Persistent atrial fibrillation; It is time to regroup.

Pulmonary vein isolation (PVI) is the only proven ablation strategy for paroxysmal and persistent atrial fibrillation (AF). However, when AF recurs despite durable PVI in a subgroup of patients with persistent AF, there is no scientifically proven ablation strategy to pursue. Here, we summarized how we approach persistent AF at Johns Hopkins Hospital.

Targeted deep sequencing of the PEAR1 locus for platelet aggregation in European and African American families.

Coronary artery disease (CAD) remains a major cause of mortality and morbidity worldwide. The aggregation of activated platelets on a ruptured atherosclerotic plaque is a critical step in most acute cardiovascular events like myocardial infarction. Platelet aggregation both at baseline and after aspirin is highly heritable. Genome-wide association studies (GWAS) have identified a common variant within the first intron of the platelet endothelial aggregation receptor1 (PEAR1), to be robustly associated with platelet aggregation. In this study, we used targeted deep sequencing to fine-map the prior GWAS peak and identify additional rare variants of PEAR1 that account for missing heritability in platelet aggregation within the GeneSTAR families. In this study, 1709 subjects (1043 European Americans, EA and 666 African Americans, AA) from families in the GeneSTAR study were included. In vitro platelet aggregation in response to collagen, ADP and epinephrine was measured at baseline and 14 days after aspirin therapy (81 mg/day). Targeted deep sequencing of PEAR1 in addition to 2kb of upstream and downstream of the gene was performed. Under an additive genetic model, the association of single variants of PEAR1 with platelet aggregation phenotypes were examined. Additionally, we examined the association between the burden of PEAR1 rare non-synonymous variants and platelet aggregation phenotypes. Of 532 variants identified through sequencing, the intron 1 variant, rs12041331, was significantly associated with all platelet aggregation phenotypes at baseline and after platelet inhibition with aspirin therapy. rs12566888, which is in linkage disequilibrium with rs12041331, was associated with platelet aggregation phenotypes but to a lesser extent. In the EA families, the burden of PEAR1 missense variants was associated with platelet aggregation after aspirin therapy when the platelets were stimulated with epinephrine (p = 0.0009) and collagen (p = 0.03). In AAs, the burden of PEAR1 missense variants was associated, to a lesser degree, with platelet aggregation in response to epinephrine (p = 0.02) and ADP (p = 0.04). Our study confirmed that the GWAS-identified variant, rs12041331, is the strongest variant associated with platelet aggregation both at baseline and after aspirin therapy in our GeneSTAR families in both races. We identified additional association of rare missense variants in PEAR1 with platelet aggregation following aspirin therapy. However, we observed a racial difference in the contribution of these rare variants to the platelet aggregation, most likely due to higher residual missing heritability of platelet aggregation after accounting for rs12041331 in the EAs compared to AAs.

Correlation of right ventricular multielectrode endocardial unipolar mapping and epicardial scar.

AIMS: Prior studies identified a relationship between epicardial bipolar and endocardial unipolar voltage. Whether the relationship is valid with smaller multielectrode mapping catheters has not been reported. We explored the association of right ventricular (RV) endocardial unipolar voltage mapping with epicardial bipolar voltage mapping using a multielectrode mapping catheter. METHODS: Electrograms from patients who underwent multielectrode endocardial and epicardial RV electroanatomical mapping during ablation procedures were analyzed. Each endocardial mapping point was matched to the corresponding nearest epicardial point. The correlation between unipolar endocardial voltage and epicardial bipolar voltage was determined. The optimal unipolar threshold to detect epicardial low voltage (< 1.0 mV) and dense scar (0.5 mV) was calculated. RESULTS: A total of 4,895 points were analyzed. There was a significant correlation between endocardial unipolar and epicardial bipolar voltage (Spearman rho  =  0.499, P  =  < 0.001). The extent of the correlation was inversely associated with wall thickness. The receiver operator characteristic analysis of endocardial unipolar voltage predicting epicardial bipolar voltage of < 1.0 mV and < 0.5 showed an area under the curve of 0.769 and 0.812, respectively. The endocardial unipolar voltage that had the highest sensitivity and specificity in detecting epicardial bipolar voltage of < 1.0 mV and < 0.5 mV was 3.3 mV (70.3% sensitivity, 70.3% specificity), and 2.8 mV (sensitivity 73.8%, specificity 73.3%), respectively. CONCLUSION: Epicardial low voltage of the RV can be assessed by unipolar endocardial voltage using small multielectrode catheters. The strength of the association was inversely correlated with the wall thickness.

