-(pyridin-4-yl)piperidine-4-carboxamide derivative 1, which has already been experimentally shown to inhibit thr with a K_i value of 6 nM, has been flagged by a new, upcoming release of MuSSeL as a binder of cholinesterase (ChE) isoforms (acetyl- and butyrylcholinesterase, AChE and BChE), as well as thr, fXa, and other enzymes and receptors. Interestingly, the inhibition potency of 1 was predicted by the MuSSeL platform to fall within the low-to-submicromolar range and this was confirmed by experimental K_i values, which were found equal to 0.058 and 6.95 μM for eeAChE and eqBChE, respectively. Thirty analogs of 1 were then assayed as inhibitors of thr, fXa, AChE, and BChE to increase our knowledge of their structure-activity relationships, while the molecular determinants responsible for the multiple activities towards the target enzymes were rationally investigated by molecular cross-docking screening.

Synthesis and Bioactivities of Marine Pyran-Isoindolone Derivatives as Potential Antithrombotic Agents

2,5-Bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-teraahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid (FGFC1) is a marine pyran-isoindolone derivative isolated from a rare marine microorganism Stachybotrys longispora FG216, which showed moderate antithrombotic(fibrinolytic) activity. To further enhance its antithrombotic effect, a series of new FGFC1 derivatives (F1-F7) were synthesized via chemical modification at C-2 and C-2' phenol groups moieties and C-1″ carboxyl group. Their fibrinolytic activities in vitro were evaluated. Among the derivatives, F1-F4 and F6 showed significant fibrinolytic activities with EC50 of 59.7, 87.1, 66.6, 82.8, and 42.3 μM, respectively, via enhancement of urokinase activity. Notably, derivative F6 presented the most remarkable fibrinolytic activity (2.72-fold than that of FGFC1). Furthermore, the cytotoxicity of derivative F6 was tested as well as expression of Fas/Apo-1 and IL-1 on HeLa cells. The results showed that, compared to FGFC1, derivative F6 possessed moderate cytotoxicity and apoptotic effect on HeLa cells (statistical significance p > 0.1), making F6 a potential antithrombotic agent towards clinical application.

Spontaneous Reports of Serious Adverse Drug Reactions Resulting From Drug-Drug Interactions: An Analysis From the French Pharmacovigilance Database

Few data are available on the clinical impact of drug-drug interactions (DDIs). Most of the studies are limited to the analysis of exposure to potential DDI or the targeted impact of the combination of a few drugs or therapeutic classes. The analysis of adverse drug reaction (ADR) reports could be a mean to study generally the adverse effects identified due to a DDI. Our objective was to describe the characteristics of ADRs resulting from DDIs reported to the French Pharmacovigilance system and to identify the drugs most often implicated in these ADRs. Considering all ADR reports from January 01, 2012, to December 31, 2016, we identified all cases of ADR resulting from a DDI (DDI-ADRs). We then described these in terms of patients' characteristics, ADR seriousness, drugs involved (two or more per case), and ADR type. Of the 4,027 reports relating to DDI-ADRs, 3,303 were related to serious ADRs. Patients with serious DDI-ADRs had a median age of 76 years (interquartile range: 63-84); 53% were male. Of all serious DDI-ADRs, 11% were life-threatening and 8% fatal. In 36% of cases, the DDI causing the ADR involved at least three drugs. Overall, 8,424 different drugs were mentioned in the 3,303 serious DDI-ADRs considered. Altogether, drugs from the "antithrombotic agents" subgroup were incriminated in 34% of serious DDI-ADRs. Antidepressants were the second most represented therapeutic/pharmacological subgroup (5% of serious DDI-ADRs). Among the 3,843 ADR types reported in the 3,303 serious DDI-ADRs considered, the most frequently represented were hemorrhage (40% clinical hemorrhage; 6% biological hemorrhage), renal failure (8%), pharmacokinetic alteration (5%), and cardiac arrhythmias (4%). Hemorrhagic accidents are still an important part of serious ADRs resulting from DDIs reported in France. The other clinical consequences of DDIs seem less well identified by pharmacovigilance. Moreover, more than one-third of serious DDI-ADRs involved at least three drugs.

Effect of Instruction on Preventing Delayed Bleeding after Colorectal Polypectomy and Endoscopic Mucosal Resection

Background: The frequency of delayed bleeding after colorectal polypectomy has been reported as 0.6–2.8%. With the increasing performance of polypectomy under continuous use of antithrombotic agents, care is required regarding delayed post-polypectomy bleeding (DPPB). Better instruction to educate endoscopists is therefore needed. We aimed to evaluate the effect of instruction and factors associated with delayed bleeding after endoscopic colorectal polyp resection. Methods: This single-center, retrospective study was performed to assess instruction in checking complete hemostasis and risk factors for onset of DPPB. The incidence of delayed bleeding, comorbidities, and medications were evaluated from medical records. Characteristics of historical control patients and patients after instruction were compared. Results: A total of 3318 polyps in 1002 patients were evaluated. The control group comprised 1479 polyps in 458 patients and the after-instruction group comprised 1839 polyps in 544 patients. DPPB occurred in 1.1% of polyps in control, and 0.4% in after-instruction. Instruction significantly decreased delayed bleeding, particularly in cases with antithrombotic agents. Hot polypectomy, clip placement, and use of antithrombotic agents were significant independent risk factors for DPPB even after instruction. Conclusion: The rate of delayed bleeding significantly decreased after instruction to check for complete hemostasis. Even after instruction, delayed bleeding can still occur in cases with antithrombotic agents or hot polypectomy.

Postinterventional antithrombotic management after venous stenting of the iliofemoral tract in acute and chronic thrombosis: A systematic review

Venous stenting has become a common treatment option for central deep venous outflow obstructions and postthrombotic syndrome. Following successful recanalization and stenting, stent patency is endangered by in-stent thrombosis and recurrent venous thromboembolism. Antithrombotic therapy might reduce patency loss. This systematic review summarizes the literature on antithrombotic therapy following (post)thrombotic venous stenting. A systematic PubMed, MEDLINE, EMBASE, and Cochrane search was performed for studies addressing antithrombotic therapy prescribed following venous stenting of the iliofemoral tract indicated by acute or chronic thrombotic pathology. A total of 277 articles was identified of which 64 (56 original studies) were selected. Overall, a mean primary patency rate of 82.3% was seen 1 year after the intervention, which decreased to 73.3% after 2 years. In the majority (43 of 56 studies, 77%), treatment was based on use of vitamin K antagonists, either with (18%) or without (59%) use of antiplatelet drugs. Only two studies (4%) directly assessed the effect of antithrombotic therapy on treatment outcomes. The impact of postinterventional antithrombotic therapy on stent patency remains unknown because of limited and insufficient data available in current literature. Further clinical research should more clearly address the role of antithrombotic therapy for preservation of long-term patency following venous stenting.

The Development of New Low-Molecular-Weight Factor Xa Inhibitors That Are Potential Anticoagulants

BACKGROUND

Despite the introduction of direct oral anticoagulants, the search for new oral anticoagulants remains an urgent task.

OBJECTIVE

Using the docking and scoring, based on physical methods, simple chemical rules, methods of synthesis and activity measurement, to develop new low-molecular-weight inhibitors of factor Xa, which are potential anticoagulants.

METHOD

The development of leads was based on chemical synthesis and the structure-based drug design methods. The basic idea is to combine the two approaches: one based on predictive modeling, and the other - on the experimental data.

RESULTS

In frame of our concept we developed some nanomolar leads. Further chemical modification improved the inhibition constant by more than one order.

