Platelet GP IIb-IIIa Receptor Antagonists in Primary Angioplasty: Back to the Future

Platelets in thrombosis and atherosclerosis: a double-edged sword

This review focuses on the dual role of platelets in atherosclerosis and thrombosis, exploring their involvement in inflammation, angiogenesis, and plaque formation, as well as their hemostatic and prothrombotic functions. Beyond their thrombotic functions, platelets engage in complex interactions with diverse cell types, influencing disease resolution and progression. The contribution of platelet degranulation helps in the formation of atheromatous plaque, while the reciprocal interaction with monocytes adds complexity. Alterations in platelet membrane receptors and signaling cascades contribute to advanced atherosclerosis, culminating in atherothrombotic events. Understanding these multifaceted roles of platelets will lead to the development of targeted antiplatelet strategies for effective cardiovascular disease prevention and treatment. Understanding platelet functions in atherosclerosis and atherothrombosis at different stages of disease will be critical for designing targeted treatments and medications to prevent or cure the disease Through this understanding, platelets can be targeted at specific times in the atherosclerosis process, possibly preventing the development of atherothrombosis.

Novel strategies in antithrombotic therapy: targeting thrombosis while preserving hemostasis

Antithrombotic therapy is a delicate balance between the benefits of preventing a thrombotic event and the risks of inducing a major bleed. Traditional approaches have included antiplatelet and anticoagulant medications, require careful dosing and monitoring, and all carry some risk of bleeding. In recent years, several new targets have been identified, both in the platelet and coagulation systems, which may mitigate this bleeding risk. In this review, we briefly describe the current state of antithrombotic therapy, and then present a detailed discussion of the new generation of drugs that are being developed to target more safely existing or newly identified pathways, alongside the strategies to reverse direct oral anticoagulants, showcasing the breadth of approaches. Combined, these exciting advances in antithrombotic therapy bring us closer than we have ever been to the "holy grail" of the field, a treatment that separates the hemostatic and thrombotic systems, preventing clots without any concurrent bleeding risk.

Efficacy and safety of intracoronary versus intravenous tirofiban in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: A meta-analysis of randomized controlled trials

Background

Effective antiplatelet therapy is critical for patients with ST-segment elevation myocardial infarction (STEMI) and receiving primary percutaneous coronary interventions (PPCI). Intracoronary (IC) and intravenous (IV) administration of tirofiban are commonly used during the procedure of PPCI. However, which is the better administration route of tirofiban have not been fully evaluated.

Methods

A comprehensive literature search of RCTs that comparing IC with IV tirofiban in STEMI patients undergoing PPCI was conducted, which were published as of May 7, 2022, in PubMed, Embase, Cochrane Library, Web of Science, Scopus and ClinicalTrials.gov. The primary efficacy endpoint was 30-day major adverse cardiovascular events (MACE) and the primary safety endpoint was in-hospital bleeding events.

Results

This meta-analysis included 9 trials involving 1177 patients. IC tirofiban significantly reduced the incidence of 30-day MACE (RR 0.65, 95% CI: 0.44 to 0.95, P = 0.028) and improved the rate of the thrombolysis in myocardial infarction (TIMI) grade 3 flow in high-dose (25 μg/kg) group (RR = 1.13, 95% CI: 0.99-1.30, P = 0.001), in-hospital (WMD 2.03, 95% CI: 1.03 to 3.02, P < 0.001), and 6-month left ventricular injection fraction (LVEF) (WMD 6.01, 95% CI: 5.02 to 6.99, P < 0.001) compared with IV. There was no significant difference in the incidences of in-hospital bleeding events (RR 0.96, 95% CI: 0.67 to 1.38, P = 0.82) and thrombocytopenia (RR 0.63, 95% CI: 0.26 to 1.57, P = 0.32) between the two groups.

Conclusions

IC tirofiban significantly improved the incidence of TIMI 3 in the high-dose group, in-hospital and 6-month LVEF, and reduced the 30-day MACE incidence without increasing the risk of bleeding compared with IV.

