Bleeding risk prediction models in atrial fibrillation

Co-expression Network Analysis Revealing the Potential Regulatory Roles of LncRNAs in Atrial Fibrillation

Background:

Atrial fibrillation (AF) is one of the most common heart arrhythmic disorders all over the world. However, it is worth noting that the mechanism underlying AF is still dimness.

Methods:

In this study, we implemented a series of bioinformatics methods to explore the mechanisms of lncRNAs underlying AF pathogenesis. The present study analyzed the public datasets (GSE2240 and GSE115574) to identify differentially expressed long non-coding RNAs (lncRNAs) and mRNAs in the progression of AF.

Results:

Totally, 71 differentially expressed lncRNAs and 390 DEGs were identified in AF.Next, we performed bioinformatics analyses to explore the functions of lncRNAs in AF. Gene Ontology (GO) analysis indicated that differentially expressed lncRNAs were involved in regulating multiple key biological processes, such as cell cycle and signal transduction. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated these lncRNAs were associated with the regulation of MAPK and Wnt signaling pathways. Eight lncRNAs (RP5-1154L15.2, RP11- 339B21.15, RP11-448A19.1, RP11-676J12.4, LOC101930415, MALAT1, NEAT1, and PWAR6) were identified to be key lncRNAs and widely co-expressed with a series of differentially expressed genes (DEGs).

Conclusion:

Although further validation was still needed, our study may be helpful to elucidate the mechanisms of lncRNAs underlying AF pathogenesis and providing further insight into identifying novel biomarkers for AF.

Combined metabolic, phenomic and genomic data to prioritize atrial fibrillation-related metabolites

Metabolites in atrial fibrillation (AF) were characterized to further explore the molecular mechanisms of AF by integrating metabolic, phenomic and genomic data. Gene expression data on AF (E-GEOD-79768) were downloaded from the EMBL-EBI database, followed by identification of differentially expressed genes (DEGs) which were used to construct gene-gene network. Then, multi-omics composite networks were constructed. Subsequently, random walk with restart was expanded to a multi-omics composite network to identify and prioritize the metabolites according to the AF-related seed genes deposited in the OMIM database, the whole metabolome as candidates and the phenotype of AF. Using the interaction score among metabolites, we extracted the top 50 metabolites, and identified the top 100 co-expressed genes interacted with the top 50 metabolites. Based on the FDR <0.05, 622 DEGs were extracted. In order to demonstrate the intrinsic mode of this method, we sorted the metabolites of the composite network in descending order based on the interaction scores. The top 5 metabolites were respectively weighed potassium, sodium ion, chitin, benzo[a]pyrene-7,8-dihydrodiol-9,10-oxide, and celebrex (TN). Potassium and sodium ion possessed higher degrees in the subnetwork of the entire composite network and the co-expressed network. Metabolites such as potassium and sodium ion may provide valuable clues for early diagnostic and therapeutic targets for AF.

The expression profile analysis of atrial mRNA in rats with atrial fibrillation: the role of IGF1 in atrial fibrosis

Background

Structural remodeling is critical to the initiation and maintenance of atrial fibrillation (AF). IGF1, insulin like growth factor 1, has been recognized as contributor to fibrosis. However, the roles and mechanisms of IGF1 in structural remodeling during AF is still unclear.

Methods

We investigated the transcriptional expression profiles of left atria in AF and non-AF rat models by using microarray analysis. And quantitative real-time polymerase chain reaction (qRT-PCR) was performed to validate the accuracy. After bioinformatics analysis, IGF1 was selected to explore its effects and mechanisms on atrial fibrosis. The fibroblasts were extracted from atria of rats, and randomly divided into negative control group, mIGF1 overexpression group and mIGF1 silencing group. Then 30 healthy male Wistar rats were randomly divided into negative control group (n = 10), pacing group (n = 10), pacing + mIGF1 silencing viruses group (n = 10). Then the intracardiac electrophysiological examination, qRT-PCR, Western Blotting, masson staining were conducted after IGF1 interfering experiments.

Results

A total of 956 differentially expressed transcripts were identified, in which 395 transcripts were down-regulated and 561 transcripts were up-regulated. Bioinformatics analysis was conducted to predict the functions and interactions of the aberrantly expressed genes. The inhibition of IGF1 function in AF model could ameliorate the inducibility of AF. The IGF1 plays a fibrotic role by activating the PI3K-Akt pathway to increase the expression of CTGF and AT1R.

