1,25-Dihydroxyvitamin D3 attenuates platelet aggregation potentiated by SARS-CoV-2 spike protein via inhibiting integrin αIIbß3 outside-in signaling.

Platelet hyperreactivity contributes to the pathogenesis of COVID-19, which is associated with a hypercoagulability state and thrombosis disorder. It has been demonstrated that Vitamin D deficiency is associated with the severity of COVID-19 infection. Vitamin D supplement is widely used as a dietary supplement due to its safety and health benefits. In this study, we investigated the direct effects and underlying mechanisms of 1,25(OH)2D3 on platelet hyperreactivity induced by SRAS-CoV-2 spike protein via Western blot and platelet functional studies in vitro. Firstly, we found that 1,25(OH)2D3 attenuated platelet aggregation and Src-mediated signaling. We further observed that 1,25(OH)2D3 attenuated spike protein-potentiated platelet aggregation in vitro. Mechanistically, 1,25(OH)2D3 attenuated spike protein upregulated-integrin αIIbß3 outside-in signaling such as platelet spreading and the phosphorylation of ß3, c-Src and Syk. Moreover, using PP2, the Src family kinase inhibitor to abolish spike protein-stimulated platelet aggregation and integrin αIIbß3 outside-in signaling, the combination of PP2 and 1,25(OH)2D3 did not show additive inhibitory effects on spike protein-potentiated platelet aggregation and the phosphorylation of ß3, c-Src and Syk. Thus, our data suggest that 1,25(OH)2D3 attenuates platelet aggregation potentiated by spike protein via downregulating integrin αIIbß3 outside-in signaling.

Differential Use of Glycoprotein IIb/IIIa Inhibitors with Bivalirudin in Patients with STEMI Undergoing PCI: A Systematic Review and Meta-Analysis.

AIM: The efficacy and safety of bivalirudin when used concurrently with glycoprotein IIb/IIIa inhibitors (GPI) is uncertain. In this systematic review and meta-analysis, we aimed to evaluate the efficacy and safety of bivalirudin versus heparin in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) and to explore the impact of differential use (greater and balanced) of GPI. METHODS: Online databases were queried from inception to March 2023 to identify eight randomized controlled trials (n = 22,483) for inclusion. The primary outcomes included all-cause mortality, major bleeding, major adverse cardiovascular events (MACE), and net adverse clinical events (NACE). Secondary efficacy endpoints included cardiac death, reinfarction, stent thrombosis (ST), and stroke. Data were pooled using a random-effects model to derive risk ratios (RRs) and 95% confidence intervals (CIs). RESULTS: When compared to heparin, bivalirudin was associated with a significant reduction in all-cause mortality (RR 0.83; 95% CI 0.72-0.97; P = 0.02), major bleeding (RR 0.73; 95% CI 0.57-0.93; P = 0.01), cardiac death (RR 0.79; 95% CI 0.66-0.94; P = 0.01), and NACE (RR 0.80; 95% CI 0.72-0.89; P < 0.0001). However, while the bivalirudin arm showed an increased likelihood of ST in the greater GPI subgroup (RR 1.70; 95% CI 1.13-2.56; P = 0.01), it was associated with a decreased likelihood of ST in the balanced GPI subgroup (RR 0.40; 95% CI 0.24-0.65; P = 0.0003). CONCLUSION: Overall, our findings suggest that bivalirudin may be a more efficacious intervention than heparin for reducing certain adverse events in patients with STEMI undergoing primary PCI.

Practicability of Bivalirudin plus Glycoprotein IIb/IIIa Inhibitors in Patients Undergoing Percutaneous Coronary Intervention: A Meta-Analysis.

A variety of antithrombotic drugs are used during percutaneous coronary interventions (PCIs). We aimed to investigate the practicability of the use of bivalirudin and GPIs in patients receiving PCI. We searched 7 of 629 relevant records from PubMed, the Cochrane Library, EMBASE, and Web of Science for randomised controlled trials. There were no significant differences in the rates of major adverse cardiac events (MACE) between bivalirudin plus GPI and heparin (all P  >  .05). Bivalirudin plus planned GPI was similar to bivalirudin monotherapy in terms of the risk of MACE (risk ratio [RR] = 1.07; 95% confidence interval [CI] = .91 - 1.27; P = .55). Bivalirudin plus provisional GPI was associated with lower bleeding risk (RR = .57; 95% CI = .47 - .69; P < .01) compared to using heparin plus GPI. Compared to bivalirudin alone, bivalirudin plus planned GPI evidently increased bleeding risk (RR = 2.20; 95% CI = 1.73 - 2.79; P < .01). Patients receiving bivalirudin or heparin therapy had semblable efficacy endpoints, but those receiving bivalirudin had a significantly lower bleeding risk. For high-risk bleeding patients, bivalirudin plus provisional GPI can have a better antithrombotic effect than heparin, without increasing the bleeding risk.

