Ticlopidine protects hepatic ischemia-reperfusion injury via suppressing ferroptosis.

Hepatic ischemia-reperfusion injury (IRI) is a major cause of liver damage during hepatic resection, transplantation, and other surgical procedures, often leading to graft failure and liver dysfunction. Recent studies have identified ferroptosis, a form of regulated cell death characterized by iron-dependent lipid peroxidation, as a key contributor to IRI. In this study, we investigated the protective effects of Ticlopidine, a thienopyridine compound and platelet aggregation inhibitor, on hepatic IRI. Using a C57BL/6J mouse model, we demonstrated that prophylactic Ticlopidine treatment significantly reduced necrotic and fibrotic areas in liver tissues, as well as serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST). Prussian Blue staining revealed that Ticlopidine pretreatment decreased iron accumulation in hepatic tissues, whereas markers of lipid peroxidation (malondialdehyde and 4-hydroxynonenal) and ferroptosis (PTGS2) were significantly downregulated. Additionally, Ticlopidine ameliorated inflammatory infiltration as indicated by reduced Gr-1 staining. In vitro, Ticlopidine dose-dependently inhibited ferroptosis induced by various inducers in liver cancer cell lines HUH7 and fibrosarcoma cells HT1080. The protective effects involved partial rescue of lipid peroxidation, significant reduction of ferrous iron levels, and strong protection against mitochondrial damage. These findings suggested that Ticlopidine acts as a broad-spectrum ferroptosis inhibitor, offering a promising therapeutic approach for protecting the liver against IRI.

Association of clopidogrel resistance and ABCD-GENE score with long-term clinical prognosis in patients with ischemic stroke or TIA.

BACKGROUND: Clopidogrel resistance (CR) is associated with adverse clinical outcomes in acute ischemic stroke or transient ischemic attack (TIA) patients. However, whether CR affects the long-term clinical prognosis remains to be clarified. The ABCD-GENE score is a novel risk model that identifies CR in cardiovascular disease patients; its diagnostic ability and application in ischemic stroke or TIA remain to be studied. This study aimed to investigate the diagnostic ability of the ABCD-GENE score for CR and analyze the relationship between CR and long-term clinical prognosis in patients with ischemic stroke or TIA. METHODS: From January 2018 to January 2021, 251 ischemic stroke or TIA patients who were treated with clopidogrel for more than three months after onset and maintained the medication until the follow-up time were enrolled, and platelet reactivity was detected by thromboelastography. CYP2C19 gene analysis was performed. Adverse clinical outcomes were recorded from 3months after onset. The median follow-up time was 878days. RESULTS: The prevalence of CR was 33.9%. The proportion of CYP2C19 loss-of-function carriers was 62.2%. The ABCD-GENE score≥10 was independently associated with CR (OR=1.82, 95% CI: 1.02-3.24, P=0.041), and the C-statistic value of the score (as a binary and integer variable) on CR was 0.58 and 0.63, respectively. The risk of long-term adverse clinical outcomes was not significantly different between CR and clopidogrel sensitive groups (12.94% vs. 11.44%, HR=1.22, 95% CI: 0.57-2.62, P=0.603). A similar result was observed between ABCD-GENE score≥10 and ABCD-GENE score<10 groups (10.38% vs. 12.64%, HR=1.19, 95% CI: 0.55-2.60, P=0.666). CONCLUSIONS: In ischemic stroke or TIA patients, the ABCD-GENE score could identify the risk of CR. CR was not associated with long-term adverse clinical outcomes.

Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA.

BACKGROUND: Combination antiplatelet therapy with clopidogrel and aspirin may reduce the rate of recurrent stroke during the first 3 months after a minor ischemic stroke or transient ischemic attack (TIA). A trial of combination antiplatelet therapy in a Chinese population has shown a reduction in the risk of recurrent stroke. We tested this combination in an international population. METHODS: In a randomized trial, we assigned patients with minor ischemic stroke or high-risk TIA to receive either clopidogrel at a loading dose of 600 mg on day 1, followed by 75 mg per day, plus aspirin (at a dose of 50 to 325 mg per day) or the same range of doses of aspirin alone. The dose of aspirin in each group was selected by the site investigator. The primary efficacy outcome in a time-to-event analysis was the risk of a composite of major ischemic events, which was defined as ischemic stroke, myocardial infarction, or death from an ischemic vascular event, at 90 days. RESULTS: A total of 4881 patients were enrolled at 269 international sites. The trial was halted after 84% of the anticipated number of patients had been enrolled because the data and safety monitoring board had determined that the combination of clopidogrel and aspirin was associated with both a lower risk of major ischemic events and a higher risk of major hemorrhage than aspirin alone at 90 days. Major ischemic events occurred in 121 of 2432 patients (5.0%) receiving clopidogrel plus aspirin and in 160 of 2449 patients (6.5%) receiving aspirin plus placebo (hazard ratio, 0.75; 95% confidence interval [CI], 0.59 to 0.95; P=0.02), with most events occurring during the first week after the initial event. Major hemorrhage occurred in 23 patients (0.9%) receiving clopidogrel plus aspirin and in 10 patients (0.4%) receiving aspirin plus placebo (hazard ratio, 2.32; 95% CI, 1.10 to 4.87; P=0.02). CONCLUSIONS: In patients with minor ischemic stroke or high-risk TIA, those who received a combination of clopidogrel and aspirin had a lower risk of major ischemic events but a higher risk of major hemorrhage at 90 days than those who received aspirin alone. (Funded by the National Institute of Neurological Disorders and Stroke; POINT ClinicalTrials.gov number, NCT00991029 .).

