Platelet-active drugs: the relationships among dose, effectiveness, and side effects

Biomimetic Tissue Engineering Strategies for Craniofacial Applications

Biomimetics is the science of imitating nature's designs and processes to create innovative solutions for various fields, including dentistry and craniofacial reconstruction. In these areas, biomimetics involves drawing inspiration from living organisms/systems to develop new materials, techniques, and devices that closely resemble natural tissue structures and enhance functionality. This field has successfully demonstrated its potential to revolutionize craniofacial procedures, significantly improving patient outcomes. In dentistry, biomimetics offers exciting possibilities for the advancement of new dental materials, restorative techniques, and regenerative potential. By analyzing the structure/composition of natural teeth and the surrounding tissues, researchers have developed restorative materials that mimic the properties of teeth, as well as regenerative techniques that might assist in repairing enamel, dentin, pulp, cementum, periodontal ligament, and bone. In craniofacial reconstruction, biomimetics plays a vital role in developing innovative solutions for facial trauma, congenital defects, and various conditions affecting the maxillofacial region. By studying the intricate composition and mechanical properties of the skull and facial bones, clinicians and engineers have been able to replicate natural structures leveraging computer-aided design and manufacturing (CAD/CAM) and 3D printing. This has allowed for the creation of patient-specific scaffolds, implants, and prostheses that accurately fit a patient's anatomy. This review highlights the current evidence on the application of biomimetics in the fields of dentistry and craniofacial reconstruction.

Bone Tissue Engineering (BTE) of the Craniofacial Skeleton, Part I: Evolution and Optimization of 3D-Printed Scaffolds for Repair of Defects

Bone tissue regeneration is a complex process that proceeds along the well-established wound healing pathway of hemostasis, inflammation, proliferation, and remodeling. Recently, tissue engineering efforts have focused on the application of biological and technological principles for the development of soft and hard tissue substitutes. Aim is directed towards boosting pathways of the healing process to restore form and function of tissue deficits. Continued development of synthetic scaffolds, cell therapies, and signaling biomolecules seeks to minimize the need for autografting. Despite being the current gold standard treatment, it is limited by donor sites' size and shape, as well as donor site morbidity. Since the advent of computer-aided design/computer-aided manufacturing (CAD/CAM) and additive manufacturing (AM) techniques (3D printing), bioengineering has expanded markedly while continuing to present innovative approaches to oral and craniofacial skeletal reconstruction. Prime examples include customizable, high-strength, load bearing, bioactive ceramic scaffolds. Porous macro- and micro-architecture along with the surface topography of 3D printed scaffolds favors osteoconduction and vascular in-growth, as well as the incorporation of stem and/or other osteoprogenitor cells and growth factors. This includes platelet concentrates (PCs), bone morphogenetic proteins (BMPs), and some pharmacological agents, such as dipyridamole (DIPY), an adenosine A 2A receptor indirect agonist that enhances osteogenic and osteoinductive capacity, thus improving bone formation. This two-part review commences by presenting current biological and engineering principles of bone regeneration utilized to produce 3D-printed ceramic scaffolds with the goal to create a viable alternative to autografts for craniofacial skeleton reconstruction. Part II comprehensively examines recent preclinical data to elucidate the potential clinical translation of such 3D-printed ceramic scaffolds.

Three-Dimensional Printing Bioceramic Scaffolds Using Direct-Ink-Writing for Craniomaxillofacial Bone Regeneration

Defects characterized as large osseous voids in bone, in certain circumstances, are difficult to treat, requiring extensive treatments which lead to an increased financial burden, pain, and prolonged hospital stays. Grafts exist to aid in bone tissue regeneration (BTR), among which ceramic-based grafts have become increasingly popular due to their biocompatibility and resorbability. BTR using bioceramic materials such as β-tricalcium phosphate has seen tremendous progress and has been extensively used in the fabrication of biomimetic scaffolds through the three-dimensional printing (3DP) workflow. 3DP has hence revolutionized BTR by offering unparalleled potential for the creation of complex, patient, and anatomic location-specific structures. More importantly, it has enabled the production of biomimetic scaffolds with porous structures that mimic the natural extracellular matrix while allowing for cell growth-a critical factor in determining the overall success of the BTR modality. While the concept of 3DP bioceramic bone tissue scaffolds for human applications is nascent, numerous studies have highlighted its potential in restoring both form and function of critically sized defects in a wide variety of translational models. In this review, we summarize these recent advancements and present a review of the engineering principles and methodologies that are vital for using 3DP technology for craniomaxillofacial reconstructive applications. Moreover, we highlight future advances in the field of dynamic 3D printed constructs via shape-memory effect, and comment on pharmacological manipulation and bioactive molecules required to treat a wider range of boney defects.

Antiplatelet Therapy in Neurointervention

The aim of this review is to provide an overview of the use of antiplatelet medication in neurointervention, with a focus on the clinical indications for antiplatelet use in both preventing and reducing platelet aggregation. This review will cover current antiplatelet medications, pharmacokinetics, and pharmacodynamics. We will provide an overview of different endovascular devices and discuss the antiplatelet regimes in neurointervention, highlighting gaps in evidence and scope for future studies.Two randomized controlled trials have evaluated antiplatelet use in the setting of acute large vessel occlusion stroke, with neither demonstrating benefit in their overall cohorts. Evidence on antiplatelet medication for both acute and elective stenting for acute stroke and treatment of cerebral aneurysms is currently based on large case series, and practice in neurointervention has increasingly utilized dual antiplatelet regimes with clopidogrel and second-line agents like prasugrel and ticagrelor. Clopidogrel function testing has an increasing role in neurointerventional procedures, particularly for high metal surface area stents such as the braided flow diverter type stents. Intravenous glycoprotein IIB/IIIA inhibitors have been utilized for both acute bridging and rescue therapy.Antiplatelet decision making is complex, and there are few randomized control trials to guide clinical practice. Comparative trials to guide decision making remain important in both the acute and elective settings. Standardised protocols incorporating platelet function testing may play a role in assisting decision making until more robust clinical evidence is available, particularly in the context of acute neurointerventional stenting for stroke and ruptured cerebral aneurysms.

Coping Strategies and Posttraumatic Growth Following Transient Ischemic Attack: A Qualitative Study

A transient ischemic attack (TIA) is defined as a temporary neurological dysfunction due to focal brain ischemia. We aimed to identify common coping strategies and the possible occurrence of posttraumatic growth in TIA patients. Semistructured interviews were conducted with TIA patients three months after TIA. We asked the participants about possible changes in the aftermath of their TIA and their way of coping with said changes. All interviews were tape-recorded and subsequently transcribed verbatim. Thematic content analysis was performed to identify main categories and themes. Seventeen patients with a median age of 66 years completed the semistructured interviews. Qualitative content analysis revealed 332 single codes, from which the three main categories "impairments as a consequence of TIA", "coping strategies" and "posttraumatic growth" were generated. The main categories were further subdivided into seven categories and thirty-six themes. TIA patients may suffer from various physical impairments, which also involve medication side effects. Activating resources on the one hand, and avoiding negative thoughts and feelings on the other hand, were identified to be the relevant coping strategies in TIA patients. Posttraumatic growth seems to be a common phenomenon after TIA, which may have important implications for treatment and rehabilitation.

