Antithrombotic Therapy After Transcatheter Aortic Valve Implantation

Optimal Anticoagulation on TAVI Patients Based on Thrombotic and Bleeding Risk and the Challenge Beyond: A Systematic Review and Meta-Analysis

Transcatheter Aortic Valve Replacement (TAVR) has been established as the treatment of choice for symptomatic aortic stenosis, while it is expanding in all risk-related group categories of patients, gaining gradually ground over the surgical approach. However, complications and adverse events are yet to be effectively limited and diminished with thrombotic and hemorrhagic events being rooted as a crucial topic of discussion. Favorable anticoagulation pharmacotherapy options are constantly being revised and tested, whilst guidelines are being modified to meet current clinical evidence. This review aims to systematically assess already existing guidelines on anticoagulation in post-TAVI patients and examine novel regimens for the specific use, like apixaban, rivaroxaban, and other anticoagulants, essentially constructing a holistic point of view on future progress on this matter. The added complexity brought by coagulation-affecting comorbidities such as atrial fibrillation, coronary artery disease, and more contributes to the direct association of the topic to the quality of healthcare as a public service. The literature was systematically searched to examine the effectiveness and safety of various anticoagulation treatments and cross-evaluate them based on the according category of patients that were assigned to. Clinical trials, observational studies and systematic reviews were included and, eventually, conclusive remarks and future considerations were developed and presented. In the category of patients without prior indication to anticoagulation, SAPT was proven safer and still effective, when antiplatelet therapies were compared, while a comparison of antiplatelet versus anticoagulation strategies noted the first one, with limited data, as the optimal one. Lastly, direct oral anticoagulants were shown to be safe substitutes for vitamin K antagonists for patients with prior indication to anticoagulation.

Antithrombotic Therapy After Transcatheter Aortic Valve Replacement: An Overview

Transcatheter aortic valve replacement (TAVR) is an established procedure for the treatment of patients with severe aortic stenosis. The optimal antithrombotic regimen following TAVR, currently unknown and inconsistently applied, is impacted by thromboembolic risk, frailty, bleeding risk, and comorbidities. There is a quickly growing body of literature examining the complex issues underlying antithrombotic regimens post-TAVR. This review provides an overview of thromboembolic and bleeding events following TAVR, summarizes the evidence regarding optimal antiplatelet and anticoagulant use post-TAVR, and highlights current challenges and future directions. By understanding appropriate indications and outcomes associated with different antithrombotic regimens post-TAVR, morbidity and mortality can be minimized in a generally frail and elderly patient population.

Non-Vitamin K Oral Anticoagulant After Transcatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis

Objective: We aimed to compare non-vitamin K oral anticoagulants (NOACs) with a traditional antithrombotic such as vitamin K antagonist (VKA) and antiplatelet agents in patients after transcatheter aortic valve replacement (TAVR).

Methods: We conducted a search in PubMed, EMBASE, and the Cochrane Library until November 2021 for studies involving comparisons of any type of NOACs, including dabigatran, apixaban, rivaroxaban, and edoxaban, with VKA or antiplatelet agents after TAVR. A comparison of NOACs versus VKA was performed in patients with an indication for oral anticoagulation. In addition, we compared NOACs versus antiplatelet in patients without such indication. We calculated the hazard ratios with 95% confidence intervals (CIs) to determine long-term outcomes. The primary outcome was a combined endpoint consisting of all-cause mortality, stroke, major bleeding, or any related clinical adverse events. Secondary outcomes were all-cause mortality, major bleeding, and stroke, respectively.

Results: A total of 10 studies including 10,563 patients after TAVR were included in this meta-analysis. There were no significant differences in any of the long-term outcomes between the NOAC and VKA groups. Although there were no significant differences in the combined endpoint, major bleeding, or stroke, a significant difference was observed in the all-cause mortality (HR 1.74, 95% CI 1.25–2.43, p = 0.001) between the NOAC and antiplatelet groups.

Conclusion: For patients with an indication for oral anticoagulation after TAVR, NOACs seem to be associated with noninferior outcomes compared with VKA therapy. However, for patients without an indication for oral anticoagulation, NOACs appear to be associated with a higher risk of all-cause death as compared with antiplatelet treatment.

Systematic Review Registration:https://clinicaltrials.gov/, identifier CRD42020155122.