Conclusions

IGF1 develops vital function in regulating structural remodeling during AF, which could illustrate the mechanism of AF pathogenesis and supply potential targets for its precise treatment.

[Oral anticoagulation therapy in the elderly population with atrial fibrillation. A review article]

Aging is an important risk factor for patients with atrial fibrillation. The estimated prevalence of atrial fibrillation in patients aged ≥80 years is 9-10%, and is associated with a four to five fold increased risk of embolic stroke, and with an estimated increased stroke risk of 1.45-fold per decade in aging. Older age is also associated with an increased risk of major bleeding with oral anticoagulant therapy. This review will focus on the role of oral anticoagulation with new oral anticoagulants, non-vitamin K antagonist in populations with common comorbid conditions, including age, chronic kidney disease, coronary artery disease, on multiple medication, and frailty. In patients 75 years and older, randomised trials have shown new oral anticoagulants to be as effective as warfarin, or in some cases superior, with an overall better safety profile, consistently reducing rates of intracranial haemorrhages. Prior to considering oral anticoagulant therapy in an elderly frail patient, a comprehensive assessment should be performed to include the risks and benefits, stroke risk, baseline kidney function, cognitive status, mobility and fall risk, multiple medication, nutritional status assessment, and life expectancy.

Importance of time in therapeutic range on bleeding risk prediction using clinical risk scores in patients with atrial fibrillation

Bleeding risk with vitamin K antagonists (VKAs) is closely related to the quality of anticoagulation in atrial fibrillation (AF) patients, reflected by time in therapeutic range (TTR). Here we compared the discrimination performance of different bleeding risk scores and investigated if adding TTR would improve their predictive value and clinical usefulness. We included 1361 AF patients stables on VKA for at least 6 months. Bleeding risk was assessed by the HAS-BLED, ATRIA, ORBIT and HEMORR₂HAGES scores. Major bleeding events were recorded after a median of 6.5 years follow-up. In this period 250 patients suffered major bleeds. Comparison of receiver operating characteristic (ROC) curves demonstrated that HAS-BLED had the best discrimination performance, but adding the ‘labile INR’ criteria (i.e. TTR <65%) to ATRIA, ORBIT and HEMORR₂HAGES increased their ability of discrimination and predictive value, with significant improvements in reclassification and discriminatory performance. Decision curve analyses (DCA) showed improvements of the clinical usefulness and a net benefit of the modified risk scores. In summary, in AF patients taking VKAs, the HAS-BLED score had the best predictive ability. Adding ‘labile INR’ to ATRIA, ORBIT and HEMORR₂HAGES improved their predictive value for major bleeding leading to improved clinical usefulness compared to the original scores.

Altered long non-coding RNA expression profile in rabbit atria with atrial fibrillation: TCONS_00075467 modulates atrial electrical remodeling by sponging miR-328 to regulate CACNA1C

Electrical remodeling has been reported to play a major role in the initiation and maintenance of atrial fibrillation (AF). Long non-coding RNAs (lncRNAs) have been increasingly recognized as contributors to the pathology of heart diseases. However, the roles and mechanisms of lncRNAs in electrical remodeling during AF remain unknown. In this study, the lncRNA expression profiles of right atria were investigated in AF and non-AF rabbit models by using RNA sequencing technique and validated using quantitative real-time polymerase chain reaction (qRT-PCR). A total of 99,843 putative new lncRNAs were identified, in which 1220 differentially expressed transcripts exhibited >2-fold change. Bioinformatics analysis was conducted to predict the functions and interactions of the aberrantly expressed genes. On the basis of a series of filtering pipelines, one lncRNA, TCONS_00075467, was selected to explore its effects and mechanisms on electrical remodeling. The atrial effective refractory period was shortened in vivo and the L-type calcium current and action potential duration were decreased in vitro by silencing of TCONS_00075467 with lentiviruses. Besides, the expression of miRNA-328 was negatively correlated with TCONS_00075467. We further demonstrated that TCONS_00075467 could sponge miRNA-328 in vitro and in vivo to regulate the downstream protein coding gene CACNA1C. In addition, miRNA-328 could partly reverse the effects of TCONS_00075467 on electrical remodeling. In summary, dysregulated lncRNAs may play important roles in modulating electrical remodeling during AF. Our study may facilitate the mechanism studies of lncRNAs in AF pathogenesis and provide potential therapeutic targets for AF.

