Antithrombotic Therapy for Symptomatic Peripheral Arterial Disease: A Systematic Review and Network Meta-Analysis

Association of antiplatelet therapy with clinical outcomes in patients with peripheral artery disease

BACKGROUND

The beneficial role of dual anti-platelet therapy (DAPT) in coronary artery disease is well established. However, there is limited data describing the effects of DAPT in patients with atherosclerotic peripheral artery disease (PAD). The aim of this meta-analysis is to compare clinical outcomes associated with DAPT versus single anti-platelet therapy (SAPT) in patients with symptomatic PAD.

METHODS

We performed a literature search for studies assessing the risk of adverse cardiovascular and limb events in cohorts receiving either DAPT or SAPT. The primary endpoint was all cause mortality. The secondary endpoints included graft failure, amputation, total bleeding, severe bleeding and fatal bleeding. The search included the following databases: Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar. The search was not restricted to time or publication status.

RESULTS

A total of 11 studies with 54,331 participants (24,449 on SAPT and 29,882 on DAPT) were included. Patients with PAD treated with SAPT had higher all-cause mortality compared to patients treated with DAPT (OR 1.37, 95 % CI 1.09-1.74; p < 0.01). There was no difference in risk of graft failure or amputation between patients treated with SAPT or DAPT (OR 0.9, 95 % CI 0.77-1.06; p = 0.19; OR 1.11, 95 % CI 0.88-1.41; p = 0.37). Patients treated with SAPT had lower total bleeds compared to patients treated with DAPT (OR 0.53, 95 % CI 0.36-0.77; p < 0.01). However, For SAPT plus AC vs SAPT, a total of 8 studies with 17,100 participants (3447 with SAPT plus AC and 8619 with only SAPT) were included. Patients on SAPT plus AC did not have a statistically significant difference in risk for all-cause mortality, (OR 0.91, 95 % CI 0.67-1.24; p = 0.56). SAPT plus AC had significantly lower risk of MI (OR 0.82, 95 % CI 0.69-0.97; p = 0.02), amputation (OR 0.72, 95 % CI 0.53-0.97; p = 0.03), and graft failure (OR 0.66, 95 % CI 0.48-0.93; p = 0.02). There was no significant different in risk of fatal bleeding be-tween the two groups (OR 1.60, 95 % CI 0.76-3.35; p = 0.22).

CONCLUSIONS

In patients with symptomatic PAD, a strategy of DAPT may confer a mortality benefit when compared to SAPT without significantly increasing the risk of serious bleeding events.

Rationale and design for the randomized placebo-controlled double-blind trial studying the effect of single antiplatelet therapy (clopidogrel) versus dual antiplatelet therapy (clopidogrel/acetylsalicylic acid) on the occurrence of atherothrombotic events following lower extremity peripheral transluminal angioplasty (CLEAR-PATH)

RATIONALE

Antiplatelet therapy (APT) is the standard of care after endovascular revascularization (EVR) in patients with peripheral artery disease (PAD). APT aims to prevent both major adverse cardiovascular events (MACE) and major adverse limb events (MALE). Nonetheless, the rates of MACE and MALE after EVR remain high. In coronary artery and cerebrovascular disease, dual APT (DAPT)compared to acetylsalicylic acid alone has been proven to reduce MACE without increasing the risk of major bleeding when applied for a restricted number of weeks. However, within the PAD population, insufficient data are available to understand the potential attributable effect of DAPT over single APT (SAPT). Therefore, prospective randomized studies in targeted study populations are warranted.

TRIAL DESIGN

CLEAR-PATH is a Dutch multicenter, double-blind, placebo-controlled, randomized trial comparing SAPT (clopidogrel 75 mg plus placebo) with DAPT (clopidogrel 75 mg plus acetylsalicylic acid 80 mg) in patients with PAD undergoing EVR. CLEAR-PATH includes a time-to-event analysis with a follow-up of one year. The primary composite efficacy endpoint consists of all-cause mortality, nonfatal stroke, nonfatal myocardial infarction, severe limb ischemia, (indication for) re-intervention due to any symptomatic restenosis, re-occlusion, or due to acute limb ischemia, and major amputation. The primary safety endpoint contains major bleeding following the Thrombolysis in Myocardial Infarction classification. The enrolment started in August 2022. In total 450 primary efficacy outcome events are required which expectedly amounts to 1696 subjects. Recruitment will take approximately 36 months.

CONCLUSION

CLEAR-PATH will assess the efficacy and safety of DAPT compared to SAPT following EVR in PAD patients.

TRIAL REGISTRATION NUMBER

NL80009.041.21.

[Conservative Treatment and Secondary Prevention of PAD (Peripheral Artery Disease)]

The immediate and long-term success of endovascular and surgical revascularization crucially depends on the conservative treatment of the PAD. The "gentle, preserving" treatment should be understood as he absolutely basic therapy for every PAD patient, because conservative treatment adresses the "big five" of atherosclerotic risk factors. This article presents both the full spectrum of pharmacological and non-pharmacological strategies.

