Enhanced thrombin generation in patients with arterial hypertension

Predictors of aneurysmal occlusion following intracranial aneurysms treatment with pipeline embolization device

PURPOSE

Pipeline embolization device (PED) is thought to induce aneurysmal occlusion through diversion of flow away from the aneurysmal sac with subsequent thrombosis and endothelialization. The impact of different factors especially hypertension (HTN)-a known predisposing factor to hypercoagulability and altered endothelial function-on aneurysmal occlusion after flow diversion has not been studied. We sought to determine predictors of aneurysmal occlusion following PED treatment focusing on impact of blood pressure.

METHODS

Database of patients with cerebral aneurysms treated with PED from 2013 to 2019 at our institution was retrospectively reviewed. Patients were defined as hypertensive if (1) they had a documented history of HTN requiring anti-HTN medications or (2) average systolic blood pressure on three measurements was > 130 mmHg. The primary outcome was aneurysm occlusion status at the last imaging follow-up. Multivariable logistic regression model was constructed to assess the effect of HTN on occlusion, controlling for age, smoking, aneurysmal size, fusiform morphology, posterior circulation location, and incorporated branches.

RESULTS

A total of 331 aneurysms in 294 patients were identified for this analysis. The mean age was 59 years (79.9% female). Fifty-five percent of the cohort were classified as hypertensive. When controlling for other potential confounders, hypertensive patients trended toward higher odds of achieving complete occlusion compared to non-hypertensive patients (OR = 2.05; 95% CI = 0.99-4.25; p = 0.052). Meanwhile, age (OR = 0.91; 95% CI = 0.88-0.95; p < 0.001) and an incorporated branch into an aneurysm (OR = 0.22; 95% CI = 0.08-0.58; p < 0.002) were associated with decreased odds for complete aneurysmal occlusion.

CONCLUSION

Hypertensive patients show a trend toward higher odds of achieving complete occlusion when controlling for potential confounders. The HTN-induced hypercoagulable state, enhanced endothelial activation, and altered extracellular matrix regulation might be the contributing factors. Further research is warranted to explore clinical implications of these findings.

Estrogen depletion modulates aortic prothrombotic signaling in normotensive and spontaneously hypertensive female rats

AIM

In this study, we investigated how platelets and aorta contribute to the creation and maintenance of a prothrombotic state in an experimental model of postmenopausal hypertension in ovariectomized rats.

METHODS

Bilateral ovariectomy was performed in both 14-week-old female spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. The animals were kept in phytoestrogen free diet. Vascular parameters, platelet, coagulation and aortic prothrombotic functions and mechanisms were assessed.

RESULTS

Exacerbated platelet aggregation was observed in both SHR and WKY animals after ovariectomy. The mechanism was related to aortic COX2 downregulation and reduction in AMP, ADP, and ATP hydrolysis in serum and platelets. A procoagulant potential was observed in plasma from ovariectomized rats and this was confirmed by kallikrein and factor Xa generation in aortic rings. Aortic rings derived from ovariectomized SHR presented a greater thrombin generation capacity compared to equivalent rings from WKY animals. The mechanism involved tissue factor and PAR-1 upregulation as well as an increase in extrinsic coagulation and fibrinolysis markers in aorta and platelets. Aortic smooth muscle cells pre-treated with a plasma pool derived from estrogen-depleted animals developed a procoagulant profile with tissue factor upregulation. This procoagulant profile was dependent on inflammatory signalling, since NFκB inhibition attenuated the procoagulant activity and tissue factor expression.

CONCLUSIONS

A prothrombotic phenotype was observed in both WKY and SHR ovariectomized rats being associated with platelet hyperreactivity and tissue factor upregulation in aorta and platelets. The mechanism involves proinflammatory signalling that supports greater thrombin generation in aorta and vascular smooth muscle cells.