Low performance of bleeding risk models in the very elderly with atrial fibrillation using vitamin K antagonists

Essentials Under-treatment of oral anticoagulation in the elderly with atrial fibrillation is common. As bleeding prediction is challenging, we compared HAS-BLED, ATRIA and HEMORR2 HAGES. All three were associated with major bleeding in the elderly, but with poor predictive abilities. Future studies with focus on elderly-specific risk factors for bleeding are warranted.

SUMMARY

Background Anticipated bleeding complications contribute to underuse of oral anticoagulants, especially in elderly patients with atrial fibrillation (AF). Bleeding risk models could provide guidance; however, these were developed in the general AF population. Objective To study and compare the performance of the HAS-BLED, ATRIA and HEMORR2 HAGES for major bleeding in very elderly AF patients. Methods Subjects were a random sample (N = 1157) of AF patients ≥ 80 years using a vitamin-K antagonist with prospective clinical follow-up from 2011 to 2014. The primary outcome was major bleeding (International Society on Thrombosis and Haemostasis criteria). Results Patients aged 84 years (median; 25th-75th 82-87) were classified as low risk by HAS-BLED (25.2%), ATRIA (59.6%) and HEMORR2 HAGES (23.3%). Three-year rates of major, clinically relevant and any bleeding were 6.7%, 28.3% and 42.3%, respectively. We observed a statistically significant association for all models with major bleeding, but discriminatory abilities were rather poor (C-statistics < 0.60) without clear superiority for any of the three. Only two (anemia and antiplatelet therapy) of the various classical risk factors were associated with bleeding. An estimated risk-benefit profile indicated a favorable trade-off for oral anticoagulation in this specific cohort (number needed to treat, 22; number needed to harm, 91). Conclusions In this large prospective cohort of very elderly AF patients, the currently used bleeding risk scores were all associated with major bleeding, but with poor predictive abilities. Use of the ATRIA model may inadvertently result in less attention being paid to modifiable risk factors in this particular population. In light of the issues of under-treatment and the suggested favorable risk-benefit profile, future models with incorporation of elderly-specific risk factors may provide more guidance in this growing population of AF patients.

The HAS-BLED Score for Predicting Major Bleeding Risk in Anticoagulated Patients With Atrial Fibrillation: A Systematic Review and Meta-analysis

Our objective was to compare the diagnostic accuracy between the HAS-BLED score and any of HEMORR2 HAGES, ATRIA, CHADS2 , or CHA2 DS2 -VASc scores in anticoagulated patients with atrial fibrillation. We systematically searched the Cochrane Library, MEDLINE, PubMed, and Embase databases for relevant studies. Data were extracted and analyzed according to predefined clinical endpoints. Eleven studies were identified. Discrimination analysis demonstrates that HAS-BLED has no significant C-statistic differences for bleeding risk prediction compared with ATRIA or HEMORR2 HAGES, but it has significant differences compared with CHADS2 or CHA2 DS2 -VASc. The significant positive net reclassification improvement and integrated discrimination improvement values also show that HAS-BLED is superior to that of any of HEMORR2 HAGES, ATRIA, CHADS2 , or CHA2 DS2 -VASc scores. According to calibration analysis of HAS-BLED, it overpredicts the risk of bleeding in the low (risk ratio [RR]: 1.16, 95% confidence interval [CI]: 0.63-2.13, P = 0.64) risk stratification but underpredicts that in the moderate (RR: 0.66, 95% CI: 0.51-0.86, P = 0.002) and high (RR: 0.88, 95% CI: 0.70-1.10, P = 0.27) risk stratifications. The HAS-BLED score not only performs better than the HEMORR2 HAGES and ATRIA bleeding scores, but it also is superior to the CHADS2 and CHA2 DS2 -VASc stroke scores for bleeding prediction. The HAS-BLED score should be the optimal choice to assess major bleeding risk in clinical practice.

Atrial fibrillation and microRNAs

Atrial fibrillation (AF) is the most common sustained arrhythmia, especially in the elderly, and has a significant genetic component. Recently, several independent investigators have demonstrated a functional role for small non-coding RNAs (microRNAs) in the pathophysiology of this cardiac arrhythmia. This report represents a systematic and updated appraisal of the main studies that established a mechanistic association between specific microRNAs and AF, focusing both on the regulation of electrical and structural remodeling of cardiac tissue.