A Comprehensive Review on Antithrombotic Therapy for Peripheral Artery Disease

Platelet function testing and clinical outcomes in peripheral arterial disease: Systematic review and narrative synthesis

OBJECTIVE

This systematic review aims to comprehensively assess the contemporary literature on platelet function testing (PFT) in individuals undergoing revascularization therapy for peripheral arterial disease (PAD). The goal is to identify whether PFT can aid in detecting antiplatelet resistance, predicting post-procedural thrombotic complications, and informing tailored treatment strategies.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a literature review was conducted using PubMed databases. Search terms included relevant medical subject headings (MeSH) terms. Eligible articles published in English between 1990 and 2023 were analyzed. Studies that examined PFT outcomes in patients with PAD after lower extremity revascularization were included.

RESULTS

Ten studies met the inclusion criteria. Various PFT methods were used, including thromboelastography with platelet mapping, multiplate analyzer, Cytochrome P450 2C19 testing, VerifyNow, corrected whole blood aggregometry, platelet function analyzer-100, and light transmission aggregometry. PFT identified individuals who were resistant or non-sensitive to antiplatelet therapy, with such patients facing increased risks of graft/stent thrombosis, amputation, and reintervention. However, substantial heterogeneity in surgical procedures, drug regimens, and testing methods was observed among the studies.

CONCLUSIONS

PFTs can play a crucial role in detecting resistance and non-sensitivity to antiplatelet drugs in patients with PAD post-revascularization. However, heterogeneity of data and methods underlines the need for standardized protocols and consensus-building among PFTs. Enhancing clinical utility and reliability could help optimize antiplatelet thromboprophylaxis, minimize thrombotic complications, and improve treatment strategies in vascular surgery. Further research is necessary to solidify the role of PFTs in guiding antiplatelet therapy post-revascularization in patients with PAD.

Comparison of rivaroxaban-based dual antithrombotic and antiplatelet therapies for symptomatic patients with lower-extremity peripheral artery disease post-revascularization: a retrospective cohort study

Background

Patients with symptomatic lower-extremity peripheral artery disease (LE-PAD) are prone to serious cardiovascular and limb events. Few studies have evaluated the effect of rivaroxaban-based dual antithrombotic therapy in high-risk patients with LE-PAD in Asian populations.

Objectives

To investigate the efficacy and safety of rivaroxaban-based dual antithrombotic therapy in symptomatic patients with LE-PAD.

Design

Retrospective cohort study.

Methods

This study included patients with LE-PAD treated at the Nanjing Drum Tower Hospital from 1 January 2018 to 31 December 2021. These participants were divided into antiplatelet (APT) or antiplatelet therapy combined with rivaroxaban (RAPT) groups. The efficacy outcomes in this study were the occurrence of major adverse cardiovascular events (MACE), including myocardial infarction, ischemic stroke, or death from cardiovascular causes, and major adverse limb events (MALE), including urgent revascularization, acute limb ischemia, and major amputation. The safety outcomes included major and clinically relevant non-major (CRNM) bleeding. Patients were followed up until the time of death or the end of the study (31 March 2023).

Results

We included 1144 patients with LE-PAD (APT: 502 patients; RAPT: 642 patients). The RAPT group had a lower risk of primary composite efficacy outcomes [hazard ratio (HR): 0.40] and a nonsignificant increase in major bleeding risk (HR: 2.33) than the APT group. The RATP group also had a significantly lower risk of secondary efficacy outcomes, including ischemic stroke (HR: 0.41), myocardial infarction (HR: 0.31), cardiovascular death (HR: 0.40), and MALE (HR: 0.65), than the APT group. The CRNM bleeding incidence varied between the two groups (HR: 3.96). Moreover, no significant interactions were observed between the subgroups and treatment groups in the composite efficacy analysis.

Conclusion

Rivaroxaban-based dual antithrombotic therapy significantly reduced the occurrence of MACE in patients with LE-PAD without increasing major bleeding events. High-risk patients benefited from the dual antithrombotic therapy.

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.

The Novel Role of Noncoding RNAs in Modulating Platelet Function: Implications in Activation and Aggregation

It is currently believed that plaque complication, with the consequent superimposed thrombosis, is a key factor in the clinical occurrence of acute coronary syndromes (ACSs). Platelets are major players in this process. Despite the considerable progress made by the new antithrombotic strategies (P2Y12 receptor inhibitors, new oral anticoagulants, thrombin direct inhibitors, etc.) in terms of a reduction in major cardiovascular events, a significant number of patients with previous ACSs treated with these drugs continue to experience events, indicating that the mechanisms of platelet remain largely unknown. In the last decade, our knowledge of platelet pathophysiology has improved. It has been reported that, in response to physiological and pathological stimuli, platelet activation is accompanied by de novo protein synthesis, through a rapid and particularly well-regulated translation of resident mRNAs of megakaryocytic derivation. Although the platelets are anucleate, they indeed contain an important fraction of mRNAs that can be quickly used for protein synthesis following their activation. A better understanding of the pathophysiology of platelet activation and the interaction with the main cellular components of the vascular wall will open up new perspectives in the treatment of the majority of thrombotic disorders, such as ACSs, stroke, and peripheral artery diseases before and after the acute event. In the present review, we will discuss the novel role of noncoding RNAs in modulating platelet function, highlighting the possible implications in activation and aggregation.

