Clinical recurrence and antiplatelet drug resistance among patients with lower limb ischemia

There is a high prevalence rate of peripheral artery disease worldwide, with estimated cases exceeding 200 million. Most patients are under-diagnosed and under-treated, and there is a lack of knowledge regarding the best therapeutic regimen and therapy duration, which leads to many cases of recurrence, complications, and amputations. This study aims to explore clinical recurrence, which was defined as the worsening of chronic peripheral artery disease requiring hospital admission, and its relationship with antiplatelet drug resistance among patients with lower limb ischemia. This cohort study includes both retrospective and prospective recruitment of patients with chronic lower limb ischemia. Platelet aggregation tests were offered to the patients. Between February 2018 and November 2020, 147 patients were recruited from King Abdullah University Hospital and followed up for at least 1 year. Platelet aggregation tests were done for 93 patients who agreed to participate in this part of the study. The prevalence of chronic lower limb ischemia was higher in young male patients who are current smokers with co-morbid diseases such as hypertension, diabetes mellitus, and/or dyslipidemia. There was a significant association only of clinical recurrence with younger age (P = .011) and with low platelets count in severe stages of the disease (P = .047). No significant association was found in terms of laboratory resistance. The clinical recurrence rates of chronic lower limb ischemia were higher in younger patients and among those with low platelet counts in the severe stages of the disease. Despite the laboratory responsiveness to anti-platelet therapy, we observed significant clinical resistance and increased recurrence rates.

Evaluation of the therapeutic effects of oestradiol on the systemic inflammatory response and on lung injury caused by the occlusion of the proximal descending aorta in male rats

OBJECTIVES

Ischaemia and reperfusion-induced microvascular dysfunction is a serious problem encountered during a variety surgical procedures, leading to systemic inflammation and affecting remote organs, specially the lungs. 17β-Oestradiol reduces pulmonary repercussions from various acute lung injury forms. Here, we focused on the 17β-oestradiol therapeutic effects after aortic ischaemia and reperfusion (I/R) by evaluating lung inflammation.

METHODS

Twenty-four Wistar rats were submitted to I/R by insufflation of a 2-F catheter in thoracic aorta for 20 min. Reperfusion took 4 h and 17β-oestradiol (280 µg/kg, i.v.) was administered after 1 h of reperfusion. Sham-operated rats were controls. Bronchoalveolar lavage was performed and lung samples were prepared for histopathological analysis and tissue culture (explant). Interleukin (IL)-1β, IL-10 and tumour necrosis factor-α were quantified.

RESULTS

After I/R, higher number of leukocytes in bronchoalveolar lavage were reduced by 17β-oestradiol. The treatment also decreased leukocytes in lung tissue. I/R increased lung myeloperoxidase expression, with reduction by 17β-oestradiol. Serum cytokine-induced neutrophil chemoattractant 1 and IL-1β increased after I/R and 17β-oestradiol decreased cytokine-induced neutrophil chemoattractant 1. I/R increased IL-1β and IL-10 in lung explants, reduced by 17β-oestradiol.

CONCLUSIONS

Our results showed that 17β-oestradiol treatment performed in the period of reperfusion, modulated the systemic response and the lung repercussions of I/R by thoracic aortic occlusion. Thus, we can suggest that 17β-oestradiol might be a supplementary approach leading the lung deterioration after aortic clamping in surgical procedures.

Using T1 mapping indices to evaluate muscle function and predict conservative treatment outcomes in diabetic patients with peripheral arterial disease

OBJECTIVES

To investigate interstitial muscle fibrosis via T1 mapping indices and its relationships with muscle function and conservative treatment outcomes.

METHODS

A total of 49 DM patients with PAD were prospectively recruited from 2016 to 2017. All PAD patients underwent pre-treatment MRI with conservative treatment via a rehabilitation program and antiplatelet therapy. The need to require percutaneous transluminal angioplasty intervention was recorded as intolerance to conservative treatment outcomes. We quantified calf interstitial muscle fibrosis using T1 mapping indices (native T1, post-contrast T1, and the extracellular volume fraction [ECV]). Muscle function was evaluated using a 6-min walking test (6MWT) and a 3-min stepping test (3MST). PAD patients were divided into two groups according to their tolerance or intolerance of the conservative treatment. Pearson's correlation, reproducibility, and multivariable Cox hazard analyses were performed with p < 0.05 indicating statistical significance.