DISCUSSION

The method proposed in this paper, as well as other methods, includes virtual screening, screening, chemical synthesis and activity measurement. However, the most time - consuming process in this method (chemical synthesis) was decided to simplify and reduce the cost to the extent that it could be allowed: a very simple chemical reaction was chosen - the formation of an amide bond.

CONCLUSION

In this work, we demonstrated how, using simple chemical rules, based on the structure-based drug design, substances with a nanomolar concentration of activity can be developed. Using our method, we developed substances with nanomolar concentration of activity. Further chemical modification of this leads improved the inhibition constant by more than one order.

A rare case report of renal vein pseudoaneurysm after blunt trauma

RATIONALE

Renal vein pseudoaneurysm after blunt trauma is an extremely rare clinical disease. Different interventions, such as conservative, surgical, and endovascular treatments, can be considered. However, previous studies have not described the optimal treatment strategies for this condition. Furthermore, there is a significant lack of prior case reports and of standardized treatment guidelines for trauma-induced renal vein pseudoaneurysm patients who previously maintained antithrombotic agent.

PATIENT CONCERNS

A 23-year-old female patient visited the emergency department after sustaining blunt injury caused by falling. The patient was diagnosed with multiple limb and rib fractures. A right renal vein pseudoaneurysm was found on abdominal computed tomography scan. Initially, there was no other organ damage, and the patient was hemodynamically stable. Thus, nonsurgical, conservative management was considered. However, the patient's hematocrit and hemoglobin levels decreased, and there was no hemodynamic improvement. The patient required lifelong treatment with aspirin because she previously underwent Fontan surgery, and orthopedic surgery for multiple fractures was planned. Thus, considering these factors, the treatment method was changed from conservative management to endovascular stent insertion.

DIAGNOSES

Abdominal computed tomography and renal venography revealed a right renal vein pseudoaneurysm.

INTERVENTIONS

On the basis of the abdominal computed tomography scan and renal venography findings, the endovascular stent graft was inserted across the pseudoaneurysm area.

OUTCOMES

Upon placement of the endovascular stent, hemoglobin and hematocrit levels gradually returned to normal. The patient's vital signs and general condition had improved. The patient recovered without any complications and was discharged 29 days after hospitalization.

LESSONS

Some patients with traumatic renal vein pseudoaneurysm do not experience hemodynamic improvement despite conservative treatment. Hence, endovascular procedure may be considered for these patients, particularly those who require antithrombotic treatment for a previous disease.

Antithrombotic Preventive Medication Prescription Redemption and Socioeconomic Status in Hungary in 2016: A Cross-Sectional Study

This work was designed to investigate antithrombotic drug utilization and its link with the socioeconomic characteristics of specific population groups in Hungary by a comparative analysis of data for prescriptions by general practitioners and the redeemed prescriptions for antithrombotic drugs. Risk analysis capabilities were applied to estimate the relationships between socioeconomic status, which was characterized by quintiles of a multidimensional composite indicator (deprivation index), and mortality due to thromboembolic diseases as well as antithrombotic medications for the year 2016 at the district level in Hungary. According to our findings, although deprivation is a significant determinant of mortality due to thromboembolic diseases, clusters can be identified that represent exemptions to this rule: an eastern part of Hungary, consisting of two highly deprived counties, had significantly lower mortality than the country average; by contrast, the least-deprived northwestern part of the country, consisting of five counties, had significantly higher mortality than the country average. The fact that low socioeconomic status in general and poor adherence to antithrombotic drugs irrespective of socioeconomic status were associated with increased mortality indicates the importance of more efficient control of preventive medication and access to healthcare in all districts of the country to reduce mortality due to thromboembolic diseases.

Adverse Drug Reactions in Patients with CKD

BACKGROUND AND OBJECTIVES

Little is known about the burden of adverse drug reactions in CKD. We estimated the incidence of overall and serious adverse drug reactions and assessed the probability of causation, preventability, and factors associated with adverse drug reactions in patients seen by nephrologists.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Chronic Kidney Disease-Renal Epidemiology and Information Network cohort included 3033 outpatients (65% men) with CKD and eGFR<60 ml/min per 1.73 m², with follow-up for 2 years. Adverse drug reactions were identified from hospitalization reports, medical records, and participant interviews and finally assessed for causality, preventability, and immediate therapeutic management by experts in pharmacology.

RESULTS

Median (interquartile range) age was 69 (60-76) years old; 55% had eGFR≥30 ml/min per 1.73 m², and 45% had eGFR<30 ml/min per 1.73 m². Participants were prescribed a median (range) of eight (five to ten) drugs. Over 2 years, 536 patients had 751 adverse drug reactions, 150 (in 125 participants) classified as serious, for rates of 14.4 (95% confidence interval, 12.6 to 16.5) and 2.7 (95% confidence interval, 1.7 to 4.3) per 100 person-years, respectively. Among the serious adverse drug reactions, 32% were considered preventable or potentially preventable; 16 caused death, directly or indirectly. Renin-angiotensin system inhibitors (15%), antithrombotic agents (14%), and diuretics (10%) were the drugs to which the most adverse drug reactions were imputed, but antithrombotic agents caused 34% of serious adverse drug reactions. The drug was discontinued in 71% of cases, at least temporarily. Adjusted hazard ratios for serious adverse drug reaction were significantly higher in patients with eGFR<30 versus ≥30 ml/min per 1.73 m² (1.8; 95% confidence interval, 1.3 to 2.6), in those prescribed more than ten versus less than five medications (2.4; 95% confidence interval, 1.1 to 5.2), or in those with poor versus good adherence (1.6; 95% confidence interval, 1.4 to 2.4).

CONCLUSIONS

Adverse drug reactions are common and sometimes serious in patients with CKD. Many serious adverse drug reactions may be preventable. Some specific pharmacologic classes, particularly antithrombotic agents, are at risk of serious adverse drug reactions.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN), NCT03381950.

Associations of Antithrombotic Timing and Regimen with Ischemic Stroke and Bleeding Complications in Blunt Cerebrovascular Injury

BACKGROUND

Blunt cerebrovascular injuries (BCVIs) are associated with long-term neurological effects. The first-line treatment for BCVIs is antithrombotics, but consensus on the optimal choice and timing of treatment is lacking.

METHODS

This was a retrospective study on patients aged at least 18 years admitted to 6 level 1 trauma centers between 1/1/2014 and 12/31/2017 with grade 1-4 BCVI and treated with antithrombotics. Differences in treatment practices were examined across the 6 centers. The primary outcome was ischemic stroke, and secondary outcomes were related to bleeding complications: blood transfusion and intracranial hemorrhage (ICH). Treatment characteristics examined were time to diagnosis and first computerized tomography angiography, time of total treatment course, time on each antithrombotic (anticoagulants, antiplatelets, combination), time from hospital arrival to antithrombotic initiation, and treatment interruption, i.e., treatment halted for a surgical procedure and restarted postoperatively. Chi-square, Fisher exact, Spearman's rank-order correlation, Wilcoxon rank-sum, Kruskal-Wallis, and Cox proportional hazards models with time-varying covariates were used to evaluate associations with the outcomes.

