Pharmacogenetics of Antiplatelet Therapy.

Antiplatelet therapy is used in the treatment of patients with acute coronary syndromes, stroke, and those undergoing percutaneous coronary intervention. Clopidogrel is the most widely used antiplatelet P2Y12 inhibitor in clinical practice. Genetic variation in CYP2C19 may influence its enzymatic activity, resulting in individuals who are carriers of loss-of-function CYP2C19 alleles and thus have reduced active clopidogrel metabolites, high on-treatment platelet reactivity, and increased ischemic risk. Prospective studies have examined the utility of CYP2C19 genetic testing to guide antiplatelet therapy, and more recently published meta-analyses suggest that pharmacogenetics represents a key treatment strategy to individualize antiplatelet therapy. Rapid genetic tests, including bedside genotyping platforms that are validated and have high reproducibility, are available to guide selection of P2Y12 inhibitors in clinical practice. The aim of this review is to provide an overview of the background and rationale for the role of a guided antiplatelet approach to enhance patient care.

Dual Antiplatelet Treatment up to 72 Hours after Ischemic Stroke.

BACKGROUND: Dual antiplatelet treatment has been shown to lower the risk of recurrent stroke as compared with aspirin alone when treatment is initiated early (≤24 hours) after an acute mild stroke. The effect of clopidogrel plus aspirin as compared with aspirin alone administered within 72 hours after the onset of acute cerebral ischemia from atherosclerosis has not been well studied. METHODS: In 222 hospitals in China, we conducted a double-blind, randomized, placebo-controlled, two-by-two factorial trial involving patients with mild ischemic stroke or high-risk transient ischemic attack (TIA) of presumed atherosclerotic cause who had not undergone thrombolysis or thrombectomy. Patients were randomly assigned, in a 1:1 ratio, within 72 hours after symptom onset to receive clopidogrel (300 mg on day 1 and 75 mg daily on days 2 to 90) plus aspirin (100 to 300 mg on day 1 and 100 mg daily on days 2 to 21) or matching clopidogrel placebo plus aspirin (100 to 300 mg on day 1 and 100 mg daily on days 2 to 90). There was no interaction between this component of the factorial trial design and a second part that compared immediate with delayed statin treatment (not reported here). The primary efficacy outcome was new stroke, and the primary safety outcome was moderate-to-severe bleeding - both assessed within 90 days. RESULTS: A total of 6100 patients were enrolled, with 3050 assigned to each trial group. TIA was the qualifying event for enrollment in 13.1% of the patients. A total of 12.8% of the patients were assigned to a treatment group no more than 24 hours after stroke onset, and 87.2% were assigned after 24 hours and no more than 72 hours after stroke onset. A new stroke occurred in 222 patients (7.3%) in the clopidogrel-aspirin group and in 279 (9.2%) in the aspirin group (hazard ratio, 0.79; 95% confidence interval [CI], 0.66 to 0.94; P = 0.008). Moderate-to-severe bleeding occurred in 27 patients (0.9%) in the clopidogrel-aspirin group and in 13 (0.4%) in the aspirin group (hazard ratio, 2.08; 95% CI, 1.07 to 4.04; P = 0.03). CONCLUSIONS: Among patients with mild ischemic stroke or high-risk TIA of presumed atherosclerotic cause, combined clopidogrel-aspirin therapy initiated within 72 hours after stroke onset led to a lower risk of new stroke at 90 days than aspirin therapy alone but was associated with a low but higher risk of moderate-to-severe bleeding. (Funded by the National Natural Science Foundation of China and others; INSPIRES ClinicalTrials.gov number, NCT03635749.).

Tirofiban for Stroke without Large or Medium-Sized Vessel Occlusion.