RESULTS

Among the T1 mapping indices in the posterior compartment of the calf in PAD patients, the native T1 value was significantly correlated with 6MWT (r =  -0.422, p = 0.010) and 3MST (r =  -0.427, p = 0.009). All T1 mapping indices showed excellent intra-observer and inter-observer correlations. ECV was an independent predictor of conservative treatment intolerance (average ECV, hazard ratio: 1.045, 95% confidence interval: 1.011-1.079, p = 0.009).

CONCLUSIONS

T1 mapping measurements are reproducible with excellent intra-observer and inter-observer correlations. T1 mapping indices may be predictive of treatment and functional outcomes and carry promise in patient evaluation.

TRIAL REGISTRATION

Clinical Trials Identifier: NCT02850432 .

KEY POINTS

• T1 mapping measurements of the calf muscles are reproducible with excellent intra-observer and inter-observer correlations (0.98 and 0.95 for anterior and posterior compartment muscle extracellular volume matrix [ECV] measurements, respectively). • ECV is shown to independently predict conservative treatment intolerance. • T1 mapping indices may be predictive of treatment and functional outcomes and carry promise in patient evaluation.

Antithrombotic Therapy in Peripheral Artery Disease: Stepping in the Right Direction

We reviewed the various antithrombotic therapies available to treat peripheral artery disease (PAD). A literature review using the PubMed and MEDLINE databases used the following keywords: antithrombotic therapy, anticoagulation, peripheral artery disease, and peripheral vascular disease. Randomized studies written in English that assessed the use of antithrombotic therapy in patients with PAD were evaluated. PAD is a worldwide condition that limits blood flow in the lower extremities, leading to a risk of major adverse cardiovascular events and major adverse limb events. Antithrombotic therapy is necessary to prevent these complications, and the choice of therapy depends upon the stage of disease progression. For symptomatic patients in the beginning stage, single antiplatelet therapy (SAPT) is the preferred therapy, specifically, aspirin. For patients undergoing endovascular revascularization, the preferred therapy is dual antiplatelet therapy using aspirin and clopidogrel combined for at least the first month followed by long-term SAPT. For patients undergoing surgical revascularization, the preferred choice of therapy depends upon the type of graft used, with better results obtained with antiplatelet therapy for prosthetic grafts and anticoagulation for venous grafts. New studies have shown that therapy using both antiplatelets and anticoagulation in the form of aspirin plus low-dose rivaroxaban can reduce complications in all three patient populations, which has paved the way for future studies featuring direct oral anticoagulants with the potential to change current guideline recommendations.

Anti-platelet and anti-coagulant therapy in peripheral arterial disease prior to surgical intervention

OBJECTIVE

Peripheral artery disease is a major clinical co-morbidity that can significantly affect quality of life, especially in the presence of diabetes mellitus and older age. The focus of this literature review is on medical management, through anti-platelet and anti-coagulation, of peripheral artery disease prior to undergoing surgical or endovascular management.

METHOD

Extensive electronic literature search performed in four major databases (PubMed, SCOPUD, Embase and Ovid) to identify the published randomized and non-randomized studies that compared and discussed the management of peripheral artery disease with different anti-thrombotic agents.

RESULTS

A total of 17 studies were identified to meet the inclusion criteria of this review. Among them, 4 were systematic review and meta-analyses, 1 was observational study and 12 were randomized controlled trials. The reported outcomes in each study are summarized and reported separately within this review.

CONCLUSION

Peripheral artery disease is a complex and multifactorial clinical condition. The use of dual anti-platelets, such as aspirin and clopidogrel, are the key in preventing major cardiovascular events as well as stroke and death. Utilization of anti-coagulation such as direct oral anti-coagulants' as additional parameters for the prevention of disease progression, is paramount. Eventually, the choice of either dual-antiplatelet therapy or combined anti-coagulation with anti-platelets should be carefully considered, particularly following the most recent published debatable studies.

