Elevated NT-proBNP is associated with unfavorably altered plasma fibrin clot properties in atrial fibrillation

Elevated plasma protein carbonylation increases the risk of ischemic cerebrovascular events in patients with atrial fibrillation: association with a prothrombotic state

INTRODUCTION

Plasma protein carbonylation that reflects oxidative stress has been demonstrated to be associated with the prothrombotic fibrin clot phenotype. However, the role of protein carbonyls (PC) in predicting ischemic stroke in atrial fibrillation (AF) is largely unknown. This study aimed to investigate whether PC increase the risk of stroke in anticoagulated AF patients during follow-up.

METHODS

In 243 AF patients on anticoagulation (median age 69 years; median CHA2DS2-VASc of 4), we measured plasma PC using the assay by Becatti, along with plasma clot permeability (Ks), clot lysis time (CLT), thrombin generation, and fibrinolytic proteins, including plasminogen activator inhibitor type 1 (PAI-1) and thrombin activatable fibrinolysis inhibitor (TAFI). Ischemic stroke, major bleeding, and mortality were recorded during a median follow-up of 53 months.

RESULTS

Plasma PC levels (median, 3.16 [2.54-3.99] nM/mg protein) at baseline showed positive associations with age (P < 0.001), CHA2DS2-VASc (P = 0.003), and N-terminal B-type natriuretic peptide (P = 0.001), but not with type of AF or comorbidities except for heart failure (P = 0.007). PC levels were correlated with CLT (r = 0.342, P < 0.001), endogenous thrombin potential (r = 0.217, P = 0.001) and weakly with Ks (r = -0.145, P = 0.024), but not with fibrinogen, PAI-1, or TAFI levels. Stroke was recorded in 20 patients (1.9%/year), who had at baseline 36% higher PC levels (P < 0.001). Elevated PC (P = 0.003) at baseline were independently associated with stroke risk.

CONCLUSION

Our findings suggest that in patients with AF enhanced protein carbonylation is associated with increased "residual" risk of stroke despite anticoagulation, which is at least in part due to unfavorably altered fibrin clot phenotype.

Neutrophil-activating Peptide 2 as a Novel Modulator of Fibrin Clot Properties in Patients with Atrial Fibrillation

Neutrophil-activating peptide 2 (NAP-2, CXCL7), a platelet-derived neutrophil chemoattractant, is involved in inflammation. We investigated associations between NAP-2 levels, neutrophil extracellular traps (NETs) formation, and fibrin clot properties in atrial fibrillation (AF). We recruited 237 consecutive patients with AF (mean age, 68 ± 11 years; median CHA2DS2VASc score of 3 [2-4]) and 30 apparently healthy controls. Plasma NAP-2 concentrations were measured, along with plasma fibrin clot permeability (Ks) and clot lysis time (CLT), thrombin generation, citrullinated histone H3 (citH3), as a marker of NETs formation, and 3-nitrotyrosine reflecting oxidative stress. NAP-2 levels were 89% higher in AF patients than in controls (626 [448-796] vs. 331 [226-430] ng/ml; p < 0.0001). NAP-2 levels were not associated with demographics, CHA2DS2-VASc score, or the AF manifestation. Patients with NAP-2 in the top quartile (> 796 ng/ml) were characterized by higher neutrophil count (+ 31.7%), fibrinogen (+ 20.8%), citH3 (+ 86%), and 3-nitrotyrosine (+ 111%) levels, along with 20.2% reduced Ks and 8.4% prolonged CLT as compared to the remaining subjects (all p < 0.05). NAP-2 levels were positively associated with fibrinogen in AF patients (r = 0.41, p = 0.0006) and controls (r = 0.65, p < 0.01), along with citH3 (r = 0.36, p < 0.0001) and 3-nitrotyrosine (r = 0.51, p < 0.0001) in the former group. After adjustment for fibrinogen, higher citH3 (per 1 ng/ml β = -0.046, 95% CI -0.029; -0.064) and NAP-2 (per 100 ng/ml β = -0.21, 95% CI -0.14; -0.28) levels were independently associated with reduced Ks. Elevated NAP-2, associated with increased oxidative stress, has been identified as a novel modulator of prothrombotic plasma fibrin clot properties in patients with AF.

