Antiplatelet therapy - a summary for the general physicians

Life-threatening complications in ophthalmic surgery: a systematic review

Ophthalmic surgical procedures are widely acknowledged for their safety and efficacy. Undoubtedly, advances in ophthalmic surgery, along with the improvement of anaesthetic techniques, have contributed to the reduction in the occurrence of these events. However, although uncommon, systemic severe and life-threatening adverse events can still occur and it is imperative for an ophthalmologic surgeon to have a comprehensive understanding of them to act in terms of proactive prevention, prompt recognition, and optimal treatment, thus maximizing patients' outcomes. Among life-threatening complication following ophthalmic surgery, cardiovascular events represent the most common ones, including a range of different clinical entities: the oculocardiac reflex, potentially leading to haemodynamic instability and asystole; iatrogenic vascular air embolism, in form of venous air embolism or "pefluorocarbon syndrome", which can lead to obstruction of the pulmonary circulation, respiratory distress and cardiovascular collapse; postoperative venous thromboembolism, in the context of which the management of perioperative antiplatelet and anticoagulant therapy has a crucial role. Furthermore, among infectious complications, that are more commonly limited to the ocular tissues, necrotizing fasciitis represents a potentially lethal infection. This review aims to provide an up-to-date, evidence-based overview of potential life-threatening complications associated with ophthalmic surgery, exploring pathogenesis, risk factors, signs, symptoms, and, briefly, management strategies.

Postprocedural Management in Patients After Percutaneous Deep Venous Arterialization: An Expert Opinion

CLINICAL IMPACT

After percutaneous deep venous arterialization (pDVA), the created arteriovenous circuit needs time to develop. Postprocedural care in patients after pDVA is essential in order to create optimal conditions for maturation of the circuit, and thus save the limb. However, current literature mainly focusses on the procedure itself, making postprocedural care an underexposed topic. Therefore, this study presents an overview of the available literature of postprocedural care of pDVA patients and provides recommendations based on expert opinion when current knowledge is limited.

Observational Analyses of Ex Vivo Native American Platelet Responses

Platelet activation plays an essential role in clot formation to prevent blood loss following vascular damage. In pathologic conditions, platelet activation can lead to obstructive clots, disrupting blood flow and resulting in thrombosis. Native Americans suffer disproportionately from arterial disease and previous research has shown that Blacks are enriched in genetic polymorphisms that correlate with higher platelet reactivity contributing to an increased risk for thrombosis. Therefore, the current study sought to determine phenotypic variations in Native American platelet responses following stimulation with agonists, simulating vascular damage. Several donors from a small cohort of Native Americans showed atypical robust platelet aggregation when stimulated with submaximal concentrations of agonists. Further, when comparing α-granule secretion, a specific marker of platelet activation, Native Americans were more likely to have elevated responses to multiple agonist conditions of stimulation compared to Whites. Interestingly, there were no noticeable differences in integrin activation between Native Americans and Whites. Our study is the first to observe elevated Native American platelet responses compared to Whites, supporting further mechanistic studies and investigation of treatment approaches for the prevention of thrombosis.

Analyzing VEGFA/VEGFR1 Interaction: Application of the Resonant Recognition Model-Stockwell Transform Method to Explore Potential Therapeutics for Angiogenesis-Related Diseases

The interaction between vascular endothelial growth factor A (VEGFA) and VEGF receptor 1(VEGFR1) is a central focus for drug development in pathological angiogenesis, where aberrant angiogenesis underlies various anomalies necessitating therapeutic intervention. Identifying hotspots of these proteins is crucial for developing new therapeutics. Although machine learning techniques have succeeded significantly in prediction tasks, they struggle to pinpoint hotspots linked to angiogenic activity accurately. This study involves the collection of diverse VEGFA and VEGFR1 protein sequences from various species via the UniProt database. Electron-ion interaction Potential (EIIP) values were assigned to individual amino acids and transformed into frequency-domain representations using discrete Fast Fourier Transform (FFT). A consensus spectrum emerged by consolidating FFT data from multiple sequences, unveiling specific characteristic frequencies. Subsequently, the Stockwell Transform (ST) was employed to yield the hotspots. The Resonant Recognition Model (RRM) identified a characteristic frequency of 0.128007 with an associated wavelength of 1570 nm and RRM-ST identified hotspots for VEGFA (Human 36, 46, 48, 67, 71, 74, 82, 86, 89, 93) and VEGFR1 (Human 224, 259, 263, 290, 807, 841, 877, 881, 885, 892, 894, 909, 913, 1018, 1022, 1026, 1043). These findings were cross-validated by Hotspots Wizard 3.0 webserver and Protein Data Bank (PDB). The study proposes using a 1570 nm wavelength for photo bio modulation to boost VEGFA/VEGFR1 interaction in the condition that is needed. It also aims to reduce VEGFA/VEGFR2 interaction, limiting harmful angiogenesis in conditions like diabetic retinopathy. Also, the identified hotspots assist in designing agonistic or antagonistic peptides tailored to specific medical requirements with abnormal angiogenesis.

Anesthetic considerations for joint replacement surgery in hemophilic arthropathy: a comprehensive review

Managing hemophilia in patients undergoing joint replacement surgery requires a comprehensive approach encompassing preoperative assessment, meticulous intraoperative care, and tailored postoperative management. Evaluation of joint integrity, bleeding history, and inhibitor presence guides surgical planning and hemostatic therapy selection to optimize outcomes. During surgery, careful attention to factor replacement, antibiotic prophylaxis, anesthetic techniques, and orthopedic strategies minimizes bleeding risk and enhances surgical success. Postoperatively, effective pain management, continued hemostatic therapy, and individualized rehabilitation programs are vital for facilitating recovery and preventing complications. Close monitoring for potential complications, such as periprosthetic joint infection and recurrent hemarthrosis, allows for prompt intervention when necessary. Overall, a collaborative approach involving hematologists, orthopedic surgeons, anesthesiologists, and rehabilitation specialists ensures comprehensive care tailored to the unique needs of patients with hemophilia undergoing joint replacement surgery, ultimately optimizing outcomes and improving quality of life. This holistic approach addresses the multifaceted challenges posed by hemophilia and joint replacement surgery, providing patients with the best possible chance for successful outcomes and long-term joint function. By integrating specialized expertise from multiple disciplines and implementing evidence-based strategies, healthcare providers can effectively manage hemophilia in the context of joint replacement surgery, mitigating risks and maximizing benefits for patients.