Synthesis of 12-quinoline substituted andrographolide derivatives and their preliminary evaluation as anti-aggregation drugs

Based on the structure of the natural product andrographolide, a series of novel 12-quinoline substituted derivatives 9 were designed and synthesized. In preliminary biological evaluation, these synthesized compounds showed prominent anti-platelet aggregation activities in response to thrombin and adenosine diphosphate (ADP) agonists. Among them, compound 9o (inhibition rate 55.73%, IC50 0.36 µM/L) had the highest anti-platelet aggregation activity induced by ADP. Compound 9q (inhibition rate 54.31%, IC50 0.30 µM/L) showed the highest anti-platelet aggregation activity induced by thrombin. Most of the derivatives had no significant cytotoxicity. Our research results provide a novel candidate drug structure for anti-platelet aggregation and enrich the scope of application of andrographolide derivatives.

Parenteral Antiplatelet Drugs in ST-Elevation Myocardial Infarction: Current Status and Future Directions

Oral inhibitors of the platelet P2Y₁₂ receptor are indispensable in the treatment of ST-elevation myocardial infarction (STEMI), improving outcomes and even reducing mortality in some studies. However, these drugs are limited by delayed absorption and suboptimal platelet inhibition at the time of primary percutaneous coronary intervention. Despite efforts to achieve faster and more sustained platelet inhibition, strategies such as prehospital administration, higher loading doses, and crushed formulations have not led to improved coronary reperfusion. Parenteral glycoprotein IIb/IIIa inhibitors act sooner and are more potent than oral P2Y₁₂ inhibitors, but their use has been limited by the increased risk of major bleeding and thrombocytopenia. Hence, there is a clinical need to refine drugs that deliver rapid, effective, yet safe platelet inhibition in the setting of STEMI. Novel parenteral antiplatelet drugs, such as cangrelor, selatogrel, and zalunfiban, have been recently developed to achieve rapid, potent antiplatelet effects while preserving hemostasis. We provide a description of currently available parenteral antiplatelet agents and of those in clinical development for prehospital administration in STEMI patients.

Antiplatelet Therapy for Atherothrombotic Disease in 2022—From Population to Patient-Centered Approaches

Antiplatelet agents, with aspirin and P2Y₁₂ receptor antagonists as major key molecules, are currently the cornerstone of pharmacological treatment of atherothrombotic events including a variety of cardio- and cerebro-vascular as well as peripheral artery diseases. Over the last decades, significant changes have been made to antiplatelet therapeutic and prophylactic strategies. The shift from a population-based approach to patient-centered precision medicine requires greater awareness of individual risks and benefits associated with the different antiplatelet strategies, so that the right patient gets the right therapy at the right time. In this review, we present the currently available antiplatelet agents, outline different management strategies, particularly in case of bleeding or in perioperative setting, and develop the concept of high on-treatment platelet reactivity and the steps toward person-centered precision medicine aiming to optimize patient care.

Current and Novel Antiplatelet Therapies for the Treatment of Cardiovascular Diseases

Over the last decades, antiplatelet agents, mainly aspirin and P2Y₁₂ receptor antagonists, have significantly reduced morbidity and mortality associated with arterial thrombosis. Their pharmacological characteristics, including pharmacokinetic/pharmacodynamics profiles, have been extensively studied, and a significant number of clinical trials assessing their efficacy and safety in various clinical settings have established antithrombotic efficacy. Notwithstanding, antiplatelet agents carry an inherent risk of bleeding. Given that bleeding is associated with adverse cardiovascular outcomes and mortality, there is an unmet clinical need to develop novel antiplatelet therapies that inhibit thrombosis while maintaining hemostasis. In this review, we present the currently available antiplatelet agents, with a particular focus on their targets, pharmacological characteristics, and patterns of use. We will further discuss the novel antiplatelet therapies in the pipeline, with the goal of improved clinical outcomes among patients with atherothrombotic diseases.

Impact of uric acid on immature platelet fraction in patients undergoing percutaneous coronary intervention

INTRODUCTION

Reticulated platelets have been involved in the pathophysiology of coronary artery disease (CAD). Immature platelet fraction (IPF) allows their measurement in daily clinical practice, although the factors conditioning their elevation are still largely unexplored. Serum uric acid (SUA) is the end product of purine metabolism, displaying a pro-oxidant and pro-inflammatory action and increasing the cardiovascular risk. The aim of our study was to investigate the impact of SUA on IPF levels in patients undergoing percutaneous coronary intervention (PCI), and their relationship with CAD.