RESULTS

A total of 189 patients with BCVI were included. The median (IQR) time from arrival to antithrombotic initiation was 27 (8-61) hours, and 28% of patients had treatment interrupted. The ischemic stroke rate was 7.5% (n = 14), with most strokes (64%, n = 9) occurring between arrival and treatment initiation. Treatment interruption was associated with ischemic stroke (75% of patients with stroke had an interruption versus 24% of patients with no stroke; P < .01). Time on anticoagulants was not associated with ischemic stroke (P = .78), transfusion (P = .43), or ICH (P = .96). Similarly, time on antiplatelets (P = .54, P = .65, P = .60) and time on combination therapy (P = .96, P = .38, P = .57) were not associated with these outcomes.

CONCLUSIONS

The timing and consistency of antithrombotic administration are critical in preventing adverse outcomes in patients with BCVI. Most ischemic strokes in this study population occurred between arrival and antithrombotic initiation, representing events that may potentially be intervened upon by earlier treatment. Future studies should examine the safety of continuing treatment through surgical procedures.

Antithrombotics in intracerebral hemorrhage in the era of novel agents and antidotes: A review

BACKGROUND

Intracerebral hemorrhage (ICH)1 is characterized by the pathological accumulation of blood within the brain parenchyma, most commonly associated with hypertension, arteriovenous malformations, or trauma. However, it can also present in patients receiving antithrombotic drugs, either anticoagulants such as acenocoumarol/warfarin-novel oral anticoagulants or antiplatelets, for the prevention and treatment of thromboembolic disease.

OBJECTIVE

The purpose of this review is to present current bibliographic data regarding ICH irrespective of the cause, as well as post-hemorrhage use of antithrombotic agents. Moreover, this review attempts to provide guidelines concerning the termination, inversion, and of course resumption of antithrombotic therapy.

METHODS AND MATERIALS

We reviewed the most recently presented available data for patients who dealt with intracerebral hemorrhagic events while on antithrombotic agents (due to atrial fibrillation, prosthetic mechanical valves or recent/recurrent deep vein thrombosis). Furthermore, we examined and compared the thromboembolic risk, the bleeding risk, as well as the re-bleeding risk in two groups: patients receiving antithrombotic therapy versus patients not on antithrombotic therapy.

CONCLUSION

Antithrombotic therapy is of great importance when indicated, though it does not come without crucial side-effects, such as ICH. Optimal timing of withdrawal, reversal, and resumption of antithrombotic treatment should be determined by a multidisciplinary team consisting of a stroke specialist, a cardiologist, and a neurosurgeon, who will individually approach the needs and risks of each patient.

Endoscopic submucosal dissection for superficial esophageal neoplasms in elderly patients: A single-center, large-scale, retrospective study

AIM

The number of elderly patients with superficial esophageal neoplasms has steadily increased, but few studies have focused on the clinical outcomes of esophageal endoscopic submucosal dissection in these patients. Therefore, the aim of our study was to investigate the feasibility and safety of endoscopic submucosal dissection among elderly patients with superficial esophageal neoplasms.

METHODS

Patients who underwent endoscopic submucosal dissection for superficial esophageal neoplasms between December 2005 and December 2017 were eligible. The patients were divided into two groups according to age: Not-old (<75 years, n = 369) and Old (≥75 years, n = 44). Clinical features and treatment outcomes were retrospectively investigated by reviewing medical records.

RESULTS

In total, 413 patients with 459 lesions were enrolled in to this study. Comorbidities, except for a previous history of malignancy, were not significantly different between the two groups. Procedure-related characteristics and the rate of adverse events were similar in the two groups. During a median follow-up period of 33.4 months, the overall survival rate was lower in the Old group (P = 0.046), and the cumulative recurrence rate did not differ significantly between the two groups (P = 0.334).

CONCLUSION

Based on these favorable outcomes, endoscopic submucosal dissection is as feasible and effective for the treatment of superficial esophageal neoplasms among elderly patients as it is among non-elderly patients. Geriatr Gerontol Int 2020; 20: 430-435.

Antiphospholipid antibodies in patients with dysglycaemia: A neglected cardiovascular risk factor?

BACKGROUND

Cardiovascular disease is a serious complication in patients with dysglycaemia, defined as either type 2 diabetes or impaired glucose tolerance. Research focusing on the identification of potential markers for atherothrombotic disease in these subjects is warranted. The antiphospholipid syndrome is a common acquired prothrombotic condition, defined by a combination of thrombotic events and/or obstetric morbidity and positivity of specific antiphospholipid antibodies. Available information on antiphospholipid antibodies in dysglycaemia is scarce.

OBJECTIVE

This study investigates the association between antiphospholipid antibodies and dysglycaemia.

PATIENTS/METHODS

The PAROKRANK (periodontitis and its relation to coronary artery disease) study included 805 patients, investigated 6-10 weeks after a first myocardial infarction, and 805 matched controls. Participants without known diabetes (91%) underwent an oral glucose tolerance test. Associations between antiphospholipid antibodies (anti-cardiolipin and anti-β2 glycoprotein-I IgG, IgM and IgA) and dysglycaemia were analysed.

RESULTS

In total, 137 (9%) subjects had previously known type 2 diabetes and 371 (23%) newly diagnosed dysglycaemia. Compared with the normoglycaemic participants, those with dysglycaemia had a higher proportion with first myocardial infarction (61% vs 45%, p < 0.0001) and were more often antiphospholipid antibody IgG positive (8% vs 5%; p = 0.013). HbA1c, fasting glucose and 2-h glucose were significantly associated to antiphospholipid antibody IgG. Odds ratios (ORs) were 1.04 (95% confidence interval [CI] 1.02-1.06), 1.14 (95% CI 1.00 - 1.27) and 1.12 (95% CI 1.04 - 1.21), respectively, after adjustments for age, gender and smoking.

CONCLUSIONS

This study reports an association between antiphospholipid antibody IgG positivity and dysglycaemia. Further studies are needed to verify these findings and to investigate if antithrombotic therapy reduces vascular complications in antiphospholipid antibody positive subjects with dysglycaemia.

Myricetin, the Main Flavonoid in Syzygium cumini Leaf, Is a Novel Inhibitor of Platelet Thiol Isomerases PDI and ERp5

BACKGROUND

Flavonoids have been characterized as a prominent class of compounds to treat thrombotic diseases through the inhibition of thiol isomerases. Syzygium cumini is a flavonoid-rich medicinal plant that contains myricetin and gallic acid. Little is known about the potential antiplatelet properties of S. cumini and its constituent flavonoids.

OBJECTIVE

To evaluate the antiplatelet effects and mechanism of action of a polyphenol-rich extract (PESc) from S. cumini leaf and its most prevalent polyphenols, myricetin and gallic acid.

METHODS

PESc, myricetin, and gallic acid were incubated with platelet-rich plasma and washed platelets to assess platelet aggregation and activation. In vitro platelet adhesion and thrombus formation as well as in vivo bleeding time were performed. Finally, myricetin was incubated with recombinant thiol isomerases to assess its potential to bind and inhibit these, while molecular docking studies predicted possible binding sites.

RESULTS

PESc decreased platelet activation and aggregation induced by different agonists. Myricetin exerted potent antiplatelet effects, whereas gallic acid did not. Myricetin reduced the ability of platelets to spread on collagen, form thrombi in vitro without affecting hemostasis in vivo. Fluorescence quenching studies suggested myricetin binds to different thiol isomerases with similar affinity, despite inhibiting only protein disulfide isomerase (PDI) and ERp5 reductase activities. Finally, molecular docking studies suggested myricetin formed non-covalent bonds with PDI and ERp5.

CONCLUSIONS

PESc and its most abundant flavonoid myricetin strongly inhibit platelet function. Additionally, myricetin is a novel inhibitor of ERp5 and PDI, unveiling a new therapeutic perspective for the treatment of thrombotic disorders.