Current Medical Therapy and Revascularization in Peripheral Artery Disease of the Lower Limbs: Impacts on Subclinical Chronic Inflammation

Peripheral artery disease (PAD), coronary artery disease (CAD), and cerebrovascular disease (CeVD) are characterized by atherosclerosis and inflammation as their underlying mechanisms. This paper aims to conduct a literature review on pharmacotherapy for PAD, specifically focusing on how different drug classes target pro-inflammatory pathways. The goal is to enhance the choice of therapeutic plans by considering their impact on the chronic subclinical inflammation that is associated with PAD development and progression. We conducted a comprehensive review of currently published original articles, narratives, systematic reviews, and meta-analyses. The aim was to explore the relationship between PAD and inflammation and evaluate the influence of current pharmacological and nonpharmacological interventions on the underlying chronic subclinical inflammation. Our findings indicate that the existing treatments have added anti-inflammatory properties that can potentially delay or prevent PAD progression and improve outcomes, independent of their effects on traditional risk factors. Although inflammation-targeted therapy in PAD shows promising potential, its benefits have not been definitively proven yet. However, it is crucial not to overlook the pleiotropic properties of the currently available treatments, as they may provide valuable insights for therapeutic strategies. Further studies focusing on the anti-inflammatory and immunomodulatory effects of these treatments could enhance our understanding of the mechanisms contributing to the residual risk in PAD and pave the way for the development of novel therapies.

Impact of Factor Xa Inhibition on Coagulation, Platelet Reactivity, and Thrombosis in Patients with Peripheral Artery Disease

BACKGROUND

The role of thrombin in vascular pathology is a focus of investigation. The incorporation of direct Factor Xa inhibition into practice patterns is based on its theoretical dual-pathway attenuation of both thrombin generation and platelet aggregation. However, quantification of the effect of direct anti-Xa medications on platelet function is not established. Thromboelastography with platelet mapping (TEG-PM) leverages dual-pathway metrics to provide comprehensive coagulation profiles. We evaluated the effects of direct oral anticoagulants (DOACs) on coagulation and platelet function profiles and correlate these data with postoperative major adverse limb events (MALEs) in patients with PAD.

METHODS

We conducted a prospective study of patients undergoing lower extremity revascularization with serial perioperative TEG-PM analysis. Patients on DOACs were compared to those not on DOACs, and stratified by concurrent mono-antiplatelet or dual-antiplatelet regimens (MAPT/DAPT). Postoperative MALE was recorded and difference in antithrombotic regimens and TEG-PM analysis compared between groups.

RESULTS

Four hundred seventy-one samples from 141 patients were analyzed. Twenty-nine point five percent were reflective of circulating DOAC therapy. Compared to MAPT alone, patients on DOAC + MAPT exhibited longer time to clot formation (R-time) [7.4 (±2.4) vs. 6.7 (±2.7); P < 0.02], but less platelet inhibition. Patients on DAPT exhibited greater platelet inhibition compared to either group [23.7 (±26.9) vs. 31.0 (±28.3) vs. 42.2 (±31.2); P < 0.01]. Patients who experienced MALE were more likely to be on DOAC therapy [43.8% vs. 22.0% P = 0.02]. Thromboelastography with platelet mapping analysis from patients who experienced MALE also demonstrated longer R-time [8.6 (±3.9 vs. 7.3 (±3.0); P = 0.05] and increased maximum clot amplitude (MA) [66.7 (±4.2) vs. 61.8 (±8.2); P = 0.001].

CONCLUSIONS

Direct oral anticoagulant therapy resulted in a prolonged R-time but had no impact on platelet inhibition. Patients who experienced MALE were more often on DOACs and demonstrated an increased R-time, but also showed greater platelet reactivity evident by increased MA, suggesting DOACs may not be effective at protecting against MALE. Further research comparing DOAC therapy to a DAPT approach may add clarity to emerging multimodal antithrombotic recommendations.

[Conservative therapy and secondary prevention of PAD]

Today, peripheral artery disease (PAD) is treated with the most modern endovascular and open surgical revascularisation procedures. But the short and long-term success of these interventions is decisively determined by the conservative therapy of PAD, which therefore represents the absolute basic therapy of every PAD. Conservative treatment addresses the "Big Five" of atherosclerosis risk factors: smoking, lack of exercise and overweight, diabetes, hypertension, and hyperlipidemia. Despite the knowledge that PAD as a peripheral manifestation of the systemic atherosclerosis needs the same risk factor management as e.g., coronary heart disease, not even every second PAD patient in Germany receives the required therapy. This paper presents the spectrum of both drug and non-drug strategies and focuses on aspects such as platelet inhibition and anticoagulation regimes, lipid-lowering options as well as the benefits and necessity of exercise programs to promote collaterals and improve quality of life by extending the pain-free walking distance. Proven strategies to overcome smoking addiction, use and purpose of vasoactive substances are highlighted as well as the potential risks of diabetic foot syndrome for limb salvage and prevention of wounds.

Integrating Mechanisms in Thrombotic Peripheral Arterial Disease

Peripheral arterial disease (PAD), a manifestation of systemic atherosclerosis, is underdiagnosed in the general population. Despite the extensive research performed to unravel its pathophysiology, inadequate knowledge exists, thus preventing the development of new treatments. This review aims to highlight the essential elements of atherosclerosis contributing to the pathophysiology of PAD. Furthermore, emphasis will be placed on the role of thrombo-inflammation, with particular focus on platelet and coagulation activation as well as cell-cell interactions. Additional insight will be then discussed to reveal the contribution of hypercoagulability to the development of vascular diseases such as PAD. Lastly, the current antithrombotic treatments will be discussed, and light will be shed on promising new targets aiming to aid the development of new treatments.