BACKGROUND: The effects of the glycoprotein IIb/IIIa receptor inhibitor tirofiban in patients with acute ischemic stroke but who have no evidence of complete occlusion of large or medium-sized vessels have not been extensively studied. METHODS: In a multicenter trial in China, we enrolled patients with ischemic stroke without occlusion of large or medium-sized vessels and with a National Institutes of Health Stroke Scale score of 5 or more and at least one moderately to severely weak limb. Eligible patients had any of four clinical presentations: ineligible for thrombolysis or thrombectomy and within 24 hours after the patient was last known to be well; progression of stroke symptoms 24 to 96 hours after onset; early neurologic deterioration after thrombolysis; or thrombolysis with no improvement at 4 to 24 hours. Patients were assigned to receive intravenous tirofiban (plus oral placebo) or oral aspirin (100 mg per day, plus intravenous placebo) for 2 days; all patients then received oral aspirin until day 90. The primary efficacy end point was an excellent outcome, defined as a score of 0 or 1 on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]) at 90 days. Secondary end points included functional independence at 90 days and a quality-of-life score. The primary safety end points were death and symptomatic intracranial hemorrhage. RESULTS: A total of 606 patients were assigned to the tirofiban group and 571 to the aspirin group. Most patients had small infarctions that were presumed to be atherosclerotic. The percentage of patients with a score of 0 or 1 on the modified Rankin scale at 90 days was 29.1% with tirofiban and 22.2% with aspirin (adjusted risk ratio, 1.26; 95% confidence interval, 1.04 to 1.53, P = 0.02). Results for secondary end points were generally not consistent with the results of the primary analysis. Mortality was similar in the two groups. The incidence of symptomatic intracranial hemorrhage was 1.0% in the tirofiban group and 0% in the aspirin group. CONCLUSIONS: In this trial involving heterogeneous groups of patients with stroke of recent onset or progression of stroke symptoms and nonoccluded large and medium-sized cerebral vessels, intravenous tirofiban was associated with a greater likelihood of an excellent outcome than low-dose aspirin. Incidences of intracranial hemorrhages were low but slightly higher with tirofiban. (Funded by the National Natural Science Foundation of China; RESCUE BT2 Chinese Clinical Trial Registry number, ChiCTR2000029502.).

How I treat the co-occurrence of venous and arterial thromboembolism: anticoagulation, antiplatelet therapy, or both?

ABSTRACT: Arterial and venous thromboses are classically considered distinct disease states, with arterial thrombosis mediated predominantly by platelets and therefore, treated with antiplatelet therapy, and venous thrombosis mediated by the plasmatic coagulation system and treated with anticoagulation. However, co-occurrence of arterial and venous events is common, and there is increasing evidence of shared risk factors and pathophysiologic overlap. This presents a management challenge: does the patient with venous and arterial thrombosis, require anticoagulation, antiplatelet therapy, or both? Herein, we present a structured approach to the evaluation and management of patients with venous thrombosis who are also at risk for or have a history of an arterial thromboembolic event. We emphasize the importance of defining the indications for antithrombotic therapy, as well as the evaluation of factors that influence both thrombotic and bleeding risk, including disorder-specific and patient-specific factors, as well as the inherent risk balance of antithrombotic therapy regimens. We illustrate this approach in 4 cases, discussing the unique considerations and recent updates in the management of venous thrombosis, acute noncardioembolic ischemic stroke, coronary artery disease and acute myocardial infarction, and peripheral artery disease after revascularization.

An Aspirin-Free Versus Dual Antiplatelet Strategy for Coronary Stenting: STOPDAPT-3 Randomized Trial.

BACKGROUND: Bleeding rates on dual antiplatelet therapy (DAPT) within 1 month after percutaneous coronary intervention (PCI) remain high in clinical practice, particularly in patients with acute coronary syndrome or high bleeding risk. Aspirin-free strategy might result in lower bleeding early after PCI without increasing cardiovascular events, but its efficacy and safety have not yet been proven in randomized trials. METHODS: We randomly assigned 6002 patients with acute coronary syndrome or high bleeding risk just before PCI either to prasugrel (3.75 mg/day) monotherapy or to DAPT with aspirin (81-100 mg/day) and prasugrel (3.75 mg/day) after loading of 20 mg of prasugrel in both groups. The coprimary end points were major bleeding (Bleeding Academic Research Consortium 3 or 5) for superiority and cardiovascular events (a composite of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischemic stroke) for noninferiority with a relative 50% margin. RESULTS: The full analysis set population consisted of 5966 patients (no-aspirin group, 2984 patients; DAPT group, 2982 patients; age, 71.6±11.7 years; men, 76.6%; acute coronary syndrome, 75.0%). Within 7 days before randomization, aspirin alone, aspirin with P2Y12 inhibitor, oral anticoagulants, and intravenous heparin infusion were given in 21.3%, 6.4%, 8.9%, and 24.5%, respectively. Adherence to the protocol-specified antiplatelet therapy was 88% in both groups at 1 month. At 1 month, the no-aspirin group was not superior to the DAPT group for the coprimary bleeding end point (4.47% and 4.71%; hazard ratio, 0.95 [95% CI, 0.75-1.20]; Psuperiority=0.66). The no-aspirin group was noninferior to the DAPT group for the coprimary cardiovascular end point (4.12% and 3.69%; hazard ratio, 1.12 [95% CI, 0.87-1.45]; Pnoninferiority=0.01). There was no difference in net adverse clinical outcomes and each component of coprimary cardiovascular end point. There was an excess of any unplanned coronary revascularization (1.05% and 0.57%; hazard ratio, 1.83 [95%CI, 1.01-3.30]) and subacute definite or probable stent thrombosis (0.58% and 0.17%; hazard ratio, 3.40 [95% CI, 1.26-9.23]) in the no-aspirin group compared with the DAPT group. CONCLUSIONS: The aspirin-free strategy using low-dose prasugrel compared with the DAPT strategy failed to attest superiority for major bleeding within 1 month after PCI but was noninferior for cardiovascular events within 1 month after PCI. However, the aspirin-free strategy was associated with a signal suggesting an excess of coronary events. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04609111.

