A randomised controlled trial of triple antiplatelet therapy (aspirin, clopidogrel and dipyridamole) in the secondary prevention of stroke: safety, tolerability and feasibility

Variability in Contemporary Heparin Prescription and Activated Clotting Time Monitoring During Percutaneous Coronary Intervention: Call for Up-To-Date Evidence-Based Guidelines

BACKGROUND

Unfractionated heparin (UFH) is the preferred anticoagulant agent in percutaneous coronary intervention (PCI) procedures for minimising the risk of thrombotic complications. Because of the narrow therapeutic range of UFH, some society guidelines have advocated the use of the activated clotting time (ACT) test to monitor anticoagulation intensity during PCI to reduce thrombotic and bleeding complications. We aimed to assess the current practice of UFH prescription and its monitoring in Australia and New Zealand (ANZ).

METHOD

We conducted an anonymous voluntary cross-sectional survey of interventional cardiologists (ICs) who were members of the Cardiac Society of Australia and New Zealand in 2022. The survey included 10 questions pertaining to the current practice of anticoagulation during PCI.

RESULTS

Of 430 ICs surveyed, 148 responded (response rate, 34.4%). Most ICs (84.4%) prescribed 70-100 IU/kg of UFH for PCI. Over half of ICs (58.7%) routinely measured ACT during PCI, whereas only 22.2% routinely measured ACT after PCI to guide additional UFH prescription. Among ICs who prescribed additional UFH, approximately half (48%) aimed for ACT ≥250 seconds. Factors that influenced post-PCI UFH prescription included vascular access site and concomitant antiplatelet or anticoagulant therapy.

CONCLUSIONS

The contemporary practice of UFH prescription during PCI and ACT monitoring in ANZ is variable and based on outdated evidence preceding current drug-eluting stents, antiplatelet therapies, and radial-first practice. Current society guideline recommendations lack clarity and agreement, reflecting the quality of the available evidence. Up-to-date clinical trials evaluating UFH prescription and ACT monitoring are needed to optimise clinical outcomes in contemporary PCI procedures.

Therapeutic considerations for prevention and treatment of thrombotic events in COVID-19

Thrombosis is a known complication of SARS-CoV-2 infection, particularly within a severely symptomatic subset of patients with COVID-19 disease, in whom an aggressive host immune response leads to cytokine storm syndrome (CSS). The incidence of thrombotic events coinciding with CSS may contribute to the severe morbidity and mortality observed in association with COVID-19. This review provides an overview of pharmacologic approaches based upon an emerging understanding of the mechanisms responsible for thrombosis across a spectrum of COVID-19 disease involving an interplay between immunologic and pro-thrombotic events, including endothelial injury, platelet activation, altered coagulation pathways, and impaired fibrinolysis.

Effect of continuing versus stopping pre-stroke antihypertensive agents within 12 h on outcome after stroke: A subgroup analysis of the efficacy of nitric oxide in stroke (ENOS) trial

BACKGROUND

It is not known whether to continue or temporarily stop existing antihypertensive drugs in patients with acute stroke.

METHODS

We performed a prospective subgroup analysis of patients enrolled into the Efficacy of Nitric Oxide in Stroke (ENOS) trial who were randomised to continue vs stop prior antihypertensive therapy within 12 h of stroke onset. The primary outcome was functional outcome, assessed with the modified Rankin Scale at 90 days by observers blinded to treatment assignment, and analysed with ordinal logistic regression.

FINDINGS

Of 4011 patients recruited into ENOS from 2001 to 2014, 2097 patients were randomised to continue vs stop prior antihypertensive treatment, and 384 (18.3%, continue 185, stop 199) were enrolled within 12 h of ictus: mean (SD) age 71.8 (11.8) years, female 193 (50.3%), ischaemic stroke 342 (89.1%) and total anterior circulation syndrome 114 (29.7%). As compared with stopping, continuing treatment within 12 h of onset lowered blood pressure by 15.5/9.6 mmHg (p<0.001/<0.001) by 7 days, shifted the modified Rankin Scale to a worse outcome by day 90, adjusted common odds ratio (OR) 1.46 (95% CI 1.01-2.11), and was associated with an increased death rate by day 90 (hazard ratio 2.17, 95% CI 1.24-3.79). Other outcomes (disability - Barthel Index, quality of life - EQ-visual analogue scale, cognition - telephone mini-mental state examination, and mood - Zung depression scale) were also worse with continuing treatment.