Prothrombotic plasma fibrin clot phenotype is associated with spontaneous echo contrast in atrial fibrillation: The role of protein carbonylation

INTRODUCTION

Spontaneous echo contrast (SEC) and left atrial appendage thrombus (LAAT) increase the risk of stroke and its severity in patients with atrial fibrillation (AF). Formation of denser fibrin networks and impaired fibrinolysis are associated with stroke risk in AF. This study investigated whether the prothrombotic fibrin clot phenotype characterizes patients with SEC/LAAT.

METHODS

We studied 139 anticoagulated patients with AF (median age, 70 years), who underwent transesophageal echocardiography (TEE). SEC and LAAT were recorded. We assessed plasma fibrin clot properties, i.e. permeability (Ks) and clot lysis time (CLT), von Willebrand Factor (vWF) antigen, endogenous thrombin potential (ETP), proteins involved in thrombosis and fibrinolysis, as well as plasma carbonylated protein content (PC).

RESULTS

SEC/LAAT was identified in 36 subjects (25.9 %) and was associated with heart failure (HF), AF duration, higher CHA2DS2VASc score, N-terminal prohormone of brain natriuretic peptide, and growth differentiation factor 15. Patients with SEC/LAAT had lower Ks (-15 %) and prolonged CLT (+19 %), along with higher fibrinogen (+24 %), ETP (+3 %), and plasminogen activator inhibitor-1 antigen (+16 %) compared with the remainder. Thrombin-activatable fibrinolysis inhibitor antigen, plasminogen, α2 - antiplasmin, and tissue plasminogen activator antigen were similar between the two groups. PC content was 50 % higher in SEC/LAAT and correlated with Ks (r = -0.47, p < 0.001) and CLT (r = 0.40, p < 0.001). On multivariate analysis, Ks, CLT, and PC levels, along with HF, remained independently associated with SEC/LAAT.

CONCLUSIONS

We demonstrated a formation of denser and poorly lysable fibrin networks in AF patients with SEC/LAAT despite anticoagulation. We suggest that this phenomenon is in part related to enhanced oxidative stress.

Impaired fibrinolysis in patients with atrial fibrillation and elevated circulating lipopolysaccharide

It is unknown whether elevated gut-derived serum lipopolysaccharide (LPS) can affect thrombin generation, fibrinolysis, and fibrin clot properties in atrial fibrillation (AF). We aimed to evaluate associations of circulating LPS with prothrombotic markers in AF patients. A total of 157 (women, 57.3%) ambulatory anticoagulant-naïve AF patients aged from 42 to 86 years were recruited. Clinical data together with serum LPS, inflammation, endothelial injury, coagulation and fibrinolysis markers, including fibrin clot permeability (Ks) and clot lysis time (CLT), were analyzed. A median LPS concentration was 73.0 (58.0-100.0) pg/mL and it showed association with CLT (r = 0.31, p < 0.001) and plasminogen activator inhibitor-1 (PAI-1, r = 0.57, p < 0.001), but not other fibrinolysis proteins, thrombin generation, inflammatory markers, or Ks. There were weak associations of LPS with von Willebrand factor (vWF, r = 0.2, p = 0.013), cardiac troponin I (r = 0.16, p = 0.045), and growth differentiation factor-15 (r = 0.27, p < 0.001). No associations of LPS and CHA2DS2-VASc or other clinical variables were observed. Multivariable regression adjusted for potential confounders showed that serum LPS ≥ 100 pg/mL was an independent predictor of prolonged CLT. This study is the first to demonstrate antifibrinolytic effects of elevated LPS in AF patients largely driven by enhanced PAI-1 release.