Concomitant Left Atrial Appendage Occlusion and Transcatheter Aortic Valve Replacement Among Patients With Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) is common in patients undergoing transcatheter aortic valve replacement (TAVR) and is associated with increased risk of bleeding and stroke. While left atrial appendage occlusion (LAAO) is approved as an alternative to anticoagulants for stroke prevention in patients with AF, placement of these devices in patients with severe aortic stenosis, or when performed at the same time as TAVR, has not been extensively studied. METHODS: WATCH-TAVR (WATCHMAN for Patients with AF Undergoing TAVR) was a multicenter, randomized trial evaluating the safety and effectiveness of concomitant TAVR and LAAO with WATCHMAN in AF patients. Patients were randomized 1:1 to TAVR + LAAO or TAVR + medical therapy. WATCHMAN patients received anticoagulation for 45 days followed by dual antiplatelet therapy until 6 months. Anticoagulation was per treating physician preference for patients randomized to TAVR + medical therapy. The primary noninferiority end point was all-cause mortality, stroke, and major bleeding at 2 years between the 2 strategies. RESULTS: The study enrolled 349 patients (177 TAVR + LAAO and 172 TAVR + medical therapy) between December 2017 and November 2020 at 34 US centers. The mean age of patients was 81 years, and the mean scores for CHA2DS2-VASc and HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile INR, Elderly, Drugs/alcohol concomitantly) were 4.9 and 3.0, respectively. At baseline, 85.4% of patients were taking anticoagulants and 71.3% patients were on antiplatelet therapy. The cohorts were well-balanced for baseline characteristics. The incremental LAAO procedure time was 38 minutes, and the median contrast volume used for combined procedures was 119 mL versus 70 mL with TAVR alone. At the 24-month follow-up, 82.5% compared with 50.8% of patients were on any antiplatelet therapy, and 13.9% compared with 66.7% of patients were on any anticoagulation therapy in TAVR + LAAO compared with TAVR + medical therapy group, respectively. For the composite primary end point, TAVR + LAAO was noninferior to TAVR + medical therapy (22.7 versus 27.3 events per 100 patient-years for TAVR + LAAO and TAVR + medical therapy, respectively; hazard ratio, 0.86 [95% CI, 0.60-1.22]; Pnoninferiority<0.001). CONCLUSIONS: Concomitant WATCHMAN LAAO and TAVR is noninferior to TAVR with medical therapy in severe aortic stenosis patients with AF. The increased complexity and risks of the combined procedure should be considered when concomitant LAAO is viewed as an alternative to medical therapy for patients with AF undergoing TAVR. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03173534.

Stopping Aspirin Within 1 Month After Stenting for Ticagrelor Monotherapy in Acute Coronary Syndrome: The T-PASS Randomized Noninferiority Trial.