METHODS

We enrolled a cohort of consecutive patients undergoing coronary angiography in a single center. Hyperuricemia was defined by SUA ≥ 6.5 mg/dl. Significant CAD was defined as at least 1 vessel stenosis >50%, while severe CAD was defined as left main and/or three-vessel disease. IPF was measured at admission by routine blood cells count (A Sysmex XE-2100).

RESULTS

We included in our study 2217 patients, of whom 544 had high levels of SUA, while 1673 had normal levels. Hyperuricemics were older, with higher percentage of renal failure, hypertension, dilated cardiomyopathy or valvular disease as indication to angiography, higher levels of creatinine and C-reactive protein (p < 0.001, respectively) when compared to normouricemics. Immature platelet fraction (IPF) was significant higher in hyperuricemic patients (3.96% vs 3.59%, p = 0.004). A progressive direct increase in the IPF values was observed in relation to SUA levels (r = 0.101, p < 0.001), although at multivariate analysis, hyperuricemia did not result as an independent predictor of IPC in 3rd tertile (adjusted OR [95%CI] = 1.21 [0.85-1.71] P = 0.288). When stratifying hyperuricemics and normouricemics according to IPF tertiles (<2.3%; 2.3-3.9%; ≥ 4%), reticulated platelets were not associated to the prevalence of CAD (SUA ≥6.5:80.9 vs 79.3% vs 78.6%, p = 0.60; SUA < 6.5: 79.3% vs 81.3% vs 78.9%, p = 0.878) or severe CAD (SUA ≥6.5: 34.9% vs 38.9% vs 35.2%, p = 0.99; SUA < 6.5: 30.4% vs 33.5% vs 34%, p = 0.192), and the results were confirmed at multivariate analysis for CAD (SUA ≥6.5: adjusted OR [95%CI] = 1.11 [0.81-1.51] P = 0.524, SUA < 6.5: adjusted OR [95%CI] = 0.89 [0.75-1.05] P = 0.170) or severe CAD (SUA ≥6.5: adjusted OR [95%CI] = 1.03 [0.81-1.31] P = 0.795; SUA < 6.5: adjusted OR [95%CI] = 1.10 [0.96-1.26] P = 0.192).

CONCLUSIONS

In the present study we found a direct relationship between SUA levels and IPF values; however, hyperuricemia did not result as an independent predictor of higher IPF tertile values. Neither in hyperuricemics nor in normouricemics higher IPF were independently associated to the prevalence of CAD or severe CAD.

Large intracoronary thrombus and its management during primary PCI

Large intracoronary thrombus has been reported in significant number of patients with STEMI. Primary PCI is the current standard of care in patients of STEMI. Despite the availability of dual antiplatelets, GP IIb/IIIa inhibitor and effective anticoagulation regimens, large intracoronary thrombus remains one of the biggest challenge to interventional cardiologists during primary PCI. Large intracoronary thrombus may lead to distal embolization, no/slow reflow or embolization into a non-culprit vessel and is associated with adverse cardiovascular outcome. There is no ideal management strategy. We hereby discuss the current available methods/strategies to deal with large thrombus burden encountered during primary PCI, in the current manuscript.

Cangrelor dose titration using platelet function testing during cerebrovascular stent placement

BACKGROUND

Optimal antiplatelet inhibition is vital during cerebrovascular stenting procedures, yet no standardized recommendation exists for antithrombotic therapy in these scenarios. Cangrelor is an intravenous P2Y12 inhibitor with a favorable pharmacokinetic profile for use during neuroendovascular stenting.

METHODS

A retrospective review of all neuroendovascular patients who underwent stenting between 1 January 2019 and 22 March 2020 and were treated with cangrelor was conducted. Thirty-seven patients met inclusion criteria.