Use of Thromboelastography with Platelet Mapping to Identify Prothrombotic Coagulation Profiles in Patients with History of Cardiac Intervention Undergoing Lower Extremity Revascularization

BACKGROUND

Patients with concomitant coronary and peripheral artery disease (CAD and PAD) are at significant risk for major adverse limb events (MALEs). Prevention of thrombosis in this population is of paramount importance. Identifying prothrombotic coagulation profiles in this cohort may facilitate targeted thromboprophylaxis. We compared coagulation profiles of those with CAD and PAD to those with PAD alone during the perioperative period of lower extremity revascularization.

STUDY DESIGN

Patients undergoing lower extremity revascularization underwent thromboelastography-platelet mapping (TEG-PM) analysis preoperatively and at serial intervals for up to 6 months. Coagulation profiles of patients with significant CAD (defined as history of coronary artery bypass graft or percutaneous coronary intervention) and PAD were compared with those with PAD alone. MALE in the postoperative period was recorded.

RESULTS

Four hundred seventy-seven TEG-PM samples from 114 patients were analyzed; 28.1% had a history of significant CAD. The incidence of atrial fibrillation was higher in this group. The significant CAD group had lower ADP-platelet inhibition, higher ADP-platelet aggregation, and greater maximum clot strength compared with patients with PAD alone. Patients with significant CAD were more frequently on full-dose anticoagulation, but less frequently on dual antiplatelet therapy; 28.1% of patients with significant CAD developed postoperative MALE compared with 22.9% of patients with PAD alone (p = 0.40). For both groups, patients who developed postoperative MALE demonstrated greater ADP-platelet aggregation and lower ADP-platelet inhibition.

CONCLUSIONS

Patients with a history of significant CAD undergoing lower extremity revascularization demonstrated prothrombotic TEG-PM profiles, less frequent use of dual antiplatelet therapy, and greater rates of full-dose anticoagulation. Decreased platelet inhibition was also associated with postoperative MALE. This study underscores the potential utility of viscoelastic assays for coagulation profiling in complex cardiovascular patients.

Predicting Arterial Thrombotic Events Following Peripheral Revascularization Using Objective Viscoelastic Data

Background Peripheral artery disease is endemic in our globally aging population, with >200 million affected worldwide. Graft/stent thrombosis after revascularization is common and frequently results in amputation, major adverse cardiovascular events, and cardiovascular mortality. Optimizing medications to decrease thrombosis is of paramount importance; however, limited guidance exists on how to use and monitor antithrombotic therapy in this heterogeneous population. Thromboelastography with platelet mapping (TEG-PM) provides comprehensive coagulation metrics and may be integral to the next stage of patient-centered thrombophrophylaxis. This prospective study aimed to determine if TEG-PM could predict subacute graft/stent thrombosis following lower extremity revascularization, and if objective cut point values could be established to identify those high-risk patients. Methods and Results We conducted a single-center prospective observational study of patients undergoing lower extremity revascularization. Patients were followed up for the composite end point postoperative graft/stent thrombosis at 1 year. TEG-PM analysis of the time point before thrombosis in the event group was compared with the last postoperative visit in the nonevent group. Cox proportional hazards analysis examined the association of TEG-PM metrics to thrombosis. Cut point analysis explored the predictive capacity of TEG-PM metrics for those at high risk. A total of 162 patients were analyzed, of whom 30 (18.5%) experienced graft/stent thrombosis. Patients with thrombosis had significantly greater platelet aggregation (79.7±15.7 versus 58.5±26.4) and lower platelet inhibition (20.7±15.6% versus 41.1±26.6%) (all P<0.01). Cox proportional hazards analysis revealed that for every 1% increase in platelet aggregation, the hazard of experiencing an event during the study period increased by 5% (hazard ratio, 1.05 [95% CI, 1.02-1.07]; P<0.01). An optimal cut point of >70.8% platelet aggregation and/or <29.2% platelet inhibition identifies those at high risk of thrombosis with 87% sensitivity and 70% to 71% specificity. Conclusions Among patients undergoing lower extremity revascularization, increased platelet reactivity was predictive of subacute postoperative graft/stent thrombosis. On the basis of the cut points of >70.8% platelet aggregation and <29.2% platelet inhibition, consideration of an alternative or augmented antithrombotic regimen for high-risk patients may decrease the risk of postoperative thrombotic events.