Fifty years with aspirin and platelets

In 2021, we reached the 50th anniversary of the publication of Sir John Vane's seminal paper in Nature New Biology describing the experiments supporting his mechanistic hypothesis that inhibition of prostaglandin synthesis might explain the main pharmacological effects of aspirin and aspirin-like drugs, that is, reduction in pain, fever and inflammation. Bengt Samuelsson's subsequent discoveries elucidating the cyclooxygenase pathway of platelet arachidonic acid metabolism motivated my research interest towards measuring platelet thromboxane A₂ biosynthesis as a tool to investigate the clinical pharmacology of cyclooxygenase inhibition by aspirin in health and disease. What followed was a long, winding road of clinical research leading to the characterization of low-dose aspirin as a life-saving antiplatelet drug that still represents the cornerstone of antithrombotic therapy. Having witnessed and participated in these 50 years of aspirin research, I thought of providing a personal testimony of how things developed and eventually led to a remarkable success story of independent research.

Clinical pharmacology of antiplatelet drugs

INTRODUCTION

Platelets play a key role in arterial thrombosis and antiplatelet therapy is pivotal in the treatment of cardiovascular disease. Current antiplatelet drugs target different pathways of platelet activation and show specific pharmacodynamic and pharmacokinetic characteristics, implicating clinically relevant drug-drug interactions.

AREAS COVERED

This article reviews the role of platelets in hemostasis and cardiovascular thrombosis, and discusses the key pharmacodynamics, drug-drug interactions and reversal strategies of clinically used antiplatelet drugs.

EXPERT OPINION

Antiplatelet therapies target distinct pathways of platelet activation: thromboxane A₂ synthesis, adenosine diphosphate-mediated signaling, integrin α_IIbβ₃ (GPIIb/IIIa), thrombin-mediated platelet activation via the PAR1 receptor and phosphodiesterases. Key clinical drug-drug interactions of antiplatelet agents involve acetylsalicylic acid - ibuprofen, clopidogrel - omeprazole, and morphine - oral P2Y₁₂ inhibitors, all of which lead to an attenuated antiplatelet effect. Platelet function and genetic testing and the use of scores (ARC-HBR, PRECISE-DAPT, ESC ischemic risk definition) may contribute to a more tailored antiplatelet therapy. High on-treatment platelet reactivity presents a key problem in the acute management of ST-elevation myocardial infarction (STEMI). A treatment strategy involving early initiation of an intravenous antiplatelet agent may be able to bridge the gap of insufficient platelet inhibition in high ischemic risk patients with STEMI.

Oral antiplatelet therapy for acute ischaemic stroke

BACKGROUND

In people with acute ischaemic stroke, platelets become activated and can cause blood clots to form and block an artery in the brain, resulting in damage to part of the brain. Such damage gives rise to the symptoms of stroke. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and also reduce the risk of early recurrent ischaemic stroke, thereby reducing the risk of early death and improving long-term outcomes in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

OBJECTIVES

To assess the efficacy and safety of immediate oral antiplatelet therapy (i.e. started as soon as possible and no later than two weeks after stroke onset) in people with acute presumed ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE Ovid, Embase Ovid, and two trials registers, and performed forward reference/cited reference searching in August 2020.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing oral antiplatelet therapy (started within 14 days of the stroke) with control in people with definite or presumed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria and assessed trial quality. For the included trials, they extracted and cross-checked the data. They assessed risk of bias of each study using the Risk of Bias 1 (RoB1) tool and overall certainty of the evidence for each outcome using the GRADE approach.

MAIN RESULTS

We included 11 studies involving 42,226 participants. Three new trials have been added since the last update (743 participants). As per the previous version of this review, two trials testing aspirin 160 mg to 300 mg once daily, started within 48 hours of onset, contributed 96% of the data. The risk of bias was low. The maximum follow-up was six months. With treatment, there was a decrease in death or dependency at the end of follow-up (odds ratio (OR) 0.95, 95% confidence interval (CI) 0.91 to 0.99; 7 RCTs, 42,034 participants; moderate-certainty evidence). For every 1000 people treated with aspirin, 13 people would avoid death or dependency (number needed to treat for an additional beneficial outcome 79).

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in people who cannot swallow) and started within 48 hours of onset of presumed ischaemic stroke, significantly decreased death and dependency, and reduced the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications; long-term outcomes were improved.

Platelet response to aspirin in UK and Irish pregnancy cohorts: a genome-wide approach

A multi-center prospective cross-sectional and genome-wide association study (GWAS) recruited pregnant women taking low dose aspirin. Objectives were to (i) develop pregnancy-specific 95% reference intervals for a range of laboratory based platelet function tests (PFTs); (ii) select an optimal and acceptable PFT that reflected aspirin's COX-1 inhibition in women with confirmed aspirin adherence in pregnancy; and (iii) identify genomic variants that may influence pregnant women's platelet response to aspirin.The study included two independent cohorts of pregnant women. A range of PFTs and matched phenotyping with urinary 11-dehydrothromboxane B₂ (11DTXB2) and nuclear magnetic resonance (NMR) spectroscopy detection of urinary salicyluric acid as a measure of aspirin adherence were performed. Genome-wide data was acquired from the UK Biobank Axiom® (Thermo Fisher Scientific). 11DTXB2 in combination with adherence testing with NMR salicyluric acid was an accurate and acceptable testing strategy for detecting biochemical aspirin responsiveness in pregnant women, with the provision of relevant reference ranges. GWAS meta-analysis found no significant single nucleotide polymorphisms in association with response to aspirin in pregnancy. Further evaluation in relation to effective dosing of aspirin in pregnancy and optimizing the benefits to specific subgroups should now be a priority for future research.

[Aspirin in primary prevention of cardiovascular and cerebrovascular diseases]

Acetylsalicylic acid (aspirin) is one of the most used medications worldwide. The antithrombotic agent acts mainly through inhibition of cyclooxygenase-1 and consequently thromboxane A₂ synthesis, causing an irreversible suppression of platelet function. Despite of its proven benefit in the treatment and secondary prevention of atherosclerotic diseases, its use for the primary prevention remains controversial due to an unclear balance between the benefits and risks of aspirin. Moreover, the recent evidence indicates that the risk of major bleeding outweighs the potential to reduce ischemic events in patients without atherosclerotic diseases, thus, precluding the general use of aspirin for the primary prevention.

Dipyridamole-loaded 3D-printed bioceramic scaffolds stimulate pediatric bone regeneration in vivo without disruption of craniofacial growth through facial maturity

This study investigates a comprehensive model of bone regeneration capacity of dypiridamole-loaded 3D-printed bioceramic (DIPY-3DPBC) scaffolds composed of 100% beta-tricalcium phosphate (β -TCP) in an immature rabbit model through the time of facial maturity. The efficacy of this construct was compared to autologous bone graft, the clinical standard of care in pediatric craniofacial reconstruction, with attention paid to volume of regenerated bone by 3D reconstruction, histologic and mechanical properties of regenerated bone, and long-term safety regarding potential craniofacial growth restriction. Additionally, long-term degradation of scaffold constructs was evaluated. At 24 weeks in vivo, DIPY-3DPBC scaffolds demonstrated volumetrically significant osteogenic regeneration of calvarial and alveolar defects comparable to autogenous bone graft with favorable biodegradation of the bioactive ceramic component in vivo. Characterization of regenerated bone reveals osteogenesis of organized, vascularized bone with histologic and mechanical characteristics comparable to native bone. Radiographic and histologic analyses were consistent with patent craniofacial sutures. Lastly, through application of 3D morphometric facial surface analysis, our results support that DIPY-3DPBC scaffolds do not cause premature closure of sutures and preserve normal craniofacial growth. Based on this novel evaluation model, this DIPY-3DPBC scaffold strategy is a promising candidate as a safe, efficacious pediatric bone tissue engineering strategy.