INTERPRETATION

In this pre-specified subgroup analysis of the large ENOS trial, continuing prior antihypertensive therapy within 12 h of stroke onset in a predominantly ischaemic stroke population was unsafe with worse functional outcome, disability, cognition, mood, quality of life and increased death. Future studies assessing continuing or stopping prior antihypertensives in the context of thrombectomy are awaited.

Multiple versus fewer antiplatelet agents for preventing early recurrence after ischaemic stroke or transient ischaemic attack

BACKGROUND

Stroke is a leading cause of morbidity and mortality worldwide. Antiplatelet agents are considered to be the cornerstone for secondary prevention of stroke, but the role of using multiple antiplatelet agents early after stroke or transient ischaemic attack (TIA) to improve outcomes has not been established.

OBJECTIVES

To determine the effectiveness and safety of initiating, within 72 hours after an ischaemic stroke or TIA, multiple antiplatelet agents versus fewer antiplatelet agents to prevent stroke recurrence. The analysis explores the evidence for different drug combinations.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 6 July 2020), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 7 of 12, 2020) (last searched 6 July 2020), MEDLINE Ovid (from 1946 to 6 July 2020), Embase (1980 to 6 July 2020), ClinicalTrials.gov, and the WHO ICTRP. We also searched the reference lists of identified studies and reviews and used the Science Citation Index Cited Reference search for forward tracking of included studies.

SELECTION CRITERIA

We selected all randomised controlled trials (RCTs) that compared the use of multiple versus fewer antiplatelet agents initiated within 72 hours after stroke or TIA.

DATA COLLECTION AND ANALYSIS

We extracted data from eligible studies for the primary outcomes of stroke recurrence and vascular death, and secondary outcomes of myocardial infarction; composite outcome of stroke, myocardial infarction, and vascular death; intracranial haemorrhage; extracranial haemorrhage; ischaemic stroke; death from all causes; and haemorrhagic stroke. We computed an estimate of treatment effect and performed a test for heterogeneity between trials. We analysed data on an intention-to-treat basis and assessed bias for all studies. We rated the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 15 RCTs with a total of 17,091 participants. Compared with fewer antiplatelet agents, multiple antiplatelet agents were associated with a significantly lower risk of stroke recurrence (5.78% versus 7.84%, risk ratio (RR) 0.73, 95% confidence interval (CI) 0.66 to 0.82; P < 0.001; moderate-certainty evidence) with no significant difference in vascular death (0.60% versus 0.66%, RR 0.98, 95% CI 0.66 to 1.45; P = 0.94; moderate-certainty evidence). There was a higher risk of intracranial haemorrhage (0.42% versus 0.21%, RR 1.92, 95% CI 1.05 to 3.50; P = 0.03; low-certainty evidence) and extracranial haemorrhage (6.38% versus 2.81%, RR 2.25, 95% CI 1.88 to 2.70; P < 0.001; high-certainty evidence) with multiple antiplatelet agents. On secondary analysis of dual versus single antiplatelet agent therapy, benefit for stroke recurrence (5.73% versus 8.06%, RR 0.71, 95% CI 0.62 to 0.80; P < 0.001; moderate-certainty evidence) was maintained as well as risk of extracranial haemorrhage (1.24% versus 0.40%, RR 3.08, 95% CI 1.74 to 5.46; P < 0.001; high-certainty evidence). The composite outcome of stroke, myocardial infarction, and vascular death (6.37% versus 8.77%, RR 0.72, 95% CI 0.64 to 0.82; P < 0.001; moderate-certainty evidence) and ischaemic stroke (6.30% versus 8.94%, RR 0.70, 95% CI 0.61 to 0.81; P < 0.001; high-certainty evidence) were significantly in favour of dual antiplatelet therapy, whilst the risk of intracranial haemorrhage became less significant (0.34% versus 0.21%, RR 1.53, 95% CI 0.76 to 3.06; P = 0.23; low-certainty evidence).

AUTHORS' CONCLUSIONS

Multiple antiplatelet agents are more effective in reducing stroke recurrence but increase the risk of haemorrhage compared to one antiplatelet agent. The benefit in reduction of stroke recurrence seems to outweigh the harm for dual antiplatelet agents initiated in the acute setting and continued for one month. There is lack of evidence regarding multiple versus multiple antiplatelet agents. Further studies are required in different populations to establish comprehensive safety profiles and long-term outcomes to establish duration of therapy.