Ticagrelor versus Clopidogrel in Symptomatic Peripheral Artery Disease.

BACKGROUND: Peripheral artery disease is considered to be a manifestation of systemic atherosclerosis with associated adverse cardiovascular and limb events. Data from previous trials have suggested that patients receiving clopidogrel monotherapy had a lower risk of cardiovascular events than those receiving aspirin. We wanted to compare clopidogrel with ticagrelor, a potent antiplatelet agent, in patients with peripheral artery disease. METHODS: In this double-blind, event-driven trial, we randomly assigned 13,885 patients with symptomatic peripheral artery disease to receive monotherapy with ticagrelor (90 mg twice daily) or clopidogrel (75 mg once daily). Patients were eligible if they had an ankle-brachial index (ABI) of 0.80 or less or had undergone previous revascularization of the lower limbs. The primary efficacy end point was a composite of adjudicated cardiovascular death, myocardial infarction, or ischemic stroke. The primary safety end point was major bleeding. The median follow-up was 30 months. RESULTS: The median age of the patients was 66 years, and 72% were men; 43% were enrolled on the basis of the ABI and 57% on the basis of previous revascularization. The mean baseline ABI in all patients was 0.71, 76.6% of the patients had claudication, and 4.6% had critical limb ischemia. The primary efficacy end point occurred in 751 of 6930 patients (10.8%) receiving ticagrelor and in 740 of 6955 (10.6%) receiving clopidogrel (hazard ratio, 1.02; 95% confidence interval [CI], 0.92 to 1.13; P=0.65). In each group, acute limb ischemia occurred in 1.7% of the patients (hazard ratio, 1.03; 95% CI, 0.79 to 1.33; P=0.85) and major bleeding in 1.6% (hazard ratio, 1.10; 95% CI, 0.84 to 1.43; P=0.49). CONCLUSIONS: In patients with symptomatic peripheral artery disease, ticagrelor was not shown to be superior to clopidogrel for the reduction of cardiovascular events. Major bleeding occurred at similar rates among the patients in the two trial groups. (Funded by AstraZeneca; EUCLID ClinicalTrials.gov number, NCT01732822 .).

Dual Antithrombotic Therapy with Dabigatran after PCI in Atrial Fibrillation.

BACKGROUND: Triple antithrombotic therapy with warfarin plus two antiplatelet agents is the standard of care after percutaneous coronary intervention (PCI) for patients with atrial fibrillation, but this therapy is associated with a high risk of bleeding. METHODS: In this multicenter trial, we randomly assigned 2725 patients with atrial fibrillation who had undergone PCI to triple therapy with warfarin plus a P2Y12 inhibitor (clopidogrel or ticagrelor) and aspirin (for 1 to 3 months) (triple-therapy group) or dual therapy with dabigatran (110 mg or 150 mg twice daily) plus a P2Y12 inhibitor (clopidogrel or ticagrelor) and no aspirin (110-mg and 150-mg dual-therapy groups). Outside the United States, elderly patients (≥80 years of age; ≥70 years of age in Japan) were randomly assigned to the 110-mg dual-therapy group or the triple-therapy group. The primary end point was a major or clinically relevant nonmajor bleeding event during follow-up (mean follow-up, 14 months). The trial also tested for the noninferiority of dual therapy with dabigatran (both doses combined) to triple therapy with warfarin with respect to the incidence of a composite efficacy end point of thromboembolic events (myocardial infarction, stroke, or systemic embolism), death, or unplanned revascularization. RESULTS: The incidence of the primary end point was 15.4% in the 110-mg dual-therapy group as compared with 26.9% in the triple-therapy group (hazard ratio, 0.52; 95% confidence interval [CI], 0.42 to 0.63; P<0.001 for noninferiority; P<0.001 for superiority) and 20.2% in the 150-mg dual-therapy group as compared with 25.7% in the corresponding triple-therapy group, which did not include elderly patients outside the United States (hazard ratio, 0.72; 95% CI, 0.58 to 0.88; P<0.001 for noninferiority). The incidence of the composite efficacy end point was 13.7% in the two dual-therapy groups combined as compared with 13.4% in the triple-therapy group (hazard ratio, 1.04; 95% CI, 0.84 to 1.29; P=0.005 for noninferiority). The rate of serious adverse events did not differ significantly among the groups. CONCLUSIONS: Among patients with atrial fibrillation who had undergone PCI, the risk of bleeding was lower among those who received dual therapy with dabigatran and a P2Y12 inhibitor than among those who received triple therapy with warfarin, a P2Y12 inhibitor, and aspirin. Dual therapy was noninferior to triple therapy with respect to the risk of thromboembolic events. (Funded by Boehringer Ingelheim; RE-DUAL PCI ClinicalTrials.gov number, NCT02164864 .).