BACKGROUND: Stopping aspirin within 1 month after implantation of a drug-eluting stent for ticagrelor monotherapy has not been exclusively evaluated for patients with acute coronary syndrome. The aim of this study was to investigate whether ticagrelor monotherapy after <1 month of dual antiplatelet therapy (DAPT) is noninferior to 12 months of ticagrelor-based DAPT for adverse cardiovascular and bleeding events in patients with acute coronary syndrome. METHODS: In this randomized, open-label, noninferiority trial, 2850 patients with acute coronary syndrome who underwent drug-eluting stent implantation at 24 centers in South Korea were randomly assigned (1:1) to receive either ticagrelor monotherapy (90 mg twice daily) after <1 month of DAPT (n=1426) or 12 months of ticagrelor-based DAPT (n=1424) between April 24, 2019, and May 31, 2022. The primary end point was the net clinical benefit as a composite of all-cause death, myocardial infarction, definite or probable stent thrombosis, stroke, and major bleeding at 1 year after the index procedure in the intention-to-treat population. Key secondary end points were the individual components of the primary end point. RESULTS: Among 2850 patients who were randomized (mean age, 61 years; 40% ST-segment-elevation myocardial infarction), 2823 (99.0%) completed the trial. Aspirin was discontinued at a median of 16 days (interquartile range, 12-25 days) in the group receiving ticagrelor monotherapy after <1 month of DAPT. The primary end point occurred in 40 patients (2.8%) in the group receiving ticagrelor monotherapy after <1-month DAPT, and in 73 patients (5.2%) in the ticagrelor-based 12-month DAPT group (hazard ratio, 0.54 [95% CI, 0.37-0.80]; P<0.001 for noninferiority; P=0.002 for superiority). This finding was consistent in the per-protocol population as a sensitivity analysis. The occurrence of major bleeding was significantly lower in the ticagrelor monotherapy after <1-month DAPT group compared with the 12-month DAPT group (1.2% versus 3.4%; hazard ratio, 0.35 [95% CI, 0.20-0.61]; P<0.001). CONCLUSIONS: This study provides evidence that stopping aspirin within 1 month for ticagrelor monotherapy is both noninferior and superior to 12-month DAPT for the 1-year composite outcome of death, myocardial infarction, stent thrombosis, stroke, and major bleeding, primarily because of a significant reduction in major bleeding, among patients with acute coronary syndrome receiving drug-eluting stent implantation. Low event rates, which may suggest enrollment of relatively non-high-risk patients, should be considered in interpreting the trial. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03797651.

Safety and Efficacy of Ticagrelor Monotherapy in Patients With Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention: An Individual Patient Data Meta-Analysis of TWILIGHT and TICO Randomized Trials.

BACKGROUND: Dual antiplatelet therapy with a potent P2Y12 inhibitor coupled with aspirin for 1 year is the recommended treatment for patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). As an alternative, monotherapy with a P2Y12 inhibitor after a short period of dual antiplatelet therapy has emerged as a bleeding reduction strategy. METHODS: We pooled individual patient data from randomized trials that included patients with ACS undergoing PCI treated with an initial 3-month course of dual antiplatelet therapy followed by ticagrelor monotherapy versus continued ticagrelor plus aspirin. Patients sustaining a major ischemic or bleeding event in the first 3 months after PCI were excluded from analysis. The primary outcome was Bleeding Academic Research Consortium type 3 or 5 bleeding occurring between 3 and 12 months after index PCI. The key secondary end point was the composite of death, myocardial infarction, or stroke. Hazard ratios and 95% CIs were generated using Cox regression with a one-stage approach in the intention-to-treat population. RESULTS: The pooled cohort (n=7529) had a mean age of 62.8 years, 23.2% were female, and 55% presented with biomarker-positive ACS. Between 3 and 12 months, ticagrelor monotherapy significantly reduced Bleeding Academic Research Consortium 3 or 5 bleeding compared with ticagrelor plus aspirin (0.8% versus 2.1%; hazard ratio, 0.37 [95% CI, 0.24-0.56]; P<0.001). Rates of all-cause death, myocardial infarction, or stroke were not significantly different between groups (2.4% versus 2.7%; hazard ratio, 0.91 [95% CI, 0.68-1.21]; P=0.515). Findings were unchanged among patients presenting with biomarker-positive ACS. CONCLUSIONS: Among patients with ACS undergoing PCI who have completed a 3-month course of dual antiplatelet therapy, discontinuation of aspirin followed by ticagrelor monotherapy significantly reduced major bleeding without incremental ischemic risk compared with ticagrelor plus aspirin. REGISTRATION: URL: https://www.crd.york.ac.uk/prospero; Unique identifier: CRD42023449646.

Ticagrelor alone versus ticagrelor plus aspirin from month 1 to month 12 after percutaneous coronary intervention in patients with acute coronary syndromes (ULTIMATE-DAPT): a randomised, placebo-controlled, double-blind clinical trial.

