P2Y12 inhibitor versus aspirin monotherapy for secondary prevention of cardiovascular events: meta-analysis of randomized trials

Safety, Tolerability, and Pharmacodynamics of AZD3366 (Optimized Human CD39L3 Apyrase) Alone and in Combination With Ticagrelor and Acetylsalicylic Acid: A Phase 1, Randomized, Placebo-Controlled Study

BACKGROUND

ADP and ATP are importantly involved in vascular and thrombotic homeostasis, via multiple receptor pathways. Blockade of ADP P2Y12 receptors inhibits platelet aggregation and represents an effective cardiovascular disease prevention strategy. AZD3366 (APT102), a long-acting recombinant form of an optimized CD39L3 human apyrase, has effectively reduced ATP, ADP, and platelet aggregation and provided tissue protection in preclinical models, features that could be very beneficial in treating patients with cardiovascular disease.

METHODS AND RESULTS

We conducted this phase 1, first-in-human study of single ascending doses of intravenous AZD3366 or placebo, including doses added to dual antiplatelet therapy with ticagrelor and acetylsalicylic acid. The primary objective was safety and tolerability; secondary and exploratory objectives included pharmacokinetics, pharmacodynamics (measured as inhibition of platelet aggregation), adenosine diphosphatase (ADPase) activity, and ATP/ADP metabolism. In total, 104 participants were randomized. AZD3366 was generally well tolerated, with no major safety concerns observed. ADPase activity increased in a dose-dependent manner with a strong correlation to AZD3366 exposure. Inhibition of ADP-stimulated platelet aggregation was immediate, substantial, and durable. In addition, there was a prompt decrease in systemic ATP concentration and an increase in adenosine monophosphate concentrations, whereas ADP concentration appeared generally unaltered. At higher doses, there was a prolongation of capillary bleeding time without detectable changes in the ex vivo thromboelastometric parameters.

CONCLUSIONS

AZD3366 was well tolerated in healthy participants and demonstrated substantial and durable inhibition of platelet aggregation after single dosing. Higher doses prolonged capillary bleeding time without detectable changes in ex vivo thromboelastometric parameters.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique Identifier: NCT04588727.

Chronic Coronary Disease in Older Adults

The number of older adults age ≥75 with chronic coronary disease (CCD) continues to rise. CCD is a major contributor to morbidity, mortality, and disability in older adults. Older adults are underrepresented in randomized controlled trials of CCD, which limits generalizability to older adults living with multiple chronic conditions and geriatric syndromes. This review discusses the presentation of CCD in older adults, reviews the guideline-directed medical and invasive therapies, and recommends a patient-centric approach to making treatment decisions.

Colchicine in atherosclerotic cardiovascular disease

Inflammation has a direct role in the development of atherosclerotic vascular disease, and oral colchicine displays broad anti-inflammatory properties. Several large, randomised controlled trials (RCTs) have evaluated colchicine's impact on cardiovascular outcomes. Results from a meta-analysis of these trials demonstrate that colchicine reduces the risk of recurrent major adverse cardiovascular events (MACEs) by 25%, leading to its recent approval by the Food and Drug Administration for the treatment and prevention of cardiovascular disease. Despite this, colchicine has not been shown to confer any survival benefit in these trials. The non-significant reduction in cardiovascular death of 18% (95% CI: 45% decrease to 23% increase) is outweighed by a more prominent, borderline non-significant increase in the risk of non-cardiovascular death by 38% (95% CI: 1% decrease to 92% increase). Key populations including those with heart failure, those undergoing surgical revascularisation, women, elderly individuals and non-Caucasians are under-represented in completed trials, which limits generalisability. C reactive protein has been proposed as a biomarker for colchicine response and shows promise for identifying a high-risk population where the benefit on MACE reduction and specifically reduced cardiovascular death might outweigh any real increased risk of non-cardiovascular death; however, this approach is still to be validated in ongoing RCTs. In conclusion, while colchicine shows promise in reducing MACE, its net risk-benefit profile requires further elucidation before its widespread adoption into clinical practice for the secondary prevention of atherosclerotic cardiovascular disease. Much more large-scale, long-term trial data are still needed in this space.