Initial validation of a novel ECGI system for localization of premature ventricular contractions and ventricular tachycardia in structurally normal and abnormal hearts.

BACKGROUND: View into Ventricular Onset (VIVO) is a novel ECGI system that uses 3D body surface imaging, myocardial CT/MRI, and 12­lead ECG to localize earliest ventricular activation through analysis of simulated and clinical vector cardiograms. OBJECTIVE: To evaluate the accuracy of VIVO for the localization of ventricular arrhythmias (VA). METHODS: In twenty patients presenting for catheter ablation of VT [8] or PVC [12], VIVO was used to predict the site earliest activation using 12­lead ECG of the VA. Results were compared to invasive electroanatomic mapping (EAM). RESULTS: A total of 22 PVC/VT morphologies were analyzed using VIVO. VIVO accurately predicted the location of the VA in 11/13 PVC cases and 8/9 VT cases. VIVO correctly predicted right vs left ventricular foci in 20/22 cases. CONCLUSION: View into Ventricular Onset (VIVO) can accurately predict earliest activation of VA, which could aid in catheter ablation, and should be studied further.

A form of the metabolic syndrome associated with mutations in DYRK1B.

BACKGROUND: Genetic analysis has been successful in identifying causative mutations for individual cardiovascular risk factors. Success has been more limited in mapping susceptibility genes for clusters of cardiovascular risk traits, such as those in the metabolic syndrome. METHODS: We identified three large families with coinheritance of early-onset coronary artery disease, central obesity, hypertension, and diabetes. We used linkage analysis and whole-exome sequencing to identify the disease-causing gene. RESULTS: A founder mutation was identified in DYRK1B, substituting cysteine for arginine at position 102 in the highly conserved kinase-like domain. The mutation precisely cosegregated with the clinical syndrome in all the affected family members and was absent in unaffected family members and unrelated controls. Functional characterization of the disease gene revealed that nonmutant protein encoded by DYRK1B inhibits the SHH (sonic hedgehog) and Wnt signaling pathways and consequently enhances adipogenesis. Furthermore, DYRK1B promoted the expression of the key gluconeogenic enzyme glucose-6-phosphatase. The R102C allele showed gain-of-function activities by potentiating these effects. A second mutation, substituting proline for histidine 90, was found to cosegregate with a similar clinical syndrome in an ethnically distinct family. CONCLUSIONS: These findings indicate a role for DYRK1B in adipogenesis and glucose homeostasis and associate its altered function with an inherited form of the metabolic syndrome. (Funded by the National Institutes of Health.).

Anterior pericardial access to facilitate electrophysiology study and catheter ablation of ventricular arrhythmias: A single tertiary center experience.

INTRODUCTION: Epicardial ablation is becoming an important part of management in patients with ventricular tachycardia (VT). Posterior epicardial access via the Sosa or needle-in-needle (NIN) approach for epicardial VT ablation is considered to be the method of choice for most electrophysiologists. Anterior epicardial access as an alternative technique has recently been proposed, but there are limited data about its safety, efficacy, and the rate of immediate complications. In this study, we report our experience with anterior epicardial access between 2009 and 2016. METHODS: Between 2009 and June 2016, 100 consecutive patients underwent epicardial VT ablation using an anterior approach. The success rate, epicardial bleeding, and other complications related to the epicardial access in these patients were compared to the previously reported rate of complications in patients whom epicardial access was performed using the NIN or Sosa techniques. RESULTS: Anterior epicardial access was obtained successfully in 100% of patients in the first attempt. The success rate of the anterior approach was comparable with the reported success rate of the NIN technique (100% vs. 100%, P value not significant) but better than the Sosa technique (100% vs. 94%, P = 0.012). None of the patients in the anterior approach series suffered from significant pericardial bleeding (defined as greater than 80 mL of blood loss), RV puncture/damage, or need for an emergent cardiac surgery. CONCLUSION: An anterior epicardial approach is feasible and appears to have an acceptable safety profile in comparison with other epicardial approaches.