BACKGROUND: Following percutaneous coronary intervention with stent placement to treat acute coronary syndromes, international clinical guidelines generally recommend dual antiplatelet therapy with aspirin plus a P2Y12 receptor inhibitor for 12 months to prevent myocardial infarction and stent thrombosis. However, data on single antiplatelet therapy with a potent P2Y12 inhibitor earlier than 12 months after percutaneous coronary intervention for patients with an acute coronary syndrome are scarce. The aim of this trial was to assess whether the use of ticagrelor alone, compared with ticagrelor plus aspirin, could reduce the incidence of clinically relevant bleeding events without an accompanying increase in major adverse cardiovascular or cerebrovascular events (MACCE). METHODS: In this randomised, placebo-controlled, double-blind clinical trial, patients aged 18 years or older with an acute coronary syndrome who completed the IVUS-ACS study and who had no major ischaemic or bleeding events after 1-month treatment with dual antiplatelet therapy were randomly assigned to receive oral ticagrelor (90 mg twice daily) plus oral aspirin (100 mg once daily) or oral ticagrelor (90 mg twice daily) plus a matching oral placebo, beginning 1 month and ending at 12 months after percutaneous coronary intervention (11 months in total). Recruitment took place at 58 centres in China, Italy, Pakistan, and the UK. Patients were required to remain event-free for 1 month on dual antiplatelet therapy following percutaneous coronary intervention with contemporary drug-eluting stents. Randomisation was done using a web-based system, stratified by acute coronary syndrome type, diabetes, IVUS-ACS randomisation, and site, using dynamic minimisation. The primary superiority endpoint was clinically relevant bleeding (Bleeding Academic Research Consortium [known as BARC] types 2, 3, or 5). The primary non-inferiority endpoint was MACCE (defined as the composite of cardiac death, myocardial infarction, ischaemic stroke, definite stent thrombosis, or clinically driven target vessel revascularisation), with an expected event rate of 6·2% in the ticagrelor plus aspirin group and an absolute non-inferiority margin of 2·5 percentage points between 1 month and 12 months after percutaneous coronary intervention. The two co-primary endpoints were tested sequentially; the primary superiority endpoint had to be met for hypothesis testing of the MACCE outcome to proceed. All principal analyses were assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT03971500, and is completed. FINDINGS: Between Sept 21, 2019, and Oct 27, 2022, 3400 (97·0%) of the 3505 participants in the IVUS-ACS study were randomly assigned (1700 patients to ticagrelor plus aspirin and 1700 patients to ticagrelor plus placebo). 12-month follow-up was completed by 3399 (>99·9%) patients. Between month 1 and month 12 after percutaneous coronary intervention, clinically relevant bleeding occurred in 35 patients (2·1%) in the ticagrelor plus placebo group and in 78 patients (4·6%) in the ticagrelor plus aspirin group (hazard ratio [HR] 0·45 [95% CI 0·30 to 0·66]; p<0·0001). MACCE occurred in 61 patients (3·6%) in the ticagrelor plus placebo group and in 63 patients (3·7%) in the ticagrelor plus aspirin group (absolute difference -0·1% [95% CI -1·4% to 1·2%]; HR 0·98 [95% CI 0·69 to 1·39]; pnon-inferiority<0·0001, psuperiority=0·89). INTERPRETATION: In patients with an acute coronary syndrome who had percutaneous coronary intervention with contemporary drug-eluting stents and remained event-free for 1 month on dual antiplatelet therapy, treatment with ticagrelor alone between month 1 and month 12 after the intervention resulted in a lower rate of clinically relevant bleeding and a similar rate of MACCE compared with ticagrelor plus aspirin. Along with the results from previous studies, these findings show that most patients in this population can benefit from superior clinical outcomes with aspirin discontinuation and maintenance on ticagrelor monotherapy after 1 month of dual antiplatelet therapy. FUNDING: The Chinese Society of Cardiology, the National Natural Scientific Foundation of China, and the Jiangsu Provincial & Nanjing Municipal Clinical Trial Project. TRANSLATION: For the Mandarin translation of the abstract see Supplementary Materials section.

Polypill Strategy in Secondary Cardiovascular Prevention.

BACKGROUND: A polypill that includes key medications associated with improved outcomes (aspirin, angiotensin-converting-enzyme [ACE] inhibitor, and statin) has been proposed as a simple approach to the secondary prevention of cardiovascular death and complications after myocardial infarction. METHODS: In this phase 3, randomized, controlled clinical trial, we assigned patients with myocardial infarction within the previous 6 months to a polypill-based strategy or usual care. The polypill treatment consisted of aspirin (100 mg), ramipril (2.5, 5, or 10 mg), and atorvastatin (20 or 40 mg). The primary composite outcome was cardiovascular death, nonfatal type 1 myocardial infarction, nonfatal ischemic stroke, or urgent revascularization. The key secondary end point was a composite of cardiovascular death, nonfatal type 1 myocardial infarction, or nonfatal ischemic stroke. RESULTS: A total of 2499 patients underwent randomization and were followed for a median of 36 months. A primary-outcome event occurred in 118 of 1237 patients (9.5%) in the polypill group and in 156 of 1229 (12.7%) in the usual-care group (hazard ratio, 0.76; 95% confidence interval [CI], 0.60 to 0.96; P = 0.02). A key secondary-outcome event occurred in 101 patients (8.2%) in the polypill group and in 144 (11.7%) in the usual-care group (hazard ratio, 0.70; 95% CI, 0.54 to 0.90; P = 0.005). The results were consistent across prespecified subgroups. Medication adherence as reported by the patients was higher in the polypill group than in the usual-care group. Adverse events were similar between groups. CONCLUSIONS: Treatment with a polypill containing aspirin, ramipril, and atorvastatin within 6 months after myocardial infarction resulted in a significantly lower risk of major adverse cardiovascular events than usual care. (Funded by the European Union Horizon 2020; SECURE ClinicalTrials.gov number, NCT02596126; EudraCT number, 2015-002868-17.).

