Prothrombin G20210A Mutation and Lower Extremity Peripheral Arterial Disease: A Systematic Review and Meta-analysis

The Role of the Coagulation System in Peripheral Arterial Disease: Interactions with the Arterial Wall and Its Vascular Microenvironment and Implications for Rational Therapies

Peripheral artery disease (PAD) is a clinical manifestation of atherosclerotic disease with a large-scale impact on the economy and global health. Despite the role played by platelets in the process of atherogenesis being well recognized, evidence has been increasing on the contribution of the coagulation system to the atherosclerosis formation and PAD development, with important repercussions for the therapeutic approach. Histopathological analysis and some clinical studies conducted on atherosclerotic plaques testify to the existence of different types of plaques. Likely, the role of coagulation in each specific type of plaque can be an important determinant in the histopathological composition of atherosclerosis and in its future stability. In this review, we analyze the molecular contribution of inflammation and the coagulation system on PAD pathogenesis, focusing on molecular similarities and differences between atherogenesis in PAD and coronary artery disease (CAD) and discussing the possible implications for current therapeutic strategies and future perspectives accounting for molecular inflammatory and coagulation targets. Understanding the role of cross-talking between coagulation and inflammation in atherosclerosis genesis and progression could help in choosing the right patients for future dual pathway inhibition strategies, where an antiplatelet agent is combined with an anticoagulant, whose role, despite pathophysiological premises and trials' results, is still under debate.

Genetic Determinants of Peripheral Artery Disease

Peripheral artery disease-atherosclerosis of the abdominal aorta and lower extremity vascular bed-is a complex disease with both environmental and genetic determinants. Unmitigated disease is associated with major functional decline and can lead to chronic limb-threatening ischemia, amputation, and increased mortality. Over the last 10 years, major advances have been made in identifying the genetic basis of this common, complex disease. In this review, we provide an overview of the primary types of genetic analyses performed for peripheral artery disease, including heritability and linkage studies, and more recently biobank-based genome-wide association studies. Looking forward, we highlight areas of future study including efforts to identify causal peripheral artery disease genes, rare variant and structural variant analyses using whole-exome and whole-genome sequencing data, and the need to include individuals of diverse genetic ancestries.

How I treat unexplained arterial thrombosis

Most arterial thrombotic events have a clear atherosclerotic or cardioembolic etiology, but hematologists are frequently asked to assist in the diagnosis and management of a patient with a nonatherosclerotic and noncardioembolic arterial event, referred to here as an unexplained arterial thrombosis. Because there is an assorted list of factors that can precipitate an arterial event, we present a systematic diagnostic approach to ensure consideration of not only primary hypercoagulable disorders, but also pro-thrombotic medications or substances, vascular and anatomic abnormalities, and undiagnosed systemic disorders, such as malignancy and autoimmune diseases. We also review existing literature of the role of hypercoagulable disorders in arterial thrombosis and discuss our approach to thrombophilia workup in patients after an unexplained arterial event. We conclude with 3 representative cases to both illustrate the application of the outlined diagnostic schema and discuss common management considerations, specifically the selection of anticoagulation vs antiplatelet therapy for secondary prevention.

A Unique Case of Popliteal Artery Thrombosis in Isolated Prothrombin Gene Mutation

A prothrombin gene mutation (PTGM) is the second common cause of inherited thrombophilia after factor V Leiden. Hypercoagulable conditions have traditionally been reported to cause venous thrombosis, while arterial thrombosis is a rare occurrence. Studies have reported cases of preexisting hypercoagulable conditions associated with PTGM presenting as thromboembolism; however, none have been recorded with isolated PTGM. A 55-year-old patient was diagnosed to have unilateral popliteal artery thrombosis. He had a past history of provoked deep vein thrombosis. Investigations confirmed PTGM, and no other associated hypercoagulable conditions or peripheral vascular disease were identified. Embolic sources from the heart, aorta, and an atrial septal defect were ruled out. The patient responded to heparin infusion and catheter-directed thrombolysis using TPA. The case is being reported for its uniqueness since this is the first documented case of popliteal artery thrombosis in a patient with isolated PTGM.

Risk factors and therapies in vascular diseases: An umbrella review of updated systematic reviews and meta-analyses

Aberrant blood vessel functioning and systemic circulation are key causes for vascular disorders; cardiovascular, cerebrovascular, renal artery stenosis, and peripheral artery diseases. Epidemiological and basic science evidence supported genetic reasons, compounded by obesity, hypercholesterolemia, hypertension, diabetes, and smoking as risk factors. This is an umbrella review of risk factors and therapies in vascular disorders, exploring systematic reviews and meta-analyses studies in PubMed, Cochrane, Embase, and Central published in January 2000-May 2018. We made qualitative eligibility gradation of the articles based on inclusion criteria, and independently extracted descriptive and methodologic data to compile their outcomes. We considered 95% confidence interval and the between-study heterogeneity, designated by I 2 . Overall, we extracted 217 studies of impressive quality and at low risk of bias, including 124, 30, 23, 32, and 8, respectively, for the search terms "cardiovascular," "renal," "cerebral," and "limb ischemia" each in combination with "risk factors" and "therapeutics." Our search on genome-wide analyses revealed genes associated with HDL-cholesterol, matrix metalloproteases, angiogenesis, notch3, renin-angiotensin, apolipoprotein E, insulin, and cytokine levels as critical participants in the pathogenesis of vascular diseases. Hypertension and endothelial growth factor-linked polymorphisms were found to contribute to vascular damage. The studies reinforced that lifestyle and dietary patterns influenced susceptibility of circulatory system diseases. Additionally, endovascular medicines, surgical vascularization, angioplasty, and renal artery stenting appeared as major therapeutic approaches in vascular patients. Altogether, our review offers up-to-date information on pathophysiology of vascular diseases and provides insight into existing research, clinical management and clinical gaps in the field.

Peripheral Arterial Disease Genetics: Progress to Date and Challenges Ahead

PURPOSE OF REVIEW

In this paper, we review the progress made thus far in research related to the genetics of peripheral arterial disease (PAD) by detailing efforts to date in heritability, linkage analyses, and candidate gene studies. We further summarize more contemporary genome-wide association studies (GWAS) and epigenetic studies of PAD. Finally, we review current challenges and future avenues of advanced research in PAD genetics including whole genome sequencing studies.

RECENT FINDINGS

Studies have estimated the heritability of PAD to be moderate, though the contribution to this heritability that is independent of traditional cardiovascular risk factors remains unclear. Recent efforts have identified SNPs associated with PAD in GWAS analyses, but these have yet to be replicated in independent studies. Much remains to be discovered in the field of PAD genetics. An improved understanding of the genetic foundation for PAD will allow for earlier diagnosis of disease and a more complete pathophysiological understanding of the mechanisms of the disease leading to novel therapeutic interventions. Future avenues for success will likely arise from very large-scale GWAS, whole genome sequencing, and epigenetic studies involving very well-characterized cohorts.