Wild-type LRP6 inhibits, whereas atherosclerosis-linked LRP6R611C increases PDGF-dependent vascular smooth muscle cell proliferation.

Vascular smooth muscle cell (VSMC) proliferation is an important event in atherosclerosis and other vasculopathies. PDGF signaling is a key mediator of SMC proliferation, but the mechanisms that control its activity remain unclear. We previously identified a mutation in LDL receptor-related protein 6 (LRP6), LRP6(R611C), that causes early atherosclerosis. Examination of human atherosclerotic coronary arteries showed markedly increased expression of LRP6 and colocalization with PDGF receptor ß (PDGFR-ß). Further investigation showed that wild-type LRP6 inhibits but LRP6(R611C) promotes VSMC proliferation in response to PDGF. We found that wild-type LRP6 forms a complex with PDGFR-ß and enhances its lysosomal degradation, functions that are severely impaired in LRP6(R611C). Further, we observed that wild-type and mutant LRP6 regulate cell-cycle activity by triggering differential effects on PDGF-dependent pathways. These findings implicate LRP6 as a critical modulator of PDGF-dependent regulation of cell cycle in smooth muscle and indicate that loss of this function contributes to development of early atherosclerosis in humans.

LRP6 protein regulates low density lipoprotein (LDL) receptor-mediated LDL uptake.

Genetic variations in LRP6 gene are associated with high serum LDL cholesterol levels. We have previously shown that LDL clearance in peripheral B-lymphocytes of the LRP6(R611C) mutation carriers is significantly impaired. In this study we have examined the role of wild type LRP6 (LRP6(WT)) and LRP6(R611C) in LDL receptor (LDLR)-mediated LDL uptake. LDL binding and uptake were increased when LRP6(WT) was overexpressed and modestly reduced when it was knocked down in LDLR-deficient CHO (ldlA7) cells. These findings implicated LRP6 in LDLR-independent cellular LDL binding and uptake. However, LRP6 knockdown in wild type CHO cells resulted in a much greater decline in LDL binding and uptake compared with CHO-ldlA7 cells, suggesting impaired function of the LDLR. LDLR internalization was severely diminished when LRP6 was knocked down and was restored after LRP6 was reintroduced. Further analysis revealed that LRP6(WT) forms a complex with LDLR, clathrin, and ARH and undergoes a clathrin-mediated internalization after stimulation with LDL. LDLR and LRP6 internalizations as well as LDL uptake were all impaired in CHO-k1 cells expressing LRP6(R611C). These studies identify LRP6 as a critical modulator of receptor-mediated LDL endocytosis and introduce a mechanism by which variation in LRP6 may contribute to high serum LDL levels.

Low density lipoprotein (LDL) receptor-related protein 6 (LRP6) regulates body fat and glucose homeostasis by modulating nutrient sensing pathways and mitochondrial energy expenditure.

Body fat, insulin resistance, and type 2 diabetes are often linked together, but the molecular mechanisms that unify their association are poorly understood. Wnt signaling regulates adipogenesis, and its altered activity has been implicated in the pathogenesis of type 2 diabetes and metabolic syndrome. LRP6(+/-) mice on a high fat diet were protected against diet-induced obesity and hepatic and adipose tissue insulin resistance compared with their wild-type (WT) littermates. Brown adipose tissue insulin sensitivity and reduced adiposity of LRP6(+/-) mice were accounted for by diminished Wnt-dependent mTORC1 activity and enhanced expression of brown adipose tissue PGC1-α and UCP1. LRP6(+/-) mice also exhibited reduced endogenous hepatic glucose output, which was due to diminished FoxO1-dependent expression of the key gluconeogenic enzyme glucose-6-phosphatase (G6pase). In addition, in vivo and in vitro studies showed that loss of LRP6 allele is associated with increased leptin receptor expression, which is a likely cause of hepatic insulin sensitivity in LRP6(+/-) mice. Our study identifies LRP6 as a nutrient-sensitive regulator of body weight and glucose metabolism and as a potential target for pharmacological interventions in obesity and diabetes.

Evaluations of Student's Satisfaction with Externship Education in the Academic Departments of the Medical School of Kermanshah University of Medical Sciences in July and August 2021.