Reversal of atherosclerosis by restoration of vascular copper homeostasis

Atherosclerosis has traditionally been considered as a disorder characterized by the accumulation of cholesterol and thrombotic materials within the arterial wall. However, it is now understood to be a complex inflammatory disease involving multiple factors. Central to the pathogenesis of atherosclerosis are the interactions among monocytes, macrophages, and neutrophils, which play pivotal roles in the initiation, progression, and destabilization of atherosclerotic lesions. Recent advances in our understanding of atherosclerosis pathogenesis, coupled with results obtained from experimental interventions, lead us to propose the hypothesis that atherosclerosis may be reversible. This paper outlines the evolution of this hypothesis and presents corroborating evidence that supports the potential for atherosclerosis regression through the restoration of vascular copper homeostasis. We posit that these insights may pave the way for innovative therapeutic approaches aimed at the reversal of atherosclerosis.

Safety and efficacy of desmopressin (DDAVP) in preventing hematoma expansion in intracranial hemorrhage associated with antiplatelet drugs use: A systematic review and metaanalysis

INTRODUCTION

One of the most serious complications associated with antiplatelet agents is antiplatelet-associated intracranial hemorrhage (AA-ICH). Desmopressin is a synthetic antidiuretic hormone (ADH) analog. It has been linked to improving patient outcomes in antiplatelet-induced intracranial hemorrhage. The secondary outcomes included the incidence of thrombotic complications and neurological outcomes.

METHODS

A systematic search was conducted on three databases (PubMed, Cochrane, and ClinicalTrials.gov) to find eligible literature that compares desmopressin (DDAVP) versus controls in patients with AA-ICH. The Mantel-Haenszel statistic was used to determine an overall effect estimate for each outcome by calculating the risk ratios and 95% confidence intervals (CI). Heterogeneity was measured using the I2 test. The risk of bias in studies was calculated using the New Castle Ottowa Scale.

RESULTS

Five studies were included in the analysis with a total of 598 patients. DDAVP was associated with a nonsignificant decrease in the risk of hematoma expansion (RR = .8, 95% CI,.51-1.24; p = .31, I2 = 44%). It was also associated with a non-significant decrease in the risk of thrombotic events (RR,.83; 95% CI,.25-2.76; p = .76, I2 = 30%). However, patients in the DDAVP group demonstrated a significant increase in the risk of poor neurological outcomes (RR, 1.31; 95% CI, 1.07-1.61; p = .01, I2 = 0%). The risk of bias assessment showed a moderate to low level of risk.

CONCLUSION

DDAVP was associated with a nonsignificant decrease in hematoma expansion and thrombotic events. However, it was also associated with a significantly poor neurological outcome in the patients. Thus, until more robust clinical trials are conducted, the use of DDAVP should be considered on a case-to-case basis.

Successful treatment of acute coronary syndrome complicated with massive gastrointestinal bleeding: A case report

Life-threatening gastrointestinal bleeding during the rescue of acute coronary syndrome with repeated cardiac arrest is a difficult challenge to overcome during treatment. The success rate of rescue can be improved through the multidisciplinary cooperation of the rescue team, the selection of a reasonable rescue plan, and timely implementation. Surgical hemostasis has rarely been reported in the literature. Here, we have reported our successful treatment experience with a case of acute coronary syndrome that was complicated by massive gastrointestinal hemorrhage and required an operation to stop the bleeding.

Artificial Intelligence and Neurosurgery: Tracking Antiplatelet Response Patterns for Endovascular Intervention

Platelets play a critical role in blood clotting and the development of arterial blockages. Antiplatelet therapy is vital for preventing recurring events in conditions like coronary artery disease and strokes. However, there is a lack of comprehensive guidelines for using antiplatelet agents in elective neurosurgery. Continuing therapy during surgery poses a bleeding risk, while discontinuing it before surgery increases the risk of thrombosis. Discontinuation is recommended in neurosurgical settings but carries an elevated risk of ischemic events. Conversely, maintaining antithrombotic therapy may increase bleeding and the need for transfusions, leading to a poor prognosis. Artificial intelligence (AI) holds promise in making difficult decisions regarding antiplatelet therapy. This paper discusses current clinical guidelines and supported regimens for antiplatelet therapy in neurosurgery. It also explores methodologies like P2Y12 reaction units (PRU) monitoring and thromboelastography (TEG) mapping for monitoring the use of antiplatelet regimens as well as their limitations. The paper explores the potential of AI to overcome such limitations associated with PRU monitoring and TEG mapping. It highlights various studies in the field of cardiovascular and neuroendovascular surgery which use AI prediction models to forecast adverse outcomes such as ischemia and bleeding, offering assistance in decision-making for antiplatelet therapy. In addition, the use of AI to improve patient adherence to antiplatelet regimens is also considered. Overall, this research aims to provide insights into the use of antiplatelet therapy and the role of AI in optimizing treatment plans in neurosurgical settings.