Aspirin-free antiplatelet strategies after percutaneous coronary interventions

Dual antiplatelet therapy (DAPT) with aspirin and a platelet P2Y12 receptor inhibitor is the standard antithrombotic treatment after percutaneous coronary interventions (PCI). Several trials have challenged guideline-recommended DAPT after PCI by testing the relative clinical effect of an aspirin-free antiplatelet approach-consisting of P2Y12 inhibitor monotherapy after a short course (mostly 1-3 months) of DAPT-among patients undergoing PCI without a concomitant indication for oral anticoagulation (OAC). Overall, these studies have shown P2Y12 inhibitor monotherapy after short DAPT to be associated with a significant reduction in the risk of bleeding without an increase in thrombotic or ischaemic events compared with continued DAPT. Moreover, the effects of the P2Y12 inhibitor monotherapy without prior DAPT or following a very short course of DAPT after PCI are being investigated in emerging studies, of which one has recently reported unfavourable efficacy results associated with the aspirin-free approach compared with conventional DAPT. Finally, P2Y12 inhibitor alone has been compared with aspirin alone as chronic therapy after DAPT discontinuation, thus challenging the historical role of aspirin as a standard of care for secondary prevention following PCI. A thorough understanding of study designs, populations, treatments, results, and limitations of trials testing P2Y12 inhibitor monotherapy vs. DAPT or vs. aspirin is required to consider adopting this treatment in clinical practice. This review addresses the use of aspirin-free antiplatelet strategies among patients undergoing PCI without a concomitant indication for OAC, providing an overview of clinical evidence, guideline indications, practical implications, ongoing issues, and future perspectives.

Do We Still Need Aspirin in Coronary Artery Disease?

Aspirin has for some time been used as a first-line treatment for acute coronary syndromes, including ST-elevation myocardial infarction, for secondary prevention of established coronary disease, and for primary prevention in patients at risk of coronary artery disease. Although aspirin has been in use for decades, the available evidence for its efficacy largely predates the introduction of other drugs, such as statins and P2Y12 inhibitors. Based on recent trials, the recommendation for aspirin use as primary prevention has been downgraded. In addition, P2Y12 inhibitors given as a single antiplatelet therapy have been associated with a lower incidence of bleeding than dual antiplatelet therapy in combination with aspirin in patients with stable and unstable coronary artery disease. The aim of this review is to discuss the role of aspirin considering the available evidence for primary prevention, secondary prevention for stable coronary artery disease or acute coronary syndromes, and after percutaneous coronary intervention or coronary artery bypass revascularization.

Current concepts and novel targets for antiplatelet therapy

Platelets have a crucial role in haemostasis and atherothrombosis. Pharmacological control of platelet hyper-reactivity has become a cornerstone in the prevention of thrombo-ischaemic complications in atherosclerotic diseases. Current antiplatelet therapies substantially improve clinical outcomes in patients with coronary artery disease, but at the cost of increased risk of bleeding. Beyond their role in thrombosis, platelets are known to regulate inflammatory (thrombo-inflammatory) and microcirculatory pathways. Therefore, controlling platelet hyper-reactivity might have implications for both tissue inflammation (myocardial ischaemia) and vascular inflammation (vulnerable plaque formation) to prevent atherosclerosis. In this Review, we summarize the pathophysiological role of platelets in acute myocardial ischaemia, vascular inflammation and atherosclerotic progression. Furthermore, we highlight current clinical concepts of antiplatelet therapy that have contributed to improving patient care and have facilitated more individualized therapy. Finally, we discuss novel therapeutic targets and compounds for antiplatelet therapy that are currently in preclinical development, some of which have a more favourable safety profile than currently approved drugs with regard to bleeding risk. These novel antiplatelet targets might offer new strategies to treat cardiovascular disease.

Atherosclerotic Disease: Pathogenesis and Approaches to Management

Atherosclerotic disease, including stroke and myocardial infarction, is the leading cause of morbidity and mortality worldwide. Atherosclerotic plaque formation occurs in the setting of excess oxidative and hemodynamic stress and is perpetuated by smoking, poor diet, dyslipidemia, hypertension, and diabetes. Plaque may rupture, resulting in acute thrombotic events. Smoking cessation, lifestyle modification, risk factor optimization, and antithrombotic therapies are the mainstays of atherosclerotic disease management and are the cornerstones to reduce morbidity and mortality in this high-risk patient population. Novel therapeutics are in development and will add to the growing armamentarium available to physicians who manage atherosclerotic disease.

P2Y12 Inhibitor or Aspirin Monotherapy for Secondary Prevention of Coronary Events

BACKGROUND

Aspirin is the only antiplatelet agent with a Class I recommendation for long-term prevention of cardiovascular events in patients with coronary artery disease (CAD). There is inconsistent evidence on how it compares with alternative antiplatelet agents.