A signature of platelet reactivity in CBC scattergrams reveals genetic predictors of thrombotic disease risk.

Genetic studies of platelet reactivity (PR) phenotypes may identify novel antiplatelet drug targets. However, such studies have been limited by small sample sizes (n < 5000) because of the complexity of measuring PR. We trained a model to predict PR from complete blood count (CBC) scattergrams. A genome-wide association study of this phenotype in 29 806 blood donors identified 21 distinct associations implicating 20 genes, of which 6 have been identified previously. The effect size estimates were significantly correlated with estimates from a study of flow cytometry-measured PR and a study of a phenotype of in vitro thrombus formation. A genetic score of PR built from the 21 variants was associated with the incidence rates of myocardial infarction and pulmonary embolism. Mendelian randomization analyses showed that PR was causally associated with the risks of coronary artery disease, stroke, and venous thromboembolism. Our approach provides a blueprint for using phenotype imputation to study the determinants of hard-to-measure but biologically important hematological traits.

The diversity and clinical implications of genetic variants influencing clopidogrel bioactivation and response in the Emirati population.

BACKGROUND: Clopidogrel is a widely prescribed prodrug that requires activation via specific pharmacogenes to exert its anti-platelet function. Genetic variations in the genes encoding its transporter, metabolizing enzymes, and target receptor lead to variability in its activation and platelet inhibition and, consequently, its efficacy. This variability increases the risk of secondary cardiovascular events, and therefore, some variations have been utilized as genetic biomarkers when prescribing clopidogrel. METHODS: Our study examined clopidogrel-related genes (CYP2C19, ABCB1, PON1, and P2Y12R) in a cohort of 298 healthy Emiratis individuals. The study used whole exome sequencing (WES) data to comprehensively analyze pertinent variations of these genes, including their minor allele frequencies, haplotype distribution, and their resulting phenotypes. RESULTS: Our data shows that approximately 37% (n = 119) of the cohort are likely to benefit from the use of alternative anti-platelet drugs due to their classification as intermediate or poor CYP2C19 metabolizers. Additionally, more than 50% of the studied cohort exhibited variants in ABCB1, PON1, and P2YR12 genes, potentially influencing clopidogrel's transport, enzymatic clearance, and receptor performance. CONCLUSIONS: Recognizing these alleles and genotype frequencies may explain the clinical differences in medication response across different ethnicities and predict adverse events. Our findings underscore the need to consider genetic variations in prescribing clopidogrel, with potential implications for implementing personalized anti-platelet therapy among Emiratis based on their genetic profiles.

Platelet-Mimicking Nanosponges for Functional Reversal of Antiplatelet Agents.

BACKGROUND: During long-term antiplatelet agents (APAs) administration, patients with thrombotic diseases take a fairly high risk of life-threatening bleeding, especially when in need of urgent surgery. Rapid functional reversal of APAs remains an issue yet to be efficiently resolved by far due to the lack of any specific reversal agent in the clinic, which greatly restricts the use of APAs. METHODS: Flow cytometry analysis was first applied to assess the dose-dependent reversal activity of platelet-mimicking perfluorocarbon-based nanosponges (PLT-PFCs) toward ticagrelor. The tail bleeding time of mice treated with APAs followed by PLT-PFCs was recorded at different time points, along with corresponding pharmacokinetic analysis of ticagrelor and tirofiban. A hemorrhagic transformation model was established in experimental stroke mice with thrombolytic/antiplatelet therapy. Magnetic resonance imaging was subsequently applied to observe hemorrhage and thrombosis in vivo. Further evaluation of the spontaneous clot formation activity of PLT-PFCs was achieved by clot retraction assay in vitro. RESULTS: PLT-PFCs potently reversed the antiplatelet effect of APAs by competitively binding with APAs. PLT-PFCs showed high binding affinity comparable to fresh platelets in vitro with first-line APAs, ticagrelor and tirofiban, and efficiently reversed their function in both tail bleeding and postischemic-reperfusion models. Moreover, the deficiency of platelet intrinsic thrombotic activity diminished the risk of thrombogenesis. CONCLUSIONS: This study demonstrated the safety and effectiveness of platelet-mimicking nanosponges in ameliorating the bleeding risk of different APAs, which offers a promising strategy for the management of bleeding complications induced by antiplatelet therapy.