Ticagrelor Use in Indian Patients Undergoing Neuroendovascular Procedures: A Single Center Experience

PURPOSE

A safe and efficacious antiplatelet drug is needed for patients with clopidogrel resistance who undergo neuroendovascular procedures. Ticagrelor is a new reversibly binding, oral, direct-acting P2Y receptor antagonist with no known resistance. We describe our clinical experience using ticagrelor for neuroendovascular procedures in Indian patients with clopidogrel resistance at the NH Institute of Neurosciences, Narayana Health City, Bangalore.

MATERIALS AND METHODS

We retrospectively reviewed our endovascular procedure database for all patients with predefined clopidogrel resistance. Clopidogrel resistance was defined as P2Y12 inhibition <40%. Patients were administered ticagrelor along with aspirin prior to the procedure.

RESULTS

Of 127 patients, 32 (25%) were non-responders to clopidogrel (22 [69%] males, 10 [31%] females; median age, 54 years [range, 20-75]). All patients were treated with a 180-mg loading dose of ticagrelor, followed by 90 mg twice daily. Twenty patients (63%) underwent endovascular intervention for intracranial aneurysm, two (6%) for dissecting aneurysms, nine (28%) for stenotic lesions, and one (3%) for carotico-cavernous fistula. No patient experienced any adverse effects related to the use of Ticagrelor in the postoperative period.

CONCLUSION

Ticagrelor is an effective alternative to clopidogrel for use in conjunction with aspirin in patients with clopidogrel resistance. None of our patients had adverse effects from ticagrelor. Drug cost, twice-daily dosing, and risk of faster platelet aggregation activation after discontinuation should be taken into consideration prior to its use in such patients.

Triple versus guideline antiplatelet therapy to prevent recurrence after acute ischaemic stroke or transient ischaemic attack: the TARDIS RCT

BACKGROUND

Two antiplatelet agents are better than one for preventing recurrent stroke after acute ischaemic stroke or transient ischaemic attack (TIA). Therefore, intensive treatment with three agents might be better still, providing it does not cause undue bleeding.

OBJECTIVE

To compare the safety and efficacy of intensive therapy with guideline antiplatelet therapy for acute ischaemic stroke and TIA.

DESIGN

International prospective randomised open-label blinded end-point parallel-group superiority clinical trial.

SETTING

Acute hospitals at 106 sites in four countries.

PARTICIPANTS

Patients > 50 years of age with acute non-cardioembolic ischaemic stroke or TIA within 48 hours of ictus (stroke).

INTERVENTIONS

Participants were allocated at random by computer to 1 month of intensive (combined aspirin, clopidogrel and dipyridamole) or guideline (combined aspirin and dipyridamole, or clopidogrel alone) antiplatelet agents, and followed for 90 days.

MAIN OUTCOME MEASURES

The primary outcome was the incidence and severity of any recurrent stroke (ischaemic, haemorrhagic; assessed using the modified Rankin Scale) or TIA within 90 days by blinded telephone follow-up. Analysis using ordinal logistic regression was by intention to treat. Other outcomes included bleeding and its severity, death, myocardial infarction (MI), disability, mood, cognition and quality of life.

RESULTS

The trial was stopped early on the recommendation of the Data Monitoring Committee after recruitment of 3096 participants (intensive, n = 1556; guideline, n = 1540) from 106 hospitals in four countries between April 2009 and March 2016. The incidence and severity of recurrent stroke or TIA did not differ between intensive and guideline therapy in 3070 (99.2%) participants with data [93 vs. 105 stroke/TIA events; adjusted common odds ratio 0.90, 95% confidence interval (CI) 0.67 to 1.20; p = 0.47]. Major (encompassing fatal) bleeding was increased with intensive as compared with guideline therapy [39 vs. 17 participants; adjusted hazard ratio (aHR) 2.23, 95% CI 1.25 to 3.96; p = 0.006]. There were no differences between the treatment groups in all-cause mortality, or the composite of death, stroke, MI and major bleeding (aHR 1.02, 95% CI 0.77 to 1.35; p = 0.88).

LIMITATIONS

Patients and investigators were not blinded to treatment. The comparator group comprised two guideline strategies because of changes in national guidelines during the trial. The trial was stopped early, thereby reducing its statistical power.

CONCLUSIONS

The use of three antiplatelet agents is associated with increased bleeding without any significant reduction in recurrence of stroke or TIA.