Effect of GP IIb/IIIa inhibitor duration on the clinical prognosis of primary percutaneous coronary intervention in ST-segment elevation myocardial infarction with no-/slow-reflow phenomenon.

BACKGROUND: In patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI) accompanied by the no-/slow-reflow phenomenon, the maintenance duration of GP IIb/IIIa inhibitor (GPI) is controversial. We compare the efficacy and safety of short- and long-term GPI infusion in STEMI patients with the no-/slow-reflow phenomenon. METHODS: From June 2016 to December 2019, we continuously included patients with on-set STEMI who underwent pPCI, accompanied by the no-/slow-reflow, during interventional procedures at Guangdong Provincial People's Hospital and Zhuhai Golden Bay Hospital. The hemorrhage events, heart function, and major adverse cardiovascular events (MACE) were compared between < 24 h and ≥ 24 h GPI duration groups. The Kaplan-Meier curve was used to estimate the 1-year MACE-free survival at different GPI utility times. RESULTS: In total, 127 patients were divided into two groups based on the duration of tirofiban use (less and more than 24 h). There was no significant difference between two groups in terms of baseline characteristics, plaque condition, and coronary physiological function. The two groups showed similar in-hospital MACE (1 [1.85%] vs. 4 [5.48%], p = 0.394) and 1-year MACE-free survival (log-rank test p = 0.9085). The 1-year MACE remained consistent between the two groups in all subgroups of different risk factors of no-/slow-reflow. There was no significant difference in heart function and in-hospital hemorrhage events (3.7% vs. 1.37%, p = 0.179). CONCLUSION: In the real world, prolonging the duration of GPI may not significantly improve the clinical outcome in patients with STEMI with no-/slow-reflow.

Kinetics of platelet adhesion to a fibrinogen-coated surface in whole blood under flow conditions.

AIM: To test a novel method of assessment of platelet adhesion to a fibrinogen-coated surface in whole blood under flow conditions. METHODS: We developed a fluidic device that mimics blood flow in vessels. The method of detection of platelet adhesion is based on recording of a scattered laser light signal from a fibrinogen-covered surface. Testing was performed in platelet-rich plasma (PRP) and whole blood of healthy volunteers. Control measurements were performed, followed by tests with inhibition of platelet GPIIa/IIIb and GPIb receptors. Then, the same testing sequence was performed in whole blood of persons with autoimmune thrombocytopenia and type 3 von Willebrand disease. RESULTS: The change in intensity of scattered light was 2.7 (2.4; 4.1) times higher in whole blood (0.2 ± 0.08V, n = 7) than in PRP (0.05 ± 0.02 V, n = 7), p < 0.01. The blocking of GP IIb/IIIa receptors decreased the intensity of scattered light to 8.5 (6.5;12)%; the blocking of GPIb receptors decreased it to 34 (23;58)%, p < 0.01. In the whole blood of a person with autoimmune thrombocytopenia, the inhibition of GPIb receptors decreased platelet adhesion, but no effect was observed in type 3 von Willebrand disease. Inhibition of platelet GPIIb/IIIa receptors alone or combined inhibition of GPIb and GPIIb/IIIa receptors resulted in almost total suppression of adhesion in both cases. CONCLUSION: Our system effectively registers platelet adhesion to a fibrinogen-coated surface under controlled-flow conditions and may successfully be applied to the investigation of platelet adhesion kinetics.

Glycoprotein IIb/IIIa Inhibitors May Modulate the Clinical Benefit of Radial Access as Compared to Femoral Access in Primary Percutaneous Coronary Intervention: A Meta-Regression and Meta-Analysis of Randomized Trials.