Platelet functional abnormalities in pediatric patients with kaposiform hemangioendothelioma/Kasabach-Merritt phenomenon

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor of infancy that is commonly associated with a life-threatening thrombocytopenic condition, Kasabach-Merritt phenomenon (KMP). Platelet CLEC-2, tumor podoplanin interaction is considered the key mechanism of platelet clearance in these patients. Here, we aimed to assess platelet functionality in such patients. Three groups of 6 to 9 children were enrolled: group A with KHE/KMP without hematologic response (HR) to therapy; group B with KHE/KMP with HR; and group C with healthy children. Platelet functionality was assessed by continuous and end point flow cytometry, low-angle light scattering analysis (LaSca), fluorescent microscopy of blood smears, and ex vivo thrombi formation. Platelet integrin activation in response to a combination of CRP (GPVI agonist) and TRAP-6 (PAR1 agonist), as well as calcium mobilization and integrin activation in response to CRP or rhodocytin (CLEC-2 agonist) alone, were significantly diminished in groups A and B. At the same time, platelet responses to ADP with or without TRAP-6 were unaltered. Thrombi formation from collagen in parallel plate flow chambers was also noticeably decreased in groups A and B. In silico analysis of these results predicted diminished amounts of CLEC-2 on the platelet surface of patients, which was further confirmed by immunofluorescence microscopy and flow cytometry. In addition, we also noted a decrease in GPVI levels on platelets from group A. In KHE/KMP, platelet responses induced by CLEC-2 or GPVI activation are impaired because of the diminished number of receptors on the platelet surface. This impairment correlates with the severity of the disease and resolves as the patient recovers.

Critical Insights Into the Management of Postpartum Left Main Spontaneous Coronary Artery Dissection: Current Strategies and Future Directions

This review article delves into the multifaceted realm of postpartum left main spontaneous coronary artery dissection (PLMSCAD), an infrequent yet critical condition affecting women during the postpartum period. Through a comprehensive exploration of its pathophysiology, clinical presentation, diagnosis, management strategies, and future directions, this review provides a holistic understanding of PLMSCAD's complexities. The article highlights challenges in diagnosis due to overlapping symptoms and underscores the significance of prompt recognition and tailored interventions. Current management strategies, encompassing medical and interventional approaches, are analysed in the context of their short-term and long-term impact on patient outcomes. Ethical considerations and the role of patient education and support networks are explored, shedding light on the broader psychosocial dimensions of PLMSCAD management. As emerging research reveals insights into genetic influences, hormonal dynamics, and the prognosis of affected individuals, this review emphasises the necessity of collaborative research endeavours and data sharing to enhance our understanding and guide future strategies. Ultimately, this review underscores the urgency of addressing the unique needs of women experiencing PLMSCAD, urging ongoing research, multidisciplinary collaboration, and a patient-centred approach to optimise maternal health outcomes and well-being.

The Impact of Menopause on Cardiovascular Aging: A Comprehensive Review of Androgen Influences

Menopause represents a critical life stage in women, characterized by hormonal changes that significantly impact cardiovascular health. While the decline in estrogen levels has long been recognized as a major contributor to cardiovascular aging in menopausal women, the role of androgens, particularly testosterone, has gained increasing attention in recent years. This comprehensive review aims to provide a thorough understanding of the impact of menopause on cardiovascular aging, with a specific focus on the influences of androgens. A literature search was conducted to gather relevant studies and clinical evidence exploring the relationship between menopause, androgens, and cardiovascular health. The review integrates findings from various studies to present a holistic view of the topic. The review outlines the changes in hormone levels during menopause and discusses the cardiovascular risk factors associated with this transition. Furthermore, it explores the impact of menopause on cardiovascular structure and function, elucidating the underlying mechanisms that contribute to cardiovascular aging. Androgens' significance in maintaining cardiovascular homeostasis is discussed, followed by exploring the effects of androgen decline during menopause on lipid profiles, insulin sensitivity, vascular function, and other cardiovascular parameters. The review delves into the mechanisms of androgen action on the cardiovascular system, emphasizing the role of androgen receptors and the intricate interplay between androgens, estrogens, and other hormones. Clinical evidence supporting the effects of androgens on cardiovascular aging is presented, including studies investigating the association between androgen levels and cardiovascular outcomes. Additionally, the impact of androgen replacement therapy (ART) on cardiovascular risk markers and events in menopausal women is examined, along with controversies and conflicting findings surrounding the use of androgen therapy in cardiovascular aging. This structured review provides a comprehensive understanding of the impact of menopause on cardiovascular aging, with a specific focus on the role of androgens. By highlighting the significance of androgens in cardiovascular health during menopause, this review aims to create an initial impression and interest among readers, inviting potential citations in the future. The findings underscore the need for further research and offer insights into managing cardiovascular aging in menopausal women, including lifestyle interventions, pharmacological approaches, and the potential role of personalized medicine and precision therapies.

Structure-Activity Relationship Analysis of Rhosin, a RhoA GTPase Inhibitor, Reveals a New Class of Antiplatelet Agents

Current antiplatelet therapies have several clinical complications and are mostly irreversible in terms of suppressing platelet activity; hence, there is a need to develop improved therapeutic agents. Previous studies have implicated RhoA in platelet activation. Here, we further characterized the lead RhoA inhibitor, Rhosin/G04, in platelet function and present structure-activity relationship (SAR) analysis. A screening for Rhosin/G04 analogs in our chemical library by similarity and substructure searches revealed compounds that showed enhanced antiplatelet activity and suppressed RhoA activity and signaling. A screening for Rhosin/G04 analogs in our chemical library using similarity and substructure searches revealed compounds that showed enhanced antiplatelet activity and suppressed RhoA activity and signaling. SAR analysis revealed that the active compounds have a quinoline group optimally attached to the hydrazine at the 4-position and halogen substituents at the 7- or 8-position. Having indole, methylphenyl, or dichloro-phenyl substituents led to better potency. Rhosin/G04 contains a pair of enantiomers, and S-G04 is significantly more potent than R-G04 in inhibiting RhoA activation and platelet aggregation. Furthermore, the inhibitory effect is reversible, and S-G04 is capable of inhibiting diverse-agonist-stimulated platelet activation. This study identified a new generation of small-molecule RhoA inhibitors, including an enantiomer capable of broadly and reversibly modulating platelet activity.