PAR4 Antagonism in Patients With Coronary Artery Disease Receiving Antiplatelet Therapies.

BACKGROUND: BMS-986141 is a novel potent highly selective antagonist of PAR (protease-activated receptor) type 4. PAR4 antagonism has been demonstrated to reduce thrombus formation in isolation and in combination with factor Xa inhibition in high shear conditions in healthy people. We sought to determine whether PAR4 antagonism had additive antithrombotic effects in patients with coronary artery disease who were receiving antiplatelet therapy. METHODS: Forty-five patients with stable coronary heart disease and 10 healthy volunteers completed a phase 2a open-label 4-arm single-center study. Patients were allocated to 1 of 3 treatment arms for 7 days: (1) ticagrelor (90 mg BID), (2) aspirin (75 mg QD), or (3) the combination of ticagrelor and aspirin. Agonist-induced platelet aggregation, platelet activation, and ex vivo thrombus formation were measured before and 2 and 24 hours after a single oral 4-mg dose of BMS-986141 on the first study visit day in all participants. RESULTS: BMS-986141 demonstrated highly selective inhibition of PAR4-AP (agonist peptide)-induced platelet aggregation, P-selectin expression, and platelet-monocyte aggregate expression (P≤0.001 for all), which were unaffected by concomitant antiplatelet therapies. PAR4 antagonism reduced ex vivo thrombus area in high shear conditions in healthy volunteers (-21%; P=0.001) and in patients receiving ticagrelor alone (-28%; P=0.001), aspirin alone (-23%; P=0.018), or both in combination (-24%; P≤0.001). Plasma concentration of BMS-986141 correlated with PAR4-AP-induced platelet responses (P≤0.001 for all) and total thrombus area under high shear stress conditions (P≤0.01 for all). CONCLUSIONS: PAR4 antagonism has additive antithrombotic effects when used in addition to ticagrelor, aspirin, or their combination, in patients with stable coronary heart disease. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05093790.

N-Acetyl Cysteine Prevents Arterial Thrombosis in a Dose-Dependent Manner In Vitro and in Mice.

BACKGROUND: Platelet-rich thrombi occlude arteries causing fatal infarcts like heart attacks and strokes. Prevention of thrombi by current antiplatelet agents can cause major bleeding. Instead, we propose using N-acetyl cysteine (NAC) to act against the protein VWF (von Willebrand factor), and not platelets, to prevent arterial thrombi from forming. METHODS: NAC was assessed for its ability to prevent arterial thrombosis by measuring platelet accumulation rate and occlusion time using a microfluidic model of arterial thrombosis with human blood. Acute clot formation, clot stability, and tail bleeding were measured in vivo with the murine modified Folts model. The effect of NAC in the murine model after 6 hours was also measured to determine any persistent effects of NAC after it has been cleared from the blood. RESULTS: We demonstrate reduction of thrombi formation following treatment with NAC in vitro and in vivo. Human whole blood treated with 3 or 5 mmol/L NAC showed delayed thrombus formation 2.0× and 3.7× longer than control, respectively (P<0.001). Blood treated with 10 mmol/L NAC did not form an occlusive clot, and no macroscopic platelet aggregation was visible (P<0.001). In vivo, a 400-mg/kg dose of NAC prevented occlusive clots from forming in mice without significantly affecting tail bleeding times. A lower dose of NAC significantly reduced clot stability. Mice given multiple injections showed that NAC has a lasting and cumulative effect on clot stability, even after being cleared from the blood (P<0.001). CONCLUSIONS: Both preclinical models demonstrate that NAC prevents thrombus formation in a dose-dependent manner without significantly affecting bleeding time. This work highlights a new pathway for preventing arterial thrombosis, different from antiplatelet agents, using an amino acid derivative as an antithrombotic therapeutic.

Platelet RNA Biomarker of Ticagrelor-Responsive Genes Is Associated With Platelet Function and Cardiovascular Events.