OBJECTIVES: Several randomized controlled trials (RCTs) consistently reported better clinical outcomes with radial as compared to femoral access for primary percutaneous coronary intervention (PCI). Nevertheless, heterogeneous use of potent antiplatelet drugs, such as Gp IIb/IIIa inhibitors (GPI), across different studies could have biased the results in favor of radial access. We performed an updated meta-analysis and meta-regression of RCTs in order to appraise whether the use of GPI had an impact on pooled estimates of clinical outcomes according to vascular access. METHODS: We computed pooled estimates by the random-effects model for the following outcomes: mortality, major adverse cardiovascular events (death, myocardial infarction, stroke, and target vessel revascularization), and major bleedings. Additionally, we performed meta-regression analysis to investigate the impact of GPI use on pooled estimates of clinical outcomes. RESULTS: We analyzed 14 randomized controlled trials and 11090 patients who were treated by radial (5497) and femoral access (5593), respectively. Radial access was associated with better outcomes for mortality (risk difference 0.01 (0.00, 0.01), p=0.03), MACE (risk difference 0.01 (0.00, 0.02), p=0.003), and major bleedings (risk difference 0.01 (0.00, 0.02), p=0.02). At meta-regression, we observed a significant correlation of mortality with both GPI use (p=0.011) and year of publication (p=0.0073), whereas no correlation was observed with major bleedings. CONCLUSIONS: In this meta-analysis, the use of radial access for primary PCI was associated with better clinical outcomes as compared to femoral access. However, the effect size on mortality was modulated by GPI rate, with greater benefit of radial access in studies with larger use of these drugs.

Role of platelets in the pathogenesis of delayed injury after subarachnoid hemorrhage.

Aneurysmal subarachnoid hemorrhage (aSAH) patients develop delayed cerebral ischemia and delayed deficits (DCI) within 2 weeks of aneurysm rupture at a rate of approximately 30%. DCI is a major contributor to morbidity and mortality after SAH. The cause of DCI is multi-factorial with contributions from microthrombi, blood vessel constriction, inflammation, and cortical spreading depolarizations. Platelets play central roles in hemostasis, inflammation, and vascular function. Within this review, we examine the potential roles of platelets in microthrombi formation, large artery vasospasm, microvessel constriction, inflammation, and cortical spreading depolarization. Evidence from experimental and clinical studies is provided to support the role(s) of platelets in each pathophysiology which contributes to DCI. The review concludes with a suggestion for future therapeutic targets to prevent DCI after aSAH.

Acute myocardial infarction in a 41-year-old woman due to elevated factor VIII: a case report.

Myocardial infarction is a life-threatening emergency with a high mortality rate. A high plasma level of factor VIII is an established risk for both arterial and venous thrombotic events. In this mini-review, we report the case of a 41-year-old woman without cardiovascular risk factors or a previous history of thrombotic events, admitted for ST-elevation myocardial infarction, in whom coronary angiography showed a thrombotic occlusion in the left anterior descending artery. The patient underwent primary percutaneous coronary intervention (PCI), with GPIIB-IIIA antagonist, then, a pre-dilation with a semi-compliant balloon-catheter, followed by implantation of 2 stents. The etiological assessment revealed a high level of coagulation factor VIII (FVIII). She underwent anticoagulation therapy (with acenocoumarol) with well-controlled international normalised ratio (INR).

Cangrelor vs. glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention.

BACKGROUND: To date, there are no real-world studies comparing cangrelor to glycoprotein IIb/IIIa inhibitors (GPI) during percutaneous coronary intervention (PCI). Thus, we performed this study to evaluate the safety and effectiveness of cangrelor compared to GPI during PCI. METHODS: We identified patients who underwent PCI at our institution who received either cangrelor or GPI during PCI. Patients already on GPI or cangrelor prior to PCI or who received both cangrelor and GPI were excluded. Baseline demographics and clinical outcomes were extracted. Major bleeding is defined as a composite of major hematoma >4 cm, hematocrit drop >15, and gastrointestinal bleeding. RESULTS: A total of 2072 patients received adjunctive antiplatelet therapy during PCI (cangrelor [n=478]; GPI [n=1594]). Patients' mean age was 61±12 years. Most (66%) presented with acute coronary syndrome. Patients who received cangrelor were older and had a higher percentage of acute coronary syndrome and lower baseline hematocrit in comparison with patients who received GPI. Procedural success was achieved in 94% of patients, with no difference between groups. Major bleeding events (1.7% vs. 5.1%, P=.001), any vascular complication rates, and hospital length of stay were significantly lower in the cangrelor group. In-hospital ischemic events did not differ between groups. On regression analysis, patients on cangrelor were noted to have significantly lower major bleeding events (OR 0.23; 95% CI, 0.09-0.59). CONCLUSIONS: Balancing ischemic and bleeding risks with adjunctive antiplatelet drugs is of prime importance during PCI. Our real-world analysis shows that cangrelor is safe and effective when compared to GPI during PCI.