RESULTS

All patients were administered a bolus of 5 mcg/kg of cangrelor followed by a maintenance infusion. Antiplatelet effects of cangrelor were monitored using platelet reactivity units (PRU). Based on the initial PRU, seven patients' doses were adjusted with subsequent PRUs in or near the goal range of 50-150. One patient experienced an acute intraprocedural occlusion likely related to a subtherapeutic PRU which subsequently resolved with cangrelor dose adjustment and intra-arterial tirofiban administration, and one patient experienced a post-procedure stent occlusion which required a thrombectomy and intra-arterial tirofiban administration. No hemorrhagic complications occurred.

DISCUSSION

Cangrelor utilization during neuroendovascular stenting with maintenance doses of <2 mcg/kg/min with dose adjustments based on platelet function testing has not been previously described. Cangrelor presents many advantages compared to standard therapy in patients undergoing stent placement related to its pharmacokinetic profile, rapid onset of action, ease of transition to oral P2Y₁₂ antiplatelet agents, and measurability.

CONCLUSION

Cangrelor is a promising alternative to currently available therapies, especially in patients with a high hemorrhagic risk.

Synthesis of 3,15-Disuccinate-12-Coumarin Substituted Andrographolide Derivatives and Their Antiplatelet Aggregation Activities In Vitro

In order to develop a series of novel compounds with antiplatelet aggregation activities, 3,15-disuccinate-12-coumarin substituted derivatives were designed and synthesized based on the natural product andrographolide. In vitro antiplatelet aggregation activities were evaluated by the turbidimetric method with thrombin, adenosine diphosphate (ADP), arachidonic acid (AA), and collagen as inducers. The biological evaluation revealed that compound 11k showed significant inhibition activity for thrombin, AA, and collagen-induced platelet aggregation at the same time and exhibited a dose-dependent behavior. Compound 11c showed the highest antiplatelet aggregation activity induced by ADP. Most of the derivatives had no significant cytotoxicity. Therefore, our work proved that 3,15-disuccinate-12-coumarin substituted andrographolide derivatives had the potential to become a novel candidate structure for antiplatelet aggregation and deserved further study.

Impact of active smoking on the immature platelet fraction and its relationship with the extent of coronary artery disease

INTRODUCTION

Smoking represents a major cardiovascular risk factor, due to the induction of oxidative stress and low-grade, continuous, inflammation that contribute to promote atherothrombosis. However, the mechanisms leading to increased platelet aggregability associated with smoking are only partially defined. A potential role has been hypothesized for immature platelets, a younger and potentially more reactive fraction, previously associated with the main determinants of coronary artery disease (CAD). Therefore, the aim of our study was to define the impact of smoking on the immature platelet fraction (IPF) and its relationship with prevalence and extent of coronary artery disease.

METHODS

We enrolled a cohort of consecutive patients undergoing coronary angiography in a single centre. Significant CAD was defined as at least 1 vessel stenosis >50%, while severe CAD was defined as left main and/or three-vessel disease. IPF was measured at admission by routine blood cell count (Sysmex XE-2100).

RESULTS

We included in our study 2553 patients who were divided according to smoking status (active smokers: 512; nonactive smokers: 2041). Smokers were younger, more frequent males, with lower rate of diabetes mellitus, previous PCI and previous CABG (P < .001, respectively) and were in treatment less often with ARB, BB, nitrates, statins, ASA, clopidogrel, CCB and diuretics (P < .001, respectively) as compared to nonactive smokers. Higher percentage of smokers was observed in patients with higher IPF values, and at multivariate analysis, active smoking resulted as an independent predictor of higher IPF (adjusted OR [95% CI] = 1.59[1.03-2.45], P = .035). Among smokers, higher IPF was associated with lower ejection fraction (P = .034), percentage of acute coronary syndrome (P = .002) and platelet count (P < .001) compared to ones with lower IPF. However, the IPF (according to quartiles values) was not associated with the prevalence and extent of CAD (82.5%, 80.4%, 86.1% and 80.9%, from 1st to 4th quartile, respectively, adjusted OR[95% CI] = 0.98[0.79-1.23], P = .89) and severe CAD (31%, 31.1%, 39.1% and 35.2%, from 1st to 4th quartile, respectively, adjusted OR[95% CI] = 1.03[0.86-1.23], P = .76).