Inhibition of carboxylesterase-1 alters clopidogrel metabolism and disposition.

Clopidogrel is widely prescribed in patients with cardiovascular disease. Most research has focused on the role of hepatic CYP450 metabolism as the primary source of response variability despite 85-90% of clopidogrel being hydrolyzed by human carboxylesterase-1 (CES1).The purpose of this study is to determine the effects of the known CES1 inhibitor alcohol on clopidogrel metabolism: (1) in vitro in human recombinant CES1 and human liver S9 (HLS9) fractions and (2) in a plasma carboxylesterase deficient mouse (Es1e) strain administered 25 mg/kg oral clopidogrel alone and with 3 g/kg alcohol.Alcohol significantly inhibited the hydrolysis of clopidogrel (IC50 161 mM) and 2-oxo-clopidogrel (IC50 6 mM). In HLS9, alcohol treatment formed ethylated metabolites via transesterification and an increased formation of the H4 active metabolite. These results were replicated in Es1e mice as alcohol increased clopidogrel (91%) and H4 (22%) AUC and reduced formation of the clopidogrel (48%) and 2-oxo-clopidogrel (42%) carboxylate metabolites.Clopidogrel metabolism is highly sensitive to alterations in CES1 activity. The Es1e mouse may represent a suitable model of human CES1 drug metabolism that can be used to rapidly assess how alterations in CES1 function impact the disposition of substrate drugs.

6-month versus 12-month or longer dual antiplatelet therapy after percutaneous coronary intervention in patients with acute coronary syndrome (SMART-DATE): a randomised, open-label, non-inferiority trial.

