The Intriguing Relationships of von Willebrand Factor, ADAMTS13 and Cardiac Disease

Multimodality Imaging and Biomarker Approach to Characterize the Pathophysiology of Heart Failure in Left Ventricular Non-Compaction with Preserved Ejection Fraction

Left ventricular non-compaction (LVNC) with preserved ejection fraction (EF) is still a controverted entity. We aimed to characterize structural and functional changes in LVNC with heart failure with preserved EF (HFpEF).

METHODS

We enrolled 21 patients with LVNC and HFpEF and 21 HFpEF controls. For all patients, we performed CMR, speckle tracking echocardiography (STE), and biomarker assessment for HFpEF (NT-proBNP), for myocardial fibrosis (Galectin-3), and for endothelial dysfunction [ADAMTS13, von Willebrand factor, and their ratio]. By CMR, we assessed native T1 and extracellular volume (ECV) for each LV level (basal, mid, and apical). By STE, we assessed longitudinal strain (LS), globally and at each LV level, base-to-apex gradient, LS layer by layer, from epicardium to endocardium, and transmural deformation gradient.

RESULTS

In the LVNC group, mean NC/C ratio was 2.9 ± 0.4 and the percentage of NC myocardium mass was 24.4 ± 8.7%. LVNC patients, by comparison with controls, had higher apical native T1 (1061 ± 72 vs. 1008 ± 40 ms), diffusely increased ECV (27.2 ± 2.9 vs. 24.4 ± 2.5%), with higher values at the apical level (29.6 ± 3.8 vs. 25.2 ± 2.8%) (all p < 0.01); they had a lower LS only at the apical level (-21.4 ± 4.4 vs. -24.3 ± 3.2%), with decreased base-to-apex gradient (3.8 ± 4.7 vs. 6.9 ± 3.4%) and transmural deformation gradient (3.9 ± 0.8 vs. 4.8 ± 1.0%). LVNC patients had higher NT-proBNP [237 (156-489) vs. 156 (139-257) pg/mL] and Galectin-3 [7.3 (6.0-11.5) vs. 5.6 (4.8-8.3) ng/mL], and lower ADAMTS13 (767.3 ± 335.5 vs. 962.3 ± 253.7 ng/mL) and ADAMTS13/vWF ratio (all p < 0.05).

CONCLUSION

LVNC patients with HFpEF have diffuse fibrosis, which is more extensive at the apical level, explaining the decrease in apical deformation and overexpression of Galectin-3. Lower transmural and base-to-apex deformation gradients underpin the sequence of myocardial maturation failure. Endothelial dysfunction, expressed by the lower ADAMTS13 and ADAMTS13/vWF ratio, may play an important role in the mechanism of HFpEF in patients with LVNC.

From the Discovery of ADAMTS13 to Current Understanding of Its Role in Health and Disease

ADAMTS13 (a disintegrin-like metalloprotease domain with thrombospondin type 1 motif, member 13) is a protease of crucial importance in the regulation of the size of von Willebrand factor multimers. Very low ADAMTS13 activity levels result in thrombotic thrombocytopenic purpura, a rare and life-threatening disease. The mechanisms involved can either be acquired (immune-mediated thrombotic thrombocytopenic purpura [iTTP]) or congenital (cTTP, Upshaw-Schulman syndrome) caused by the autosomal recessive inheritance of disease-causing variants (DCVs) located along the ADAMTS13 gene, which is located in chromosome 9q34. Apart from its role in TTP, and as a regulator of microthrombosis, ADAMTS13 has begun to be identified as a prognostic and/or diagnostic marker of other diseases, such as those related to inflammatory processes, liver damage, metastasis of malignancies, sepsis, and different disorders related to angiogenesis. Since its first description almost 100 years ago, the improvement of laboratory tests and the description of novel DCVs along the ADAMTS13 gene have contributed to a better and faster diagnosis of patients under critical conditions. The ability of ADAMTS13 to dissolve platelet aggregates in vitro and its antithrombotic properties makes recombinant human ADAMTS13 treatment a potential therapeutic approach targeting not only patients with cTTP but also other medical conditions.

To Clot or Not to Clot: Is That the Question?

Hemostasis can be defined as a homeostatic process in which the body attempts to minimize loss of blood by balancing out pro- and anti-procoagulant forces [...].

Automated and Rapid ADAMTS13 Testing Using Chemiluminescence: Utility for Identification or Exclusion of TTP and Beyond

Thrombotic thrombocytopenic purpura (TTP) is a prothrombotic condition caused by a significant deficiency of the enzyme, ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13). In the absence of adequate levels of ADAMTS13 (i.e., in TTP), plasma VWF accumulates, in particular as "ultra-large" VWF multimers, and this leads to pathological platelet aggregation and thrombosis. In addition to TTP, ADAMTS13 may be mildly to moderately reduced in a range of other conditions, including secondary thrombotic microangiopathies (TMA) such as those caused by infections (e.g., hemolytic uremic syndrome (HUS)), liver disease, disseminated intravascular coagulation (DIC), and sepsis, during acute/chronic inflammatory conditions, and sometimes also in COVID-19 (coronavirus disease 2019)). ADAMTS13 can be detected by a variety of techniques, including ELISA (enzyme-linked immunosorbent assay), FRET (fluorescence resonance energy transfer) and by chemiluminescence immunoassay (CLIA). The current report describes a protocol for assessment of ADAMTS13 by CLIA. This protocol reflects a rapid test able to be performed within 35 min on the AcuStar instrument (Werfen/Instrumentation Laboratory), although certain regional approvals may also permit this testing to be performed on a BioFlash instrument from the same manufacturer.