Regeneration of a Pediatric Alveolar Cleft Model Using Three-Dimensionally Printed Bioceramic Scaffolds and Osteogenic Agents: Comparison of Dipyridamole and rhBMP-2

BACKGROUND

Alveolar clefts are traditionally treated with secondary bone grafting, but this is associated with morbidity and graft resorption. Although recombinant human bone morphogenetic protein-2 (rhBMP-2) is under investigation for alveolar cleft repair, safety concerns remain. Dipyridamole is an adenosine receptor indirect agonist with known osteogenic potential. This study compared dipyridamole to rhBMP-2 at alveolar cleft defects delivered using bioceramic scaffolds.

METHODS

Skeletally immature New Zealand White rabbits underwent unilateral, 3.5 × 3.5-mm alveolar resection adjacent to the growing suture. Five served as negative controls. The remaining defects were reconstructed with three-dimensionally printed bioceramic scaffolds coated with 1000 μm of dipyridamole (n = 6), 10,000 μm of dipyridamole (n = 7), or 0.2 mg/ml of rhBMP-2 (n = 5). At 8 weeks, new bone was quantified. Nondecalcified histologic evaluation was performed, and new bone was evaluated mechanically. Statistical analysis was performed using a generalized linear mixed model and the Wilcoxon rank sum test.

RESULTS

Negative controls did not heal, whereas new bone formation bridged all three-dimensionally printed bioceramic treatment groups. The 1000-μm dipyridamole scaffolds regenerated 28.03 ± 7.38 percent, 10,000-μm dipyridamole scaffolds regenerated 36.18 ± 6.83 percent (1000 μm versus 10,000 μm dipyridamole; p = 0.104), and rhBMP-2-coated scaffolds regenerated 37.17 ± 16.69 percent bone (p = 0.124 versus 1000 μm dipyridamole, and p = 0.938 versus 10,000 μm dipyridamole). On histology/electron microscopy, no changes in suture biology were evident for dipyridamole, whereas rhBMP-2 demonstrated early signs of suture fusion. Healing was highly cellular and vascularized across all groups. No statistical differences in mechanical properties were observed between either dipyridamole or rhBMP-2 compared with native bone.

CONCLUSION

Dipyridamole generates new bone without osteolysis and early suture fusion associated with rhBMP-2 in skeletally immature bone defects.

Local delivery of adenosine receptor agonists to promote bone regeneration and defect healing

Adenosine receptor activation has been investigated as a potential therapeutic approach to heal bone. Bone has enhanced regenerative potential when influenced by either direct or indirect adenosine receptor agonism. As investigators continue to elucidate how adenosine influences bone cell homeostasis at the cellular and molecular levels, a small but growing body of literature has reported successful in vivo applications of adenosine delivery. This review summarizes the role adenosine receptor ligation plays in osteoblast and osteoclast biology and remodeling/regeneration. It also reports on all the modalities described in the literature at this point for delivery of adenosine through in vivo models for bone healing and regeneration.

The role of 3D printing in treating craniomaxillofacial congenital anomalies

Craniomaxillofacial congenital anomalies comprise approximately one third of all congenital birth defects and include deformities such as alveolar clefts, craniosynostosis, and microtia. Current surgical treatments commonly require the use of autogenous graft material which are difficult to shape, limited in supply, associated with donor site morbidity and cannot grow with a maturing skeleton. Our group has demonstrated that 3D printed bio-ceramic scaffolds can generate vascularized bone within large, critical-sized defects (defects too large to heal spontaneously) of the craniomaxillofacial skeleton. Furthermore, these scaffolds are also able to function as a delivery vehicle for a new osteogenic agent with a well-established safety profile. The same 3D printers and imaging software platforms have been leveraged by our team to create sterilizable patient-specific intraoperative models for craniofacial reconstruction. For microtia repair, the current standard of care surgical guide is a two-dimensional drawing taken from the contralateral ear. Our laboratory has used 3D printers and open source software platforms to design personalized microtia surgical models. In this review, we report on the advancements in tissue engineering principles, digital imaging software platforms and 3D printing that have culminated in the application of this technology to repair large bone defects in skeletally immature transitional models and provide in-house manufactured, sterilizable patient-specific models for craniofacial reconstruction.

Synergistic effect of nutlin-3 combined with aspirin in hepatocellular carcinoma HepG2 cells through activation of Bcl-2/Bax signaling pathway

Aspirin as an antitumor drug has been studied in various malignancies with regards to its effects on apoptosis, proliferation, metastasis and senescence of tumor cells. However, the clinical application is limited by its side effects. Nutlin-3 is a novel antitumor compound, which has not been clinically approved. The present study investigated the value of combining aspirin and nutlin-3 on hepatocellular carcinoma (HCC) cells. MTT was performed to detect the proliferation of HepG2 cells treated with aspirin or/and nutlin-3. Transwell invasion assays were performed to estimate the invasion ability of HepG2 cells treated with aspirin or/and nutlin-3. Then the apoptotic analysis of HepG2 cells evaluated the synergistic effect of aspirin and nutlin-3. Apoptosis markers, including B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3, caspase-8 and caspase-9 were estimated by western blot analysis at various time points. In addition, a Xenograft mouse model was established by infection with HepG2 cells, and aspirin and/or nutlin-3 was administrated to verify the anti-apoptotic effect of the two drugs in vivo. A high dose of aspirin and nutlin-3 inhibit the proliferation and apoptosis of HepG2 cells. The antitumor effect was enhanced with the combined treatment of the two drugs, particularly in the group with a low concentration of aspirin and nutlin-3. Nutlin-3 was able to increase the level of Bax in HepG2 cells treated with aspirin significantly after treatment for 8 h. When treated with a low concentration of aspirin and nutlin-3, the level of Bax in HepG2 cells was enhanced for 2 h. In the animal model, tumor volume and tumor angiogenesis were significantly decreased in combination group compared with other groups (P<0.01). Although there were side effects in the group treated with aspirin alone, no side effects were observed in the combination group. Nutlin-3 enhanced the apoptotic effect of a low dose of aspirin by upregulating Bax expression in the HepG2 cell line and in vivo. The synergistic effect of nutlin-3 in aspirin antitumor therapy contributed to diminishing the dose of aspirin required and decreased the occurrence of adverse drug events in HCC through targeting the Bcl-2/Bax signaling pathway.