The practices and beliefs of dental professionals regarding the management of patients taking anticoagulant and antiplatelet drugs

AIM

This study aimed to inform the implementation of the updated Scottish Dental Clinical Effectiveness Programme (SDCEP) guidance, 'Management of Dental Patients taking Anticoagulant or Antiplatelet Drugs', and to determine training needs by investigating dental professionals' current practice and beliefs regarding management of patients taking these medications.

METHODS

Dental professionals were recruited via the NHS Education for Scotland Portal. The online questionnaire collected demographic information, data on current practice and information about beliefs regarding behaviours related to the management of patients on anticoagulant or antiplatelet medication. Quantitative data were analysed using SPSS and subjected to frequency calculations, t-tests, one-way ANOVA and linear regression. Qualitative data were collected via free text boxes and analysed using thematic analysis.

RESULTS

One hundred and fifty-seven participants responded to the questionnaire. The majority of respondents stated they were aware of the guidance and always based their practice on it. The majority of respondents always assessed the patient's individual bleeding risk prior to dental procedures. Most respondents felt that they did not know how to appropriately manage patients taking low doses of low molecular weight heparins (LMWH), and only 38% of respondents always followed SDCEP guidance about direct oral anticoagulants (DOAC) medication and procedures with a low associated risk of bleeding.

DISCUSSION

This study demonstrates a need for further educational support surrounding LMWHs and management of patients on DOAC medication. Time and remuneration represent barriers to guidance implementation in primary care.

CONCLUSION

There is good awareness and adherence to the guidance in primary care settings, however training needs were identified to support implementation.

Biochemical and hydrogen-deuterium exchange studies of the single nucleotide polymorphism Y649C in human platelet 12-lipoxygenase linked to a bleeding disorder

Human platelet 12-lipoxygenase (h12-LOX) is responsible for the formation of oxylipin products that play an important role in platelet aggregation. Single nucleotide polymorphisms (SNPs) of h12-LOX have been implicated in several diseases. In this study, we investigate the structural, dynamical, and functional impact of a h12-LOX SNP that generates a tyrosine-to-cysteine mutation at a buried site (Y649C h12-LOX) and was previously ascribed with reduced levels of 12(S)-hydroxyeicosatetraenoic acid (12S-HETE) production in isolated platelets. Herein, in vitro Michaelis-Menten kinetics show reduced catalytic rates for Y649C compared to WT h12-LOX at physiological or lower temperatures. Both proteins exhibited similar melting temperatures, metal content, and oligomerization state. Liposome binding for both proteins was also dependent upon the presence of calcium, temperature, and liposome composition; however, the Y649C variant was found to have lowered binding capacity to liposomes compared to WT at physiological temperatures. Further, hydrogen-deuterium exchange mass spectrometry (HDX-MS) experiments revealed a regional defined enhancement in the peptide mobility caused by the mutation. This increased instability for the mutation stemmed from a change in an interaction with an arched helix that lines the substrate binding site, located ≥15 Å from the mutation site. Finally, differential scanning calorimetry demonstrated a reduced protein (un)folding enthalpy, consistent with the HDX results. Taken together, these results demonstrate remarkable similarity between the mutant and WT h12-LOX, and yet, subtle changes in activity, membrane affinity and protein stability may be responsible for the significant physiological changes that the Y649C SNP manifests in platelet biology.

Estimation of Platelet Count and Bleeding Time of Mice Treated with Musa paradisiaca var. sapientum (L.) Kuntze Extract

Objective

The aim of this study was to estimate the platelet count and bleeding time on peripheral blood smear of mice tail wound using Musa paradisiaca var. sapientum (L.) Kuntze (ambonese banana stem extract).

Design

Randomized post-test-only control group design.

Materials and Methods

Twenty-four male mice (Mus Musculus) were randomly divided into 4 groups. A negative control group was treated with carboxymethyl cellulose (CMC), a positive control group (K+) treated aspirin 100 mg/kg body weight, group P1 treated with aspirin 100 mg/kg body weight and tranexamic acid 50 mg/kg body weight, and group P2 treated with 30% of ambonese banana stem extract (ABSE). The mean and standard deviation data of platelet counts and bleeding time were analyzed by one-way ANOVA statistical software.

Results and Discussion

Tranexamic acid had no significant effect on platelets count compared to CMC group (p = 0.871), but administration of aspirin resulted in low platelets count significantly (p = 0.003). The platelet counts of ABSE and CMC groups were not significant different (p = 0.937). Aspirin has significantly shown prolonged bleeding time than CMC, tranexamic acid, and ABSE groups. However, there was no difference between the tranexamic acid and ABSE groups (p=0.934). The bleeding time of tranexamic acid and ABSE groups was similar, although the platelet count in the ABSE group was lower than in the CMC group.

Conclusion

This study proved that ambonese banana stem extract has a potency to shorten the bleeding time in mice tail wound without interfering to platelet count.

The Pharmacological Effects of Silver Nanoparticles Functionalized with Eptifibatide on Platelets and Endothelial Cells

Purpose

In the search for new drug delivery platforms for cardiovascular diseases and coating of medical devices, we synthesized eptifibatide-functionalized silver nanoparticles (AgNPs-EPI) and examined the pharmacological activity of AgNPs-EPI on platelets and endothelial cells in vitro and ex vivo.

Methods

Spherical AgNPs linked to eptifibatide were synthesized and characterized. Cytotoxicity was measured in microvascular endothelial cells (HMEC-1), platelets and red blood cells. Platelet mitochondrial respiration was measured using the Oxygraph-2k, a high-resolution modular respirometry system. The effect of AgNPs-EPI on the aggregation of washed platelets was measured by light aggregometry and the ex vivo occlusion time was determined using a reference laboratory method. The surface amount of platelet receptors such as P-selectin and GPIIb/IIIa was measured. The influence of AgNPS-EPI on blood coagulation science was assessed. Finally, the effect of AgNPs-EPI on endothelial cells was measured by the levels of 6-keto-PGF1alpha, tPa, cGMP and vWF.