BACKGROUND: Current guidelines recommend dual antiplatelet therapy (DAPT) of aspirin plus a P2Y12 inhibitor for at least 12 months after implantation of drug-eluting stents (DES) in patients with acute coronary syndrome. However, available data about the optimal duration of DAPT in patients with acute coronary syndrome undergoing percutaneous coronary intervention are scant. We aimed to investigate whether a 6-month duration of DAPT would be non-inferior to the conventional 12-month or longer duration of DAPT in this population. METHODS: We did a randomised, open-label, non-inferiority trial at 31 centres in South Korea. Patients were eligible if they had unstable angina, non-ST-segment elevation myocardial infarction, or ST-segment elevation myocardial infarction, and underwent percutaneous coronary intervention. Enrolled patients were randomly assigned, via a web-based system by computer-generated block randomisation, to either the 6-month DAPT group or to the 12-month or longer DAPT group, with stratification by site, clinical presentation, and diabetes. Assessors were masked to treatment allocation. The primary endpoint was a composite of all-cause death, myocardial infarction, or stroke at 18 months after the index procedure in the intention-to-treat population. Secondary endpoints were the individual components of the primary endpoint; definite or probable stent thrombosis as defined by the Academic Research Consortium; and Bleeding Academic Research Consortium (BARC) type 2-5 bleeding at 18 months after the index procedure. The primary endpoint was also analysed per protocol. This trial is registered with ClinicalTrials.gov, number NCT01701453. FINDINGS: Between Sept 5, 2012, and Dec 31, 2015, we randomly assigned 2712 patients; 1357 to the 6-month DAPT group and 1355 to the 12-month or longer DAPT group. Clopidogrel was used as a P2Y12 inhibitor for DAPT in 1082 (79·7%) patients in the 6-month DAPT group and in 1109 (81·8%) patients in the 12-month or longer DAPT group. The primary endpoint occurred in 63 patients in the 6-month DAPT group and in 56 patients in the 12-month or longer DAPT group (cumulative event rate 4·7% vs 4·2%; absolute risk difference 0·5%; upper limit of one-sided 95% CI 1·8%; pnon-inferiority=0·03 with a predefined non-inferiority margin of 2·0%). Although all-cause mortality did not differ significantly between the 6-month DAPT group and the 12-month or longer DAPT group (35 [2·6%] patients vs 39 [2·9%]; hazard ratio [HR] 0·90 [95% CI 0·57-1·42]; p=0·90) and neither did stroke (11 [0·8%] patients vs 12 [0·9%]; 0·92 [0·41-2·08]; p=0·84), myocardial infarction occurred more frequently in the 6-month DAPT group than in the 12-month or longer DAPT group (24 [1·8%] patients vs ten [0·8%]; 2·41 [1·15-5·05]; p=0·02). 15 (1·1%) patients had stent thrombosis in the 6-month DAPT group compared with ten (0·7%) in the 12-month or longer DAPT group (HR 1·50 [95% CI 0·68-3·35]; p=0·32). The rate of BARC type 2-5 bleeding was 2·7% (35 patients) in the 6-month DAPT group and 3·9% (51 patients) in the 12-month or longer DAPT group (HR 0·69 [95% CI 0·45-1·05]; p=0·09). Results from the per-protocol analysis were similar to those from the intention-to-treat analysis. INTERPRETATION: The increased risk of myocardial infarction with 6-month DAPT and the wide non-inferiority margin prevent us from concluding that short-term DAPT is safe in patients with acute coronary syndrome undergoing percutaneous coronary intervention with current-generation DES. Prolonged DAPT in patients with acute coronary syndrome without excessive risk of bleeding should remain the standard of care. FUNDING: Abbott Vascular Korea, Medtronic Vascular Korea, Biosensors Inc, and Dong-A ST.

Ticagrelor plus aspirin for 1 month, followed by ticagrelor monotherapy for 23 months vs aspirin plus clopidogrel or ticagrelor for 12 months, followed by aspirin monotherapy for 12 months after implantation of a drug-eluting stent: a multicentre, open-label, randomised superiority trial.

BACKGROUND: We hypothesised that ticagrelor, in combination with aspirin for 1 month, followed by ticagrelor alone, improves outcomes after percutaneous coronary intervention compared with standard antiplatelet regimens. METHODS: GLOBAL LEADERS was a randomised, open-label superiority trial at 130 sites in 18 countries. Patients undergoing percutaneous coronary intervention with a biolimus A9-eluting stent for stable coronary artery disease or acute coronary syndromes were randomly assigned (1:1) to 75-100 mg aspirin daily plus 90 mg ticagrelor twice daily for 1 month, followed by 23 months of ticagrelor monotherapy, or standard dual antiplatelet therapy with 75-100 mg aspirin daily plus either 75 mg clopidogrel daily (for patients with stable coronary artery disease) or 90 mg ticagrelor twice daily (for patients with acute coronary syndromes) for 12 months, followed by aspirin monotherapy for 12 months. Randomisation was concealed, stratified by centre and clinical presentation (stable coronary artery disease vs acute coronary syndrome), and blocked, with randomly varied block sizes of two and four. The primary endpoint at 2 years was a composite of all-cause mortality or non-fatal centrally adjudicated new Q-wave myocardial infarction as assessed by a core lab in a blinded manner. The key secondary safety endpoint was site-reported bleeding assessed according to the Bleeding Academic Research Consortium criteria (grade 3 or 5). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01813435, and is closed to new participants, with follow-up completed. FINDINGS: Between July 1, 2013, and Nov 9, 2015, 15 968 participants were randomly assigned, 7980 to the experimental group and 7988 to the control group. At 2 years, 304 (3·81%) participants in the experimental group had died or had a non-fatal centrally adjudicated new Q-wave myocardial infarction, compared with 349 (4·37%) participants in the control group (rate ratio 0·87 [95% CI 0·75-1·01]; p=0·073]). There was no evidence for a difference in treatment effects for the primary endpoint across prespecified subgroups of acute coronary syndromes and stable coronary artery disease (p=0·93). Grade 3 or 5 bleeding occurred in 163 participants in the experimental group and 169 in the control group (2·04% vs 2·12%; rate ratio 0·97 [95% CI 0·78-1·20]; p=0·77). INTERPRETATION: Ticagrelor in combination with aspirin for 1 month followed by ticagrelor alone for 23 months was not superior to 12 months of standard dual antiplatelet therapy followed by 12 months of aspirin alone in the prevention of all-cause mortality or new Q-wave myocardial infarction 2 years after percutaneous coronary intervention. FUNDING: AstraZeneca, Biosensors, and The Medicines Company.