CONCLUSION

The present study shows an independent association between active smoking and the levels of immature platelet fraction in patients undergoing coronary angiography. However, among active smokers, IPF did not result as an independent predictor of CAD or severe CAD.

Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting

Integrins are a family of transmembrane glycoprotein signaling receptors that can transmit bioinformation bidirectionally across the plasma membrane. Integrin αIIbβ3 is expressed at a high level in platelets and their progenitors, where it plays a central role in platelet functions, hemostasis, and arterial thrombosis. Integrin αIIbβ3 also participates in cancer progression, such as tumor cell proliferation and metastasis. In resting platelets, integrin αIIbβ3 adopts an inactive conformation. Upon agonist stimulation, the transduction of inside-out signals leads integrin αIIbβ3 to switch from a low- to high-affinity state for fibrinogen and other ligands. Ligand binding causes integrin clustering and subsequently promotes outside-in signaling, which initiates and amplifies a range of cellular events to drive essential platelet functions such as spreading, aggregation, clot retraction, and thrombus consolidation. Regulation of the bidirectional signaling of integrin αIIbβ3 requires the involvement of numerous interacting proteins, which associate with the cytoplasmic tails of αIIbβ3 in particular. Integrin αIIbβ3 and its signaling pathways are considered promising targets for antithrombotic therapy. This review describes the bidirectional signal transduction of integrin αIIbβ3 in platelets, as well as the proteins responsible for its regulation and therapeutic agents that target integrin αIIbβ3 and its signaling pathways.

Effects of Bailout Tirofiban on In-Hospital Outcomes and Long-Term Mortality in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Intervention

We retrospectively analyzed short- and long-term outcomes of patients who received bailout tirofiban during primary percutaneous intervention (pPCI). A total of 2681patients who underwent pPCI between 2009 and 2014 were analyzed; 1331 (49.6%) out of 2681 patients received bailout tirofiban. Using propensity score matching, 2100 patients (1050 patient received bail-out tirofiban) with similar preprocedural characteristics were identified. Patients who received bailout tirofiban had a significantly higher incidence of acute stent thrombosis, myocardial infarction, and major cardiac or cerebrovascular events during the in-hospital period. There were numerically fewer deaths in the bailout tirofiban group in the unmatched cohort (1.7% vs 2.5%, P = .118). In the matched cohort, in-hospital mortality was significantly lower (1.1% vs 2.4%, P = .03), and survival at 12 and 60 months were higher (96.9% vs 95.2%, P = .056 for 12 months and 95.1% vs 92.0%, P = .01 for 60 months) in the bailout tirofiban group. After multivariate adjustment, bailout tirofiban was associated with a lower mortality at 12 months (odds ratio [OR]: 0.554, 95% confidence interval [CI], 0.349-0.880, P = .012) and 60 months (OR: 0.595, 95% CI, 0.413-0.859, P = .006). In conclusion, bailout tirofiban strategy during pPCI is associated with a lower short- and long-term mortality, although in-hospital complications were more frequent.

Optimal pharmacological therapy in ST-elevation myocardial infarction-a review : A review of antithrombotic therapies in STEMI

Antithrombotic therapy is an essential component in the optimisation of clinical outcomes in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention. There are currently several intravenous anticoagulant drugs available for primary percutaneous coronary intervention. Dual antiplatelet therapy comprising aspirin and P2Y12 inhibitor represents the cornerstone treatment for STEMI. However, these effective treatment strategies may be associated with bleeding complications. Compared with clopidogrel, prasugrel and ticagrelor are more potent and predictable, which translates into better clinical outcomes. Therefore, these agents are the first-line treatment in primary percutaneous coronary intervention. However, patients can still experience adverse ischaemic events, which might be in part attributed to alternative pathways triggering thrombosis. In this review, we provide a critical and updated review of currently available antithrombotic therapies used in patients with STEMI undergoing primary PCI. Finding a balance that minimises both thrombotic and bleeding risk is difficult, but crucial. Further randomised trials for this optimal balance are needed.