FUTURE WORK

The safety and efficacy of dual antiplatelet therapy (combined aspirin and clopidogrel) versus aspirin remains to be defined. Further research is required on identifying individual patient response to antiplatelets, and the relationship between response and the subsequent risks of vascular recurrent events and bleeding complications.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN47823388.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 48. See the NIHR Journal Library website for further project information. The Triple Antiplatelets for Reducing Dependency after Ischaemic Stroke (TARDIS) vanguard phase was funded by the British Heart Foundation (grant PG/08/083/25779, from 1 April 2009 to 30 September 2012) and indirect funding was provided by the Stroke Association through its funding of the Stroke Trials Unit, Division of Clinical Neuroscience, University of Nottingham, Nottingham, UK. There was no commercial support for the trial and antiplatelet drugs were sourced locally at each site. The trial was sponsored by the University of Nottingham.

The Dipyridamole Added to Dual Antiplatelet Therapy in Cerebral Infarction After First Acute Myocardial Infarction: A Nationwide, Case-Control Study

Background and Purpose: No previous study has compared the impact of dipyridamole-based triple antiplatelet therapy on secondary stroke prevention and long-term outcomes to that of dual antiplatelet therapy (DAPT) in patients with acute myocardial infarction (AMI) and previous stroke. This study aimed to evaluate the impact of dipyridamole added to DAPT on stroke prevention and long-term outcomes in patients with cerebral infarction after first AMI.

Methods: This nationwide, case-control study included 75,789 patients with cerebral infarction after first AMI. A 1:4 propensity score matching ratio was adopted based on multiple variables. Finally, the data of 4,468 patients included in the DAPT group and 1,117 patients included in the Dipyridamole-DAPT group were analyzed. Primary outcome was overall survival. Secondary outcomes were cumulative event rate of recurrent MI or stroke, and cumulative intracerebral hemorrhage (ICH) and gastrointestinal bleeding rate.

Results: Long-term survival rate was comparable between the two groups (log-rank P = 0.1117), regardless of sex analyses. However, after first year, DAPT subgroup revealed better survival over DAPT-dipyridamole subgroup (log-rank P = 0.0188). In age subgroup analysis, a lower survival rate was detected in younger patients from the Dipyridamole-DAPT group after first year (log-rank P = 0.0151), but no survival difference for older patients. No benefit of Dipyridamole-DAPT was detected for patients after AMI, regardless of the myocardial infarction type. DAPT was superior to Dipyridamole-DAPT in patients who underwent percutaneous coronary intervention (PCI) (log-rank P = 0.0153) and ST elevation myocardial infarction after first year (log-rank P = 0.0019). Dipyridamole-DAPT did not reduce cumulative event rate of recurrent MI or stroke in patients after AMI. Moreover, Dipyridamole-DAPT increased the cumulative ICH rate (log-rank P = 0.0026), but did not affect the cumulative event rate of gastrointestinal bleeding. In Cox analysis, dipyridamole did not improve long-term survival.

Conclusions: This nationwide study showed that Dipyridamole-DAPT, compared with DAPT, did not improve long-term survival in patients with stroke after AMI, and was related to poor outcomes after 1 year. Dipyridamole-DAPT did not reduce recurrent rate of MI or stroke, but increased the ICH rate without impacting the incidence of gastrointestinal bleeding.

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.

Preventing cognitive decline and dementia from cerebral small vessel disease: The LACI-1 Trial. Protocol and statistical analysis plan of a phase IIa dose escalation trial testing tolerability, safety and effect on intermediary endpoints of isosorbide mononitrate and cilostazol, separately and in combination

Rationale

The pathophysiology of most lacunar stroke, a form of small vessel disease, is thought to differ from large artery atherothrombo- or cardio-embolic stroke. Licensed drugs, isosorbide mononitrate and cilostazol, have promising mechanisms of action to support their testing to prevent stroke recurrence, cognitive impairment, or radiological progression after lacunar stroke.

Aim

LACI-1 will assess the tolerability, safety, and efficacy, by dose, of isosorbide mononitrate and cilostazol, alone and in combination, in patients with ischemic lacunar stroke.

Sample size

A sample of 60 provides 80+% power (significance 0.05) to detect a difference of 35% (90% versus 55%) between those reaching target dose on one versus both drugs.

Methods and design

LACI-1 is a phase IIa partial factorial, dose-escalation, prospective, randomized, open label, blinded endpoint trial. Participants are randomized to isosorbide mononitrate and/or cilostazol for 11 weeks with dose escalation to target as tolerated in two centers (Edinburgh, Nottingham). At three visits, tolerability, safety, blood pressure, pulse wave velocity, and platelet function are assessed, plus magnetic resonance imaging to assess cerebrovascular reactivity in a subgroup.

Study outcomes

Primary: proportion of patients completing study achieving target maximum dose.