Growth Differentiation Factor-15 and Clinical Outcomes in Lower Extremity Artery Disease

AIM

Lower extremity artery disease (LEAD) is an increasingly common health problem that is associated with high mortality due to thrombotic and bleeding events. Growth differentiation factor-15 (GDF15), a stress-response cytokine belonging to the transforming growth factor-beta superfamily, is associated with cardiovascular disease and its outcomes. The aim of the present study was to examine the effect of serum GDF15 levels on clinical outcomes in patients with LEAD.

METHODS

We measured serum GDF15 levels in 200 patients with LEAD before their initial endovascular therapy. The primary endpoint was the all-cause mortality rate. The secondary endpoints, on the other hand, were thrombotic and bleeding events, such as cerebral infarction, acute coronary syndrome, acute limb ischemia, and Bleeding Academic Research Consortium types 3 and 5.

RESULTS

The serum GDF15 levels increased with advancing Fontaine class. Kaplan-Meier analysis revealed that the high-GDF15 group (≥ 2,275 pg/mL) had higher rates of all-cause deaths and thrombotic and bleeding events than the low-GDF15 group (＜2,275 pg/mL). Multivariate Cox proportional-hazards regression analysis revealed that GDF15 was an independent predictor of all-cause mortality and thrombotic and bleeding events after adjusting for confounding risk factors. When the ABC-AF-bleeding score was substituted for GDF15, similar results were obtained.

CONCLUSION

Serum GDF15 levels were associated with all-cause mortality and thrombotic and bleeding events in patients with LEAD. Serum GDF15 is a potentially useful marker of clinical outcomes, specifically for tracking thrombotic and bleeding events in patients with LEAD.

Vascular Endothelial Dysfunction and Immunothrombosis in the Pathogenesis of Atrial Fibrillation

Atrial Fibrillation (AF) induces proinflammatory processes which incite vascular endothelial activation and dysfunction. This study seeks to examine the potential relationship between various endothelial, inflammatory, thrombotic, and renin-angiotensin-system (RAS) biomarkers in AF patients.Blood samples were from AF patients (n = 110) prospectively enrolled in this study prior to their first AF ablation. Control plasma samples (n = 100) were used as reference. All samples were analyzed for endothelial (NO, ICAM-1, VEGF, TF, TFPI, TM, Annexin V), inflammatory (IL-6, TNFα, CRP), thrombotic (vWF, tPA, PAI-1, TAFI, D-dimer), and RAS (Renin, Ang-II) biomarkers using ELISA methods. Biomarker average comparisons and Spearman correlations were performed.AF patients showed varying levels of biomarker increase compared to controls. We observed a significant decrease of Ang-II in the AF population relative to controls when stratified for the use of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) upon study enrollment. AF patients showed statistically significant correlations between the following biomarkers: TNFα vs IL-6 (rs = 0.317, p = .004), ICAM-1 vs TNFα (rs = 0.527, p = .012), Annexin V vs VEGF (rs = 0.620, p < .001), CRP vs VEGF (rs = 0.342, p = .031), Ang-II vs tPA (rs = -0.592, p = .010), and tPA vs PAI-1 (rs = 0.672, p < .001).Our study demonstrated significant elevation of endothelial, inflammatory, and thrombotic biomarkers in AF patients compared to controls, with significant correlations between these biomarkers in the AF population. Future investigations are required to better elucidate the mechanistic pathways that lead to endothelial dysfunction and thromboinflammation in AF. This may provide novel therapeutic targets, that in addition to current anticoagulation practices, can best curtail thrombogenicity in AF.