Variability of antiplatelet response in patients with peripheral artery disease

OBJECTIVE

Antiplatelet therapy has been a pillar of management for peripheral artery disease (PAD). However, a significant subset of patients with PAD will be resistant to certain antiplatelet medications and, therefore, have an increased risk of graft and/or stent thrombosis unknown to the surgeon. At present, no point-of-care testing to identity which patients will experience benefit from these medications has been incorporated into the treatment guidelines. Thromboelastography with platelet mapping affords an opportunity to evaluate real-time coagulation dynamics and platelet function. In the present prospective, observational study, we aimed to delineate the variation in response to antiplatelet therapy in patients with PAD undergoing revascularization.

METHODS

All patients who were undergoing named vessel revascularization during December 2020 through April 2022 were prospectively enrolled. Platelet mapping assays were performed in three clinical phases: preoperative, postoperative inpatient, and postoperative outpatient. The distribution of platelet reactivity within patients receiving mono- vs dual antiplatelet therapy was assessed, and a between-group inferential analysis was performed. The effect of comorbidities and intervention subtype on platelet inhibition was also analyzed.

RESULTS

A total of 521 platelet mapping samples from 143 individual patients were analyzed using thromboelastography with platelet mapping. We found wide variability in the distribution of platelet inhibition, with a range of 0 to 100 and an interquartile range of 37.6. Although platelet inhibition with clopidogrel 75 mg was higher on average (44.8 ± 30.2) than that with aspirin 81 mg (24.6 ± 23.7) or aspirin 325 mg (27.1 ± 26.4; P = .001), clopidogrel at 75 mg demonstrated the highest variability in response.

CONCLUSIONS

These data have demonstrated significant variability in the response to both mono- and dual antiplatelet therapy in PAD patients undergoing lower extremity revascularization. Future research on the effect of this variability in response on the clinical outcomes could provide invaluable understanding of the perioperative thrombotic risk.

A highly selective and sensitive competitive aptasensor capable of quantifying thrombin elevated with side effects in severe COVID-19

To protect critical injury from blood clots with side effects in severe COVID-19, a highly selective and sensitive biosensor was developed for the quantification of trace levels of thrombin using the combination of a DNA aptamer (TBA) of thrombin and a complementary strand of TBA. TBA rapidly binds with thrombin, whereas it slowly binds with the complementary strand to form a double stranded DNA (dsDNA). SFC green intercalated into dsDNA cannot emit light in 1,1′-oxalyldiimidazole chemiluminescence (ODI-CL) reaction because high-energy intermediates formed from ODI-CL reaction cannot transfer energy to SFC trapped in dsDNA. However, SFC freely existing with the formation of G-quadruplex from the reaction of thrombin and TBA emits bright chemiluminescence because the high-energy intermediates can transfer energy to SFC (or camel) in solution. Thus, the brightness of light emitted in ODI-CL reaction was proportionally enhanced with the increase of thrombin in a sample due to the increase of G-quadruplex and reduction of dsDNA. The limit of detection (LOD) of the label free aptasensor operated with good linear calibration curve (10–320 mU/ml) was as low as 3 mU/ml (or 43 pM). Also, the biosensor was quantified trace levels of thrombin with good accuracy, precision, and reliability.

Antithrombotic and antiplatelet effects of plant-derived compounds: a great utility potential for primary, secondary, and tertiary care in the framework of 3P medicine

Thromboembolism is the third leading vascular disease, with a high annual incidence of 1 to 2 cases per 1000 individuals within the general population. The broader term venous thromboembolism generally refers to deep vein thrombosis, pulmonary embolism, and/or a combination of both. Therefore, thromboembolism can affect both – the central and peripheral veins. Arterial thromboembolism causes systemic ischemia by disturbing blood flow and oxygen supply to organs, tissues, and cells causing, therefore, apoptosis and/or necrosis in the affected tissues. Currently applied antithrombotic drugs used, e.g. to protect affected individuals against ischemic stroke, demonstrate significant limitations. For example, platelet inhibitors possess only moderate efficacy. On the other hand, thrombolytics and anticoagulants significantly increase hemorrhage. Contextually, new approaches are extensively under consideration to develop next-generation antithrombotics with improved efficacy and more personalized and targeted application. To this end, phytochemicals show potent antithrombotic efficacy demonstrated in numerous in vitro, ex vivo, and in vivo models as well as in clinical evaluations conducted on healthy individuals and persons at high risk of thrombotic events, such as pregnant women (primary care), cancer, and COVID-19-affected patients (secondary and tertiary care). Here, we hypothesized that specific antithrombotic and antiplatelet effects of plant-derived compounds might be of great clinical utility in primary, secondary, and tertiary care. To increase the efficacy, precise patient stratification based on predictive diagnostics is essential for targeted protection and treatments tailored to the person in the framework of 3P medicine. Contextually, this paper aims at critical review toward the involvement of specific classes of phytochemicals in antiplatelet and anticoagulation adapted to clinical needs. The paper exemplifies selected plant-derived drugs, plant extracts, and whole plant foods/herbs demonstrating their specific antithrombotic, antiplatelet, and fibrinolytic activities relevant for primary, secondary, and tertiary care. One of the examples considered is antithrombotic and antiplatelet protection specifically relevant for COVID-19-affected patient groups.