Incidence of Delayed Bleeding among Patients Continuing Antithrombotics during Gastric Endoscopic Submucosal Dissection

objective In patients continuing antithrombotics, delayed bleeding after gastric endoscopic submucosal dissection (ESD) is a severe complication. Vonoprazan (VPZ) exerts a rapid, potent, and long-lasting antacid effect compared with traditional proton-pump inhibitors (PPIs). This study aimed to compare the incidence of delayed bleeding after gastric ESD between the use of VPZ and PPIs in patients continuing antithrombotics. Methods In this retrospective analysis, we examined 71 patients with 101 lesions treated with traditional PPIs (PPI group) and 59 patients with 90 lesions treated with VPZ (VPZ group). After 2 days (day 0 and 1) of intravenous PPI administration, either an oral PPI or VPZ was administered from postoperative day 2 to 8 weeks after ESD. We assessed the incidence of overall delayed bleeding as well as bleeding that occurred from day 2 until 8 weeks after ESD. Results There was no significant difference in the use of antithrombotic agents between the groups. Overall delayed bleeding occurred 13 times (18%) in 9 patients in the PPI group and 18 times (31%) in 17 patients in the VPZ group (p=0.10). Bleeding from day 2 until 8 weeks after ESD occurred 12 times (17%) in 9 patients in the PPI group and 8 times (14%) in 8 patients in the VPZ group. Conclusion Even with a potent antacid agent, such as VPZ, the incidence of delayed bleeding was high in patients undergoing ESD with continuous antithrombotic agents.

Nattokinase: A Promising Alternative in Prevention and Treatment of Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of death in the world and our approach to the control and management of CVD mortality is limited. Nattokinase (NK), the most active ingredient of natto, possesses a variety of favourable cardiovascular effects and the consumption of Natto has been linked to a reduction in CVD mortality. Recent research has demonstrated that NK has potent fibrinolytic activity, antihypertensive, anti-atherosclerotic, and lipid-lowering, antiplatelet, and neuroprotective effects. This review covers the major pharmacologic effects of NK with a focus on its clinical relevance to CVD. It outlines the advantages of NK and the outstanding issues pertaining to NK pharmacokinetics. Available evidence suggests that NK is a unique natural compound that possesses several key cardiovascular beneficial effects for patients with CVD and is therefore an ideal drug candidate for the prevention and treatment of CVD. Nattokinase is a promising alternative in the management of CVD.

Periprocedural Antithrombotic Treatment During Acute Mechanical Thrombectomy for Ischemic Stroke: A Systematic Review

BACKGROUND

More than one-third of the patients with ischemic stroke caused by an intracranial large vessel occlusion do not recover to functional independence despite fast and successful recanalization by acute mechanical thrombectomy (MT). This may partially be explained by incomplete microvascular reperfusion. Some antithrombotics, e.g., antiplatelet agents and heparin, may be able to restore microvascular reperfusion. However, antithrombotics may also increase the risk of symptomatic intracranial hemorrhage (sICH). The aim of this review was to assess the potential safety and functional outcome of periprocedural antiplatelet or heparin use during acute MT for ischemic stroke.

METHODS

We systematically searched PubMed, Embase, Medline, Web of Science, and Cochrane for studies investigating the safety and functional outcome of periprocedural antiplatelet or heparin treatment during acute MT for ischemic stroke. The primary outcome was the risk for sICH. Secondary outcomes were functional independence after 3-6 months (modified Rankin Scale 0-2) and mortality within 6 months.

RESULTS

837 studies were identified through the search, of which 19 studies were included. The sICH risks of the periprocedural use of antiplatelets ranged from 6 to 17%, and for heparin from 5 to 12%. Two of four studies reporting relative effects of the use of antithrombotics are pointing toward an increased risk of sICH. Among patients treated with antiplatelet agents, functional independence varied from 23 to 60% and mortality from 18 to 33%. For heparin, this was, respectively, 19-54% and 19-33%. The three studies presenting relative effects of antiplatelets on functional independence showed neutral effects. Both studies reporting relative effects of heparin on functional independence found it to increase this chance.

CONCLUSION

Randomized controlled trials investigating the effect of periprocedural antithrombotic treatment in MT are lacking. Some observational studies report a slight increase in sICH risk, which may be acceptable because they also suggest a beneficial effect on functional outcome. Therefore, randomized controlled trials are warranted to address the question whether the potentially higher risk of sICH could be outweighed by improved functional outcome.

A promising oral fucoidan-based antithrombotic nanosystem: Development, activity and safety

Fucoidan-loaded nanoparticles emerge as great candidates to oral anticoagulant therapy, due to increasing of bioavailability and circulation time of this natural anticoagulant. Crosslink between chitosan chains are performed using glutaraldehyde to confer higher gastric pH resistance to nanoparticle matrices. In this work, chitosan-fucoidan nanoparticles, without (NpCF) and with glutaraldehyde crosslink (NpCF 1% and NpCF 2%), were prepared to evaluate their anticoagulant, antithrombotic and hemorrhagic profile. Nanoparticles were characterized by average diameter, polydispersity index, zeta potential, Fourier transform infrared spectroscopy and fucoidan in vitro release. Anticoagulant and antithrombotic activities were determined by in vitro and in vivo models, respectively. Hemorrhagic profile was in vivo evaluated by tail bleeding assay. Preparations showed nanometric and homogeneous average diameters. Zeta potentials of NpCF and NpCF 1% were stable over gastrointestinal pH range, which was confirmed by low fucoidan release in gastric and enteric media. In pH 7.4, NpCF and NpCF 1% demonstrated fucoidan release of 65.5% and 60.6%, respectively, within the first 24 hours. In comparison to fucoidan, NpCF and NpCF 1% showed increased in vitro anticoagulant activity. A significant difference on oral antithrombotic profile of NpCF 1% was found in comparison to fucoidan. Bleeding profile of NpCF and NpCF 1% showed no differences to control group, indicating the safety of these systems. Surprisingly, oral antithrombotic profile of commercially available fucoidan, from Fucus vesiculosus, has not been previously determined, which reveals new possibilities. In this work, significant advances were observed in anticoagulant and antithrombotic profiles of fucoidan through the preparation of NpCF 1%.

[SAFETY AND EFFICACY OF CONTINUOUS ADMINISTRATION OF ANTITHROMBOTIC DRUGS DURING TRANSURETHRAL RESECTION OF BLADDER TUMORS]

(Objectives) We evaluated the safety and efficacy of continuous administration of antithrombotic drugs during transurethral resection of bladder tumors (TURBT). (Methods) We performed a retrospective review of 351 TURBT procedures performed at our institute from April 2011 to October 2015. Among these, antithrombotic drugs were continued in 31 TURBT cases throughout their perioperative period (continuation group), antithrombotic drugs were discontinued in 26 TURBT cases (discontinuation group), and bridging anticoagulation therapy with heparin after interruption of antithrombotic drugs was performed in 4 TURBT cases (heparin bridging group). The safety and efficacy of continuous administration of antithrombotic drugs during TURBT was evaluated by comparing the rate of perioperative complications, median operative time, duration of hematuria, urethral catheter placement, duration of stay after surgery, and by comparing the duration of stay among the three groups. (Results) The median operative time was 40.0 min in the continuation group, 39.0 min in the discontinuation group, and 31.0 min in the heparin bridging group with no significant differences. There were no significant differences in the median duration of hematuria (1.00 days vs. 1.00 days vs. 1.00 days), urethral catheter placement (3.00 days vs. 2.50 days vs. 2.00 days), or stay after TURBT (4.00 days vs. 3.50 days vs. 3.00 days) among the continuation, discontinuation, and heparin bridging groups. The median duration of stay was 6.00 days in the continuation group, 7.00 days in the discontinuation group, and 16.0 days in the heparin bridging group with significant differences between the continuation group vs. the heparin bridging group and the discontinuation group vs. the heparin bridging group. The rate of complications was 6 (19.4%) in the continuation group and 3 (11.5%) in the discontinuation group with no significant differences. However, a serious complication, cerebral infarction leading to hemiplegia, occurred in the discontinuation group. (Conclusion) Continuous administration of antithrombotic drugs during TURBT is considered to be safe and useful because it may prevent serious thromboembolism without adversely affecting the perioperative course.