Secondary

symptoms whilst taking medications; safety (hemorrhage, recurrent vascular events, falls); blood pressure, platelet function, arterial stiffness, and cerebrovascular reactivity.

Discussion

This study will inform the design of a larger phase III trial of isosorbide mononitrate and cilostazol in lacunar stroke, whilst providing data on the drugs’ effects on vascular and platelet function.

Trial registration

ISRCTN (ISRCTN12580546) and EudraCT (2015-001953-33).

Baseline characteristics of the 3096 patients recruited into the 'Triple Antiplatelets for Reducing Dependency after Ischemic Stroke' trial

Background The risk of recurrence following ischemic stroke or transient ischemic attack is highest immediately after the event. Antiplatelet agents are effective in reducing the risk of recurrence and two agents are superior to one in the early phase after ictus. Design The triple antiplatelets for reducing dependency after ischemic stroke trial was an international multicenter prospective randomized open-label blinded-endpoint trial that assessed the safety and efficacy of short-term intensive antiplatelet therapy with three agents (combined aspirin, clopidogrel and dipyridamole) as compared with guideline treatment in acute ischemic stroke or transient ischemic attack. The primary outcome was stroke recurrence and its severity, measured using the modified Rankin Scale at 90 days. Secondary outcomes included recurrent vascular events, functional measures (cognition, disability, mood, quality of life), and safety (bleeding, death, serious adverse events). Data are number (%) or mean (standard deviation, SD). Results Recruitment ran from April 2009 to March 2016; 3096 patients were recruited from 106 sites in four countries (Denmark 1.6%, Georgia 2.7%, New Zealand 0.2%, UK 95.4%). Randomization characteristics included: age 69.0 (10.1) years; male 1945 (62.8%); time onset to randomization 29.4 (11.9) h; stroke severity (National Institutes for Health Stroke Scale) 2.8 (3.6); blood pressure 143.5 (18.2)/79.5 (11.4) mmHg; IS 2143 (69.2%), transient ischemic attack 953 (30.8%). Conclusion Triple antiplatelets for reducing dependency after ischemic stroke was a large trial of intensive/triple antiplatelet therapy in acute ischemic stroke and transient ischemic attack, and included participants from four predominantly Caucasian countries who were representative of patients in many western stroke services.

Effect of Hyperacute Administration (Within 6 Hours) of Transdermal Glyceryl Trinitrate, a Nitric Oxide Donor, on Outcome After Stroke: Subgroup Analysis of the Efficacy of Nitric Oxide in Stroke (ENOS) Trial

BACKGROUND AND PURPOSE

Nitric oxide donors are candidate treatments for acute stroke, potentially through hemodynamic, reperfusion, and neuroprotectant effects, especially if given early. Although the large Efficacy of Nitric Oxide in Stroke (ENOS) trial of transdermal glyceryl trinitrate (GTN) was neutral, a prespecified subgroup suggested that GTN improved functional outcome if administered early after stroke onset.

METHODS

Prospective analysis of subgroup of patients randomized into the ENOS trial within 6 hours of stroke onset. Safety and efficacy of GTN versus no GTN were assessed using data on early and late outcomes.

RESULTS

Two hundred seventy-three patients were randomized within 6 hours of ictus: mean (SD) age, 69.9 (12.7) years; men, 154 (56.4%); ischemic stroke, 208 (76.2%); Scandinavian Stroke Scale, 32.1 (11.9); and total anterior circulation syndrome, 86 (31.5%). When compared with no GTN, the first dose of GTN lowered blood pressure by 9.4/3.3 mm Hg (P<0.01, P=0.064) and shifted the modified Rankin Scale to a better outcome by day 90, adjusted common odds ratio, 0.51 (95% confidence interval, 0.32-0.80). Significant beneficial effects were also seen with GTN for disability (Barthel Index), quality of life (EuroQol-Visual Analogue Scale), cognition (telephone Mini-Mental State Examination), and mood (Zung Depression Scale). GTN was safe to administer with less serious adverse events by day 90 (GTN 18.8% versus no GTN 34.1%) and death (hazard ratio, 0.44; 95% confidence interval, 0.20-0.99; P=0.047).

CONCLUSIONS

In a subgroup analysis of the large ENOS trial, transdermal GTN was safe to administer and associated with improved functional outcome and fewer deaths when administered within 6 hours of stroke onset.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00989716.