Results

We describe the synthesis of AgNPs using eptifibatide as the stabilizing ligand. The molecules of this drug are directly bonded to the surface of the nanoparticles. The synthesized AgNPs-EPI did not affect the viability of platelets, endothelial cells and erythrocytes. Preincubation of platelets with AgNPs-EPI protected by mitochondrial oxidative phosphorylation capacity. AgNPs-EPI inhibited aggregation-induced P-selectin expression and GPIIb/IIIa conformational changes in platelets. AgNPs-EPI caused prolongation of the occlusion time in the presence of collagen/ADP and collagen/adrenaline. AgNPs-EPI regulated levels of 6-keto-PGF1alpha, tPa, vWf and cGMP produced in thrombin stimulated HMEC-1 cells.

Conclusion

AgNPs-EPI show anti-aggregatory activity at concentrations lower than those required by the free drug acting via regulation of platelet aggregation, blood coagulation, and endothelial cell activity. Our results provide proof-of-principle evidence that AgNPs may be used as an effective delivery platform for antiplatelet drugs.

Does individualized guided selection of antiplatelet therapy improve outcomes after percutaneous coronary intervention? A systematic review and meta-analysis

Background

The potential benefits of individualized guided selection of antiplatelet therapy over standard antiplatelet therapy in improving outcomes in patients undergoing percutaneous coronary intervention (PCI) have not been established. Therefore, we pooled evidence from available clinical trials to assess the effectiveness by comparing the two regimens in patients undergoing PCI.

Methods

We queried two electronic databases, MEDLINE and Cochrane CENTRAL, from their inception to April 20, 2021 for published randomized controlled trials in any language that compared guided antiplatelet therapy, using either genetic testing or platelet function testing, versus standard antiplatelet therapy in patients undergoing PCI. The results from trials were presented as risk ratios (RRs) with 95% confidence intervals (CIs) and were pooled using a random-effects model.

Results

Eleven eligible studies consisting of 18,465 patients undergoing PCI were included. Pooled results indicated that guided antiplatelet therapy, compared to standard therapy, was associated with a significant reduction in the incidence of MACE [RR 0·78, 95% CI (0·62–0·99), P = 0·04], MI [RR 0·73, 95% CI (0·56–0.96), P = 0·03], ST [RR 0·66, 95% CI (0·47–0.94), P = 0·02], stroke [RR 0·71, 95% CI (0·50–1.00), P = 0·05], and minor bleeding [RR 0·78, 95% CI (0·66–0.91), P = 0·003].

Conclusions

Individualized guided selection of antiplatelet therapy significantly reduced the incidence of MACE, MI, ST, stroke, and minor bleeding in adult patients when compared with standard antiplatelet therapy. Our findings support the implementation of genetic and platelet function testing to select the most beneficial antiplatelet agent.

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Benefits of individualized guided selection of antiplatelet therapy over standard antiplatelet therapy in improving outcomes in patients undergoing percutaneous coronary intervention (PCI) have not been established.

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Guided therapy, consisting of either genetic testing or platelet function testing, can identify patients with this genetic variation allowing clinicians to provide modified and alternative treatment strategies and prescribe optimal antiplatelet agents.

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Individualized guided selection of antiplatelet therapy reduced the incidence of MACE, MI, ST, stroke, and minor bleeding in adult patients when compared with standard antiplatelet therapy.

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Can be more cost-effective than medication cost for every stroke, in-stent thrombosis, or MI case that needs hospitalization requiring more imaging and tests which can increase the total cost of treatment.

Inhibition of factor Xa activity, platelet aggregation, and experimentally induced thrombosis by Sparstolonin B

BACKGROUND

Sparstolonin B (SsnB) is an isocumarin compound extracted from medicinal plants such as Sparganium stoloniferum and Scirpus yagara with well documented anti-inflammatory activity. Here we examined if SsnB also possesses antithrombotic activity and the underlying mechanisms.

METHODS

Anti-thrombotic effects of SsnB were determined by measuring in vitro/ex vivo/in vivo clotting times, platelet aggregation assay, production and activity of factor Xa, nitric oxide, and expressions of relative proteins.

RESULTS

Treatment with SsnB prolonged the clotting time of human platelet-poor serum at concentrations comparable to the clinical anticoagulant rivaroxaban (as a positive control) and inhibited human platelet aggregation induced by adenosine diphosphate (ADP) or the thromboxane A2 analog U46619. SsnB also inhibited U46619-induced and ADP-induced phosphorylation of phospholipase C (PLC)γ2/protein kinase C (PKC) and intracellular calcium mobilization, both of which are required for platelet aggregation. In addition, SsnB inhibited expression of the cell adhesion factors P-selectin and PAC-1. SsnB increased production of the vasodilator nitric oxide and suppressed secretion of the vasoconstrictor endothelin-1 from ADP- or U46619-treated human umbilical vein endothelial cells. Further, SsnB reduced coagulation factor Xa (FXa) catalytic activity and production by endothelial cells as well as FXa-induced platelet aggregation.

CONCLUSION

Finally, SsnB injection reduced thrombus formation time, number, size, and related mortality in mouse models of thromboembolism. SsnB is a promising antithrombotic agent targeting both FXa and platelet aggregation pathways, which can overcome the side effects of existing antithrombotic agents.

The Era of Polypills in the Management of Cardiovascular Diseases: Are We There Yet?

Cardiovascular Diseases (CVD) are the leading cause of mortality globally. Wald and Law proposed the idea of a 'polypill'; a fixed dose combination therapy (FDC) in the form of a single pill to curb the CVD epidemic. Such a drug would include the combination of a broad spectrum of drugs including cholesterol lowering drugs, antihypertensive drugs, anti-platelet drugs, anti-coagulation drugs, anti-arrhythmic drugs, which are frequently integrated to combat specific CVDs. This 'polypill' holds the potential to pose several advantages like increased compliance, improved quality of life, risk factor control, psychological relief, and cost effectiveness along with minimal side effects. Several trials (like TIPS, UMPIRE, PolyIran etc.) have tested different treatment strategies to test the hypothesis of Wald and Law. Unlike the past physicians are now highly aware of this new strategy.The future of polypill in the management of CVD lies in a strategy where polypills are treated supplementary to the already existing preventive care, which includes lifestyle modifications and efforts to reduce tobacco use.