Curcumin, hemostasis, thrombosis, and coagulation

Atherothrombotic cardiovascular disease is a major cause of mortality throughout the world. Platelet activation and aggregation play a central role in hemostasis and thrombosis. Herbal medicines have been traditionally used in the management of cardiovascular disease and can help in modifying its progression, particularly in hemostasis and the coagulation process, as well as altering platelet function tests and some coagulation parameters. Curcumin is a polyphenol derived from the Curcuma longa plant and has been used extensively in complementary and alternative medicine, as it is nontoxic and safe with various therapeutic properties. Modern scientific research has demonstrated its anti-inflammatory, antioxidant, anti-carcinogenic, antithrombotic, and cardiovascular protective effects. The present study reviewed previous studies in the literature, which support the positive activity of curcumin in hemostasis, anticoagulation, and fibrinolysis. We also presented molecular mechanisms associated with the antiplatelet and anticoagulant activities of curcumin and potential implications for the treatment of cardiovascular disease.

Long-term follow-up of antithrombotic management patterns in patients with acute coronary syndrome in Russia: an observational study (EPICOR-RUS study)

OBJECTIVE

This study sought to describe the short- and long-term (up to 2 years) antithrombotic management patterns in a real-life setting for patients hospitalized for an acute coronary syndrome (ACS) event, and to document clinical outcomes.

RESEARCH DESIGN AND METHODS

EPICOR-RUS was a multicenter (34 centers), prospective, observational, longitudinal cohort study conducted across Russia on antithrombotic management in hospitalized (within 24 hours of symptom onset) ACS patients with 2 year follow-up.

CLINICAL TRIAL REGISTRATION

NCT01373957.

RESULTS

A total of 600 ACS patients (71.1% male, mean age 60 years) were enrolled; 599 were included for analysis. Diagnosis comprised STEMI (n = 375, 62.6%), NSTEMI (n = 147, 24.5%), and unstable angina (UA) (n = 77, 12.9%). Percutaneous coronary intervention (PCI) was conducted in 64.3% of patients with STEMI (with or without thrombolysis), 36.7% with NSTEMI, and 58.4% with UA. There was undertreatment with dual antiplatelet therapy (DAPT) for STEMI, NSTEMI, and UA: 14.7%, 25.9% and 16.9% of patients, respectively, were not receiving DAPT during hospitalization, and 10.1%, 21.8% and 16.9% at discharge. Post-discharge, of the STEMI group, only 72.4% of patients who were managed by PCI and 39.8% of conservatively treated patients received DAPT at 12 months. The respective figures in the NSTEMI group were 77.3% and 26.4%. In the STEMI cohort the cumulative incidence of all-cause mortality was 3.2% at 1 year and 5.1% at 2 years of follow-up; in the NSTEMI cohort this was 2.7% and 4.8%, respectively. There were no deaths by 12 months and one death by 24 months (1.3%) in the UA population.

CONCLUSION

Despite evidence-based guidelines for the management of ACS, the real-world setting in Russia shows discrepancies in clinical practice, highlighting the need for improvements for the optimal management of high-risk patients with ACS.

Antithrombotic therapy in end-stage renal disease

The delicate balance of risk vs. benefit of using antiplatelet and antithrombotic agents in the general population is well established. The decision to use these agents in the end stage renal disease (ESRD) population remains complex and difficult. The concomitant association of a prothombotic state with high risk of bleeding in the ESRD population requires individualization and careful clinical judgment before implementing such therapy. There remains a paucity of clinical trials and lack of substantial evidence in literature for safe and effective use of antithrombotic drugs in patients with advanced chronic kidney disease. The current review summarizes the pros and cons of using antiplatelet and antithrombotic agents in primary and secondary prevention of cardiovascular events, evaluate the risks with routine use of anticoagulation for cerebrovascular stroke prevention with nonvalvular atrial fibrillation and role of newer oral anticoagulants as alternate agents in the dialysis population.

Novel antiplatelet role for a protein disulfide isomerase-targeted peptide: evidence of covalent binding to the C-terminal CGHC redox motif

Essentials Inhibitors of protein disulfide isomerase (PDI) have been considered a new antithrombotic class. CxxC is a PDI-targeted peptide that has been previously shown to inhibit its reductase activity. CxxC binds to surface PDI and inhibits ADP- and thrombin-evoked platelet activation and aggregation. CxxC binds to Cys400 on CGHC redox motif of PDI a' domain, a site for PDI prothrombotic activity.

SUMMARY

Background Protein disulfide isomerase (PDI) plays a major role in platelet aggregation, and its inhibitors have emerged as novel antithrombotic drugs. In previous work, we designed a peptide based on a PDI redox motif (CGHC) that inhibited both PDI reductase activity and PDI-modulated superoxide generation by neutrophil Nox2. Thus, we hypothesized that this peptide would also inhibit platelet aggregation by association with surface PDI. Methods Three peptides were used: CxxC, containing the PDI redox motif; Scr, presenting a scrambled sequence of the same residues and AxxA, with cysteines replaced by alanine. These peptides were tested under platelet aggregation and flow cytometry protocols to identify their possible antiplatelet activity. We labeled membrane free thiol and electrospray ionization liquid chromatography tandem mass spectrometry to test for an interaction. Results CxxC decreased platelet aggregation in a dose-dependent manner, being more potent at lower agonist concentrations, whereas neither AxxA nor Scr peptides exerted any effect. CxxC decreased aIIbb3 activation, but had no effect on the other markers. CxxC also decreased cell surface PDI pulldown without interfering with the total thiol protein content. Finally, we detected the addition of one CxxC molecule to reduced PDI through binding to Cys400 through mass spectrometry. Interestingly, CxxC did not react with oxidized PDI. Discussion CxxC has consistently shown its antiplatelet effects, both in PRP and washed platelets, corroborated by decreased aIIbb3 activation. The probable mechanism of action is through a mixed dissulphide bond with Cys400 of PDI, which has been shown to be essential for PDI's actions. Conclusion In summary, our data support antiplatelet activity for CxxC through binding to Cys400 in the PDI a0 domain, which can be further exploited as a model for sitedriven antithrombotic agent development.

[Management of antithrombotic agents for endoscopic procedures in elderly Chinese patients: a retrospective study]

OBJECTIVE

To investigate the peri-endoscopic management of antithrombotic drugs and adverse events in elderly patients un-dergoing gastrointestinal endoscopy in order to provide clinical guidance of peri-endoscopic management of antithrombotic drugs for elderly pa-tients.