Safety and efficacy of intensive vs. guideline antiplatelet therapy in high-risk patients with recent ischemic stroke or transient ischemic attack: rationale and design of the Triple Antiplatelets for Reducing Dependency after Ischaemic Stroke (TARDIS) trial (ISRCTN47823388)

RATIONALE

The risk of recurrence following a stroke or transient ischemic attack is high, especially immediately after the event.

HYPOTHESIS

Because two antiplatelet agents are superior to one in patients with non-cardioembolic events, more intensive treatment might be even more effective.

SAMPLE SIZE ESTIMATES

The sample size of 4100 patients will allow a shift to less recurrence, and less severe recurrence, to be detected (odds ratio 0·68) with 90% power at 5% significance.

METHODS AND DESIGN

Triple Antiplatelets for Reducing Dependency after Ischaemic Stroke (ISRCTN47823388) is comparing the safety and efficacy of intensive (combined aspirin, clopidogrel, and dipyridamole) vs. guideline antiplatelet therapy, both given for one-month. This international collaborative parallel-group prospective randomized open-label blinded-end-point phase III trial plans to recruit 4100 patients with acute ischemic stroke or transient ischemic attack. Randomization and data collection are performed over a secure Internet site with real-time data validation and concealment of allocation. Outcomes, serious adverse events, and neuroimaging are adjudicated centrally with blinding to treatment allocation.

STUDY OUTCOME

The primary outcome is stroke recurrence and its severity ('ordinal recurrence' based on modified Rankin Scale) at 90 days, with masked assessment centrally by telephone. Secondary outcomes include vascular events, functional measures (disability, mood, cognition, quality of life), and safety (bleeding, death, serious adverse events).

DISCUSSION

The trial has recruited more than 50% of its target sample size (latest number: 2399) and is running in 104 sites in 4 countries. One-third of patients presented with a transient ischemic attack.

Dual antiplatelet therapy with clopidogrel and aspirin for secondary stroke prevention

Stroke is a major public health concern worldwide, and 25 % of stroke victims would have another stroke. Although administration of antiplatelet agents has been confirmed to be one of the major approaches for secondary prevention of noncardioembolic stroke, the short-term or long-term use of aspirin plus clopidogrel for secondary stroke prevention remains to be controversial. This article aims at providing a comprehensive review of the evidence on the use of aspirin plus clopidogrel for secondary stroke prevention, with special focus on important studies that may impact clinical practice of treating patients with stroke or transient ischemic attack.

Management of Antiplatelet Agents and Anticoagulants in Patients with Gastrointestinal Bleeding

Antithrombotic drugs (anticoagulants, aspirin, and other antiplatelet agents) are used to treat cardiovascular disease and to prevent secondary thromboembolic events. These drugs are independently associated with an increased risk of gastrointestinal bleeding (GIB), and, when prescribed in combination, further increase the risk of adverse bleeding events. Clinical evidence to inform the choice of endoscopic hemostatic procedure, safe temporary drug cessation, and use of reversal agents is reviewed to optimize management following clinically significant GIB.

Statistical analysis plan for the 'Triple Antiplatelets for Reducing Dependency after Ischaemic Stroke' (TARDIS) trial

Rationale

Antiplatelet agents such as aspirin, clopidogrel and dipyridamole are effective in reducing the risk of recurrence after a stroke. Importantly, the risk of recurrence is highest immediately after the index event while antiplatelets cause bleeding.

Aims and/or hypothesis

The ‘Triple Antiplatelets for Reducing Dependency after Ischaemic Stroke’ (TARDIS) trial is testing whether short-term intensive antiplatelet therapy is safe and effective in reducing the early risk of recurrence as compared with standard guideline-based therapy.

Design

TARDIS is an international multi-center prospective randomized open-label blinded–end-point trial, with funding from the UK Health Technology Assessment program. Patients with acute ischemic stroke or transient ischemic attack are randomized within 48 h to intensive/triple antiplatelet therapy or guideline antiplatelets taken for one-month. Patients or relatives give written informed (proxy) consent and all sites have research ethics approval. Analyses will be done by intention-to-treat.

Study Outcome

The primary outcome is shift in stroke recurrent events and their severity, assessed using the modified Rankin Scale, at three-months.

Discussion

This paper and attachment describe the trial's statistical analysis plan, as developed from the protocol during recruitment and prior to unblinding of data. The statistical analysis plan contains design and methods for analyses, and unpopulated tables and figures for the primary and baseline publications. The data from the trial will provide the first large-scale randomized evidence for the use of intensive antiplatelet therapy for preventing recurrence after acute stroke and transient ischemic attack.