OBJECTIVES

This study compared P2Y12 inhibitor monotherapy vs aspirin in patients with CAD.

METHODS

We conducted a patient-level meta-analysis of randomized trials comparing P2Y12 inhibitor monotherapy vs aspirin monotherapy for the prevention of cardiovascular events in patients with established CAD. The primary outcome was the composite of cardiovascular death, myocardial infarction, and stroke. Prespecified key secondary outcomes were major bleeding and net adverse clinical events (the composite of the primary outcome and major bleeding). Data were pooled in a 1-step meta-analysis.

RESULTS

Patient-level data were obtained from 7 trials. Overall, 24,325 participants were available for analysis, including 12,178 patients assigned to receive P2Y12 inhibitor monotherapy (clopidogrel in 7,545 [62.0%], ticagrelor in 4,633 [38.0%]) and 12,147 assigned to receive aspirin. Risk of the primary outcome was lower with P2Y12 inhibitor monotherapy compared with aspirin over 2 years (HR: 0.88; 95% CI: 0.79-0.97; P = 0.012), mainly owing to less myocardial infarction (HR: 0.77; 95% CI: 0.66-0.90; P < 0.001). Major bleeding was similar (HR: 0.87; 95% CI: 0.70-1.09; P = 0.23) and net adverse clinical events were lower (HR: 0.89; 95% CI: 0.81-0.98; P = 0.020) with P2Y12 inhibitors. The treatment effect was consistent across prespecified subgroups and types of P2Y12 inhibitors.

CONCLUSIONS

Given its superior efficacy and similar overall safety, P2Y12 inhibitor monotherapy might be preferred over aspirin monotherapy for long-term secondary prevention in patients with established CAD. (P2Y12 Inhibitor or Aspirin Monotherapy as Secondary Prevention in Patients With Coronary Artery Disease: An Individual Patient Data Meta-Analysis of Randomized Trials [PANTHER collaborative initiative]; CRD42021290774).

Advances in Clinical Cardiology 2022: A Summary of Key Clinical Trials

INTRODUCTION

Over the course of 2022, numerous key clinical trials with valuable contributions to clinical cardiology were published or presented at major international conferences. This review seeks to summarise these trials and to reflect on their clinical context.

METHODS

The authors reviewed clinical trials presented at major cardiology conferences during 2022, including the American College of Cardiology (ACC), European Association for Percutaneous Cardiovascular Interventions (EuroPCR), European Society of Cardiology (ESC), Transcatheter Cardiovascular Therapeutics (TCT), American Heart Association (AHA), European Heart Rhythm Association (EHRA), Society for Cardiovascular Angiography and Interventions (SCAI), TVT-The Heart Summit (TVT) and Cardiovascular Research Technologies (CRT). Trials with a broad relevance to the cardiology community and those with potential to change current practice were included.

RESULTS

A total of 93 key cardiology clinical trials were identified for inclusion. Interventional cardiology data included trials evaluating the use of new generation novel stent technology and new intravascular physiology strategies such as quantitative flow ratio (QFR) to guide revascularisation in stable and unstable coronary artery disease. New trials in acute coronary syndromes and intervention focused on long-term outcomes of optimal medical therapy (OMT), revascularisation in ischaemic dysfunction and left main (LM) intervention. Structural intervention trials included latest data on optimal timing and anticoagulation strategies in transcatheter aortic valve replacement (TAVR), in addition to expanding evidence in mitral and tricuspid valve interventions. Heart failure data included trials with sodium-glucose cotransporter 2 (SGLT2) inhibitors, iron replacement and novel drugs such as omecamtiv. Prevention trials included new data on proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors and polypill strategies. In electrophysiology, new data regarding optimal timing of ablative therapy for atrial fibrillation (AF) in addition to novel screening strategies were evaluated.

CONCLUSION

This article presents a summary of key clinical cardiology trials published and presented during the past year and should be of interest to both practising clinicians and researchers.

What Is the Optimal Duration of Antiplatelet Therapy for Patients with Coronary Heart Disease?

PURPOSE OF REVIEW

Optimal duration of antiplatelet therapy continues to attract extensive debates and has been progressively adjusted in the setting of advancements in stent design and assessment of patient clinical characteristics. Given the ever-changing landscape of antiplatelet therapy and the multitude of clinical trials that have examined this duration, there are varying scenarios for optimal duration based on patient presentation and risk profile. This review highlights the current concepts and recommendations regarding duration of antiplatelet therapy in coronary heart disease.

