Genetic polymorphisms and atrial fibrillation: Insights into the prothrombotic state and thromboembolic risk

Subclinical Measures of Peripheral Atherosclerosis and the Risk of New-Onset Atrial Fibrillation in the General Population: the Rotterdam Study

Background

Limited population‐based data on the (sex‐specific) link between subclinical measures of peripheral atherosclerosis and new‐onset atrial fibrillation (AF) exist.

Methods and Results

Subclinical measures of peripheral atherosclerosis including carotid intima‐media thickness (cIMT), carotid plaque, and ankle‐brachial index (ABI) were assessed at baseline and follow‐up examinations. A total of 12 840 participants free of AF at baseline from the population‐based Rotterdam Study were included. Cox proportional hazards models and joint models, adjusted for cardiovascular risk factors, were used to determine the associations between baseline and longitudinal measures of cIMT, carotid plaque, and ABI with new‐onset AF. During a median follow‐up of 9.2 years, 1360 incident AF cases occurred among 12 840 participants (mean age 65.2 years, 58.3% women). Higher baseline cIMT (fully‐adjusted hazard ratio [HR], 95% CI, 1.81, 1.21–2.71; P=0.0042), presence of carotid plaque (fully‐adjusted HR, 95% CI, 1.19, 1.04–1.35; P=0.0089), lower ABI (fully‐adjusted HR, 95% CI, 1.57, 1.14–2.18; P=0.0061) and longitudinal measures of higher cIMT (fully‐adjusted HR, 95% CI, 2.14, 1.38–3.29; P=0.0021), presence of carotid plaque (fully‐adjusted HR, 95% CI, 1.61, 1.12–2.43; P=0.0112), and lower ABI (fully‐adjusted HR, 95% CI, 4.43, 1.83–10.49; P=0.0007) showed significant associations with new‐onset AF in the general population. Sex‐stratified analyses showed that the associations for cIMT, carotid plaque, and ABI were mostly prominent among women.

Conclusions

Baseline and longitudinal subclinical measures of peripheral atherosclerosis (carotid atherosclerosis, and lower extremity peripheral atherosclerosis) were significantly associated with an increased risk of new‐onset AF, especially among women.

Registration

URL: https://www.trialregister.nl, https://www.apps.who.int/trialsearch/; Unique identifier: NL6645/NTR6831.

Soluble Fibrin Monomer Complex and Prediction of Cardiovascular Events in Atrial Fibrillation: The Observational Murcia Atrial Fibrillation Project

BACKGROUND

Soluble fibrin monomer complex (SFMC) is a biomarker of fibrin formation abnormally elevated in clinical situations of hypercoagulability.

OBJECTIVE

We investigated the association and predictive performance of SFMC for stroke, adverse cardiovascular events, cardiovascular mortality and all-cause mortality in a cohort of patients with atrial fibrillation (AF) receiving vitamin K antagonist (VKA) anticoagulant therapy.

DESIGN

During the second semester of 2007, we included 1226 AF outpatients stable on VKAs (INR 2.0-3.0) over a period of 6 months. SFMC levels were assessed at baseline. During 6.5 (IQR 4.4-8.0) years of follow-up, we recorded all ischemic strokes, adverse cardiovascular events (composite of stroke, acute heart failure, acute coronary syndrome and cardiovascular death), cardiovascular deaths and all-cause deaths.

PARTICIPANTS

All patients were recruited consecutively. We excluded patients with rheumatic mitral valves, prosthetic heart valves, acute coronary syndrome, stroke, hemodynamic instability, hospital admissions or surgical interventions within the preceding 6 months.

MAIN MEASURES

SFMC levels were measured in plasma by immunoturbidimetry in an automated coagulometer (STALiatestFM, Diagnostica Stago, Asnieres, France).