METHODS

Between January 1^st 2008 and December 31^st 2014, clinical data of 3 747 patients (aged 46~99 years, 96.1% male) who were hospitalized for elective gastrointestinal endoscopy were analyzed retrospectively. The general clinical data, cardiovascular disease and re-lated risk factors, medication, management of peri-endoscopic antithrombotics and adverse events were recorded. The differences of peri-endo-scopic adverse events including thromboembolism and bleeding between patients with different management strategies of peri-endoscopic an-tithrombotics were analyzed.

RESULTS

The overall incidences of peri-endoscopic thromboembolism and bleeding were 2.24% and 1.89%, re-spectively. The incidences of thromboembolism and bleeding when stopping antithrombotics at 0~7 days pre-procedure were 1.87% and 2.38% respectively. The incidences of thromboembolism and bleeding when resuming antithrombotics at 2~7 days after endoscopy were 2.07% and 0.63% respectively. When discontinuing antithrombotics, the differences in peri-endoscopic thromboembolism and bleding be-tween patients who did and did not undergo low-molecular-weight heparin (LMWH) bridging therapy were not significant. The incidence of bleeding in patients who underwent LMWH bridging therapy was higher than that in patients who didn't undergo LMWH bridging therapy, but the diference was not significant.

CONCLUSIONS

Our findings suggest that cessation of antithrombotics < 7 days pre-procedures and resumption of antithrombotic agents after 2-7 days post-porcedures is optimal in elderly Chinese patients undergoing endoscopy.

Bleeding risk of endoscopic ultrasound-guided fine-needle aspiration in patients undergoing antithrombotic therapy

OBJECTIVES

Bleeding events related to endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) are rare. However, for patients treated with antithrombotic agents, the bleeding risk of EUS-FNA is uncertain. Hence, the aim of this study was to assess the bleeding event rate associated with EUS-FNA in patients receiving antithrombotic treatment.

METHODS

A retrospective study was conducted in 742 consecutive patients who underwent EUS-FNA for solid lesions between 2008 and 2015. We compared the bleeding event rates among patients who were not administered antithrombotic agents, those whose agent use was discontinued, those who continued treatment with aspirin or cilostazol, and those who were administered heparin as a replacement.

RESULTS

There were 131 patients (17.7 %) treated with antithrombotic agents. Seven experienced bleeding events, and the overall bleeding event rate was 0.9 % (7/742). All bleeding events were intraoperative; there were no postoperative bleeding episodes. Subgroup analysis by antithrombotic agent revealed bleeding event rates of 1.0 % (6/611), 0 % (0/62), 1.6 % (1/61), and 0 % (0/8) for the non-administration, discontinuation of agents, continuation of aspirin or cilostazol, and heparin replacement groups, respectively. Only one severe bleeding event necessitated hemostatic treatment (1/742; 0.1 %); this occurred in a patient in the non-administration group, and there were no severe bleeding events in patients receiving antithrombotic treatment.

CONCLUSIONS

The present study found a low incidence of EUS-FNA-related bleeding in patients receiving antithrombotic treatment. The bleeding event rate was low even in patients who underwent EUS-FNA while continuing aspirin or cilostazol.

Perioperative complications following preoperative cessation of antithrombotic agents for total knee arthroplasty: A retrospective study

The number of elderly patients undergoing total knee arthroplasty (TKA) has steadily increased. Elderly patients undergoing TKA usually have underlying diseases, and some of them take antithrombotic agents for the prevention or treatment of these co-morbidities, including cardiovascular, cerebrovascular, or thromboembolic diseases. When these patients are scheduled to undergo TKA, preoperative cessation of antithrombotic agents is considered on the basis of its risks and benefits. This study was aimed to evaluate the impact of discontinuing antithrombotic agents for primary total knee arthroplasty (TKA) on perioperative complications.Patients who underwent primary TKA between 2008 and 2012 were identified, and classified into two groups: group A, in whom antithrombotic agents were ceased preoperatively, and group B, in which patients did not receive antithrombotic therapy. Patient characteristics, history of antithrombotic therapy, intraoperative blood loss, perioperative blood transfusion, postoperative 30-day complications, and postoperative hospital stay were recorded.Of 885 patients undergoing primary TKA, 218 (24.6%) patients were included in group A, and 667 (75.4%) in group B. Group A received transfusion more frequently than group B (P < 0.001). However, there was no difference between the two groups in terms of intraoperative blood loss, postoperative 30-day complications, and postoperative hospital stay.Patients who discontinued antithrombotic drugs before primary TKA do not have a higher incidence of postoperative 30-day complications, including cardiovascular, cerebrovascular, or thromboembolic events. Moreover, the estimated intraoperative blood loss was not different compared with patients not receiving antithrombotic agents preoperatively. Larger prospective studies of this issue are required.

Update on Brazilian biosimilar enoxaparins

INTRODUCTION

Brazil is among the first countries approving the commercialization and clinical use of biosimilar enoxaparins. Our research group has performed quality control assessments of these drugs over the last decade. Areas covered: We have not found noticeable differences between Brazilian biosimilar enoxaparins and the original product regarding their physicochemical properties, disaccharide composition, anticoagulant activity, bioavailability and safety. Expert commentary: In spite of clinical and pharmacological advantages of enoxaparin, subcutaneous formulations of unfractionated heparin are employed by the Brazilian public health system for prevention and treatment of thromboembolism. The underuse of both original and biosimilar enoxaparins in Brazil directly correlates with their high cost.

Left atrial appendage closure: A single center experience and comparison of two contemporary devices

OBJECTIVES

To compare indications and clinical outcomes of two contemporary left atrial appendage (LAA) percutaneous closure systems in a "real-world" population.

BACKGROUND

Percutaneous LAA occlusion is an emerging therapeutic option for stroke prevention in atrial fibrillation. Some questions however remain unanswered, such as the applicability of results of randomized trials to current clinical practice. Moreover, currently available devices have never been directly compared.

METHODS

We retrospectively analyzed consecutive patients who underwent LAA closure at San Raffaele Hospital, Milan, Italy between 2009 and 2015. Clinical indications and device selection were left to operators' decision; routine clinical and transesophageal echocardiography (TEE) follow-up was performed.

RESULTS

One-hundred and sixty-five patients were included in the study, of which 99 were treated with the Amplatzer Cardiac Plug (ACP) and 66 with the Watchman system. During the follow-up period (median 15 months, interquartile range 6-26 months) five patients died. The incidence of ischemic events was low, with one patient suffering a transient ischemic attack and no episodes recorded of definitive strokes. Twenty-six leaks ≥1 mm were detected (23%); leaks were less common with the ACP and with periprocedural three-dimensional TEE evaluation, but were not found to correlate with clinical events. Clinical outcomes were comparable between the two devices.

CONCLUSIONS

Our data show excellent safety and efficacy of LAA closure, irrespectively of the device utilized, in a population at high ischemic and hemorrhagic risk. The use of ACP and 3D-TEE minimized the incidence of residual leaks; however, the clinical relevance of small peri-device flow warrants further investigation. © 2016 Wiley Periodicals, Inc.

Prior Antithrombotic Use Is Associated With Favorable Mortality and Functional Outcomes in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Antithrombotics are the mainstay of treatment in primary and secondary prevention of stroke, and their use before an acute event may be associated with better outcomes.

METHODS

Using data from Get With The Guidelines-Stroke with over half a million acute ischemic strokes recorded between October 2011 and March 2014 (n=540 993) from 1661 hospitals across the United States, we examined the unadjusted and adjusted associations between previous antithrombotic use and clinical outcomes.