Dipyridamole enhances osteogenesis of three-dimensionally printed bioactive ceramic scaffolds in calvarial defects

PURPOSE

The objective of this study was to test the osteogenic capacity of dipyridamole-loaded, three-dimensionally printed, bioactive ceramic (3DPBC) scaffolds using a translational, skeletally mature, large-animal calvarial defect model.

MATERIALS AND METHODS

Custom 3DPBC scaffolds designed to present lattice-based porosity only towards the dural surface were either coated with collagen (control) or coated with collagen and immersed in a 100 μM concentration dipyridamole (DIPY) solution. Sheep (n = 5) were subjected to 2 ipsilateral trephine-induced (11-mm diameter) calvarial defects. Either a control or a DIPY scaffold was placed in each defect, and the surgery was repeated on the contralateral side 3 weeks later. Following sacrifice, defects were evaluated through microcomputed tomography and histologic analysis for bone, scaffold, and soft tissue quantification throughout the defect. Parametric and non-parametric methods were used to determine statistical significance based on data distribution.

RESULTS

No exuberant or ectopic bone formation was observed, and no histologic evidence of inflammation was noted within the defects. Osteogenesis was higher in DIPY-coated scaffolds compared to controls at 3 weeks (p = 0.013) and 6 weeks (p = 0.046) in vivo. When bone formation was evaluated as a function of defect radius, average bone formation was higher for DIPY relative to control scaffolds at both time points (significant at defect central regions at 3 weeks and at margins at 6 weeks, p = 0.046 and p = 0.031, respectively).

CONCLUSION

Dipyridamole significantly improves the calvarial bone regeneration capacity of 3DPBC scaffolds. The most significant difference in bone regeneration was observed centrally within the interface between the 3DPBC scaffold and the dura mater.

Exploring clinicians' attitudes about using aspirin for risk reduction in people with Lynch Syndrome with no personal diagnosis of colorectal cancer

Recent research has shown that aspirin reduces the risk of cancers associated with Lynch Syndrome. However, uncertainty exists around the optimal dosage, treatment duration and whether the benefits of aspirin as a risk-reducing medication (RRM) outweigh adverse medication related side-effects. Little is known about clinicians' attitudes, current practice, and perceived barriers to recommending aspirin as a RRM. To explore the attitudes of clinicians who discuss risk management options with patients with Lynch Syndrome towards using aspirin as a RRM. Clinicians were invited through professional organisations to complete an online survey. Topics included their clinical experience with Lynch Syndrome, views and practice of recommending aspirin as a RRM, and knowledge about clinical risk management guidelines for Lynch Syndrome. Comparison of attitudes was made between three professional groups. 181 respondents were included in the analysis: 59 genetics professionals (genetic counsellors and clinical geneticists, medical oncologists with specialist training in familial cancer), 49 gastroenterologists and 73 colorectal surgeons. Most clinicians (76 %) considered aspirin to be an effective RRM and most (72 %) were confident about discussing it. In all professional categories, those who were confident about discussing aspirin with patients perceived it to be an effective RRM (OR = 2.8 [95 % CI = 1.8-4.2], p < 0.001). Eighty percent (47/59) of genetics professionals reported having discussed the use of aspirin with Lynch Syndrome patients compared to 69 % of gastroenterologists and 68 % of colorectal surgeons. Those who considered aspirin as an effective RRM or who felt confident in their knowledge of the aspirin literature were more likely (OR = 10 [95 % CI = 1.5-65], p = 0.010, OR = 6 [95 % CI = 2.2-16], p < 0.001, respectively) to discuss it with their patients than other professionals in the study. Similarly health professionals who felt confident in their knowledge of literature of aspirin/confident in discussing with the patients were more likely (OR = 6 [95 % CI = 2.2-16], p < 0.001) to discuss with their patients. Health professionals who saw more than ten patients with Lynch Syndrome per year were more likely to be confident in their knowledge of the aspirin literature and discussing it with patients (OR = 4.1 [95 % CI = 1.6-10.2], p = 0.003). Explicit recommendations to take aspirin, was reported by 65/83 (78 %) of health professionals. Eighty-seven percent of health professionals reported a need for patient educational materials about aspirin. Continuing training is needed to increase clinicians' confidence in their knowledge of the literature on the use of aspirin as a RRM. Patient education materials may be helpful in improving consistency in patient care and facilitate communication between clinicians and people living with Lynch Syndrome.

Coxibs, Traditional NSAIDs, and Cardiovascular Safety Post-PRECISION: What We Thought We Knew Then and What We Think We Know Now

The aim of the present review is to analyze how thinking about the cardiovascular safety of nonsteroidal antiinflammatory drugs has evolved during the past two decades, and discuss to what extent the additional information from the Prospective Randomized Evaluation of Celecoxib Integrated Safety Versus Ibuprofen or Naproxen study may alter our current mechanistic understanding and/or clinical practice.

The application of thromboelastogram in detection of indexes of antiplatelet therapy for coronary heart disease

BACKGROUND

This study aims to explore the application value of thromboelastogram (TEG) in antiplatelet therapy in coronary artery intervention.

METHODS

A retrospective analysis of 90 cases of coronary interventional treatment was conducted in our hospital from January 2010 to January 2012. Cases were divided into three groups, according to the kind of coronary heart disease: angina pectoris (AP) group (30 cases), unstable angina pectoris (UAP) group (30 cases) and acute myocardial infarction (AMI) group (30 cases). TEG changes in patients between the three groups were analyzed.

RESULTS

The differences in international normalized ratio (INR) and activated partial thromboplastin time (APTT) indexes among the three groups of patients were statistically significant (P<0.05), but these indexes significantly decreased in the AMI group. Furthermore, D-D, Fgb, Angle and MA indexes significantly increased in the UAP and AMI groups, compared with the AP group; while TEG regular parameter K and R values were markedly reduced. Coagulation graphics were higher in the UAP and AMI groups than in the AP group (χ²=4.261, 3.908; P<0.05), suggesting that the difference was statistically significant. In 11 cases of ischemic events, arachidonic acid (AA)-induced platelet inhibition rate was 63.63%, while adenosine diphosphate (ADP)-induced platelet inhibition rate was 36.37% (χ²=5.026; P<0.05); suggesting that ADP-induced platelet inhibition rate was markedly reduced. This is the main risk of ischemic events within three months after percutaneous coronary intervention.

CONCLUSIONS

The detection of indexes of antiplatelet therapy in coronary artery intervention is helpful for antiplatelet medication, thus can effectively reduce the incidence of ischemic events.

Patterns in the use of low-dose acetylsalicylic acid and other therapies following upper gastrointestinal bleeding

BACKGROUND

Anticoagulants and/or antiplatelet agents such as acetylsalicylic acid (ASA) are important in prevention of cardiovascular (CV) events, but may be associated with upper gastrointestinal bleeding (UGIB). However, discontinuing these agents may leave patients at risk of CV events.

OBJECTIVES

This study aimed to assess patterns of therapy after UGIB in routine clinical practice.

METHODS

The Health Improvement Network UK primary care database was used to identify a cohort of patients aged 40-84 years with a UGIB event between 2000 and 2007 (n = 2,036). Patients were followed up for 1 year from the recorded UGIB. Re-prescription rates for antithrombotics and drugs that can modify the risk of UGIB were estimated at 30, 90, 180, and 365 days.