OBJECTIVES: Determining the level of satisfaction in each field will help to examine and eliminate the existing problems and shortcomings. Using this information, students' satisfaction can be provided as much as possible while strengthening the positive factors and correcting the negative factors. The aim of this study was to evaluate the Student's Satisfaction with externship Education in the Academic Departments of the Medical School of Kermanshah University of Medical Sciences in 2021. METHODS: This descriptive cross-sectional study, was performed in the medical school of Kermanshah University of Medical Sciences. The statistical population was all externship students. The validity of the questionnaire's content was determined by consulting experts, and its reliability was obtained by Cronbach's alpha method based on a sample of 20 students. The questionnaires were completed virtually on the Google site using the Google Form. Data analysis was performed Stata V14.2 software using descriptive statistics, t-test, and chi-square, and the significant level was considered 0.05. RESULTS: The results showed that 55% of the participants were female and 45% were male. The level of students 'satisfaction with the quality of supervisors' education was moderate to high and in other cases was moderate to low. Students were more satisfied with teaching anesthesia than other departments and were dissatisfied with the infectious department. No statistically significant difference was found between people's satisfaction with the overall clinical education process in terms of age. CONCLUSION: The results of this study showed that students have moderate to poor satisfaction with externship education in educational groups.

Genetic determinants of telomere length from 109,122 ancestrally diverse whole-genome sequences in TOPMed.

Genetic studies on telomere length are important for understanding age-related diseases. Prior GWAS for leukocyte TL have been limited to European and Asian populations. Here, we report the first sequencing-based association study for TL across ancestrally-diverse individuals (European, African, Asian and Hispanic/Latino) from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. We used whole genome sequencing (WGS) of whole blood for variant genotype calling and the bioinformatic estimation of telomere length in n=109,122 individuals. We identified 59 sentinel variants (p-value <5×10-9) in 36 loci associated with telomere length, including 20 newly associated loci (13 were replicated in external datasets). There was little evidence of effect size heterogeneity across populations. Fine-mapping at OBFC1 indicated the independent signals colocalized with cell-type specific eQTLs for OBFC1 (STN1). Using a multi-variant gene-based approach, we identified two genes newly implicated in telomere length, DCLRE1B (SNM1B) and PARN. In PheWAS, we demonstrated our TL polygenic trait scores (PTS) were associated with increased risk of cancer-related phenotypes.

Genome sequencing unveils a regulatory landscape of platelet reactivity.

Platelet aggregation at the site of atherosclerotic vascular injury is the underlying pathophysiology of myocardial infarction and stroke. To build upon prior GWAS, here we report on 16 loci identified through a whole genome sequencing (WGS) approach in 3,855 NHLBI Trans-Omics for Precision Medicine (TOPMed) participants deeply phenotyped for platelet aggregation. We identify the RGS18 locus, which encodes a myeloerythroid lineage-specific regulator of G-protein signaling that co-localizes with expression quantitative trait loci (eQTL) signatures for RGS18 expression in platelets. Gene-based approaches implicate the SVEP1 gene, a known contributor of coronary artery disease risk. Sentinel variants at RGS18 and PEAR1 are associated with thrombosis risk and increased gastrointestinal bleeding risk, respectively. Our WGS findings add to previously identified GWAS loci, provide insights regarding the mechanism(s) by which genetics may influence cardiovascular disease risk, and underscore the importance of rare variant and regulatory approaches to identifying loci contributing to complex phenotypes.

The non-syndromic familial thoracic aortic aneurysms and dissections maps to 15q21 locus.