Recombinant GPVI-Fc added to single or dual antiplatelet therapy in vitro prevents plaque-induced platelet thrombus formation

The efficiency of current dual antiplatelet therapy might be further improved by its combination with a glycoprotein (GP) VI-targeting strategy without increasing bleeding. GPVI-Fc, a recombinant dimeric fusion protein binding to plaque collagen and concealing binding sites for platelet GPVI, acts as a lesion-focused antiplatelet drug, and does not increase bleeding in vivo. We investigated, whether GPVI-Fc added in vitro on top of acetylsalicylic acid (ASA), the P2Y12 antagonist ticagrelor, and the fibrinogen receptor antagonist abciximab alone or in combination would increase inhibition of platelet activation by atherosclerotic plaque. Under static conditions, GPVI-Fc inhibited plaque-induced platelet aggregation by 53%, and increased platelet inhibition by ASA (51%) and ticagrelor (64%) to 66% and 80%, respectively. Under arterial flow, GPVI-Fc inhibited plaque-induced platelet aggregation by 57%, and significantly increased platelet inhibition by ASA (28%) and ticagrelor (47%) to about 81% each. The triple combination of GPVI-Fc, ASA and ticagrelor achieved almost complete inhibition of plaque-induced platelet aggregation (93%). GPVI-Fc alone or in combination with ASA or ticagrelor did not increase closure time measured by the platelet function analyzer (PFA)-200. GPVI-Fc added on top of abciximab, a clinically used anti-fibrinogen receptor antibody which blocks platelet aggregation, strongly inhibited total (81%) and stable (89%) platelet adhesion. We conclude that GPVI-Fc added on top of single or dual antiplatelet therapy with ASA and/or a P2Y12 antagonist is likely to improve anti-atherothrombotic protection without increasing bleeding risk. In contrast, the strong inhibition of platelet adhesion by GPVI-Fc in combination with GPIIb/IIIa inhibitors could be harmful.

Note: The review process for this manuscript was fully handled by Gregory Y. H. Lip, Editor in Chief.

Supplementary Material to this article is available at www.thrombosis-online.com.

Combined thrombectomy and intracoronary administration of glycoprotein IIb/IIIa inhibitors improves myocardial reperfusion in patients undergoing primary percutaneous coronary intervention: a meta-analysis

BACKGROUND

Suboptimal myocardial reperfusion is common in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Furthermore, it results in increased infarct size and mortality rates. We performed a meta-analysis to evaluate the role of aspiration thrombectomy (AT) combined with intracoronary administration of glycoprotein IIb/IIIa inhibitors (GPI) in the improvement of myocardial reperfusion and clinical outcomes.

METHODS

PubMed, Embase, Web of Science, and CENTRAL databases were searched for randomized controlled trials (RCTs) investigating combined AT and intracoronary GPI treatment versus AT alone. Outcomes of interest were thrombolysis in myocardial infarction myocardial perfusion grade (TMPG), infarct size (IS) assessed by cardiac magnetic resonance imaging, left ventricular ejection fraction (LVEF), major adverse cardiac events (MACE) at short-term (≤ 1 month) and long-term (6-12 months) follow-up, and bleeding complications during the hospital stay.

RESULTS

Eight trials involving 923 patients were included. Compared with AT alone, combined AT and intracoronary GPI significantly increased TMPG 3 flow (RR: 1.15, 95% CI: 1.04 to 1.26), reduced IS [mean difference (MD): -3.46, 95% CI: -5.18 to -1.73], and improved LVEF (MD: 1.44, 95% CI: 0.54 to 2.33). Furthermore, GPI use decreased the risk of MACE at long-term follow-up (RR: 0.60, 95% CI: 0.37 to 0.98). There was no significant difference between the two groups in the incidence of minor and major bleeding complications.

CONCLUSIONS

Our findings showed that compared with AT alone, combined AT and intracoronary GPI treatment resulted in improved myocardial reperfusion, better cardiac function, and MACE-free survival benefits at the long-term follow-up for patients with STEMI undergoing PPCI.