RESULTS

At 365 days, the re-prescription rate was 43 % for ASA, 66 % for warfarin, 69 % for clopidogrel, and 49 % for dipyridamole. The re-prescription rate of gastroprotective agents at 365 days for current users of histamine H2-receptor antagonists was 36 % and that of proton pump inhibitors (PPIs) was 97 %. In patients who were prescribed ASA before UGIB (n = 572), only 24 % were prescribed a PPI in the previous year. In patients who were prescribed ASA in the year after UGIB (n = 337), 92 % were prescribed a PPI.

CONCLUSIONS

Antiplatelet use fell after UGIB events. In patients who were prescribed a PPI after a UGIB event, there was increased re-prescription of antiplatelet agents and antithrombotics.

Oral antiplatelet therapy for acute ischaemic stroke

BACKGROUND

In people with acute ischaemic stroke, platelets become activated and can cause blood clots to form and block an artery in the brain, resulting in damage to part of the brain. Such damage gives rise to the symptoms of stroke. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and also reduce the risk of early recurrent ischaemic stroke, thereby reducing the risk of early death and improving long-term outcomes in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

OBJECTIVES

To assess the efficacy and safety of immediate oral antiplatelet therapy (that is started as soon as possible and no later than two weeks after stroke onset) in people with acute presumed ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 16 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2013), MEDLINE (June 1998 to May 2013), and EMBASE (June 1998 to May 2013). In 1998, for a previous version of this review, we searched the register of the Antiplatelet Trialists' Collaboration, MedStrategy and contacted relevant drug companies.

SELECTION CRITERIA

Randomised trials comparing oral antiplatelet therapy (started within 14 days of the stroke) with control in people with definite or presumed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria and assessed trial quality. For the included trials, they extracted and cross-checked the data.

MAIN RESULTS

We included eight trials involving 41,483 participants. No new trials have been added since the last update.Two trials testing aspirin 160 mg to 300 mg once daily, started within 48 hours of onset, contributed 98% of the data. The risk of bias was low. The maximum follow-up was six months. With treatment, there was a significant decrease in death or dependency at the end of follow-up (odds ratio (OR) 0.95, 95% confidence interval (CI) 0.91 to 0.99). For every 1000 people treated with aspirin, 13 people would avoid death or dependency (number needed to treat 79). Antiplatelet therapy was associated with a small but definite excess of symptomatic intracranial haemorrhages, but this small hazard was significantly outnumbered by the benefit, the reduction in recurrent ischaemic stroke and pulmonary embolus.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in people who cannot swallow) and started within 48 hours of onset of presumed ischaemic stroke, reduced the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications; long-term outcomes were improved.

Perioperative management of antiplatelet therapy

Worldwide, cardiovascular events represent the major cause of morbidity and mortality. A key role in the pathogenesis of these events is played by platelets. Interventional procedures, with placement of coronary and vascular stents, often represent the preferred therapeutic strategy. Antiplatelet medications are considered first-line therapy in preventing cardiovascular thrombotic events. A wide array of antiplatelet agents is available, each with different pharmacological properties. When patients on antiplatelet agents present for surgery, the perioperative team must design an optimal strategy to manage antiplatelet medications. Each patient is stratified according to risk of developing a cardiovascular thrombotic event and inherent risk of surgical bleeding. After risk stratification analysis, various therapeutic pathways include continuing or discontinuing all antiplatelet agents or maintaining one antiplatelet agent and discontinuing the other. This review focuses on the pharmacological and pharmacokinetic properties of both older and novel antiplatelet drugs, and reviews current literature and guidelines addressing options for perioperative antiplatelet management.

Indications for platelet aggregation inhibitors after venous stents

Iliofemoral venous obstruction may arise from either primary compressive lesions or may be secondary to an episode of deep venous thrombosis. Regardless of aetiology, these lesions, either alone or in association with more distal reflux, may be responsible for lower extremity pain, swelling, and ulceration. Conventional surgical procedures for the treatment of iliofemoral venous obstruction have largely been supplanted by endovascular approaches relying on the deployment of venous stents. Large series have reported good technical and clinical results from venous stenting, particularly for primary lesions. However, early stent occlusions and late re-stenosis do occur. Although most of these appear related to technical factors, there is likely a role for pharmacological adjuncts in maintaining stent patency. The use of anticoagulants and antiplatelet agents is largely based on the underlying pathophysiology and extrapolation from arterial interventions, which likely are significantly different with respect to their pathophysiology and natural history. Although lacking substantial evidence demonstrating efficacy, the use of adjunctive antiplatelet agents in stents placed for primary lesions and consideration of anticoagulation for high-risk post-thrombotic lesions appears to be reasonable.

Evaluative comparison of systemic aspirin therapy effects on gingival bleeding in post non-surgical periodontal therapy individuals

BACKGROUND

Gingival bleeding is considered as an important clinical sign for diagnosis of periodontal disease pathogenesis. Immune inflammatory reactions caused by local factors are considered as essential reasons for gingival bleeding, as also for the systemic bleeding disorders. In disease-free conditions of gingiva, the bleeding disorders are considered to be the main contender for bleeding. Other than these variables, many systemic drugs including systemic aspirin could also cause gingival bleeding. The main aim of the study was to evaluate the effect of buffered aspirin therapy on gingival bleeding.

MATERIALS AND METHODS

Totally, 36 systemically healthy individuals were included in the 15-day randomized, double-blinded, placebo-controlled clinical trial. The 15 days were divided as: control period for the first 7 days and study period for the following 7 days. On the 1(st) day, all individuals were given oral prophylaxis after recording gingival parameters such as Plaque Index, probing depth, and Bleeding Index, and then blood samples were collected for hematological investigations. Then, all individuals were administered placebo capsules for 1 week as once daily dose. On the 8(th) day, all procedures were repeated and the individuals were prescribed with 325 coated aspirin capsules for 1 week. On the 15(th) day, all parameters were repeated and the results were statistically analyzed.

RESULTS

In the study period, the parameters such as Bleeding Index, bleeding time, and prothrombin time were increased significantly, compared to the control period.

CONCLUSION

The variables such as systemic drug therapy should be considered for the examination of gingiva while the diagnosis is considered mainly based on gingival bleeding.

Minimizing cardiovascular complications during the treatment of osteoarthritis

Individuals with osteoarthritis face an increased risk of cardiovascular (CV) disease compared with age-matched control subjects. Both conditions share some common risk factors (eg, age, obesity, and hypertension) and the consequences or treatment of osteoarthritis may increase CV risk by impairing physical activity and exacerbating CV risk factors. Nonsteroidal anti-inflammatory drugs may have prothrombotic and/or hypertensive effects and a negative impact on renal function, all of which contribute to the increased risk of CV disease associated with these agents. The magnitude of these effects differs between agents and is, in part, determined by the relative balance of cyclo-oxygenase-1 or cyclo-oxygenase-2 inhibition. To minimize risk of CV disease in patients with osteoarthritis taking nonsteroidal anti-inflammatory drugs, physicians need to 1) monitor blood pressure and the new appearance or exacerbation of edema; 2) encourage lifestyle changes/nonpharmacologic treatments for pain/risk factor management; 3) choose the lowest effective dose of appropriate drug therapy to achieve adequate pain relief while minimizing CV risk; 4) change nonsteroidal anti-inflammatory drugs as needed to one with lower propensity to aggravate CV risk; and 5) modulate antihypertensive therapy and diuretic management as needed to maintain target blood pressure and weight.