Fibrin clot properties in cardiovascular disease: from basic mechanisms to clinical practice

Fibrinogen conversion into insoluble fibrin and the formation of a stable clot is the final step of the coagulation cascade. Fibrin clot porosity and its susceptibility to plasmin-mediated lysis are the key fibrin measures, describing the properties of clots prepared ex vivo from citrated plasma. Cardiovascular disease (CVD), referring to coronary heart disease, heart failure, stroke, and hypertension, has been shown to be associated with the formation of dense fibrin networks that are relatively resistant to lysis. Denser fibrin mesh characterized acute patients at the onset of myocardial infarction or ischaemic stroke, while hypofibrinolysis has been identified as a persistent fibrin feature in patients following thrombotic events or in those with stable coronary artery disease. Traditional cardiovascular risk factors, such as smoking, diabetes mellitus, hyperlipidaemia, obesity, and hypertension, have also been linked with unfavourably altered fibrin clot properties, while some lifestyle modifications and pharmacological treatment, in particular statins and anticoagulants, may improve fibrin structure and function. Prospective studies have suggested that prothrombotic fibrin clot phenotype can predict cardiovascular events in short- and long-term follow-ups. Mutations and splice variants of the fibrinogen molecule that have been proved to be associated with thrombophilia or increased cardiovascular risk, along with fibrinogen post-translational modifications, prothrombotic state, inflammation, platelet activation, and neutrophil extracellular traps formation, contribute also to prothrombotic fibrin clot phenotype. Moreover, about 500 clot-bound proteins have been identified within plasma fibrin clots, including fibronectin, α2-antiplasmin, factor XIII, complement component C3, and histidine-rich glycoprotein. This review summarizes the current knowledge on the mechanisms underlying unfavourable fibrin clot properties and their implications in CVD and its thrombo-embolic manifestations.

Altered fibrin clot properties and fibrinolysis in patients with atrial fibrillation: practical implications

Compelling evidence indicates that a hypercoagulable state occurs in patients with atrial fibrillation (AF) including those in sinus rhythm following paroxysmal and persistent AF. Activation of blood coagulation in AF reflects heightened thrombin generation with the subsequent increased formation of fibrin as evidenced by elevated soluble fibrin monomers and D-dimer. Formation of denser fibrin meshworks, relatively resistant to plasmin-mediated lysis has been demonstrated in patients with AF. The presence of stroke risk factors in AF, such as diabetes, heart failure, hypertension, previous myocardial infarction, or stroke, advanced age have been shown to be linked to the prothrombotic clot characteristics, including reduced clot permeability and lysability. Importantly, biomarkers, including cardiac troponins and N-terminal pro-brain natriuretic peptide, are associated with thrombin generation and fibrin-related markers in AF patients. Recently, increased fibrin clot density (low clot permeability measured in plasma-based assays) and impaired fibrinolysis measured off anticoagulation have been demonstrated to predict ischaemic cerebrovascular events in patients with AF receiving vitamin K antagonists and those on rivaroxaban. The current review summarizes evidence for a role of altered fibrin clot properties and hypofibrinolysis in AF and their prognostic value in terms of adverse events.

Presence of retained calcified fibrin sheath after central venous catheter removal: A systematic literature review

Central venous catheters (CVC) are used in many clinical settings for a variety of indications. We performed a systematic literature review concerning case reports of retained calcified fibrin sheaths after dialysis CVC removal. The aim of our study was to systematize the knowledge regarding clinical management of this phenomenon, placing special emphasis on diagnostic radiological features in different imaging modalities, including chest radiography, echocardiography, computed tomography, and magnetic resonance imaging. We discuss the most common risk factors associated with this CVC complication. In our review, we found eight cases of hemodialysis patients. The most common risk factors associated with calcified fibrin sheath formation in the analyzed cases were pro-thrombotic and pro-calcification factors related to patient comorbidities, and prolonged catheter dwell time. Differentiating between a calcified fibrin sheath (present in about 6% of patients with long-term indwelling CVC as diagnosed by computed tomography) and a retained catheter tip can be challenging. The initial diagnosis based on imaging methods was incorrect in most of the analyzed cases. This suggests that some cases of retained fibrin sheaths may remain undetected or misinterpreted. This is important in patients with known pro-thrombotic and pro-calcification risk factors and prolonged catheter dwell time. Therefore, implementation of preventive strategies, familiarity with radiological findings of this phenomenon, comparison with previous imaging studies, and an overall comprehensive assessment with clinical data is imperative.