Fibrin clot properties and fibrinolysis in patients with endocrine hypertension due to aldosterone or catecholamines excess

OBJECTIVE

The aim of the study was to investigate a new possible background of increased risk of cardiovascular events in two forms of endocrine hypertension: in primary aldosteronism (PA) and pheochromocytoma/paraganglioma (PPGL) in comparison to essential hypertension (EHT).

CONTEXT

Prothrombotic properties of the fibrin clot structure, impaired fibrinolysis and enhanced thrombin generation have been reported to be associated with increased cardiovascular risk.

DESIGN

Patients with PA and PPGL were evaluated at baseline and re-evaluated 3 months after causative treatment. At baseline PA and PPGL patients were compared to matched EHT patients and to healthy controls.

PATIENTS

The study included 35 patients with PA, 16 patients with PPGL and two reference groups of patients with EHT (32 and 22 patients) and healthy controls (35 and 23 subjects).

MEASUREMENTS

All subjects underwent evaluation according to the study protocol that included plasma fibrin clot permeability (Ks), clot lysis time, endogenous thrombin potential.

RESULTS

There were no differences in clot structure and fibrinolytic activity in PA and PPGL patients as compared to matched patients with EHT, whereas all hypertensive groups were characterized by more compact fibrin clot structure, faster clot formation and enhanced thrombin generation in comparison to healthy controls. Both in PA and PPGL patients, fibrin clot properties and fibrinolytic parameters remained stable after the causative treatment.

CONCLUSIONS

Patients with PA and PPGL are at a prothrombic state comparable to patients with EHT. The results suggest the higher risk of cardiovascular events observed in hypertensive PA and PPGL as compared to EHT is not mediated through investigated prothrombic mechanisms.

Evaluation of procoagulant imbalance in Cushing's syndrome after short- and long-term remission of disease

OBJECTIVE

Patients with Cushing's syndrome (CS) are at high risk of venous thromboembolism related to a hypercoagulability due to procoagulant imbalance. However, whether these alterations are reversible after disease remission is still unclear. The endogenous thrombin potential (ETP) measured with and without the addition of thrombomodulin provides a global representation of coagulation and previous data confirmed hypercoagulable profile in patients with active hypercortisolism. Aim of this study was to assess the short- and long-term modification of ETP in patients with CS after disease remission.

DESIGN AND METHODS

Nineteen patients with CS for whom surgical remission was achieved, were prospectively evaluated for clinical characteristics, cortisol secretion profile and ETP at different time points: (i) before surgical intervention; (ii) after 6 months and (iii) 5 years from the time of persistent remission. Nineteen healthy subjects matched for age and gender were also evaluated as control group.

RESULTS

Before surgery, patients showed higher ETP-ratio (with/without thrombomodulin) than controls (0.62 ± 0.09-vs-0.56 ± 0.09, p = 0.034). No significant correlation between ETP-ratio and cortisol secretion was found. 6 months after remission, ETP-ratio was still significantly increased compared to controls (0.64 ± 0.09-vs-0.56 ± 0.09, p = 0.01), but was similar to baseline (0.64 ± 0.09-vs-0.62 ± 0.09, p = 0.87). At 5 years, ETP-ratio showed a significant decrease (0.55 ± 0.14-vs-0.62 ± 0.09, p = 0.02) and was comparable to controls (0.55 ± 0.14-vs-0.56 ± 0.09, p = 0.7).

CONCLUSIONS

Plasma hypercoagulability detected in patients with active hypercortisolism persists at short-term evaluation and seems to be completely reversible after long-term remission of disease. These data, as part of a whole evaluation of thrombotic risk, can contribute to make appropriate therapeutic choice in these patients.