Antiplatelet therapy with aspirin, clopidogrel, and dipyridamole versus clopidogrel alone or aspirin and dipyridamole in patients with acute cerebral ischaemia (TARDIS): a randomised, open-label, phase 3 superiority trial.

BACKGROUND: Intensive antiplatelet therapy with three agents might be more effective than guideline treatment for preventing recurrent events in patients with acute cerebral ischaemia. We aimed to compare the safety and efficacy of intensive antiplatelet therapy (combined aspirin, clopidogrel, and dipyridamole) with that of guideline-based antiplatelet therapy. METHODS: We did an international, prospective, randomised, open-label, blinded-endpoint trial in adult participants with ischaemic stroke or transient ischaemic attack (TIA) within 48 h of onset. Participants were assigned in a 1:1 ratio using computer randomisation to receive loading doses and then 30 days of intensive antiplatelet therapy (combined aspirin 75 mg, clopidogrel 75 mg, and dipyridamole 200 mg twice daily) or guideline-based therapy (comprising either clopidogrel alone or combined aspirin and dipyridamole). Randomisation was stratified by country and index event, and minimised with prognostic baseline factors, medication use, time to randomisation, stroke-related factors, and thrombolysis. The ordinal primary outcome was the combined incidence and severity of any recurrent stroke (ischaemic or haemorrhagic; assessed using the modified Rankin Scale) or TIA within 90 days, as assessed by central telephone follow-up with masking to treatment assignment, and analysed by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN47823388. FINDINGS: 3096 participants (1556 in the intensive antiplatelet therapy group, 1540 in the guideline antiplatelet therapy group) were recruited from 106 hospitals in four countries between April 7, 2009, and March 18, 2016. The trial was stopped early on the recommendation of the data monitoring committee. The incidence and severity of recurrent stroke or TIA did not differ between intensive and guideline therapy (93 [6%] participants vs 105 [7%]; adjusted common odds ratio [cOR] 0·90, 95% CI 0·67-1·20, p=0·47). By contrast, intensive antiplatelet therapy was associated with more, and more severe, bleeding (adjusted cOR 2·54, 95% CI 2·05-3·16, p<0·0001). INTERPRETATION: Among patients with recent cerebral ischaemia, intensive antiplatelet therapy did not reduce the incidence and severity of recurrent stroke or TIA, but did significantly increase the risk of major bleeding. Triple antiplatelet therapy should not be used in routine clinical practice. FUNDING: National Institutes of Health Research Health Technology Assessment Programme, British Heart Foundation.

How I use laboratory monitoring of antiplatelet therapy.

Antiplatelet therapy is of proven benefit in coronary artery disease and a number of other clinical settings. This article reviews platelet function, molecular targets of antiplatelet agents, and clinical indications for antiplatelet therapy before focusing on a frequent question to hematologists about the 2 most commonly used antiplatelet therapies: Could the patient be aspirin "resistant" or clopidogrel "resistant"? If so, should results of a platelet function test be used to guide the dose or type of antiplatelet therapy? Whether such guided therapy is of clinical benefit to patients has been a source of controversy. The present article reviews this subject in the context of 2 prototypical clinical cases. Available evidence does not support the use of laboratory tests to guide the dose of aspirin or clopidogrel in patients with so-called aspirin or clopidogrel "resistance."

Critical Role of P2Y12 Receptor in Regulation of Th17 Differentiation and Experimental Autoimmune Encephalomyelitis Pathogenesis.

Adenosine 5'-diphosphate is a key endogenous cell-signaling molecule that can activate P2 purinergic receptor family members. ADP-P2Y signaling is reported to be associated with inflammation, but its function in T cell differentiation and autoimmune diseases pathogenesis is unclear. In this study, we found that the P2Y12 receptor was upregulated in the peripheral immune tissues of experimental autoimmune encephalomyelitis (EAE) mice. Deficiency of P2Y12 led to a reduced peak severity and cumulative disease score in EAE mice, followed by a dramatic reduction of leukocyte infiltration and less extensive demyelination. The percentage of Th17, one of the main pathogenic T cells in EAE, was sharply decreased in P2Y12 knockout mice, accompanied by decreased IL-17A production and a low mRNA level of Th17-related genes. In vitro culture assay further verified that P2Y12 directly regulated Th17 differentiation. More interestingly, clopidogrel and ticagrelor, two P2Y12-specific antagonists, effectively alleviated the disease severity of EAE and inhibited Th17 differentiation both in vivo and in vitro. Further study demonstrated that blocking the P2Y12 receptor also ameliorated the symptoms of 2,4,6-trinitrobenzenesulfonic acid-induced colitis and multiple low-dose streptozocin-induced type 1 diabetes. Our findings not only revealed the critical role of P2Y12 in Th17 differentiation and EAE pathogenesis, but also suggested the promising potential of P2Y12 antagonists in the treatment of autoimmune diseases.