Refractory Stroke Thrombectomy: Prevalence, Etiology, and Adjunctive Treatment in a North American Cohort.

BACKGROUND AND PURPOSE: Acute stroke intervention refractory to mechanical thrombectomy may be due to underlying vessel wall pathology including intracranial atherosclerotic disease and intracranial arterial dissection or recalcitrant emboli. We studied the prevalence and etiology of refractory thrombectomy, the safety and efficacy of adjunctive interventions in a North American-based cohort. MATERIALS AND METHODS: We performed a multicenter, retrospective study of refractory thrombectomy, defined as unsuccessful recanalization, vessel reocclusion in <72 hours, or required adjunctive antiplatelet glycoprotein IIb/IIIa inhibitors, intracranial angioplasty and/or stenting to achieve and maintain reperfusion. Clinical and imaging criteria differentiated etiologies for refractory thrombectomy. Baseline demographics, cerebrovascular risk factors, technical/clinical outcomes, and procedural safety/complications were compared between refractory and standard thrombectomy groups. Multivariable logistic regression analysis was performed to determine independent predictors of refractory thrombectomy. RESULTS: Refractory thrombectomy was identified in 25/302 cases (8.3%), correlated with diabetes (44% versus 22%, P = .02) as an independent predictor with OR = 2.72 (95% CI, 1.05-7.09; P = .04) and inversely correlated with atrial fibrillation (16% versus 45.7%, P = .005). Refractory etiologies were secondary to recalcitrant emboli (20%), intracranial atherosclerotic disease (60%), and/or intracranial arterial dissection (44%). Four (16%) patients were diagnosed with early vessel reocclusion, and 21 patients underwent adjunctive salvage interventions with glycoprotein IIb/IIIa inhibitor infusion alone (32%) or intracranial angioplasty and/or stenting (52%). There were no significant differences in TICI 2b/3 reperfusion efficacy (85.7% versus 90.9%, P = .48), symptomatic intracranial hemorrhage rates (0% versus 9%, P = .24), favorable clinical outcomes (39.1% versus 48.3%, P = .51), or mortality (13% versus 28.3%, P = .14) versus standard thrombectomy. CONCLUSIONS: Refractory stroke thrombectomy is encountered in <10% of cases, independently associated with diabetes, and related to underlying vessel wall pathology (intracranial atherosclerotic disease and/or intracranial arterial dissection) or, less commonly, recalcitrant emboli. Emergent salvage interventions with glycoprotein IIb/IIIa inhibitors or intracranial angioplasty and/or stenting are safe and effective adjunctive treatments.

Exogenous Integrin αIIbß3 Inhibitors Revisited: Past, Present and Future Applications.

The integrin αIIbß3 is the most abundant integrin on platelets. Upon platelet activation, the integrin changes its conformation (inside-out signalling) and outside-in signalling takes place leading to platelet spreading, platelet aggregation and thrombus formation. Bloodsucking parasites such as mosquitoes, leeches and ticks express anticoagulant and antiplatelet proteins, which represent major sources of lead compounds for the development of useful therapeutic agents for the treatment of haemostatic disorders or cardiovascular diseases. In addition to hematophagous parasites, snakes also possess anticoagulant and antiplatelet proteins in their salivary glands. Two snake venom proteins have been developed into two antiplatelet drugs that are currently used in the clinic. The group of proteins discussed in this review are disintegrins, low molecular weight integrin-binding cysteine-rich proteins, found in snakes, ticks, leeches, worms and horseflies. Finally, we highlight various oral antagonists, which have been tested in clinical trials but were discontinued due to an increase in mortality. No new αIIbß3 inhibitors are developed since the approval of current platelet antagonists, and structure-function analysis of exogenous disintegrins could help find platelet antagonists with fewer adverse side effects.