Preventing Major Amputations in Patients with Critical Limb Ischemia

PURPOSE OF REVIEW

This review summarizes the risks of lower extremity amputation associated with critical limb ischemia (CLI) and discusses current therapies that can prevent amputation in CLI.

RECENT FINDINGS

CLI remains an under-recognized condition associated with high rates of major amputation and disparities in care. Optimal medical therapy can reduce the risk of major adverse cardiovascular and limb events, but revascularization combined with close wound care remains the cornerstone of amputation prevention. Endovascular revascularization has become more common over time and has been associated with a reduction in amputation rates. Ongoing clinical trials will help inform best practices for revascularization strategies and techniques. Vascular care is inconsistent across the USA, with significant variation in access to care revascularization rates and rates of major amputation. Major amputation can be prevented in patients with CLI when optimal medical therapy, lifestyle modification, and revascularization are provided in a multidisciplinary setting.

Ticagrelor in Peripheral Artery Disease Endovascular Revascularization (TI-PAD): Challenges in clinical trial execution

There is limited evidence to guide clinical decision-making for antiplatelet therapy in peripheral artery disease (PAD) in the setting of lower extremity endovascular treatment. The Ticagrelor in Peripheral Artery Disease Endovascular Revascularization Study (TI-PAD) evaluated the role of ticagrelor versus aspirin as monotherapy in the management of patients following lower extremity endovascular revascularization. The trial failed to recruit the targeted number of patients, likely due to aspects of the design including the lack of option for dual antiplatelet therapy, and inability to identify suitable patients at study sites. In response, the protocol underwent amendments, but these changes did not adequately stimulate recruitment, and thus TI-PAD was prematurely terminated. This article describes the rationale for TI-PAD and challenges in trial design, subject recruitment and trial operations to better inform the conduct of future trials in PAD revascularization. ClinicalTrials.gov Identifier: NCT02227368.

Antithrombotic treatment in peripheral artery disease

Abstract. This review treats antithrombotic use for peripheral arterial disease (PAD). In asymptomatic patients, there are no scientific data to support single antiplatelet therapy (SAPT) for primary prophylaxis. In symptomatic PAD, SAPT with aspirin or clopidogrel is indicated. The efficacy of aspirin is controversial. Clopidogrel may be preferred over aspirin. Ticagrelor is not superior to clopidogrel in reducing major adverse cardiovascular events and major adverse limb events, but lowers the risk of ischaemic stroke. In symptomatic PAD, dual antiplatelet therapy (DAPT) with clopidogrel and aspirin does not provide benefit over SAPT with aspirin alone and is associated with increased risk of major bleeding. DAPT with ticagrelor 60 mg b. i. d. and aspirin provides a significant major adverse cardiovascular events reduction in symptomatic PAD patients and may be considered in PAD patients with prior myocardial infarction. The use of a new thrombin receptor antagonist, vorapaxar, on top of SAPT or DAPT with aspirin and/or clopidogrel, reduces the risk of acute limb ischaemia and peripheral artery revascularization in patients with symptomatic PAD, at the cost of an increased risk for bleeding. Rivaroxaban (2.5 mg b. i. d.) plus aspirin (100 mg daily) is the first antithrombotic association that proved significant benefit for PAD patients, in terms of strong endpoints – total mortality and cardiovascular mortality. Therefore, this association shows the strongest evidence for secondary prevention of symptomatic PAD patients. In PAD patients undergoing percutaneous peripheral interventions, at least four weeks of DAPT with aspirin and clopidogrel is recommended after infrainguinal stent implantation. Stenting below-the-knee arteries is often followed by a longer period of DAPT, but no specific evidence is available. Anticoagulation is mandatory to prevent arterial occlusion during radial or brachial invasive procedures. The strategy includes use of unfractioned heparin, bivalirudin or enoxaparin. Vitamin K antagonists may be considered after autologous vein infrainguinal bypass.