Platelet Mechanobiology Inspired Microdevices: From Hematological Function Tests to Disease and Drug Screening

Platelet function tests are essential to profile platelet dysfunction and dysregulation in hemostasis and thrombosis. Clinically they provide critical guidance to the patient management and therapeutic evaluation. Recently, the biomechanical effects induced by hemodynamic and contractile forces on platelet functions attracted increasing attention. Unfortunately, the existing platelet function tests on the market do not sufficiently incorporate the topical platelet mechanobiology at play. Besides, they are often expensive and bulky systems that require large sample volumes and long processing time. To this end, numerous novel microfluidic technologies emerge to mimic vascular anatomies, incorporate hemodynamic parameters and recapitulate platelet mechanobiology. These miniaturized and cost-efficient microfluidic devices shed light on high-throughput, rapid and scalable platelet function testing, hematological disorder profiling and antiplatelet drug screening. Moreover, the existing antiplatelet drugs often have suboptimal efficacy while incurring several adverse bleeding side effects on certain individuals. Encouraged by a few microfluidic systems that are successfully commercialized and applied to clinical practices, the microfluidics that incorporate platelet mechanobiology hold great potential as handy, efficient, and inexpensive point-of-care tools for patient monitoring and therapeutic evaluation. Hereby, we first summarize the conventional and commercially available platelet function tests. Then we highlight the recent advances of platelet mechanobiology inspired microfluidic technologies. Last but not least, we discuss their future potential of microfluidics as point-of-care tools for platelet function test and antiplatelet drug screening.

Computational-approach understanding the structure-function prophecy of Fibrinolytic Protease RFEA1 from Bacillus cereus RSA1

Microbial fibrinolytic proteases are therapeutic enzymes responsible to ameliorate thrombosis, a fatal cardiac-disorder which effectuates due to excessive fibrin accumulation in blood vessels. Inadequacies such as low fibrin specificity, lethal after-effects and short life-span of available fibrinolytic enzymes stimulates an intensive hunt for novel, efficient and safe substitutes. Therefore, we herewith suggest a novel and potent fibrinolytic enzyme RFEA1 from Bacillus cereus RSA1 (MK288105). Although, attributes such as in-vitro purification, characterization and thrombolytic potential of RFEA1 were successfully accomplished in our previous study. However, it is known that structure-function traits and mode of action significantly aid to commercialization of an enzyme. Also, predicting structural model of a protein from its amino acid sequence is challenging in computational biology owing to intricacy of energy functions and inspection of vast conformational space. Our present study thus reports In-silico structural-functional analysis of RFEA1. Sequence based modelling approaches such as-Iterative threading ASSEmbly Refinement (I-TASSER), SWISS-MODEL, RaptorX and Protein Homology/analogY Recognition Engine V 2.0 (Phyre2) were employed to model three-dimensional structure of RFEA1 and the modelled RFEA1 was validated by structural analysis and verification server (SAVES v6.0). The modelled crystal structure revealed the presence of high affinity Ca1 binding site, associated with hydrogen bonds at Asp147, Leu181, Ile185 and Val187residues. RFEA1 is structurally analogous to Subtilisin E from Bacillus subtilis 168. Molecular docking analysis using PATCH DOCK and FIRE DOCK servers was performed to understand the interaction of RFEA1 with substrate fibrin. Strong RFEA1-fibrin interaction was observed with high binding affinity (-21.36 kcal/mol), indicating significant fibrinolytic activity and specificity of enzyme RFEA1. Overall, the computational research suggests that RFEA1 is a subtilisin-like serine endopeptidase with proteolytic potential, involved in thrombus hydrolysis.

Discovery of Benzyl Tetraphosphonate Derivative as Inhibitor of Human Factor Xia

The inhibition of factor XIa (FXIa) is a trending paradigm for the development of new generations of anticoagulants without a substantial risk of bleeding. In this report, we present the discovery of a benzyl tetra-phosphonate derivative as a potent and selective inhibitor of human FXIa. Biochemical screening of four phosphonate/phosphate derivatives has led to the identification of the molecule that inhibited human FXIa with an IC50 value of ∼7.4 μM and a submaximal efficacy of ∼68 %. The inhibitor was at least 14-fold more selective to FXIa over thrombin, factor IXa, factor Xa, and factor XIIIa. It also inhibited FXIa-mediated activation of factor IX and prolonged the activated partial thromboplastin time of human plasma. In Michaelis-Menten kinetics experiment, inhibitor 1 reduced the VMAX of FXIa hydrolysis of a chromogenic substrate without significantly affecting its KM suggesting an allosteric mechanism of inhibition. The inhibitor also disrupted the formation of FXIa - antithrombin complex and inhibited thrombin-mediated and factor XIIa-mediated formation of FXIa from its zymogen factor XI. Inhibitor 1 has been proposed to bind to or near the heparin/polyphosphate-binding site in the catalytic domain of FXIa. Overall, inhibitor 1 is the first benzyl tetraphosphonate small molecule that allosterically inhibits human FXIa, blocks its physiological function, and prevents its zymogen activation by other clotting factors under in vitro conditions. Thus, we put forward benzyl tetra-phosphonate 1 as a novel lead inhibitor of human FXIa to guide future efforts in the development of allosteric anticoagulants.

Bedside testing of CYP2C19 gene for treatment of patients with PCI with antiplatelet therapy

Background

To mitigate the risk of stent thrombosis, patients treated by percutaneous coronary intervention (PCI) are administered dual anti-platelet therapy comprising aspirin and a platelet P2Y₁₂ receptor inhibitor. Clopidogrel is a prodrug requiring activation by the cytochrome P450 enzyme, CYP2C19. In Saudi Arabia, it has been reported that approximately 26% of the population carries CYP2C19*2 and/or *3 loss-of-function polymorphisms in addition to a high prevalence of CVD.