Effect of Learning Dataset for Identification of Active Molecules: A Case Study of Integrin αIIbß3 Inhibitors.

Efficient in silico approaches are needed to identify strong integrin αIIbß3 inhibitors through a small number of measurements. To address the challenge, we investigated the effect of learning dataset on the classification performance of machine learning models focusing on weak and inactive compounds. The structure and activity information of the compounds were obtained from ChEMBL, and pCHEMBL values were used to classify them as active, inactive, or weak. Datasets with various imbalance levels from active:inactive=1 : 1 to 1 : 1000 were used for the machine learning. The prediction scores of the weak samples were found to lie between the predictive values of active and inactive compounds. In addition, another dataset that consists of 149 actives and 6.9 million inactives was screened; the results indicated that the number of positive predictions decreased for models trained with a higher number of inactives. Although there is a trade-off between false positives and false negatives, for determination of compounds with strong activity using a reduced number of measurements, it is better to use a large number of inactives for learning and identifying compounds that score higher than the weak samples.

Thrombocytopenia induced by glycoprotein (GP) IIb-IIIa antagonists: about two cases.

In this paper, we report two cases of induced thrombocytopenia after the infusion of glycoprotein (GP) IIb/IIIa receptors antagonists, following a coronary angioplasty. The first patient is a 65-year-old woman, admitted with acute coronary syndrome requiring percutaneous angioplasty with stenting. The patient was given tirofiban + unfractionated heparin (UFH). Ten hours later, the patient revealed very severe thrombocytopenia and went into hemorrhagic shock (hematemesis and hematoma at the injection site). The patient was transfused with nine units of red blood cells (RBCs), 24 platelets pellets and 4 units of fresh frozen plasma (FFP). The second patient is a 76-year-old woman. She was admitted to hospital for acute coronary syndrome necessitating percutaneous angioplasty with stenting and a glycoprotein IIb/IIIa receptor antagonists, tirofiban + unfractionated (UFH). Four hours later, the patient presented with gingivorrhagia associated thrombocytopenia. She received six platelet pellets transfusion with well clinical and biological improvement. These two observations raise the significance of a close monitoring of platelet count after the initiation of GP IIb/IIIa antagonists infusion, which are sometimes responsible for life-threatening adverse events.

Combined glycoprotein IIb/IIIa inhibitor therapy with ticagrelor for patients with acute coronary syndrome.

This study was to compare the efficacy and safety of combined glycoprotein IIb/IIIa inhibitor (GPI) and ticagrelor versus ticagrelor in patients with acute coronary syndrome (ACS). An observational study was conducted using the Improving Care for Cardiovascular Disease in China-ACS project. Totally, 13,264 patients with ACS and received combination therapy or ticagrelor therapy were analyzed. The primary outcome was the composite of major cardiovascular events (MACE: all-cause mortality, myocardial infarction [MI], stent thrombosis, cardiogenic shock, and ischemic stroke), and secondary outcomes included all-cause mortality, MI, stent thrombosis, cardiogenic shock, and ischemic stroke. The multivariable adjusted analysis indicated that combination therapy was associated with an increased risk of major cardiovascular events (MACE) (P = 0.001), any bleeding (P<0.001), and major bleeding (P = 0.005). Moreover, the multivariable adjusted for propensity score-matched (PSM) analysis suggested that combination therapy produced additional risk of MACE (P = 0.014), any bleeding (P<0.001), and major bleeding (P = 0.005). Moreover, PSM analysis suggested that combination therapy was associated with greater risk of stent thrombosis (P = 0.012) and intracranial bleeding (P = 0.020). Combined GPI and ticagrelor therapies did not have any beneficial effects on MACE, stent thrombosis, intracranial bleeding, any bleeding, or major bleeding.

Secondary Metabolites from the Leather Coral-Derived Fungal Strain Xylaria sp. FM1005 and Their Glycoprotein IIb/IIIa Inhibitory Activity.