RESULTS

There were 250 104 (46%) stroke patients not receiving any antithrombotic before stroke; of whom approximately one third had a documented previous vascular indication. After controlling for clinical and hospital factors, patients who were receiving antithrombotics before stroke had better outcomes than those who did not, regardless of whether a previous vascular indication was present or not: adjusted odds ratio (95% confidence intervals) were 0.82 (0.80-0.84) for in-hospital mortality, 1.18 (1.16-1.19) for home as the discharge destination, 1.15 (1.13-1.16) for independent ambulatory status at discharge, and 1.15 (1.12-1.17) for discharge modified Rankin Scale score of 0 or 1.

CONCLUSIONS

Previous antithrombotic therapy was independently associated with improved clinical outcomes after acute ischemic stroke. Ensuring the use of antithrombotics in appropriate patient populations may be associated with benefits beyond stroke prevention.

Advanced age and high-residual platelet reactivity in patients receiving dual antiplatelet therapy with clopidogrel or ticagrelor

ESSENTIALS: Dual antiplatelet therapy (DAPT) in elderly patients requires balancing bleedings and thrombosis. Impact of age on high residual on-treatment platelet reactivity (HRPR) on DAPT was studied. A reduced effectiveness of adenosine diphosphate antagonists was observed over 70 years of age. The occurrence of HRPR was increased among elderly patients with both clopidogrel and ticagrelor.

BACKGROUND

The aim of the present study was to evaluate the impact of age on platelet function and the occurrence of high residual on-treatment platelet reactivity (HRPR) in patients treated with dual antiplatelet therapy (DAPT) using acetylsalicilic acid (ASA) and clopidogrel or ticagrelor.

METHODS

Patients treated with DAPT (ASA and clopidogrel or ticagrelor) were scheduled for platelet function assessment at 30-90 days post-discharge. By whole blood impedance aggregometry, HRPR was considered for ASPI test values > 862 AU*min (for ASA) and adenosine diphosphate (ADP) test values > 417 AU*min (for ADP antagonists). Elderly patients were defined as those aged ≥ 70 years.

RESULTS

Among 494 patients on DAPT, 224 (45.3%) were ≥ 70 years old. ADP-mediated platelet aggregation increased with decades of age (279.3 ± 148.6 vs. 319.6 ± 171.1 vs. 347.3 ± 190.1 vs. 345.7 ± 169.2), whereas no difference was observed for ASA response. A reduced effectiveness of ADP antagonists was observed among elderly patients; in fact, among the 117 patients displaying HRPR (23.7%), a higher prevalence was observed among patients over 70 years old (30.4% vs. 18.1%; adjusted odds ratio (OR) [95% confidence interval (CI)] = 2.19 [1.29-3.71]). Similar results were obtained among the 266 clopidogrel-treated patients (38.5% vs. 27.9%; adjusted OR [95% CI] = 2.91 [1.46-5.8]) and in the 228 patients receiving ticagrelor (19.1% vs. 8.1%; adjusted OR [95% CI] = 2.55 [1.02-8.59]).

CONCLUSION

In patients receiving dual antiplatelet therapy, advanced age is independently associated with a reduced effectiveness of ADP antagonists and a higher rate of HRPR with both clopidogrel and ticagrelor.

Design, green synthesis and pharmacological evaluation of novel 5,6-diaryl-1,2,4-triazines bearing 3-morpholinoethylamine moiety as potential antithrombotic agents (.)

The aim of this research work was to investigate a series of novel 5,6-diaryl-1,2,4-triazines (3a-3q) containing 3-morpholinoethylamine side chain, and to address their antiplatelet activity by in vitro, ex vivo and in vivo methods. All compounds were synthesized by environment benign route and their structures were unambiguously confirmed by spectral data. Compounds (3l) and (3m) were confirmed by their single crystal X-ray structures. Out of all the synthesized compounds, 10 were found to be more potent in vitro than aspirin; six of them were found to be prominent in ex vivo assays and one compound (3d) was found to have the most promising antithrombotic profile in vivo. Moreover, compound (3d) demonstrated less ulcerogenicity in rats as compared to aspirin. The selectivity of the most promising compound (3d) for COX-1 and COX-2 enzymes was determined with the help of molecular docking studies and the results were correlated with the biological activity.

Characterization of a novel function-blocking antibody targeted against the platelet P2Y1 receptor

OBJECTIVE

Platelet hyperactivity is associated with vascular disease and contributes to the genesis of thrombotic disorders. ADP plays an important role in platelet activation and activates platelets through 2 G-protein-coupled receptors, the Gq-coupled P2Y1 receptor (P2Y1R), and the Gi-coupled P2Y12 receptor. Although the involvement of the P2Y1R in thrombogenesis is well established, there are no antagonists that are currently available for clinical use.

APPROACH AND RESULTS

Our goal is to determine whether a novel antibody targeting the ligand-binding domain, ie, second extracellular loop (EL2) of the P2Y1R (EL2Ab) could inhibit platelet function and protect against thrombogenesis. Our results revealed that the EL2Ab does indeed inhibit ADP-induced platelet aggregation, in a dose-dependent manner. Furthermore, EL2Ab was found to inhibit integrin GPIIb-IIIa activation, dense and α granule secretion, and phosphatidylserine exposure. These inhibitory effects translated into protection against thrombus formation, as evident by a prolonged time for occlusion in a FeCl3-induced thrombosis model, but this was accompanied by a prolonged tail bleeding time. We also observed a dose-dependent displacement of the radiolabeled P2Y1R antagonist [(3)H]MRS2500 from its ligand-binding site by EL2Ab.

CONCLUSIONS

Collectively, our findings demonstrate that EL2Ab binds to and exhibits P2Y1R-dependent function-blocking activity in the context of platelets. These results add further evidence for a role of the P2Y1R in thrombosis and validate the concept that targeting it is a relevant alternative or complement to current antiplatelet strategies.

Amiodarone, anticoagulation, and clinical events in patients with atrial fibrillation: insights from the ARISTOTLE trial

BACKGROUND

Amiodarone is an effective medication in preventing atrial fibrillation (AF), but it interferes with the metabolism of warfarin.

OBJECTIVES

This study sought to examine the association of major thrombotic clinical events and bleeding with the use of amiodarone in the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial.

METHODS

Baseline characteristics of patients who received amiodarone at randomization were compared with those who did not receive amiodarone. The interaction between randomized treatment and amiodarone was tested using a Cox model, with main effects for randomized treatment and amiodarone and their interaction. Matching on the basis of a propensity score was used to compare patients who received and who did not receive amiodarone at the time of randomization.

RESULTS

In ARISTOTLE, 2,051 (11.4%) patients received amiodarone at randomization. Patients on warfarin and amiodarone had time in the therapeutic range that was lower than patients not on amiodarone (56.5% vs. 63.0%; p < 0.0001). More amiodarone-treated patients had a stroke or a systemic embolism (1.58%/year vs. 1.19%/year; adjusted hazard ratio [HR]: 1.47, 95% confidence interval [CI]: 1.03 to 2.10; p = 0.0322). Overall mortality and major bleeding rates were elevated, but were not significantly different in amiodarone-treated patients and patients not on amiodarone. When comparing apixaban with warfarin, patients who received amiodarone had a stroke or a systemic embolism rate of 1.24%/year versus 1.85%/year (HR: 0.68, 95% CI: 0.40 to 1.15), death of 4.15%/year versus 5.65%/year (HR: 0.74, 95% CI: 0.55 to 0.98), and major bleeding of 1.86%/year versus 3.06%/year (HR: 0.61, 95% CI: 0.39 to 0.96). In patients who did not receive amiodarone, the stroke or systemic embolism rate was 1.29%/year versus 1.57%/year (HR: 0.82, 95% CI: 0.68 to 1.00), death was 3.43%/year versus 3.68%/year (HR: 0.93, 95% CI: 0.83 to 1.05), and major bleeding was 2.18%/year versus 3.03%/year (HR: 0.72, 95% CI: 0.62 to 0.84). The interaction p values for amiodarone use by apixaban treatment effects were not significant.