BACKGROUND: Identifying patients with the optimal risk:benefit for ticagrelor is challenging. The aim was to identify ticagrelor-responsive platelet transcripts as biomarkers of platelet function and cardiovascular risk. METHODS: Healthy volunteers (n=58, discovery; n=49, validation) were exposed to 4 weeks of ticagrelor with platelet RNA data, platelet function, and self-reported bleeding measured pre-/post-ticagrelor. RNA sequencing was used to discover platelet genes affected by ticagrelor, and a subset of the most informative was summarized into a composite score and tested for validation. This score was further analyzed (1) in CD34+ megakaryocytes exposed to an P2Y12 inhibitor in vitro, (2) with baseline platelet function in healthy controls, (3) in peripheral artery disease patients (n=139) versus patient controls (n=30) without atherosclerosis, and (4) in patients with peripheral artery disease for correlation with atherosclerosis severity and risk of incident major adverse cardiovascular and limb events. RESULTS: Ticagrelor exposure differentially expressed 3409 platelet transcripts. Of these, 111 were prioritized to calculate a Ticagrelor Exposure Signature score, which ticagrelor reproducibly increased in discovery and validation cohorts. Ticagrelor's effects on platelets transcripts positively correlated with effects of P2Y12 inhibition in primary megakaryocytes. In healthy controls, higher baseline scores correlated with lower baseline platelet function and with minor bleeding while receiving ticagrelor. In patients, lower scores independently associated with both the presence and extent of atherosclerosis and incident ischemic events. CONCLUSIONS: Ticagrelor-responsive platelet transcripts are a biomarker for platelet function and cardiovascular risk and may have clinical utility for selecting patients with optimal risk:benefit for ticagrelor use.

Glycoursodeoxycholic Acid Alleviates Arterial Thrombosis via Suppressing Diacylglycerol Kinases Activity in Platelet.

BACKGROUND: Glycoursodeoxycholic acid (GUDCA) has been acknowledged for its ability to regulate lipid homeostasis and provide benefits for various metabolic disorders. However, the impact of GUDCA on arterial thrombotic events remains unexplored. The objective of this study is to examine the effects of GUDCA on thrombogenesis and elucidate its underlying mechanisms. METHODS: Plasma samples from patients with arterial thrombotic events and diet-induced obese mice were collected to determine the GUDCA concentrations using mass spectrometry. Multiple in vivo murine thrombosis models and in vitro platelet functional assays were conducted to comprehensively evaluate the antithrombotic effects of GUDCA. Moreover, lipidomic analysis was performed to identify the alterations of intraplatelet lipid components following GUDCA treatment. RESULTS: Plasma GUDCA level was significantly decreased in patients with arterial thrombotic events and negatively correlated with thrombotic propensity in diet-induced obese mice. GUDCA exhibited prominent suppressing effects on platelet reactivity as evidenced by the attenuation of platelet activation, secretion, aggregation, spreading, and retraction (P<0.05). In vivo, GUDCA administration robustly alleviated thrombogenesis (P<0.05) without affecting hemostasis. Mechanistically, GUDCA inhibited DGK (diacylglycerol kinase) activity, leading to the downregulation of the phosphatidic acid-mediated signaling pathway. Conversely, phosphatidic acid supplementation was sufficient to abolish the antithrombotic effects of GUDCA. More importantly, long-term oral administration of GUDCA normalized the enhanced DGK activity, thereby remarkably alleviating the platelet hyperreactivity as well as the heightened thrombotic tendency in diet-induced obese mice (P<0.05). CONCLUSIONS: Our study implicated that GUDCA reduces platelet hyperreactivity and improves thrombotic propensity by inhibiting DGKs activity, which is a potentially effective prophylactic approach and promising therapeutic agent for arterial thrombotic events.

In mild ischemic stroke or high-risk TIA, DAPT started ≤72 h after onset reduced new stroke and increased bleeding at 90 d.

SOURCE CITATION: Gao Y, Chen W, Pan Y, et al; INSPIRES Investigators. Dual antiplatelet treatment up to 72 hours after ischemic stroke. N Engl J Med. 2023;389:2413-2424. 38157499.

After stent implantation for ACS, ticagrelor monotherapy after <1 mo of DAPT vs. 12 mo of DAPT improved 1-y net clinical benefit.

SOURCE CITATION: Hong SJ, Lee SJ, Suh Y, et al; T-PASS (Ticagrelor Monotherapy in Patients Treated With New-Generation Drug-Eluting Stents for Acute Coronary Syndrome) Investigators. Stopping aspirin within 1 month after stenting for ticagrelor monotherapy in acute coronary syndrome: the T-PASS randomized noninferiority trial. Circulation. 2024;149:562-573. 37878786.

In cryptogenic stroke and atrial cardiopathy, apixaban did not reduce recurrent stroke vs. aspirin.

SOURCE CITATION: Kamel H, Longstreth WT Jr, Tirschwell DL, et al; ARCADIA Investigators. Apixaban to prevent recurrence after cryptogenic stroke in patients with atrial cardiopathy: the ARCADIA randomized clinical trial. JAMA. 2024;331:573-581. 38324415.