Methods

This prospective (April 2013–December 2020) parallel assignment clinical trial focuses on ST-Elevation Myocardial Infarction (STEMI) patient outcomes. The clinical trial includes 1500 STEMI patients from two hospitals in the Eastern Province of Saudi Arabia. Patients are assigned to one of two groups; the control arm receives conventional therapy with clopidogrel, while in the active arm the Spartan RX CYP2C19 assay is used to determine the *2 genotype. Carriers of a CYP2C19*2 loss-of-function allele receive prasugrel or ticagrelor, while non-carriers are treated with clopidogrel. Follow-up is one year after primary PCI. The primary end point is the number of patients who develop an adverse major cardiovascular event, including recurrent MI, non-fatal stroke, cardiovascular death, or major bleeding one year after PCI.

Discussion

The risk of stent thrombosis in PCI patients is usually reduced by dual anti-platelet therapy, comprising aspirin and a P2Y12 inhibitor, such as clopidogrel. However, clopidogrel requires activation by the cytochrome P450 enzyme, CYP2C19. Approximately 20% of the population are unable to activate clopidogrel as they possess the CYP2C19*2 loss-of function (LoF) allele. The primary goal of this trial is to study the benefits of treating only those patients that cannot activate clopidogrel with an alternative that has shown to be a more effective platelet inhibitor and does not require bioactivation by the cytochrome P450 enzyme. We expect an improvement in net clinical benefit outcome in the active arm patients, thus supporting pharmacogenetic testing in PCI patients post STEMI.

Trial registration

Trial registration name is “Bedside Testing of CYP2C19 Gene for Treatment of Patients with PCI with Antiplatelet Therapy” (number NCT01823185) retrospectively registered with clinicaltrials.gov on April 4, 2013. This trial is currently at the patient recruitment stage.

Introduction to Purinergic Signaling

Purinergic signaling was proposed in 1972, after it was demonstrated that adenosine 5'-triphosphate (ATP) was a transmitter in nonadrenergic, noncholinergic inhibitory nerves supplying the guinea-pig taenia coli. Later, ATP was identified as an excitatory cotransmitter in sympathetic and parasympathetic nerves, and it is now apparent that ATP acts as a cotransmitter in most, if not all, nerves in both the peripheral nervous system and central nervous system (CNS). ATP acts as a short-term signaling molecule in neurotransmission, neuromodulation, and neurosecretion. It also has potent, long-term (trophic) roles in cell proliferation, differentiation, and death in development and regeneration. Receptors to purines and pyrimidines have been cloned and characterized: P1 adenosine receptors (with four subtypes), P2X ionotropic nucleotide receptors (seven subtypes) and P2Y metabotropic nucleotide receptors (eight subtypes). ATP is released from different cell types by mechanical deformation, and after release, it is rapidly broken down by ectonucleotidases. Purinergic receptors were expressed early in evolution and are widely distributed on many different nonneuronal cell types as well as neurons. Purinergic signaling is involved in embryonic development and in the activities of stem cells. There is a growing understanding about the pathophysiology of purinergic signaling and there are therapeutic developments for a variety of diseases, including stroke and thrombosis, osteoporosis, pain, chronic cough, kidney failure, bladder incontinence, cystic fibrosis, dry eye, cancer, and disorders of the CNS, including Alzheimer's, Parkinson's. and Huntington's disease, multiple sclerosis, epilepsy, migraine, and neuropsychiatric and mood disorders.

Long-term assessment of aspirin desensitization shows successful bridging with non-aspirin nonsteroidal anti-inflammatory drugs for procedures

Background: Aspirin (ASA) desensitization and continuous daily ASA therapy is the criterion standard treatment for ASA-exacerbated respiratory disease (AERD). However, the optimal maintenance dosage of ASA and safety of "bridging" patients with AERD and with alternative cyclooxygenase-1 inhibitors for surgery have not been determined and require further investigation. Objective: This study was designed to compare the long-term effects of different maintenance doses of ASA and to assess the success of bridging subjects with AERD for surgery without losing desensitization. Methods: We retrospectively assessed 36 subjects with AERD who successfully underwent ASA desensitization from 2011 to 2017. We performed comprehensive medical record reviews and subsequent telephone interviews with a questionnaire. Results: Of 36 subjects, the average age was 52.8 years, with an average of 3.2 years since desensitization, and 65% were women. The subjects reported a decrease in frequency of nasal symptoms (p < 0.001), asthma symptoms (p = 0.016), and sinus infections (p < 0.001) after desensitization. Improvements were reported in sense of smell, taste, quality of sleep, and quality of life (p < 0.001) in all dosage groups. Thirteen subjects required stopping of ASA for surgeries. Six subjects (46%) were bridged with ibuprofen on an average of 5.9 days before surgery and restarted ASA on an average of 1.3 days after surgery, with no incidence of major adverse events or loss of desensitization. Seven subjects (54%) were not bridged, with three subjects restarting ASA after surgery without symptoms and four subjects losing desensitization. Conclusion: There did not seem to be a difference of benefits between 325 mg once or twice a day compared with 650 mg once or twice a day, but our small subject numbers made this conclusion difficult to prove. Desensitization improved subjective reporting on sleep quality as well as quality of life. Bridging the subjects with AERD who required surgery by using ibuprofen seemed to be safe and effective in maintaining ASA desensitization.