Purinergic receptor P2RY12-dependent microglial closure of the injured blood-brain barrier.

Microglia are integral functional elements of the central nervous system, but the contribution of these cells to the structural integrity of the neurovascular unit has not hitherto been assessed. We show here that following blood-brain barrier (BBB) breakdown, P2RY12 (purinergic receptor P2Y, G-protein coupled, 12)-mediated chemotaxis of microglia processes is required for the rapid closure of the BBB. Mice treated with the P2RY12 inhibitor clopidogrel, as well as those in which P2RY12 was genetically ablated, exhibited significantly diminished movement of juxtavascular microglial processes and failed to close laser-induced openings of the BBB. Thus, microglial cells play a previously unrecognized protective role in the maintenance of BBB integrity following cerebrovascular damage. Because clopidogrel antagonizes the platelet P2Y12 receptor, it is widely prescribed for patients with coronary artery and cerebrovascular disease. As such, these observations suggest the need for caution in the postincident continuation of P2RY12-targeted platelet inhibition.

International Expert Consensus on Switching Platelet P2Y12 Receptor-Inhibiting Therapies.

Dual antiplatelet therapy with aspirin and a P2Y12 inhibitor is the treatment of choice for the prevention of atherothrombotic events in patients with acute coronary syndromes and for those undergoing percutaneous coronary interventions. The availability of different oral P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) has enabled physicians to contemplate switching among therapies because of specific clinical scenarios. The recent introduction of an intravenous P2Y12 inhibitor (cangrelor) further adds to the multitude of modalities and settings in which switching therapies may occur. In clinical practice, it is not uncommon to switch P2Y12 inhibitor, and switching may be attributed to a variety of factors. However, concerns about the safety of switching between these agents have emerged. Practice guidelines have not fully elaborated on how to switch therapies, leaving clinicians with limited guidance on when and how to switch therapies when needed. This prompted the development of this expert consensus document by key leaders from North America and Europe with expertise in basic, translational, and clinical sciences in the field of antiplatelet therapy. This expert consensus provides an overview of the pharmacology of P2Y12 inhibitors, different modalities and definitions of switching, and available literature and recommendations for switching between P2Y12 inhibitors.

Ticagrelor Compared With Clopidogrel in Patients With Prior Lower Extremity Revascularization for Peripheral Artery Disease.

BACKGROUND: In patients with symptomatic peripheral artery disease with a history of limb revascularization, the optimal antithrombotic regimen for long-term management is unknown. METHODS: The EUCLID trial (Examining Use of Ticagrelor In PAD) randomized 13 885 patients with peripheral artery disease to treatment with ticagrelor 90 mg twice daily or clopidogrel 75 mg daily. Patients were enrolled based on an abnormal ankle-brachial index ≤0.80 or a previous lower extremity revascularization. This analysis focuses on the 7875 (57%) patients enrolled based on the previous lower extremity revascularization criterion. Patients could not be enrolled within 30 days of most recent revascularization, and patients with an indication for dual antiplatelet therapy were excluded. The primary efficacy end point was a composite of cardiovascular death, myocardial infarction, or ischemic stroke. The primary safety end point was major bleeding. RESULTS: Patients with a previous revascularization had a mean age of 66 years, 73% were male, and the median baseline ankle-brachial index was 0.78. After adjustment for baseline characteristics, patients enrolled based on previous revascularization had similar rates of the primary composite end point (hazard ratio [HR] 1.10, 95% confidence interval [CI] 0.98-1.23, P=0.12) and statistically significantly higher rates of myocardial infarction (HR 1.29, 95% CI 1.08-1.55, P=0.005) and acute limb ischemia (HR 4.23, 95% CI 2.86-6.25, P<0.001) when compared with patients enrolled based on ankle-brachial index criteria. No differences in ticagrelor- versus clopidogrel-treated patients were found for the primary efficacy end point (11.4% vs 11.3%; HR 1.01, 95% CI 0.88-1.15; P=0.90), all-cause mortality (9.2% vs 9.2%; HR 0.99, 95% CI 0.86-1.15; P=0.93), acute limb ischemia (2.5% vs 2.5%; HR 1.03, 95% CI 0.78-1.36; P=0.84), or major bleeding (1.9% vs 1.8%; HR 1.15, 95% CI 0.83-1.59; P=0.41). The median duration of follow-up was ≈30 months. CONCLUSIONS: After adjustment for baseline characteristics, patients enrolled based on previous revascularization for peripheral artery disease had higher rates of myocardial infarction and acute limb ischemia, with similar composite rates of cardiovascular death, myocardial infarction, and stroke when compared with patients enrolled based on the ankle-brachial index criterion. No significant differences were found between ticagrelor and clopidogrel for reduction of cardiovascular or acute limb events. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01732822.