RECENT FINDINGS

In particular, we review the current data on the use of dual antiplatelet therapy in the different clinical scenarios. Relatively longer dual antiplatelet therapy is perhaps limited to patients with higher risk for cardiovascular events and/or high-risk lesions and shorter durations of dual antiplatelet therapy have been shown to reduce bleeding complications at the same time as stabilization of ischemic endpoints. More recent trials have demonstrated the safety of shorter durations of dual antiplatelet therapy in appropriate patients with coronary heart disease.

Sex Differences in Outcomes After Transcatheter Aortic Valve Replacement: A POPular TAVI Subanalysis

BACKGROUND

Stroke and bleeding are complications after transcatheter aortic valve replacement (TAVR). A higher incidence of bleeding and stroke has been reported in women, but the role of antithrombotic management pre- and post-TAVR has not been studied.

OBJECTIVES

The study sought to compare bleeding and ischemic complications after TAVR between women and men stratified by antiplatelet and oral anticoagulant (OAC) regimen.

METHODS

The POPular TAVI (Antiplatelet Therapy for Patients Undergoing Transcatheter Aortic Valve Implantation) trial was a randomized clinical trial to test the hypothesis that monotherapy with aspirin or OAC after TAVR is safer than the addition of clopidogrel. The primary endpoints of interest of this post hoc subanalysis were: 1) all bleeding; and 2) a composite of ischemic events consisting of stroke and myocardial infarction. Secondary endpoints were: 1) nonprocedural bleeding; 2) major or life-threatening bleeding; 3) minor bleeding; 4) stroke; 5) myocardial infarction; and 6) all-cause death.

RESULTS

A total of 978 patients (466 [47.6%] women) were included in this study. All bleeding and the composite of myocardial infarction and stroke rates were similar between sexes (all bleeding: 106 [22.8%] women vs 121 [23.6%] men; P = 0.815; ischemic events: 26 [5.6%] vs 36 [7.0%]; P = 0.429). However, major or life-threatening bleeding occurred more often in women (58 [12.5%]) vs men (38 [7.4%]) (P = 0.011), most of which were access site bleedings. The use of aspirin pre- and post-TAVR increased major or life-threatening bleeding in women but not in men.

CONCLUSIONS

After TAVR, overall bleeding and ischemic outcomes were similar between women and men. However, women had more major or life-threatening bleedings, especially those receiving aspirin pre- and post-TAVR.

Redefining the Roles of Aspirin across the Spectrum of Cardiovascular Disease Prevention

Even before its role in platelet inhibition was fully characterized in the 1980s, aspirin had been incorporated into the cardiovascular disease care algorithm. Early trials examining its use in unstable angina and acute myocardial infarction revealed evidence of its protective role in the secondary prevention of atherosclerotic cardiovascular disease (ASCVD). Large trials assessing use in the primary prevention setting and optimal dosing regimens were studied in the late 1990s and early 2000s. As a cornerstone of cardiovascular care, aspirin was incorporated into primary and secondary ASCVD prevention guidelines in the United States and mechanical heart valve guidelines. However, in recent years, with significant advances in medical and interventional ASCVD therapies, scrutiny has been placed on the bleeding profile of aspirin, and guidelines have adapted to new evidence. Updates in primary prevention guidelines reserve aspirin only for patients at higher ASCVD risk and low bleeding risk - though questions remain in ASCVD risk assessment as risk-enhancing factors have proven difficult to incorporate on a population level. New thoughts regarding aspirin use in secondary prevention - especially with the concomitant use of anticoagulants - have altered recommendations as additional data accrued. Finally, a recommendation for aspirin and vitamin K antagonists with mechanical heart valves has been modified. Despite aspirin losing a foothold in cardiovascular care, new evidence has strengthened claims for its use in women at high risk for preeclampsia.

Clopidogrel Monotherapy versus Aspirin Monotherapy in Patients with Established Cardiovascular Disease: Systematic Review and Meta-Analysis

BACKGROUND

 There is no clear consensus on whether aspirin offers better outcomes in terms of secondary cardiovascular disease prevention compared with clopidogrel.

OBJECTIVE

 The aim of the study was to compare the safety and efficacy of clopidogrel versus aspirin in patients with established cardiovascular disease.