An Overview of Laboratory Testing for ADAMTS13

ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is also called von Willebrand factor (VWF) cleaving protease (VWFCP). ADAMTS13 acts to cleave VWF multimers and thus reduce plasma VWF activity. In the absence of ADAMTS13 (i.e., in thrombotic thrombocytopenia purpura, TTP), plasma VWF can accumulate, in particular as "ultra-large" VWF multimers, and this can lead to thrombosis. Relative deficiencies in ADAMTS13 can also occur in a variety of other conditions, including secondary thrombotic microangiopathies (TMA). Of contemporary interest, COVID-19 (coronavirus disease 2019) may also be associated with relative reduction of ADAMTS13 and also pathological accumulation of VWF, with this likely contributing to the thrombosis risk seen in affected patients. Laboratory testing for ADAMTS13 can assist in the diagnosis of these disorders (i.e., TTP, TMA), as well as in their management, and can be achieved using a variety of assays. This chapter therefore provides an overview of laboratory testing for ADAMTS13 and the value of such testing to assist the diagnosis and management of associated disorders.

Novel Classification of Thrombotic Disorders Based on Molecular Hemostasis and Thrombogenesis Producing Primary and Secondary Phenotypes of Thrombosis

Thrombosis, the common and deadliest disorder among human diseases, develops as a result of the intravascular hemostasis following an intravascular injury, which can be caused by a variety of trauma, non-traumatic insults or clinical illnesses. Thrombosis can occur at any location of the vascular system supplied by blood from the heart to large and smallest arterial and venous systems and may affect the function and anatomy of the organ and tissue. It more commonly occurs in the smaller circulatory system of the vascular tree such as arterioles and capillaries, and venules of the organs, especially in the brain, lungs, heart, pancreas, muscle and kidneys, and sinusoids of the liver. Thrombosis has been referred as the disease of "blood clots", which concept is incompletely defined, but represents many different hemostatic diseases from microthrombosis to fibrin clot disease, macrothrombosis, and combined micro-macrothrombosis. Thrombosis is produced following an intravascular injury via one or more combination of four different mechanisms of thrombogenesis: microthrombogenesis, fibrinogenesis, macrothrombogenesis and micro-macrothrombogenesis initiated by normal physiological hemostasis in vivo. The clinical phenotype expression of thrombosis is determined by: (1) depth of the intravascular wall injury, (2) extent of the injury affecting the vascular tree system, (3) physiological character of the involved vascular system, (4) locality of the vascular injury, and (5) underlying non-hemostatic conditions interacting with hemostasis. Recent acquisition of "two-path unifying theory" of hemostasis and "two-activation theory of the endothelium" has opened a new frontier in science of medicine by identifying the pathophysiological mechanism of different thrombotic disorders and also contributing to the better understanding of many poorly defined human diseases, including different phenotypes of stroke and cardiovascular disease, trauma, sepsis and septic shock, multiorgan dysfunction syndrome, and autoimmune disease, and others. Reviewed are the fundamentals in hemostasis, thrombogenesis and thrombosis based on hemostatic theories, and proposed is a novel classification of thrombotic disorders.

Biomarkers of Clot Activation and Degradation and Risk of Future Major Cardiovascular Events in Acute Exacerbation of COPD: A Cohort Sub-Study in a Randomized Trial Population

Cardiovascular diseases are common in patients with chronic obstructive pulmonary disease (COPD). Clot formation and resolution secondary to systemic inflammation may be a part of the explanation. The aim was to determine whether biomarkers of clot formation (products of von Willebrand Factor formation and activation) and clot resolution (product of fibrin degeneration) during COPD exacerbation predicted major cardiovascular events (MACE). The cohort was based on clinical data and biobank plasma samples from a trial including patients admitted with an acute exacerbation of COPD (CORTICO-COP). Neo-epitope biomarkers of formation and the activation of von Willebrand factor (VWF-N and V-WFA, respectively) and cross-linked fibrin degradation (X-FIB) were assessed using ELISAs in EDTA plasma at the time of acute admission, and analyzed for time-to-first MACE within 36 months, using multivariable Cox proportional hazards models. In total, 299/318 participants had samples available for analysis. The risk of MACE for patients in the upper quartile of each biomarker versus the lower quartile was: X-FIB: HR 0.98 (95% CI 0.65–1.48), VWF-N: HR 1.56 (95% CI 1.07–2.27), and VWF-A: HR 0.78 (95% CI 0.52–1.16). Thus, in COPD patients with an acute exacerbation, VWF-N was associated with future MACE and warrants further studies in a larger population.