Chronic Kidney Disease and Its Impact on a Prothrombotic State in Patients with Atrial Fibrillation

It is unclear whether chronic kidney disease (CKD) increases thromboembolism in atrial fibrillation (AF). We conducted a retrospective cross-sectional analysis of 502 non-anticoagulated AF patients (median age, 66 (60–73) years, median CHA₂DS₂-VASc score, 3.0 (2.0–4.0)) with an estimated glomerular filtration rate (eGFR) ≥ 15 mL/min/1.73 m². Endogenous thrombin potential (ETP), clot permeability (K_s), and clot lysis time (CLT), among others, were determined. Patients with stage 4 CKD (n = 87; 17.3%) had higher ETP and prolonged CLT compared with those with stage 3 CKD. In patients with stages 3 to 4 CKD (n = 180; 35.9%) N-terminal pro-B-type natriuretic peptide predicted low K_s (the lowest quartile, odds ratio [OR] per 100 pg/mL: 1.03, 95% confidence interval [CI]: 1.01–1.06) and prolonged CLT (the top quartile, OR per 100 pg/mL: 1.05, 95% CI: 1.02–1.08), but not high ETP. In the whole cohort, after adjustment for CHA₂DS₂-VASc score, stage 4 CKD, but not stage 3 CKD, predicted high ETP (OR: 9.06; 95% CI: 4.44−18.46) and prolonged CLT (OR: 3.58; 95% CI: 1.76–7.28), but not low K_s. compared to the reference eGFR category. This study is the first to demonstrate the prothrombotic and antifibrinolytic alterations in AF patients with stage 4 CKD, but not stage 3 CKD irrespective of clinical stroke risk factors.

Prothrombotic fibrin clot properties associated with NETs formation characterize acute pulmonary embolism patients with higher mortality risk

Venous thromboembolism is associated with formation of denser fibrin clots resistant to lysis. We investigated whether prothrombotic plasma clot properties are associated with the severity of acute pulmonary embolism (PE). We enrolled 126 normotensive acute PE patients (aged 58 ± 14 years) and 25 age- and sex-matched healthy controls. Plasma fibrin clot permeability (K_s), clot lysis time (CLT), endogenous thrombin potential (ETP), plasminogen activator inhibitor-1 (PAI-1), and citrullinated histone H3 (citH3) were evaluated on admission. PE patients compared to controls had 370% higher citH3 levels, 41% higher ETP, 16.5% reduced K_s, and 25.6% prolonged CLT. Patients with intermediate-high (n = 29) and intermediate-low (n = 77) PE mortality risk had reduced K_s and prolonged CLT, increased PAI-1 and ETP as compared to low-risk PE (n = 20) patients. Prolonged CLT was predicted by PAI-1 and citH3, while low K_s by C-reactive protein. During a 12-month follow-up 9 (7.1%) patients who had 24% higher ETP, 45% higher citH3 levels, and 18% prolonged CLT at baseline died. High ETP combined with elevated citH3 levels and prolonged CLT was associated with eightfold increased risk of PE-related death. Prothrombotic fibrin clot properties and enhanced neutrophil extracellular traps formation are associated with higher early mortality risk in acute PE patients, which suggests a prognostic role of these biomarkers.

Clot Lysis Time Predicts Stroke During Anticoagulant Therapy in Patients with Atrial Fibrillation

BACKGROUND

Formation of dense fibrin clots has been reported in both atrial fibrillation (AF) and ischemic stroke. We have previously demonstrated that such clot properties can predict thromboembolism and major bleeding in AF patients treated with vitamin K antagonists (VKAs). In this longitudinal cohort study, we evaluated whether impaired fibrinolysis is associated with clinical outcomes in AF.

METHODS

In 236 patients with AF receiving VKAs, we measured ex vivo plasma clot lysis time (CLT), a measure of global fibrinolysis along, with von Willebrand factor antigen (vWF), plasminogen activator inhibitor 1 antigen (PAI-1), and other fibrinolysis modulators. The primary outcome were ischemic cerebrovascular events. Secondary end points were death and major bleeding.