METHODS

 A systematic review of MEDLINE (via PubMed), Scopus, and Cochrane Library databases (last search date: August 28, 2021) was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) statement for randomized control trials (RCTs) of clopidogrel versus aspirin as monotherapy in patients with established cardiovascular disease. Random-effects meta-analyses were performed.

RESULTS

 Five RCTs incorporating 26,855 patients (clopidogrel: 13,426; aspirin: 13,429) were included. No statistically significant difference was observed between clopidogrel and aspirin in terms of all-cause mortality (odds ratio [OR]: 1.01 [95% confidence interval, CI: 0.91-1.13]; p = 0.83), ischemic stroke (OR: 0.87 [95% CI: 0.71-1.06]; p = 0.16), and major bleeding rates (OR: 0.77 [95% CI: 0.56-1.06]; p = 0.11). Patients receiving clopidogrel had borderline lower risk for major adverse cardiovascular events (MACE) (OR: 0.84 [95% CI: 0.71-1.00]; p = 0.05) and lower risk for nonfatal myocardial infarction (OR: 0.83 [95% CI: 0.71-0.97]; p = 0.02, relative risk reduction = 16.9%, absolute risk reduction = 0.5%, number needed to treat = 217 for a mean period of 20 months) compared with patients receiving aspirin.

CONCLUSION

 In patients with established cardiovascular disease, clopidogrel was associated with a 17% relative-risk reduction for nonfatal MI, borderline decreased risk for MACE, and similar risk for all-cause mortality, stroke, and major bleeding compared with aspirin.

PROTOCOL REGISTRATION

 PROSPERO CRD42021283866.

Aspirin Resistance in Vascular Disease: A Review Highlighting the Critical Need for Improved Point-of-Care Testing and Personalized Therapy

Aspirin resistance describes a phenomenon where patients receiving aspirin therapy do not respond favorably to treatment, and is categorized by continued incidence of adverse cardiovascular events and/or the lack of reduced platelet reactivity. Studies demonstrate that one in four patients with vascular disease are resistant to aspirin therapy, placing them at an almost four-fold increased risk of major adverse limb and adverse cardiovascular events. Despite the increased cardiovascular risk incurred by aspirin resistant patients, strategies to diagnose or overcome this resistance are yet to be clinically validated and integrated. Currently, five unique laboratory assays have shown promise for aspirin resistance testing: Light transmission aggregometry, Platelet Function Analyzer-100, Thromboelastography, Verify Now, and Platelet Works. Newer antiplatelet therapies such as Plavix and Ticagrelor have been tested as an alternative to overcome aspirin resistance (used both in combination with aspirin and alone) but have not proven to be superior to aspirin alone. A recent breakthrough discovery has demonstrated that rivaroxaban, an anticoagulant which functions by inhibiting active Factor X when taken in combination with aspirin, improves outcomes in patients with vascular disease. Current studies are determining how this new regime may benefit those who are considered aspirin resistant.

A Comprehensive Review of the Pleiotropic Effects of Ticagrelor

AIMS

This review summarizes the findings of preclinical studies evaluating the pleiotropic effects of ticagrelor. These include attenuation of ischemia-reperfusion injury (IRI), inflammation, adverse cardiac remodeling, and atherosclerosis. In doing so, it aims to provide novel insights into ticagrelor's mechanisms and benefits over other P2Y12 inhibitors. It also generates viable hypotheses for the results of seminal clinical trials assessing ticagrelor use in acute and chronic coronary syndromes.

METHODS AND RESULTS

A comprehensive review of the preclinical literature demonstrates that ticagrelor protects against IRI in the setting of both an acute myocardial infarction (MI), and when MI occurs while on chronic treatment. Maintenance therapy with ticagrelor also likely mitigates adverse inflammation, cardiac remodeling, and atherosclerosis, while improving stem cell recruitment. These effects are probably mediated by ticagrelor's ability to increase local interstitial adenosine levels which activate downstream cardio-protective molecules. Attenuation and augmentation of these pleiotropic effects by high-dose aspirin and caffeine, and statins respectively may help explain variable outcomes in PLATO and subsequent randomized controlled trials (RCTs).

CONCLUSION

Most RCTs and meta-analyses have not evaluated the pleiotropic effects of ticagrelor. We need further studies comparing cardiovascular outcomes in patients treated with ticagrelor versus other P2Y12 inhibitors that are mindful of the unique pleiotropic advantages afforded by ticagrelor, as well as possible interactions with other therapies (e.g., aspirin, statins, caffeine).