Platelet antiaggregants in stroke prevention

Antiplatelet agents are one of the main interventions for recurrent ischemic stroke prevention. Their time of use, dosage, and combination of therapy have different effects in terms of stroke risk reduction and adverse effects. This review provides an evidence-based update of the latest on antiplatelet therapy for stroke prevention.

Preventive aspects in peripheral artery disease

The prevalence of peripheral artery disease is steadily increasing and is associated with significant morbidity, including a significant percentage of amputations. Peripheral artery disease often goes undiagnosed, making its prevention increasingly important. Patients with peripheral arterial disease are at increased risk of adverse cardiovascular outcomes which makes prevention even more important. Several risk factors have been identified in the pathophysiology of peripheral artery disease which should be modified to decrease risk. Smoking, hyperlipidemia, hypertension, and diabetes are among proven risk factors for the development of peripheral artery disease, thus smoking cessation, lipid control, blood pressure control, and glucose control have been tried and shown to be effective in preventing the morbidity associated with this disease. Pharmacologic agents such as aspirin and clopidogrel alone or in combination have been shown to be effective, though risk of bleeding might be increased with the combination. Anticoagulation use is recommended only for acute embolic cases. Other treatment modalities that have been tried or are under investigation are estrogen replacement, naftidrofuryl, pentoxifylline, hyperbaric oxygen, therapeutic angiogenesis, and advanced glycation inhibitors. The treatment for concomitant vascular diseases does not change in the presence of peripheral artery disease, but aggressive management of risk factors should be undertaken in such cases.

Adenosine derived from ADP can contribute to inhibition of platelet aggregation in the presence of a P2Y12 antagonist

OBJECTIVE

To investigate whether adenosine diphosphate (ADP)-derived adenosine might inhibit platelet aggregation, especially in the presence of a P2Y₁₂ antagonist, where the effects of ADP at the P2Y₁₂ receptor would be prevented.

METHODS AND RESULTS

Platelet aggregation was measured in response to thrombin receptor activator peptide by platelet counting in platelet-rich plasma (PRP) and whole blood in the presence of ADP and the P2Y₁₂ antagonists cangrelor, prasugrel active metabolite, and ticagrelor. In the presence of a P2Y₁₂ antagonist, preincubation of PRP with ADP inhibited aggregation; this effect was abolished by adenosine deaminase. No inhibition of aggregation occurred in whole blood except when dipyridamole was added to inhibit adenosine uptake into erythrocytes. The effects of ADP in PRP and whole blood were replicated using adenosine and were directly related to changes in cAMP (assessed by vasodilator-stimulated phosphoprotein phosphorylation). All results were the same irrespective of the P2Y₁₂ antagonist used.

CONCLUSIONS

ADP inhibits platelet aggregation in the presence of a P2Y₁₂ antagonist through conversion to adenosine. Inhibition occurs in PRP but not in whole blood except when adenosine uptake is inhibited. None of the P2Y₁₂ antagonists studied replicated the effects of dipyridamole in the experiments that were performed.

Triple antiplatelet therapy for preventing vascular events: a systematic review and meta-analysis

BACKGROUND

Dual antiplatelet therapy is usually superior to mono therapy in preventing recurrent vascular events (VEs). This systematic review assesses the safety and efficacy of triple antiplatelet therapy in comparison with dual therapy in reducing recurrent vascular events.

METHODS

Completed randomized controlled trials investigating the effect of triple versus dual antiplatelet therapy in patients with ischaemic heart disease (IHD), cerebrovascular disease or peripheral vascular disease were identified using electronic bibliographic searches. Data were extracted on composite VEs, myocardial infarction (MI), stroke, death and bleeding and analysed with Cochrane Review Manager software. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using random effects models.

RESULTS

Twenty-five completed randomized trials (17,383 patients with IHD) were included which involving the use of intravenous (iv) GP IIb/IIIa inhibitors (abciximab, eptifibatide, tirofiban), aspirin, clopidogrel and/or cilostazol. In comparison with aspirin-based therapy, triple therapy using an intravenous GP IIb/IIIa inhibitor significantly reduced composite VEs and MI in patients with non-ST elevation acute coronary syndromes (NSTE-ACS) (VE: OR 0.69, 95% CI 0.55-0.86; MI: OR 0.70, 95% CI 0.56-0.88) and ST elevation myocardial infarction (STEMI) (VE: OR 0.39, 95% CI 0.30-0.51; MI: OR 0.26, 95% CI 0.17-0.38). A significant reduction in death was also noted in STEMI patients treated with GP IIb/IIIa based triple therapy (OR 0.69, 95% CI 0.49-0.99). Increased minor bleeding was noted in STEMI and elective percutaneous coronary intervention (PCI) patients treated with GP IIb/IIIa based triple therapy. Stroke events were too infrequent for us to be able to identify meaningful trends and no data were available for patients recruited into trials on the basis of stroke or peripheral vascular disease.