Aspirin resistance: disparities and clinical implications

Abstract Aspirin is one of the most widely prescribed drugs for the prevention of thrombosis in patients with vascular disease. Yet, aspirin is unable to prevent thrombosis in all patients. The term "aspirin resistance" has been used to broadly define the failure of aspirin to prevent a thrombotic event. Whether this is directly related to aspirin itself through biochemical aspirin resistance or treatment failure, or if it is because of aspirin's inability to overcome the thrombogenic aspects of the disease process itself, has not been elucidated. This can have dramatic clinical implications for a variety of vascular disease subsets and is cause for concern, considering the high prevalence of aspirin use for both primary and secondary prevention. Disparities exist in the rates of aspirin resistance among certain patient populations, such as women, patients with diabetes mellitus, and those with heart failure, and across clinical conditions, such as cardiovascular and cerebrovascular disease. Clinical trial data from studies observing resistance have revealed that regardless of study size, dose of aspirin, control for drug interactions and adherence, or assay used to measure platelet function, aspirin resistance is associated with an increased risk for adverse events. Although the evidence is mounting, there has yet to be a consensus on the appropriate clinical response to aspirin resistance.

Use of antiplatelet agents for prevention of ischemic stroke

Overall management to lower risk for ischemic stroke is multifaceted. Management includes measures to treat risk factors for accelerated atherosclerosis and stroke, antithrombotic therapies to lower the risk for thromboembolism, and surgery to treat a defined arterial or cardiac lesion. Treatment decisions are made on a case-by-case basis, with most patients receiving some combination of medication and recommendations for lifestyle modification. Some patients will also undergo surgical or endovascular interventions. This article discusses antithrombotic treatment for ischemic stroke prevention, placing major emphasis on the indications for and administration of antiplatelet therapy.

Antiplatelet therapy for acute ischaemic stroke

BACKGROUND

In patients with acute ischaemic stroke, platelets become activated. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and reduce the risk of early recurrent ischaemic stroke. This might reduce the risk of early death and improve long-term outcome in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

OBJECTIVES

To assess the efficacy and safety of antiplatelet therapy in acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched June 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2007), MEDLINE (June 1998 to May 2007), and EMBASE (June 1998 to May 2007). In 1998, for a previous version of this review, we searched the register of the Antiplatelet Trialists' Collaboration, MedStrategy and contacted relevant drug companies.

SELECTION CRITERIA

Randomised trials comparing antiplatelet therapy (started within 14 days of the stroke) with control in patients with definite or presumed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria and assessed trial quality, and for the included trials, extracted and cross-checked the data.

MAIN RESULTS

Twelve trials involving 43,041 participants were included. Two trials testing aspirin 160 mg to 300 mg once daily started within 48 hours of onset contributed 94% of the data. The maximum follow up was six months. With treatment, there was a significant decrease in death or dependency at the end of follow up (odds ratio 0.95, 95% confidence interval 0.91 to 0.99). For every 1000 patients treated with aspirin, 13 patients will avoid death or dependency (number needed to treat to benefit: 79). Antiplatelet therapy was associated with a small but definite excess of symptomatic intracranial haemorrhages, but this was more than offset by the reduction of recurrent ischaemic strokes and pulmonary embolus.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in patients who cannot swallow), and started within 48 hours of onset of presumed ischaemic stroke reduces the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications and improves long-term outcome.

A practice survey of shoulder glucocorticoid injections in patients on antiplatelet drugs or vitamin K antagonists

OBJECTIVE

Little is known about practice patterns regarding shoulder glucocorticoid injections in patients taking antiplatelet drugs or vitamin K antagonists. The objective of this study was to collect relevant data among rheumatologists in France.

METHODS

We conducted a postal questionnaire survey among 2015 rheumatologists.

RESULTS

We received 1018 completed questionnaires (response rate, 1018/2015, 50.5%). The proportion of rheumatologists who discontinued drugs with antithrombotic effects prior to shoulder injections varied across drugs, as follows: nonsteroidal antiinflammatory drugs (NSAIDs), 2.6%; dipyridamole, 7.5%; aspirin, 9%; ticlopidine, 25%; clopidogrel, 28%; and vitamin K antagonists, 74%. Among rheumatologists who discontinued vitamin K antagonist therapy, 82% prescribed replacement therapy with low-molecular-weight heparin. Time from discontinuation to injection was not consistently appropriate to the duration of drug effects. Prior to the injection, hemostasis tests were obtained by 1% of rheumatologists for patients on NSAIDs, 6% for those on clopidogrel, and 65% for those on vitamin K antagonists. Only 1% of rheumatologists had observed bleeding events in patients on aspirin, compared to 10% in patients on vitamin K antagonists. The mean number of shoulder glucocorticoid injections per rheumatologist per month was 19.6; 4% of rheumatologists routinely obtained hemostasis tests before shoulder injections.

CONCLUSION

Considerable variations were found among rheumatologists regarding practice patterns for performing shoulder glucocorticoid injections. This variability reflects the absence of official guidelines. The GREP is working with French hematologists to develop clinical practice guidelines.

Non?ST segment elevation acute coronary syndromes: Treatment guidelines for the nurse practitioner

PURPOSE

To increase awareness among nurse practitioners (NPs) of the American College of Cardiology (ACC)/American Heart Association (AHA) 2002 guideline update for the diagnosis and treatment of acute coronary syndrome, and for secondary prevention in patients with unstable angina (UA) and non-ST segment elevation myocardial infarction (NSTEMI).

DATA SOURCES

ACC/AHA 2002 guideline update for the management of patients with UA and NSTEMI, ACC/AHA guidelines for patients with coronary and other atherosclerotic vascular disease, 2006 update, selected research and clinical articles.

CONCLUSIONS

Recent research has shown that patients with UA/NSTEMI benefit from the routine, long-term use of dual antiplatelet therapy with aspirin and clopidogrel. In suitable patients, outcome is also improved by adoption of an early invasive strategy combined with aggressive medical therapy.

IMPLICATIONS FOR PRACTICE

Familiarity with the patient as well as current management recommendations can improve clinical outcomes for patients with UA/NSTEMI. Thus, NPs can play a pivotal role in the management of coronary disease, both during and following an acute ischemic event.

Design of a transdermal delivery system for aspirin as an antithrombotic drug

Aspirin has become the gold standard to which newer antiplatelet drugs are compared for reducing risks of cardiovascular diseases, while keeping low cost. Oral aspirin has a repertoire of gastrointestinal side effects even at low doses and requires high frequent dosing because it undergoes extensive presystemic metabolism. Transdermal delivery offers an alternative route that bypasses the gut and may be more convenient and safer for aspirin delivery especially during long-term use. This study comprised formulation of aspirin in different topical bases. Release studies revealed that hydrocarbon gel allowed highest drug release. In vitro permeation studies revealed high drug permeation from hydrocarbon gel. Several chemical penetration enhancers were monitored for augmenting the permeation from this base. Combination of propylene glycol and alcohol showed maximum enhancing effect and, hence, was selected for biological investigation. The biological performance of the selected formulation was assessed by measuring the inhibition of platelet aggregation relevant to different dosage regimens aiming to minimize both drug dose and frequency of application. The results demonstrated the feasibility of successfully influencing platelet function and revealed that the drug therapeutic efficacy in transdermal delivery system is dose independent. Biological performance was re-assessed after storage and the results revealed stability and persistent therapeutic efficacy.