Use of Antiplatelet Agents and Survival of Tuberculosis Patients: A Population-Based Cohort Study

While evidence is accumulating that platelets contribute to tissue destruction in tuberculosis (TB) disease, it is still not known whether antiplatelet agents are beneficial to TB patients. We performed this retrospective cohort study and identified incident TB cases in the Taiwan National Tuberculosis Registry from 2008 to 2014. These cases were further classified into antiplatelet users and non-users according to the use of antiplatelet agents prior to the TB diagnosis, and the cohorts were matched using propensity scores (PSs). The primary outcome was survival after a TB diagnosis. In total, 74,753 incident TB cases were recruited; 9497 (12.7%) were antiplatelet users, and 7764 (10.4%) were aspirin (ASA) users. A 1:1 PS-matched cohort with 8864 antiplatelet agent users and 8864 non-users was created. After PS matching, antiplatelet use remained associated with a longer survival (adjusted hazard ratio (HR): 0.91, 95% confidence interval (CI): 0.88–0.95, p < 0.0001). The risk of major bleeding was not elevated in antiplatelet users compared to non-users (p = 0.604). This study shows that use of antiplatelet agents has been associated with improved survival in TB patients. The immunomodulatory and anti-inflammatory effects of antiplatelet agents in TB disease warrant further investigation. Antiplatelets are promising as an adjunct anti-TB therapy.

Massive Hyphaema Following Laser Iridotomy in a Patient on Dual Antiplatelet Therapy (Aspirin plus Ticagrelor): Case report and literature review

Massive hyphaema presentation after a laser iridotomy is very rare. We report a 63-year-old man with ischaemic heart disease on dual antiplatelet therapy (aspirin plus ticagrelor) who was diagnosed as a primary angle-closure suspect and was to undergo a neodymium-doped yttrium aluminium garnet laser iridotomy at Centro Oftalmológico Virgilio Galvis, Floridablanca, Colombia in 2016. While performing the iridotomy in the left eye, active bleeding occurred that finally filled approximately 75% of the anterior chamber. Intraocular pressure (IOP) increased to 62 mmHg. Mannitol and a topical dorzolamide/timolol were used to control the increase in IOP. The hyphaema slowly resolved over the following week without sequelae. This case revealed that massive hyphaema can complicate laser iridotomy in patients on dual antiplatelet therapy, although this is rare. Therefore, if patients are taking aspirin and ticagrelor, it would be advisable to stop the second medication if possible. In addition, sequential application of photocoagulation and photodisruption lasers might diminish the risk of significant bleeding.

A novel porcine model of thrombotic myocardial infarction with cardiac dysfunction sensitive to dual antiplatelet therapy

Few effective porcine models of myocardial infarction (MI) related to platelet thrombus formation are available. In this study, we established a novel porcine MI model and examined the effect of dual antiplatelet therapy (DAPT) with aspirin and prasugrel, a P2Y₁₂ antagonist, using this MI model. Thrombotic MI was photochemically induced using rose bengal. Male miniature pigs were divided into 3 treatment groups: Sham, MI, and DAPT. In the DAPT group, aspirin (10 mg/kg, p.o.) and prasugrel (1 mg/kg, p.o.) were administered 4 h before photo-irradiation. Platelet aggregation, MI volume, and cardiac function were evaluated 24 h after photo-irradiation. Inhibition of ADP-induced platelet aggregation in the DAPT group was about 45%, similar to the effects of DAPT in a clinical setting. No MI was observed in the Sham group, and MI volume was 12.9 ± 2.9% in the left ventricle (P = 0.0016) in the MI group. Additionally, an increase in end-systolic volume (P = 0.0006), and a decrease in stroke volume (P = 0.0001) and ejection fraction (P < 0.0001) were observed in the MI group compared to the Sham group without any changes in end-diastolic volume. DAPT significantly decreased MI volume (P = 0.0006) and ameliorated cardiac dysfunction compared to the MI group. In conclusion, a novel porcine model of thrombotic MI with cardiac dysfunction was established. In this model, DAPT decreased MI volume and ameliorated of cardiac dysfunction, suggesting that this porcine MI model could be useful for future research on MI and antithrombotic agents.

Design, development and characterization of ACT017, a humanized Fab that blocks platelet's glycoprotein VI function without causing bleeding risks

Glycoprotein VI is a platelet-specific collagen receptor critical for in vivo formation of arterial thrombosis. It is also considered as an attractive target for the development of anti-thrombotic drugs because blocking glycoprotein (GP)VI inhibits platelet aggregation without inducing detrimental effects on physiologic hemostasis.

Here, we present data on the identification, in vitro and ex vivo pharmacology of a humanized Fab fragment designated as ACT017. ACT017 was selected out of 15 humanized variants based upon structural and functional properties. It was produced under GMP-like conditions followed by detailed physico-chemical analysis and functional characterization indicating high antigen-binding specificity and affinity. In addition, we demonstrate, in a dose-escalation study, that ACT017 has a high capacity to specifically inhibit collagen-induced platelet aggregation ex vivo after injection to the macaque without inducing thrombocytopenia, GPVI depletion or bleeding side effects as is the case for conventional anti-platelets. Therefore, ACT017 is a promising therapeutic candidate for the development of a new generation of safe and efficient anti-thrombotic drugs.

Place of non-vitamin K antagonist oral anticoagulants in anticoagulant-antiplatelet combinations in peripheral artery disease

Non-vitamin K antagonist oral anticoagulants are becoming increasingly important in the prophylaxis and treatment of thrombosis in atrial fibrillation and venous thromboembolism. Antiplatelets are widely prescribed in the primary and secondary prevention of cardiac and vascular diseases. There are potentially numerous situations where anticoagulants and antiplatelets may be combined; these combinations have been explored in coronary artery disease, and some have been included in updated recommendations. Is it legitimate to transpose these recommendations to the management of peripheral artery disease? The specific characteristics of the treated vessels, the stents used, the respective frequencies of stent thrombosis and its effect on the target organ are probably different, and explain why opinions differ. However, because of a lack of evidence, empirical behaviours are being established without scientific validation. This review of the literature details the situations in which combinations of an anticoagulant and an antiplatelet have been explored in peripheral artery disease. We discuss the issue of antithrombotic combinations in stable peripheral artery disease and for vascular or endovascular surgery.