Five new tyrosine derivatives (1-5), one new phenylacetic acid derivative (6), two new quinazolinone analogues (7 and 8), one new naphthalenedicarboxylic acid (9), and one new 3,4-dihydroisocoumarin derivative (10), together with seven known compounds, were isolated from the fungus Xylaria sp. FM1005, which was isolated from Sinularia densa (leather coral) collected in the offshore region of the Big Island, Hawaii. The structures of compounds 1-10 were elucidated by extensive analysis of NMR spectroscopy, HRESIMS, and ECD data. Due to their structure similarity to the antiplatelet drug tirofiban, compounds 1-5 together with 6 were investigated for their antithrombotic activities. Compounds 1 and 2 strongly inhibited the binding of fibrinogen to purified integrin IIIb/IIa in a dose-dependent manner with the IC50 values of 0.89 and 0.61 µM, respectively, and compounds 1 and 2 did not show any cytotoxicity against A2780 and HEK 293 at 40 µM.

Successful rescue treatment of right posterior inferior cerebellar artery (PICA) vascular stasis with tirofiban following endovascular coil implantation.

This report describes a patient who developed intraprocedural vascular stasis immediately following elective endovascular coil emboliation. Urgent antiplatelet treatment with the GpIIb/IIIa agent tirofiban was used. It was infused intra-arterially during the procedure, followed by a fixed rate intravenous continuous infusion, and successfully restored normal circulation. There were no reports of further bleeding or haemodynamic compromise during the hospital stay. The patient's condition returned to baseline and he was discharged the following day with no neurological deficits.

First Human Use of RUC-4: A Nonactivating Second-Generation Small-Molecule Platelet Glycoprotein IIb/IIIa (Integrin αIIbß3) Inhibitor Designed for Subcutaneous Point-of-Care Treatment of ST-Segment-Elevation Myocardial Infarction.

Background Despite reductions in door-to-balloon times for primary coronary intervention, mortality from ST-segment-elevation myocardial infarction has plateaued. Early pre-primary coronary intervention treatment of ST-segment-elevation myocardial infarction with glycoprotein IIb/IIIa inhibitors improves pre-primary coronary intervention coronary flow, limits infarct size, and improves survival. We report the first human use of a novel glycoprotein IIb/IIIa inhibitor designed for subcutaneous first point-of-care ST-segment-elevation myocardial infarction treatment. Methods and Results Healthy volunteers and patients with stable coronary artery disease receiving aspirin received escalating doses of RUC-4 or placebo in a sentinel-dose, randomized, blinded fashion. Inhibition of platelet aggregation (IPA) to ADP (20 µmol/L), RUC-4 blood levels, laboratory evaluations, and clinical assessments were made through 24 hours and at 7 days. Doses were increased until reaching the biologically effective dose (the dose producing ≥80% IPA within 15 minutes, with return toward baseline within 4 hours). In healthy volunteers, 15 minutes after subcutaneous injection, mean±SD IPA was 6.9%+7.1% after placebo and 71.8%±15.0% at 0.05 mg/kg (n=6) and 84.7%±16.7% at 0.075 mg/kg (n=6) after RUC-4. IPA diminished over 90 to 120 minutes. In patients with coronary artery disease, 15 minutes after subcutaneous injection of placebo or 0.04 mg/kg (n=2), 0.05 mg/kg (n=6), and 0.075 mg/kg (n=18) of RUC-4, IPA was 14.6%±11.7%, 53.6%±17.0%, 76.9%±10.6%, and 88.9%±12.7%, respectively. RUC-4 blood levels correlated with IPA. Aspirin did not affect IPA or RUC-4 blood levels. Platelet counts were stable and no serious adverse events, bleeding, or injection site reactions were observed. Conclusions RUC-4 provides rapid, high-grade, limited-duration platelet inhibition following subcutaneous administration that appears to be safe and well tolerated. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NTC03844191.

Prediction of gastrointestinal bleeding events in patients with acute coronary syndrome undergoing percutaneous coronary intervention: An observational cohort study (STROBE compliant).