Aspirin resistance, an emerging, often overlooked, factor in the management of patients with coronary artery disease

Aspirin is the most widely used medication in patients with cardiovascular disease. It has had a greater effect on patients with cardiovascular disease than any other drug. With the importance of aspirin now known for decades, it is recently becoming clearer that some patients do not derive as great a benefit from this "wonder drug" secondary to their resistance to its effects. Aspirin resistance, its prevalence, its identification, and how to overcome or avert it with other medications then becomes a central topic of discussion as important, if not more so, than the importance of aspirin itself as a cornerstone in the treatment of patients with cardiovascular disease. This review explores the current understanding of the mechanism of aspirin resistance with regard to its prevalence and the magnitude of its clinical significance. It also examines the therapeutic implications of a diagnosis of aspirin resistance.

Antithrombotic action of annexin V proved as efficient as direct inhibition of tissue factor or thrombin

The role of phospholipid platelet membrane and tissue factor in thrombin generation and thrombus formation is accepted. In the present study we have explored antithrombotic action of strategies aimed to block exposure of negatively charged phospholipids and we compared effects with those obtained through tissue factor or a direct thrombin inhibition. Type III collagen was exposed to flowing blood (5 min, 300 s(-1)). Effects of inhibition of platelet deposition by annexin A5 (ANXA5), hirudin (HIR) or by an antibody against tissue factor (TF) were evaluated. Prothrombin fragment F1 + 2 (F1 + 2) was monitored. Pre-incubation of whole blood with HIR or ANXA5 resulted in a statistically significant reduction of platelet deposition (12.2 +/- 0.6% in control experiments vs. 8.3 +/- 0.4% and 8.5 +/- 0.5%, respectively, P < 0.05). A similar decrease was found when blood was incubated with an antibody against TF. Furthermore, ANXA5 and HIR inhibited the recruitment of platelets into forming aggregates. The height of platelet aggregates generated was decreased in the presence of HIR or ANXA5, but only incubation with both inhibitors reached levels of statistical significance. The presence of ANXA5 or HIR decreased levels of F1 + 2 suggesting a reduced activation of the coagulation system. In our experimental studies, the inhibitory potential of ANXA5 on platelet-thrombus formation was as effective as that of a direct thrombin inhibitor, as HIR, or an antibody against TF. Negatively charged phospholipids exposed on activated platelets potentiate the formation of platelet aggregates on a collagen surface and further suggest that inhibition of platelet procoagulant activity might be a specific target for antithrombotic drugs.

Clopidogrel plus aspirin versus oral anticoagulation for atrial fibrillation in the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W): a randomised controlled trial

BACKGROUND

Oral anticoagulation therapy reduces risk of vascular events in patients with atrial fibrillation. However, long-term monitoring is necessary and many patients cannot achieve optimum anticoagulation. We assessed whether clopidogrel plus aspirin was non-inferior to oral anticoagulation therapy for prevention of vascular events.

METHODS

Patients were enrolled if they had atrial fibrillation plus one or more risk factor for stroke, and were randomly allocated to receive oral anticoagulation therapy (target international normalised ratio of 2.0-3.0; n=3371) or clopidogrel (75 mg per day) plus aspirin (75-100 mg per day recommended; n=3335). Outcome events were adjudicated by a blinded committee. Primary outcome was first occurrence of stroke, non-CNS systemic embolus, myocardial infarction, or vascular death. Analyses were by intention-to-treat. This study is registered with ClinicalTrials.gov, number NCT00243178.

RESULTS

The study was stopped early because of clear evidence of superiority of oral anticoagulation therapy. There were 165 primary events in patients on oral anticoagulation therapy (annual risk 3.93%) and 234 in those on clopidogrel plus aspirin (annual risk 5.60%; relative risk 1.44 (1.18-1.76; p=0.0003). Patients on oral anticoagulation therapy who were already receiving this treatment at study entry had a trend towards a greater reduction in vascular events (relative risk 1.50, 95% CI 1.19-1.89) and a significantly (p=0.03 for interaction) lower risk of major bleeding with oral anticoagulation therapy (1.30; 0.94-1.79) than patients not on this treatment at study entry (1.27, 0.85-1.89 and 0.59, 0.32-1.08, respectively).

CONCLUSION

Oral anticoagulation therapy is superior to clopidogrel plus aspirin for prevention of vascular events in patients with atrial fibrillation at high risk of stroke, especially in those already taking oral anticoagulation therapy.

Rationale and design of ACTIVE: the atrial fibrillation clopidogrel trial with irbesartan for prevention of vascular events

BACKGROUND

Atrial fibrillation (AF) is the most frequently occurring cardiac arrhythmia with often serious clinical consequences. Many patients have contraindications to anticoagulation, and it is often underused in clinical practice. The addition of clopidogrel to aspirin (ASA) has been shown to reduce vascular events in a number of high-risk populations. Irbesartan is an angiotensin receptor-blocking agent that reduces blood pressure and has other vascular protective effects.

METHODS AND RESULTS

ACTIVE W is a noninferiority trial of clopidogrel plus ASA versus oral anticoagulation in patients with AF and at least 1 risk factor for stroke. ACTIVE A is a double-blind, placebo-controlled trial of clopidogrel in patients with AF and with at least 1 risk factor for stroke who receive ASA because they have a contraindication for oral anticoagulation or because they are unwilling to take an oral anticoagulant. ACTIVE I is a partial factorial, double-blind, placebo-controlled trial of irbesartan in patients participating in ACTIVE A or ACTIVE W. The primary outcomes of these studies are composites of vascular events. A total of 14000 patients will be enrolled in these trials.

CONCLUSIONS

ACTIVE is the largest trial yet conducted in AF. Its results will lead to a new understanding of the role of combined antiplatelet therapy and the role of blood pressure lowering with an angiotensin II receptor blocker in patients with AF.

Prevalence and incidence of gastroduodenal ulcers during treatment with vascular protective doses of aspirin

BACKGROUND

Aspirin is valuable for preventing vascular events, but information about ulcer frequency is necessary to inform risk-benefit decisions in individual patients.

AIM

To determine ulcer prevalence and incidence in a population representative of those given aspirin therapy and evaluate risk predictors.

METHODS

Patients taking aspirin 75-325 mg daily were recruited from four countries. Exclusions included use of gastroprotectant drugs or other non-steroidal anti-inflammatory drugs. We measured point prevalence of endoscopic ulcers, after quantitating dyspeptic symptoms. Incidence was assessed 3 months later in those eligible to continue (no baseline ulcer or reason for gastroprotectants).