RESULTS

During a median follow-up time of 4.3 (interquartile range 3.7-4.8) years, annual rates of death, ischemic cerebrovascular events, and major bleeding were 1.48%, 2.96%, and 3.45%, respectively. Patients with CLT in the fourth quartile (> 115 min) had 8-fold higher stroke or transient ischemic attack (TIA) rates compared with the other patients (8.67% vs 1.1%; P < 0.0001). CLT correlated with PAI-1 and vWF (r = 0.59; P < 0.0001 for both). In the multivariate Cox regression analysis adjusted for potential confounders, the independent predictors of stroke or TIA were CLT > 115 minutes (hazard ratio [HR] 7.67, 95% confidence interval [CI] 2.78-21.17; P < 0.0001), PAI-1 (HR 1.16, 95% 1.05-1.28; P = 0.003), and CHA₂DS₂-VASc score ≥3 (HR 5.18, 95% 1.76-15.29; P = 0.003). CLT was not associated with death or major and minor bleeding events.

CONCLUSIONS

Impaired fibrinolysis may predict thromboembolic events in AF patients receiving VKA.

Association of NT-proBNP and GDF-15 with markers of a prothrombotic state in patients with atrial fibrillation off anticoagulation

Abstract

We investigated whether growth differentiation factor-15 (GDF-15), also known as macrophage inhibitory cytokine-1 (MIC-1), levels are associated with a prothrombotic state in atrial fibrillation (AF) as compared to N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin I (cTnI-hs). In 103 patients with AF assessed off anticoagulation (age: 71.0 [65.0–76.0] years; CHA₂DS₂-VASc score: 4.6 ± 1.7), we measured endogenous thrombin potential (ETP), plasma fibrin clot permeability (K_s, a measure of clot density) and clot lysis time (CLT) and other hemostatic parameters, along with GDF-15, NT-proBNP, and cTnI-hs. GDF-15 positively correlated with ETP and CLT (r = 0.25, P = 0.01 and R = 0.56, P < 0.0001, respectively) but not with K_s, von Willebrand factor, thrombin-activatable fibrinolysis inhibitor, plasminogen, antiplasmin or tissue-type plasminogen activator antigen. NT-proBNP showed a stronger association with ETP (r = 0.60, P < 0.0001) and a similar correlation with CLT (R = 0.53, P < 0.0001), while cTnI-hs correlated solely with CLT (R = 0.25, P = 0.01). After adjustment for clinical and laboratory parameters, GDF-15 was a better independent predictor of CLT (unstandardized coefficient B 0.009; 95% confidence interval [CI] 0.006–0.012) than NT-proBNP (B 0.007; 95% CI 0.004–0.010, R (2) = 0.51; P < 0.0001); while among the three biomarkers, only NT-proBNP was an independent predictor of ETP. Elevated GDF-15 and NT-proBNP independently predict impaired fibrin clot lysability, while NT-proBNP is a key predictor of heightened thrombin formation in AF. Our findings suggest that a predictive value of NT-proBNP and GDF-15 in AF could be in part attributed to their association with prothrombotic blood alterations.

Graphic Abstract

Electronic supplementary material

The online version of this article (10.1007/s00392-019-01522-x) contains supplementary material, which is available to authorized users.

Prothrombotic State in Atrial Fibrillation Patients With One Additional Risk Factor of the CHA2DS2-VASc Score (Beyond Sex)

BACKGROUND

It is unclear whether a prothrombotic state occurs in atrial fibrillation (AF) with low stroke risk.

METHODS

We studied 118 patients with AF with the Congestive Heart Failure, Hypertension, Age (≥ 75 years), Diabetes, Stroke/Transient Ischemic Attack/Systemic Embolism, Vascular Disease, Age (65-74 years), Sex (Female) (CHA₂DS₂-VASc) score of 1 in men or 2 in women vs 52 patients with AF with the CHA₂DS₂-VASc score of 0 in men or 1 in women. Plasma clot permeability (K_s), a measure of fibrin clot density, and clot lysis time (CLT), endogenous thrombin potential (ETP), von Willebrand factor antigen, and plasminogen activator inhibitor-1 were evaluated in nonanticoagulated subjects.