Bleeding complications of acute coronary syndromes (ACS) after percutaneous coronary intervention (PCI) are strongly associated with adverse patient outcomes, and gastrointestinal bleeding (GIB) is the most common major bleeding event, especially in the early post-PCI period. Current guidelines recommend routinely conducting bleeding risk assessments. The existing tools are mainly used to evaluate the overall bleeding risk and guide the adjustment of antithrombotic strategies after 1 year. However, there are no specific tools for GIB risk assessment.Between January 2015 and June 2015, 4943 ACS patients underwent PCI were consecutively enrolled in the derivation cohort. GIB, cardiovascular, and cerebrovascular events were recorded within 1 year of follow-up. A validation cohort including 1000 patients who met the same inclusion and exclusion criteria was also established by propensity-score matching baseline characteristics. Multivariable cox proportional-hazards regression model was used to derive a risk-scoring system, and predictive variables were selected. A risk score nomogram based on the risk prediction model was created to estimate the 1-year risk of GIB.In this study, we found that the usage of clopidogrel (hazard ratio, HR: 2.52, 95% confidence intervals, CI: 1.573-4.021) and glycoprotein IIb/IIIa receptor inhibitors (HR: 1.863, 95% CI: 1.226-2.829), history of peptic ulcers (HR: 3.601, 95% CI: 1.226-2.829) or tumor (HR: 4.884, 95% CI: 1.226-2.829), and cardiac insufficiency (HR: 11.513, 95% CI: 7.282-18.202), renal insufficiency (HR: 2.010, 95% CI: 1.350-2.993), and prolonged activated partial thromboplastin time (HR: 4.639, 95% CI: 2.146-10.032) were independent risk factors for GIB 1 year after PCI. Based on these 7 factors, a nomogram and scoring system was established. The area under curve of risk score was 0.824 in the deviation cohort and 0.810 in the verification cohort. In both cohorts, the GIB score was significantly better than that of 3 classical bleeding scores (all P < .05).This score could well predict the risk of GIB within 1 year after PCI and could be used to guide antithrombotic strategies.

An Unusual Case of Drug-Induced Thrombocytopenia.

Drug-induced thrombocytopenia (DIT) is a differential diagnosis for consideration when acute thrombocytopenia is encountered in the outpatient or inpatient setting. The mechanism of thrombocytopenia induced by different antiplatelet therapies varies. DIT may occur due to antibody formation following the exposure to a drug, or naturally occurring preexisting antibodies may produce rapid-onset thrombocytopenia when a drug molecule binds to a platelet receptor inducing a conformational change thus rendering it to be an antigen target for naturally occurring antibodies. A 66-year-old female with history of hypertension presented with non-ST elevation myocardial infarction, had drug eluting stent placed in first obtuse marginal artery of left circumflex coronary artery. Started on antiplatelet medications aspirin 81 mg, ticagrelor 90 mg (which was later transitioned to clopidogrel 75 mg), as well as tirofiban 12.5 mg (for 12 hours only). Tirofiban is a GP IIb/IIIa antagonist, other drugs in this class have been documented to induce thrombocytopenia as well, but rates for tirofiban appear to be the highest, the reason is unclear. These antibodies are thought to be either naturally occurring or induced from conformational changes to GP IIb/IIIa binding site after binding to the GP IIb/IIIa receptor, binding of these drugs to the receptor precipitates an epitope much more specific for platelet surface antigens. Tirofiban and clopidogrel/ticagrelor can cause thrombocytopenia, but onset in this case is unusual: acute antibody reaction would be expected within hours, not delayed 30 hours after starting antiplatelet medication, and nonacute reaction would present 1 to 2 weeks out.

Biomechanical thrombosis: the dark side of force and dawn of mechano-medicine.

Arterial thrombosis is in part contributed by excessive platelet aggregation, which can lead to blood clotting and subsequent heart attack and stroke. Platelets are sensitive to the haemodynamic environment. Rapid haemodynamcis and disturbed blood flow, which occur in vessels with growing thrombi and atherosclerotic plaques or is caused by medical device implantation and intervention, promotes platelet aggregation and thrombus formation. In such situations, conventional antiplatelet drugs often have suboptimal efficacy and a serious side effect of excessive bleeding. Investigating the mechanisms of platelet biomechanical activation provides insights distinct from the classic views of agonist-stimulated platelet thrombus formation. In this work, we review the recent discoveries underlying haemodynamic force-reinforced platelet binding and mechanosensing primarily mediated by three platelet receptors: glycoprotein Ib (GPIb), glycoprotein IIb/IIIa (GPIIb/IIIa) and glycoprotein VI (GPVI), and their implications for development of antithrombotic 'mechano-medicine' .