Thrombin Inhibition Prevents Endothelial Dysfunction and Reverses 20-HETE Overproduction without Affecting Blood Pressure in Angiotensin II-Induced Hypertension in Mice

Angiotensin II (Ang II) induces hypertension and endothelial dysfunction, but the involvement of thrombin in these responses is not clear. Here, we assessed the effects of the inhibition of thrombin activity by dabigatran on Ang II-induced hypertension and endothelial dysfunction in mice with a particular focus on NO- and 20-HETE-dependent pathways. As expected, dabigatran administration significantly delayed thrombin generation (CAT assay) in Ang II-treated hypertensive mice, and interestingly, it prevented endothelial dysfunction development, but it did not affect elevated blood pressure nor excessive aortic wall thickening. Dabigatran’s effects on endothelial function in Ang II-treated mice were evidenced by improved NO-dependent relaxation in the aorta in response to acetylcholine in vivo (MRI measurements) and increased systemic NO bioavailability (NO₂⁻ quantification) with a concomitant increased ex vivo production of endothelium-derived NO (EPR analysis). Dabigatran treatment also contributed to the reduction in the endothelial expression of pro-inflammatory vWF and ICAM-1. Interestingly, the fall in systemic NO bioavailability in Ang II-treated mice was associated with increased 20-HETE concentration in plasma (UPLC-MS/MS analysis), which was normalised by dabigatran treatment. Taking together, the inhibition of thrombin activity in Ang II-induced hypertension in mice improves the NO-dependent function of vascular endothelium and normalises the 20-HETE-depedent pathway without affecting the blood pressure and vascular remodelling.

Angiotensin II triggers neutrophil extracellular traps release linking thromboinflammation with essential hypertension

Innate immunity and chronic inflammation are involved in atherosclerosis and atherothrombosis leading to target organ damage in essential hypertension (EH). However, the role of neutrophils in EH is still elusive. We investigated the association between angiotensin II (Ang II) and neutrophil extracellular traps (NETs) in pathogenesis of EH. Plasma samples, kidney biopsies and surgical specimens of abdominal aortic aneurysms (AAA) from EH patients were used. Cell-based assays, NETs/human aortic endothelial cells co-cultures and in situ studies were performed. Increased plasma levels of NETs and tissue factor (TF) activity were detected in untreated, newly-diagnosed, EH patients. Stimulation of control neutrophils with plasma from untreated EH patients generated TF-enriched NETs promoting endothelial collagen production. Ang II induced NETosis in vitro via a reactive oxygen species (ROS)/peptidylarginine deiminase type 4 and autophagy-dependent pathway. Circulating NETs and thrombin generation levels were reduced significantly in EH patients starting treatment with Ang II receptor blockers, whereas their plasma was unable to trigger procoagulant NETs. Moreover, TF-bearing NETotic neutrophils/remnants were accumulated in sites of interstitial renal fibrosis and in the subendothelial layer of AAA. These data reveal the important pathogenic role of Ang II/ROS/NETs/TF axis in EH, linking thromboinflammation with endothelial dysfunction and fibrosis.

Patients with acute and chronic coronary syndromes have elevated long-term thrombin generation

Coronary artery disease is a leading cause of morbidity and mortality worldwide. Despite significant advances in revascularization strategies and antiplatelet therapy with aspirin and/or P2Y₁₂ receptor antagonist, patients with acute coronary syndrome (ACS) continue to be at long-term risk of further cardiovascular events. Besides platelet activation, the role of thrombin generation (TG) in atherothrombotic complications is widely recognized. In this study, we hypothesized that there is an elevation of coagulation activation persists beyond 12 months in patients with ACS and chronic coronary syndrome (CCS) when compared with healthy controls. We measured TG profiles of patients within 72 h after percutaneous coronary intervention, at 6-month, 12-month and 24-month. Our results demonstrated that TG of patients with ACS (n = 114) and CCS (n = 40) were persistently elevated when compared to healthy individuals (n = 50) in peak thrombin (ACS 273.1 nM vs CCS 287.3 nM vs healthy 234.3 nM) and velocity index (ACS 110.2 nM/min vs CCS 111.0 nM/min vs healthy 72.9 nM/min) at 24-month of follow-up. Our results suggest a rationale for addition of anticoagulation to antiplatelet therapy in preventing long-term ischemic events after ACS. Further research could clarify whether the use of TG parameters to enable risk stratification of patients at heightened long-term procoagulant risk who may benefit most from dual pathway inhibition.