Platelets: Implications in Aortic Valve Stenosis and Bioprosthetic Valve Dysfunction From Pathophysiology to Clinical Care

Aortic stenosis (AS) is the most common heart valve disease requiring surgery in developed countries, with a rising global burden associated with aging populations. The predominant cause of AS is believed to be driven by calcific degeneration of the aortic valve and a growing body of evidence suggests that platelets play a major role in this disease pathophysiology. Furthermore, platelets are a player in bioprosthetic valve dysfunction caused by their role in leaflet thrombosis and thickening. This review presents the molecular function of platelets in the context of recent and rapidly evolving understanding the role of platelets in AS, both of the native aortic valve and bioprosthetic valves, where there remain concerns about the effects of subclinical leaflet thrombosis on long-term prosthesis durability. This review also presents the role of antiplatelet and anticoagulation therapies on modulating the impact of platelets on native and bioprosthetic aortic valves, highlighting the need for further studies to determine whether these therapies are protective and may increase the life span of surgical and transcatheter aortic valve implants. By linking molecular mechanisms through which platelets drive disease of native and bioprosthetic aortic valves with studies evaluating the clinical impact of antiplatelet and antithrombotic therapies, we aim to bridge the gaps between our basic science understanding of platelet biology and their role in patients with AS and ensuing preventive and therapeutic implications.

Phase I clinical trial of an antithrombotic drug protocol combining apixaban and clopidogrel in dogs

INTRODUCTION

Combining an antiplatelet drug, clopidogrel, with the direct oral Factor Xa inhibitor, apixaban, could provide an effective antithrombotic strategy in dogs. Thus, a limited 3 + 3 phase I dose-escalation clinical trial in healthy dogs was conducted to evaluate bleeding (primary end-point) and pharmacodynamic (PD)/pharmacokinetic (PK) parameters (secondary end-point).

ANIMALS

Eleven beagle dogs, median body weight 10.2 kg (9.7-10.9 kg), were enrolled.

METHODS

Four doses of apixaban (three dogs/dose) administered for eight days. Clopidogrel dose was fixed at 18.75 mg per os (PO) q 24 h with escalation of apixaban dose at 5 mg PO q 12 h, 5 mg PO q 8 h, 10 mg PO q 12 h, and 10 mg PO q 8 h. Laboratory testing included fecal occult blood, coagulation parameters, Factor X activity, apixaban concentration, platelet aggregometry, and thromboelastography on days 1, 3, and 8.

RESULTS

Evidence of bleeding was not observed at any dosage. Dose-dependent changes in PD/PK parameters between baseline and 3 h post-medication were observed including a prolongation of prothrombin time, a prolongation of activated partial thromboplastin time, a decrease of Factor X activity level, and increased apixaban concentration.

CONCLUSIONS

The combination of apixaban at a dosage range of approximately 0.5 mg/kg PO q 12 h to 1 mg/kg PO q 8 h and clopidogrel at approximately 1.8 mg/kg PO q 24 h did not cause bleeding over a one-week period in healthy dogs. Clinically relevant changes in PD/PK data occur at all dosage levels. This study provides a starting point for longer-term clinical trials to determine safety and efficacy.

Antithrombotic therapy in patients undergoing transcatheter aortic valve replacement: the complexity of the elderly

Along with epidemiologic transitions of the global population, the burden of aortic stenosis (AS) is rapidly increasing and transcatheter aortic valve replacement (TAVR) has quickly spread; indeed, it is nowadays also employed in treating patients with AS at intermediate operative risk. Nonetheless, the less invasive interventional strategy still carries relevant issues concerning post-procedural optimal antithrombotic strategy, given the current indications provided by guidelines are not completely supported by evidence-based data. Geriatric patients suffer from high bleeding and thromboembolic risks, whose balance is particularly subtle due to the presence of concomitant conditions, such as atrial fibrillation and chronic kidney disease, that make the post-TAVR antithrombotic management particularly insidious. This scenario is further complicated by the lack of specific evidence regarding the 'real-life' complex conditions typical of the geriatric syndromes, thus, the management of such a heterogeneous population, ranging from healthy ageing to frailty, is far from being defined. The aim of the present review is to summarize the critical points and the most updated evidence regarding the post-TAVR antithrombotic approach in the geriatric population, with a specific focus on the most frequent clinical settings.