RESULTS

Patients with the CHA₂DS₂-VASc score of 1 (beyond sex), compared with those with 0, had lower K_s, prolonged CLT, increased ETP, von Willebrand factor antigen, and plasminogen activator inhibitor-1 (all P < 0.001), without any sex-dependent differences. Heart failure (odds ratio [OR]: 10.28; 95% confidence interval [CI]: 2.32-45.41), age 65-74 years (OR: 4.37; 95% CI: 1.76-10.83), and hypertension (OR: 5.03; 95% CI: 1.81-13.94) were independently associated with low K_s (the lowest quartile, ≤ 6.4 × 10^-9 cm²), whereas only age 65-74 years (OR: 3.33; 95% CI: 1.59-6.96) significantly predicted prolonged CLT (the top quartile, ≥ 108 minutes). Age 65-74 years (OR: 5.21; 95% CI: 2.12-12.80), heart failure (OR: 6.58; 95% CI: 1.49-29.06), and hypertension (OR: 4.33; 95% CI: 1.54-12.15) were independently associated with high ETP (the top quartile, ≥ 1681.3 nM × minutes).

CONCLUSIONS

A prothrombotic state (increased thrombin generation, denser fibrin clots, impaired fibrinolysis, and endothelial injury) characterizes patients with AF with 1 additional clinical stroke risk factor (beyond sex), with age 65-74 years being particularly associated with prothrombotic indices.

The prothrombotic state in atrial fibrillation: pathophysiological and management implications

Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia and is associated with significant morbidity and mortality. There is plenty of evidence available to support the presence of a prothrombotic or hypercoagulable state in AF, but the contributory factors are multifactorial and cannot simply be explained by blood stasis. Abnormal changes in atrial wall (anatomical and structural, as ‘vessel wall abnormalities’), the presence of spontaneous echo contrast to signify abnormal changes in flow and stasis (‘flow abnormalities’), and abnormal changes in coagulation, platelet, and other pathophysiologic pathways (‘abnormalities of blood constituents’) are well documented in AF. The presence of these components therefore fulfils Virchow’s triad for thrombogenesis. In this review, we present an overview of the established and professed pathophysiological mechanisms for thrombogenesis in AF and its management implications.

Heart rate variability in patients with systemic lupus erythematosus: a systematic review and methodological considerations

Aim The aim of this review was to summarize current knowledge about the scientific findings and potential clinical utility of heart rate variability measures in patients with systemic lupus erythematosus. Methods PubMed, Embase and Scopus databases were searched for the terms associated with systemic lupus erythematosus and heart rate variability, including controlled vocabulary, when appropriate. Articles published in English and available in full text were considered. Finally, 11 publications were selected, according to the systematic review protocol and were analyzed. Results In general, heart rate variability, measured in the time and frequency domains, was reported to be decreased in patients with systemic lupus erythematosus compared with controls. In some systemic lupus erythematosus studies, heart rate variability was found to correlate with inflammatory markers and albumin levels. A novel heart rate variability measure, heart rate turbulence onset, was shown to be increased, while heart rate turbulence slope was decreased in systemic lupus erythematosus patients. Reports of associations of changes in heart rate variability parameters with increasing systemic lupus erythematosus activity were inconsistent, showing decreasing heart rate variability or no relationship. However, the low/high frequency ratio was, in some studies, reported to increase with increasing disease activity or to be inversely correlated with albumin levels. Conclusions Patients with systemic lupus erythematosus have abnormal heart rate variability, which reflects cardiac autonomic dysfunction and may be related to inflammatory cytokines but not necessarily to disease activity. Thus measurement of heart rate variability could be a useful clinical tool for monitoring autonomic dysfunction in systemic lupus erythematosus, and may potentially provide prognostic information.