CONCLUSIONS

Amiodarone use was associated with significantly increased stroke and systemic embolism risk and a lower time in the therapeutic range when used with warfarin. Apixaban consistently reduced the rate of stroke and systemic embolism, death, and major bleeding compared with warfarin in amiodarone-treated patients and patients who were not on amiodarone.

Variation in restarting antithrombotic drugs at hospital discharge after intracerebral hemorrhage

BACKGROUND AND PURPOSE

Whether intracerebral hemorrhage (ICH) survivors should restart antithrombotic drugs is unknown. We analyzed the frequency of restarting antithrombotic drugs in ICH survivors who had taken prophylactic antithrombotic drugs in atrial fibrillation or after thromboembolic disease in 5 cohorts and explored factors associated with doing so.

METHODS

We compared the characteristics and proportions of patients taking antithrombotic drugs at ICH onset and discharge in 4 hospital-based cohorts (Lille, France, n=542; Utrecht, The Netherlands, n=389; multicenter Clinical Relevance of Microbleeds in Stroke-2 (CROMIS-2) ICH, United Kingdom, n=667; and Amsterdam, The Netherlands, n=403) and 1 community-based study (Lothian, Scotland, n=137), using bivariate analyses. We sought characteristics associated with restarting using bivariate and multivariable logistic regression analyses.

RESULTS

A total of 942 (44%) patients with ICH took antithrombotic drugs at hospital admission (no difference between cohorts). Antithrombotic drugs were restarted in 96 (20%) of the 469 survivors who had taken antithrombotic drugs for secondary prevention or atrial fibrillation, but this proportion differed when stratified by the cohort of origin (Lille, 18%; Utrecht, 45%; Lothian, 15%; CROMIS-2 ICH, 11%; Amsterdam, 20%; P<0.001) and by type of antithrombotic drug pre-ICH (14% in patients with previous antiplatelet drugs versus 26% in patients with previous vitamin K antagonists and 41% in patients with both drugs; P<0.001). We did not find other consistent, independent associations with restarting antithrombotic drugs.

CONCLUSIONS

The variation in clinical practice and lack of consistent associations with restarting antithrombotic drugs after ICH reflect current knowledge and support the need for randomized controlled trials to resolve this dilemma.

Thiol isomerases in thrombus formation

Protein disulfide isomerase (PDI), ERp5, and ERp57, among perhaps other thiol isomerases, are important for the initiation of thrombus formation. Using the laser injury thrombosis model in mice to induce in vivo arterial thrombus formation, it was shown that thrombus formation is associated with PDI secretion by platelets, that inhibition of PDI blocked platelet thrombus formation and fibrin generation, and that endothelial cell activation leads to PDI secretion. Similar results using this and other thrombosis models in mice have demonstrated the importance of ERp5 and ERp57 in the initiation of thrombus formation. The integrins, αIIbβ3 and αVβ3, play a key role in this process and interact directly with PDI, ERp5, and ERp57. The mechanism by which thiol isomerases participate in thrombus generation is being evaluated using trapping mutant forms to identify substrates of thiol isomerases that participate in the network pathways linking thiol isomerases, platelet receptor activation, and fibrin generation. PDI as an antithrombotic target is being explored using isoquercetin and quercetin 3-rutinoside, inhibitors of PDI identified by high throughput screening. Regulation of thiol isomerase expression, analysis of the storage, and secretion of thiol isomerases and determination of the electron transfer pathway are key issues to understanding this newly discovered mechanism of regulation of the initiation of thrombus formation.

Antiplatelet therapy for stable coronary artery disease in atrial fibrillation patients taking an oral anticoagulant: a nationwide cohort study

BACKGROUND

The optimal long-term antithrombotic treatment of patients with coexisting atrial fibrillation and stable coronary artery disease is unresolved, and commonly, a single antiplatelet agent is added to oral anticoagulation. We investigated the effectiveness and safety of adding antiplatelet therapy to vitamin K antagonist (VKA) in atrial fibrillation patents with stable coronary artery disease.

METHODS AND RESULTS

Atrial fibrillation patients with stable coronary artery disease (defined as 12 months from an acute coronary event) between 2002 and 2011 were identified. The subsequent risk of cardiovascular events and serious bleeding events (those that required hospitalization) was examined with adjusted Cox regression models according to ongoing antithrombotic therapy. A total of 8700 patients were included (mean age, 74.2 years; 38% women). During a mean follow-up of 3.3 years, crude incidence rates were 7.2, 3.8, and 4.0 events per 100 person-years for myocardial infarction/coronary death, thromboembolism, and serious bleeding, respectively. Relative to VKA monotherapy, the risk of myocardial infarction/coronary death was similar for VKA plus aspirin (hazard ratio, 1.12 [95% confidence interval, 0.94-1.34]) and VKA plus clopidogrel (hazard ratio, 1.53 [95% confidence interval, 0.93-2.52]). The risk of thromboembolism was comparable in all regimens that included VKA, whereas the risk of bleeding increased when aspirin (hazard ratio, 1.50 [95% confidence interval, 1.23-1.82]) or clopidogrel (hazard ratio, 1.84 [95% confidence interval, 1.11-3.06]) was added to VKA.

CONCLUSIONS

In atrial fibrillation patients with stable coronary artery disease, the addition of antiplatelet therapy to VKA therapy is not associated with a reduction in risk of recurrent coronary events or thromboembolism, whereas risk of bleeding is increased significantly. The common practice of adding antiplatelet therapy to oral VKA anticoagulation in patients with atrial fibrillation and stable coronary artery disease warrants reassessment.

Is the antithrombotic effect of sulfated galactans independent of serpin?

BACKGROUND

Sulfated galactans are polysaccharides with heterogeneous structures that frequently show anticoagulant activity. Their anticoagulant mechanisms are complex and distinct from those observed for heparin. Sulfated galactans act through a combination of effects involving serpin-dependent and serpin-independent mechanisms. Interestingly, these polymers can also induce blood coagulation due to activation of factor XII (FXII).

OBJECTIVES

The structure of a complex sulfated galactan from the red alga Acanthophora muscoides was characterized by solution nuclear magnetic resonance. This polysaccharide and another previously characterized algal sulfated galactan from Botryocladia occidentalis were each used in in vitro and in vivo anticoagulant and antithrombotic assays to understand the possible structural determinants of their functional effects.

RESULTS AND CONCLUSIONS

The serpin-dependent anticoagulant effects and FXII-related procoagulant effects of the sulfated galactans decreased in parallel with the molecular size. The serpin-independent anticoagulation also correlated with the chemical structure of the sulfated galactans. The sulfated galactan from A. muscoides, which showed mostly serpin-independent anticoagulant activity and reduced activation of FXII, drastically reduced arterial thrombus formation. However, the sulfated galactans produced opposite effects on venous thrombosis; this difference appears to result from the tenuous balance between the various effects on coagulation, including serpin-dependent and serpin-independent anticoagulation and FXIIa-dependent procoagulation. This study of novel sulfated polysaccharides with distinct effects on coagulation and thrombosis helps to establish the minimal structural-function relationship required for the development of antithrombotic drugs.