Genetic Polymorphisms and Clopidogrel Efficacy for Acute Ischemic Stroke or Transient Ischemic Attack: A Systematic Review and Meta-Analysis.

BACKGROUND: The association of genetic polymorphisms and clopidogrel efficacy in patients with ischemic stroke or transient ischemic attack (TIA) remains controversial. We performed a systematic review and meta-analysis to assess the association between genetic polymorphisms, especially CYP2C19 genotype, and clopidogrel efficacy for ischemic stroke or TIA. METHODS: We conducted a comprehensive search of PubMed and EMBASE from their inceptions to June 24, 2016. Studies that reported clopidogrel-treated patients with stroke or TIA and with information on genetic polymorphisms were included. The end points were stroke, composite vascular events, and any bleeding. RESULTS: Among 15 studies of 4762 patients with stroke or TIA treated with clopidogrel, carriers of CYP2C19 loss-of-function alleles (*2, *3, and *8) were at increased risk of stroke in comparison with noncarriers (12.0% versus 5.8%; risk ratio, 1.92, 95% confidence interval, 1.57-2.35; P<0.001). Composite vascular events were also more frequent in carriers of CYP2C19 loss-of-function alleles than in noncarriers (13.7% versus 9.4%; risk ratio, 1.51, 95% confidence interval, 1.10-2.06; P=0.01), whereas bleeding rates were similar (2.4% versus 3.1%; risk ratio, 0.89, 95% confidence interval, 0.58-1.35; P=0.59). There was no evidence of statistical heterogeneity among the included studies for stroke, but there was for composite vascular events. Genetic variants other than CYP2C19 were not associated with clinical outcomes, with the exception that significant associations of PON1, P2Y12, and COX-1 with outcomes were observed in 1 study. CONCLUSIONS: Carriers of CYP2C19 loss-of-function alleles are at greater risk of stroke and composite vascular events than noncarriers among patients with ischemic stroke or TIA treated with clopidogrel.

Myocardial Infarction Risk After Discontinuation of Thienopyridine Therapy in the Randomized DAPT Study (Dual Antiplatelet Therapy).

BACKGROUND: Thienopyridine plus aspirin beyond 1 year after coronary stenting reduces myocardial infarction (MI) risk and increases bleeding risk in comparison with aspirin alone. The hazard associated with late thienopyridine discontinuation and risk factors for MI after discontinuation are poorly defined. METHODS: In the DAPT Study (Dual Antiplatelet Therapy), after percutaneous coronary intervention and 12 months of thienopyridine (clopidogrel or prasugrel) plus aspirin, eligible patients remained on aspirin and were randomly assigned to continued thienopyridine versus placebo for 18 months. At 30 months, patients stopped the study drug and were observed for 3 months. Cumulative incidence of MI was assessed over 3 months after randomization (months 12-15) and 3 months after study drug discontinuation (months 30-33). The MI hazard for each of these periods was assessed across randomized treatment arms and by DAPT score values <2 or ≥2. RESULTS: Among the 11 648 randomly assigned patients, the monthly cumulative incidence of MI was lower with continued thienopyridine versus placebo at 12 to 15 months (0.12% versus 0.37%, P<0.001, in all patients; 0.13% versus 0.27%, P=0.02, in patients not treated with paclitaxel-eluting stents), and higher at 30 to 33 months (0.30% versus 0.15%, P=0.013, in all patients; in patients without paclitaxel-eluting stents, 0.18% versus 0.17%, P=0.91). The majority of MIs in both time periods (74% and 76%) were not related to stent thrombosis. After multivariable adjustment, treatment arm independently predicted MI at months 12 to 15 (P<0.001) and 30 to 33 (P=0.011). During months 12 to 15, patients with DAPT scores <2 or ≥2 both had lower rates of MI with continued thienopyridine (MI monthly incidence 0.16% versus 0.51%, P<0.001, for scores ≥2; 0.08% versus 0.24%, P=0.012, for scores<2, interaction P=0.064). CONCLUSIONS: Discontinuing thienopyridine after either 12 or 30 months is associated with an early increase in MI risk, mainly unrelated to stent thrombosis; the magnitude of risk is highest in the earlier time frame, and lower in patients not treated with paclitaxel-eluting stents. Although higher DAPT scores identify patients with greater absolute ischemic benefit (relative to bleeding harm) with continued thienopyridine therapy, discontinuation at 12 months increases MI hazard regardless of DAPT score group. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00977938.