KEY RESULTS

We recorded 121 (1.52%/year) ischemic strokes, 257 (3.23%/year) cardiovascular events, 67 (0.84%/year) cardiovascular deaths and 486 (6.10%/year) all-cause deaths. SFMC >12 μg/mL was not associated with stroke but was associated with higher risk of cardiovascular events (HR 1.72, 95% CI 1.31-2.26), cardiovascular mortality (HR 2.16, 95% CI 1.30-3.57) and all-cause mortality (HR 1.26, 95% CI 1.03-1.55). When SFMC >12 μg/mL was added to the CHA₂DS₂-VASc, there were significant improvements in predictive performance, sensitivity and reclassification for adverse cardiovascular events (c-index: 0.645 vs. 0.660, p = 0.010; IDI = 0.013, p < 0.001; NRI = 0.121, p < 0.001) and cardiovascular mortality (c-index: 0.661 vs. 0.691, p = 0.006; IDI = 0.009, p = 0.049; NRI = 0.217, p < 0.001), but decision curves demonstrated a similar net benefit and clinical usefulness.

CONCLUSIONS

In AF patients taking VKAs, high SFMC levels were associated with the risk of adverse cardiovascular events, cardiovascular mortality and all-cause mortality. The addition of SFMC to the CHA₂DS₂-VASc score improved its predictive performance for these outcomes, but failed to show an improvement in clinical usefulness.

General mechanisms of coagulation and targets of anticoagulants (Section I)

Contrary to previous models based on plasma, coagulation processes are currently believed to be mostly cell surface-based, including three overlapping phases: initiation, when tissue factor-expressing cells and microparticles are exposed to plasma; amplification, whereby small amounts of thrombin induce platelet activation and aggregation, and promote activation of factors (F)V, FVIII and FXI on platelet surfaces; and propagation, in which the Xase (tenase) and prothrombinase complexes are formed, producing a burst of thrombin and the cleavage of fibrinogen to fibrin. Thrombin exerts a number of additional biological actions, including platelet activation, amplification and self-inhibition of coagulation, clot stabilisation and anti-fibrinolysis, in processes occurring in the proximity of vessel injury, tightly regulated by a series of inhibitory mechanisms. ″Classical″ anticoagulants, including heparin and vitamin K antagonists, typically target multiple coagulation steps. A number of new anticoagulants, already developed or under development, target specific steps in the process, inhibiting a single coagulation factor or mimicking natural coagulation inhibitors.

Hypercoagulability, D-dimer and atrial fibrillation: an overview of biological and clinical evidence

Atrial fibrillation (AF) is the most common among the severe cardiac arrhythmias and carries a significant risk of mortality and morbidity in the general population. The most important complication is represented by development of one or more thrombi in the left atrium of the dyskinetic heart, and their successive cerebral and peripheral embolization. The pathophysiological basis of the thromboembolic complications in AF entails the presence of a hypercoagulable state, which is mirrored by increased concentrations of a variety of prothrombotic markers. D-dimer is universally considered the gold standard among the various biomarkers that reflect activation of coagulation, fibrinolysis, or both, and several studies have assessed its diagnostic and prognostic role in AF. With a few exceptions and despite a broad heterogeneity in the study designs, published data seem to demonstrate that D-dimer values may be associated with the presence of atrial thrombosis, may be predictive of primary adverse outcomes and death, may be correlated with cerebral infarction volume, and may also be a useful parameter for assessing the degree of hypercoagulability of AF patients after cardioversion. If larger prospective studies confirm these findings, D-dimer assessment may hence become an integral part of the clinical decision-making in patients with AF.

Biomarkers in atrial fibrillation: an overview

Atrial fibrillation (AF) confers a raised risk of stroke and death, and this risk of adverse events is increased by the coexistence of other cardiovascular risk factors. The pathophysiology of AF is complex, involving the role of inflammation, structural remodelling with apoptosis, inflammation or fibrosis. These changes confer a prothrombotic or hypercoagulable state in this arrhythmia. Despite being easy to use for decision-making concerning oral anticoagulant therapy in AF, clinical risk scores used for stratification have shown modest capability in predicting thromboembolic events, and biomarkers may improve our identification of 'high risk' patients. Biomarkers, whether measured in the peripheral blood, urine or imaging-based may improve our knowledge of the pathophysiology of AF. Importantly these biomarkers could help in the assessment of AF prognosis. The aim of this review was to summarise the published data about biomarkers studied in AF, with focus on data from randomised prospective clinical trials and large community-based cohorts. We will also review the application of these biomarkers to prognosis on the main schemes used to help stratify risk in AF.