Platelet Integrin αIIbβ3 Inhibitor Rescues Progression of Apoptosis in Human Platelets

BACKGROUND Apoptosis plays an important role in the physiology of platelet function. We aimed to detect the effect of the platelet integrin αIIbβ3 inhibitor, tirofiban, on apoptotic events, including mitochondrial inner-membrane potential (ΔΨm), phosphatidylserine (PS) exposure on platelet surface, and the generation of reactive oxygen species (ROS), when washed platelets were stimulated with thrombin. MATERIAL AND METHODS The study included washed platelets from healthy humans, divided into 4 groups: vehicle, and tirofiban (0.05 μg/ml, 0.25 μg/ml, and 0.5 μg/ml). Platelets were pretreated with vehicle or tirofiban and incubated at 37°C with agitation for 6 h and 24 h. Before thrombin addition, the vehicle group divided into 2 equal groups. Except one vehicle group, the other 4 groups were all stimulated with thrombin (1 U/ml) for 30 min at 37°C. Using flow cytometry, we studied the DYm and PS exposure on platelet surfaces, and the generation of ROS in platelets. RESULTS We observed that at the time of 6 h and 24 h, thrombin-stimulated vehicle platelets induced significant depo-larization of ΔΨm, higher PS exposure, and increased ROS production compared with the vehicle group (P<0.01). However, the tirofiban group had significantly more recovery of DYm, PS exposure, and ROS production compared with the thrombin group (P<0.01). CONCLUSIONS The platelet integrin αIIbβ3 inhibitor, tirofiban, inhibits the depolarization of DYm, PS exposure on platelet surface, and ROS production when stimulated with thrombin. These results suggest that αIIbβ3 inhibitor inhibits the initiation of apoptosis in platelets, showing a potential clinical application of tirofiban as an apoptosis inhibitor.

Contemporary Management of ST-Elevation Myocardial Infarction

Recent advances have caused a major shift in the way ST-elevation myocardial infarctions are managed. This review explores the pharmacological and interventional techniques that have evidence for improving outcomes and the landmark trials that have sparked change. The new P2Y₁₂ inhibitors, ticagrelor and prasugrel, have been shown to be superior to clopidogrel in STEMI patients undergoing primary percutaneous coronary intervention. Concurrently, many technical aspects of percutaneous coronary intervention have been further clarified by trial data, with bare-metal stents, routine thrombus aspiration and femoral access showing evidence of inferiority. Ongoing trials will provide more information on the role of non-culprit lesion PCI, bioresorbable vascular scaffolds, mechanical devices in persistent ischaemia and early automatic implantable cardioverter-defibrillators for inducible ventricular tachycardia.

Relationship between early administration of abciximab and TIMI flow in STEMI patients undergoing primary angioplasty: findings from a large regional STEMI network

AIMS

The aim of this study is to assess whether in S-T Elevation Myocardial Infarction (STEMI) a relationship between early administration of abciximab and Thrombolysis In Myocardial Infarction (TIMI) flow before and after primary percutaneous coronary intervention (PCI) in 960 consecutive patients exists.

METHODS

From 1 February 2001 onward, in the Province of Mantua it has been operating a 'Cardiology Network for the Acute Infarction Care' having its Hub in the Central Coronary ICU/Cath Lab of Mantua Hospital and being its Spokes centers represented by the emergency rooms and Central Coronary ICUs of the four territorial hospitals.

RESULTS

T1 (time from symptoms onset to first medical contact) and T2 (time from first medical contact to angioplasty) are shorter for patients rescued by first aid units rather than for those presented in emergency rooms as well as Ta (time from symptoms onset to abciximab administration). Furthermore, the patients that received abciximab before hospital arrival had less frequently a coronary occlusion [odds ratio = 0.74, 95% confidence interval (0.57-0.96), P = 0.013]. The patients with T1 less than 4 h are 753/960 (78.4%). For this type of patients, there was a significant Ta difference between the pre-PCI TIMI-flow classes (F = 4.467, df = 3, P = 0.04). Planned contrasts revealed that mean time of TIMI flow 0 (M = 104.2) is statistically different from mean time of TIMI flow 3 (M = 85.7), P = 0.013.

CONCLUSION

Our results suggest that the use of abciximab, free from pharmacokinetic limits of oral P2Y12 inhibitors, should be considered in STEMI patients with early presentation before primary PCI.