RESULTS

In 187 patients, ulcer prevalence was 11% [95% confidence interval (CI) 6.3-15.1%]. Only 20% had dyspeptic symptoms, not significantly different from patients without ulcer. Ulcer incidence in 113 patients followed for 3 months was 7% (95% CI 2.4-11.8%). Helicobacter pylori infection increased the risk of a duodenal ulcer [odds ratio (OR) 18.5, 95% CI 2.3-149.4], as did age >70 for ulcers in stomach and duodenum combined (OR 3.3, 95% CI 1.3-8.7).

CONCLUSIONS

Gastroduodenal ulcers are found in one in 10 patients taking low-dose aspirin, and most are asymptomatic; this needs considering when discussing risks/benefits with patients. Risk factors include older age and H. pylori (for duodenal ulcer).

Modified-release dipyridamole combined with aspirin for secondary stroke prevention

Patients suffering from transient ischemic attack (TIA) or ischemic stroke have a high risk of suffering a first or recurrent stroke, with an annual risk of between 5 and 15%. The European Stroke Prevention Study (ESPS)2 was a randomized, double-blind, placebo-controlled trial involving 6602 patients with TIA or stroke comparing aspirin alone (50 mg daily), modified-release (MR) dipyridamole alone (200 mg twice daily), aspirin plus dipyridamole, and placebo. The 2-year relative risk reduction of stroke in the aspirin plus MR-dipyridamole group (37.0%) was significantly higher than in either the aspirin group (18.1%) or the MR-dipyridamole group (16.3%). The results of the comparison between aspirin plus MR-dipyridamole versus placebo confirmed the findings of ESPS1. The results of ESPS2 were at odds with all prior trials with dipyridamole alone or in association with aspirin, but it was also the only trial sufficiently powered to show a significant difference. For this reason, a meta-analysis was performed based on a systematic review of individual patient data from randomized controlled trials involving dipyridamole in patients with prior ischemic stroke or TIA. Recurrent stroke was reduced by dipyridamole compared with placebo, and by combined aspirin and dipyridamole versus aspirin alone, dipyridamole alone or placebo. In two post hoc analyses the efficacy of aspirin plus extended-release dipyridamole was compared with aspirin alone for the prevention of recurrent stroke among high-risk groups. Stroke models from the Framingham Study and the Stroke Prognostic Instrument II were applied to subjects in ESPS2 to assign patients to risk groups. Compared with aspirin alone, aspirin plus MR-dipyridamole demonstrated a more pronounced efficacy in reducing the risk for stroke and vascular events among patients younger than 70 years of age, with hypertension, or prior stroke; current smokers; and those with any prior cardiovascular disease. Another model (Essen risk score) showed that patients with a high risk of recurrent stroke show a much greater benefit from aspirin plus MR-dipyridamole compared with aspirin monotherapy than patients with a low risk.

Management of the anticoagulated patient

Excessive bleeding or thrombosis is a preeminent concern for all surgeons. Patients may be at risk because of medical therapy, underlying disease, or complications related to both. An understanding of the coagulation cascade--mechanisms and tests of function--permits a rational, if not always complete, basis for a plan of therapy. Newer anticoagulation medications are changing how thrombotic complications, such a VTE or graft occlusion, are treated or prevented. This entire area is undergoing rapid evolution, and the approaches that have been standard for decades soon will be supplanted. Ultimately, however, the most important assessment is made at the bedside by the clinician.

Superior efficacy of clopidogrel plus acetylsalicylic acid compared with extended-release dipyridamole plus acetylsalicylic acid in preventing arterial thrombogenesis in healthy volunteers

INTRODUCTION

Recent ex vivo platelet aggregometry data indicate that clopidogrel 75 mg/day plus acetylsalicylic acid (ASA) 75 mg/day is a more potent antiplatelet regimen than the marketed combination of dipyridamole+ASA. The present study was designed to assess the antithrombotic effect of both dual antiplatelet regimens using a human ex vivo model of arterial thrombosis.

MATERIALS AND METHODS

This was a randomized, double-blind, placebo-controlled, crossover study. During two 10-day treatment periods separated by a 14-day washout period, 23 healthy male volunteers received once-daily clopidogrel 75 mg plus acetylsalicylic acid 75 mg, or twice-daily extended-release dipyridamole 200 mg plus acetylsalicylic acid 25 mg. Assessments were made at baseline and on Day 10 of each period. Arterial thrombus formation was induced ex vivo by exposing a collagen-coated surface in a parallel-plate perfusion chamber to native blood for 3 min (arterial wall shear rate 2600 s(-1)). Total platelet and fibrin deposition was determined by immunoenzymatic methods.

RESULTS

Compared with baseline values, the mean inhibition of total platelet deposition was 63.9+/-5.9% with clopidogrel plus acetylsalicylic acid, compared with 18.4+/-5.6% for extended-release dipyridamole plus acetylsalicylic acid (67% reduction; 95% CI, 49-79%; p<0.0001). Corresponding figures for fibrin deposition were 64.9+/-4.8% and 18.3+/-9.7%, respectively (58% reduction; 95% CI, 45-67%; p<0.0001). Both treatments were well tolerated.

CONCLUSIONS

Clopidogrel plus acetylsalicylic acid showed significantly superior antithrombotic efficacy compared with extended-release dipyridamole plus acetylsalicylic acid in preventing arterial thrombogenesis in humans.

Prostaglandins participate in the late phase of the vascular response to acetylcholine iontophoresis in humans

The participation of prostaglandins (PGs) in the cutaneous vasodilatation to acetylcholine (ACh) applied via iontophoresis is under debate. Using laser Doppler flowmetry, we studied the long lasting effect (20 min) of iontophoretic application (30 s; 0.1 mA) of ACh on the human forearm. Experiments were repeated (1) using deionized water instead of ACh to test the effect of current application, (2) after scopolamine treatment to inhibit muscarinic cholinergic receptors, and (3) 2 h, 3 days and 10 days following inhibition of PG synthesis with aspirin or a placebo control. Cutaneous vascular conductance (CVC) was calculated at rest (CVC(rest)), at peak vasodilatation in the first 5 min following ACh iontophoresis (CVC(peak)), and 20 min after iontophoresis (CVC(20)). The minimal CVC (CVC(min)) following iontophoresis was also determined. Cutaneous response to ACh displayed a biphasic pattern with an early and transient peak (CVC(peak): 62 +/- 8% of the maximal CVC induced by local heating (MVC)) followed by a long lasting slower vasodilatation (CVC(min): 44 +/- 6; CVC(20): 56 +/- 5%MVC). The current itself had no major effect. Scopolamine almost abolished both phases. The long lasting phase was aspirin sensitive but not the transient phase. At hour 2 post-aspirin, CVC(peak) was 61 +/- 10, CVC(min) 26 +/- 6 and CVC(20) 29 +/- 6%MVC. At day 3, CVC(peak) was 53 +/- 9, CVC(min) 22 +/- 3 and CVC(20) 25 +/- 4%MVC. At day 10, CVC(peak) was 67 +/- 10, CVC(min) 47 +/- 7 and CVC(20) 50 +/- 8%MVC. Placebo had no effect. We conclude that PGs participate in the vasodilator response following ACh iontophoresis. Previous non-steroidal anti-inflammatory drug treatments must be taken into account when studying the effect of ACh iontophoresis.