STARTING-SICH Nomogram to Predict Symptomatic Intracerebral Hemorrhage After Intravenous Thrombolysis for Stroke.

BACKGROUND AND PURPOSE: Symptomatic intracerebral hemorrhage (sICH) is a rare but the most feared complication of intravenous thrombolysis for ischemic stroke. We aimed to develop and validate a nomogram for individualized prediction of sICH in intravenous thrombolysis-treated stroke patients included in the multicenter SITS-ISTR (Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register). METHODS: All patients registered in the SITS-ISTR by 179 Italian centers between May 2001 and March 2016 were originally included. The main outcome measure was sICH per the European Cooperative Acute Stroke Study II definition (any type of intracerebral hemorrhage with increase of ≥4 National Institutes of Health Stroke Scale score points from baseline or death <7 days). On the basis of multivariate logistic model, the nomogram was generated. We assessed the discriminative performance by using the area under the receiver-operating characteristic curve and calibration of risk prediction model by using the Hosmer-Lemeshow test. RESULTS: A total of 15 949 patients with complete data for generating the nomogram was randomly dichotomized into training (3/4; n=12 030) and test (1/4; n=3919) sets. After multivariate logistic regression, 10 variables remained independent predictors of sICH to compose the STARTING-SICH (systolic blood pressure, age, onset-to-treatment time for thrombolysis, National Institutes of Health Stroke Scale score, glucose, aspirin alone, aspirin plus clopidogrel, anticoagulant with INR ≤1.7, current infarction sign, hyperdense artery sign) nomogram. The area under the receiver-operating characteristic curve of STARTING-SICH was 0.739. Calibration was good (P=0.327 for the Hosmer-Lemeshow test). CONCLUSIONS: The STARTING-SICH is the first nomogram developed and validated in a large SITS-ISTR cohort for individualized prediction of sICH in intravenous thrombolysis-treated stroke patients.

A Meta-analysis of the Impact of Aspirin, Clopidogrel, and Dual Antiplatelet Therapy on Bleeding Complications in Noncardiac Surgery.

OBJECTIVE: The aim of this study was to determine the bleeding risks associated with single (aspirin) and dual (aspirin + clopidogrel) antiplatelet therapy (DAPT) versus placebo or no treatment in adults undergoing noncardiac surgery. SUMMARY OF BACKGROUND DATA: The impact of antiplatelet therapy on bleeding during noncardiac surgery remains controversial. A meta-analysis was performed to examine the risk associated with single and DAPT. METHODS: A systematic review of antiplatelet therapy, noncardiac surgery, and perioperative bleeding was performed. Peer-reviewed sources and meeting abstracts from relevant societies were queried. Studies without a control group, or those that only examined patients with coronary stents, were excluded. Primary endpoints were transfusion and reintervention for bleeding. RESULTS: Of 11,592 references, 46 studies met inclusion criteria. In a meta-analysis of >30,000 patients, the relative risk (RR) of transfusion versus control was 1.14 [95% confidence interval (CI) 1.03-1.26, P = 0.009] for aspirin, and 1.33 (1.15-1.55, P = 0.001) for DAPT. Clopidogrel had an elevated risk, but data were too heterogeneous to analyze. The RR of bleeding requiring reintervention was not significantly higher for any agent compared to control [RR 0.96 (0.76-1.22, P = 0.76) for aspirin, 1.84 (0.87-3.87, P = 0.11) for clopidogrel, and 1.51 (0.92-2.49, P = 0.1) for DAPT]. Subanalysis of thoracic and abdominal procedures was similar. There was no difference in RR for myocardial infarction [1.06 (0.79-1.43)], stroke [0.97 (0.71-1.33)], or mortality [0.97 (0.87-1.1)]. CONCLUSIONS: Antiplatelet therapy at the time of noncardiac surgery confers minimal bleeding risk with no difference in thrombotic complications. In many cases, it is safe to continue antiplatelet therapy in patients with important indications for their use.