CONCLUSIONS

Triple antiplatelet therapy based on iv GPIIb/IIIa inhibitors was more effective than aspirin-based dual therapy in reducing VEs in patients with acute coronary syndromes (STEMI and NSTEMI). Minor bleeding was increased among STEMI and elective PCI patients treated with a GP IIb/IIIa based triple therapy. In patients undergoing elective PCI, triple therapy had no beneficial effect and was associated with an 80% increase in transfusions and an eightfold increase in thrombocytopenia. Insufficient data exist for patients with prior ischaemic stroke and peripheral vascular disease and further research is needed in these groups of patients.

[Reversibility of vertebrobasilar stenoses following treatment with corticosteroid therapy in patients with giant cell arteritis]

INTRODUCTION

Involvement of intracranial arteries in giant cell arteritis is a rare condition but often carries a fatal prognosis. Corticosteroids seem to be insufficient to avoid ischemic cerebral complications, and could even promote the occurrence of stroke. We report the case of a patient with giant cell arteritis who experienced recurrent cerebellar stroke caused by intracranial vertebrobasilar stenoses with a favorable outcome following treatment.

CASE REPORT

A 77-year-old woman presented with a 3-month history of impaired general condition. She had new-onset headaches, jaw claudication and transient vertigo, especially when she woke-up. The brain MRI showed a recent cerebellar infarction. One week later, she was hospitalized for a clinical deterioration related to a recurrent cerebellar stroke caused by intracranial vertebro-basilar stenoses. Giant cell arteritis was confirmed on the temporal artery biopsy. A treatment with high-dose oral corticosteroids was begun associated with an intensive antiplatelet therapy. The clinical outcome was favorable with rapid improvement of gait imbalance together with a complete radiological regression of the intracranial stenoses.

CONCLUSION

Ischemic stroke in giant cell intracranial arteritis is a severe condition without a well-defined treatment. Corticosteroid therapy improves intracranial stenoses caused by vasculitis but should be initially associated with an intensive antithrombotic therapy to avoid early recurrence of cerebral infarcts.

Effect of combined aspirin and extended-release dipyridamole versus clopidogrel on functional outcome and recurrence in acute, mild ischemic stroke: PRoFESS subgroup analysis

BACKGROUND AND PURPOSE

Long-term antiplatelet therapy is effective at reducing recurrence after ischemic stroke. However, the relative safety and efficacy of combined aspirin-dipyridamole or clopidogrel are not known in patients with acute ischemic stroke.

METHODS

The factorial PRoFESS secondary prevention trial assessed antiplatelet and blood pressure-lowering strategies in 20,332 patients, 1360 of whom were randomized within 72 hours of ischemic stroke to combined aspirin (Asp; 25 mg BID) and extended-release dipyridamole (ER-DP; 200 mg BID, n=672) or clopidogrel (75 mg/d, n=688). The primary outcome for this post hoc subgroup analysis was functional outcome at 30 days; secondary outcomes included recurrence and death by 90 days. Analyses were adjusted for baseline prognostic variables and blood pressure treatment assignment.

RESULTS

Patients were representative of the whole trial (age 67 years, National Institutes of Health Stroke Scale score 3, small-artery occlusion 59%), and baseline variables were similar between treatment groups. The mean time from stroke to recruitment was 58 hours. By 90 days, treatment was no longer being taken in 121 (18%) patients randomized to Asp/ER-DP and in 86 (12.5%) assigned to clopidogrel (P=0.006). Combined death or dependency (shift analysis of modified Rankin Scale score at day 30) did not differ between treatment groups (odds ratio [OR]=0.97; 95% CI, 0.79 to 1.19). Nonsignificant trends to reduced recurrence (OR=0.56; 95% CI, 0.26 to 1.18) and vascular events (OR=0.71; 95% CI, 0.36 to 1.37) were present with Asp/ER-DP. Rates of death, major bleeding, and serious adverse events did not differ between treatment groups.

CONCLUSIONS

Treatment with combined Asp/ER-DP vs clopidogrel in 1360 patients with acute, mild ischemic stroke did not differ in terms of effects on functional outcome, recurrence, death, bleeding, or serious adverse events. Both treatments were practical to administer.