BACKGROUND: Thoracic aortic aneurysms and dissections (TAAD) is a critical condition that often goes undiagnosed with fatal consequences. While majority of the cases are sporadic, more than 20% are inherited as a single gene disorder. The most common familial TAA is Marfan syndrome (MFS), which is primarily caused by mutations in fibrillin-1 (FBN1) gene. Patients with FBN1 mutations are at higher risk for dissection compared to other patients with similar size aneurysms. METHODS: Fifteen family members were genotyped using Affymetrix-10K genechips. A genome-wide association study was carried out using an autosomal dominant model of inheritance with incomplete penetrance. Mutation screening of all exons and exon-intron boundaries of FBN1 gene which reside near the peak Lod score was carried out by direct sequencing. RESULTS: The index case presented with agonizing substernal pain and was found to have TAAD by transthoracic echocardiogram. The family history was significant for 3 first degree relatives with TAA. Nine additional family members were diagnosed with TAA by echocardiography examinations. The affected individuals had no syndromic features. A genome-wide analysis of linkage mapped the disease gene to a single locus on chromosome 15q21 with a peak Lod score of 3.6 at fibrillin-1 (FBN1) gene locus (odds ratio > 4000:1 in favour of linkage), strongly suggesting that FBN1 is the causative gene. No mutation was identified within the exons and exon-intron boundaries of FBN1 gene that segregated with the disease. Haplotype analysis identified additional mutation carriers who had previously unknown status due to borderline dilation of the ascending aorta. CONCLUSIONS: A familial non-syndromic TAAD is strongly associated with the FBN1 gene locus and has a malignant disease course often seen in MFS patients. This finding indicates the importance of obtaining detailed family history and echocardiographic screening of extended relatives of patients with non-syndromic TAAD to improve the outcome. In addition, association of non-syndromic TAAD with the Marfan disease gene locus poses the question whether secondary prevention strategies employed for Marfan syndrome patients should be applied to all patients with familial TAAD.

The time course of Akt and ERK activation on XIAP expression in HEK 293 cell line.

The cell growth is controlled by the interaction of survival and cell growth arrest pathways as well as apoptosis mechanisms which determine the outcome of cell faith as proliferation or apoptosis. In this study, we have studied the activity of survival pathways, i.e., Akt and ERK1/2 with regard to XIAP (inhibitor of apoptosis) in serum starved and stimulated conditions. The HEK-293 cells were cultured in RPMI + 10% FBS. The cells were serum starved by switching to medium with 1% FBS for 24 h and serum stimulated by changing the medium to 10% FBS following serum starvation. The expression of p-Akt, p-ERK, Akt, ERK and XIAP was studied in various time points using western blot. The apoptosis was evaluated by DNA condensation using Hoechst 33258 and Caspase-3 assay. In serum starved condition expression of p-Akt and XIAP is very low. Serum stimulation increases p-Akt and p-ERK within 5 min and sustains a high level for 30 min. The expression of total Akt and ERK1/2 has not changed significantly for 24 h. XIAP expression starts at 6 h after serum stimulation, reaches to maximum level at 12 h and decreases to baseline within 24 h. Furthermore, serum starvation for 24 h does not induced apoptosis and DNA condensation. Taken together, the results indicate that serum activates Akt and ERK pathways earlier than XIAP expression. Furthermore, XIAP expression is low in serum starvation unlike p-ERK which suggests a survival role for ERK in serums starvation. The expression pattern of XIAP indicates induction by Akt and/or ERK activation which requires further studies.

Genome-wide association and multi-omic analyses reveal ACTN2 as a gene linked to heart failure.

Heart failure is a major public health problem affecting over 23 million people worldwide. In this study, we present the results of a large scale meta-analysis of heart failure GWAS and replication in a comparable sized cohort to identify one known and two novel loci associated with heart failure. Heart failure sub-phenotyping shows that a new locus in chromosome 1 is associated with left ventricular adverse remodeling and clinical heart failure, in response to different initial cardiac muscle insults. Functional characterization and fine-mapping of that locus reveal a putative causal variant in a cardiac muscle specific regulatory region activated during cardiomyocyte differentiation that binds to the ACTN2 gene, a crucial structural protein inside the cardiac sarcolemma (Hi-C interaction p-value = 0.00002). Genome-editing in human embryonic stem cell-derived cardiomyocytes confirms the influence of the identified regulatory region in the expression of ACTN2. Our findings extend our understanding of biological mechanisms underlying heart failure.

Regional Strain by Cardiac Magnetic Resonance Imaging Improves Detection of Right Ventricular Scar Compared With Late Gadolinium Enhancement on a Multimodality Scar Evaluation in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy is an inherited cardiomyopathy characterized by fibrofatty replacement of right ventricular myocardium resulting in reentrant ventricular tachycardia (VT). Cardiac magnetic resonance imaging (CMR) can noninvasively measure regional abnormalities using tissue-tracking strain as well as late gadolinium enhancement (LGE). In this study, we examine arrhythmogenic substrate using regional CMR strain, LGE, and electroanatomic mapping (EAM) in arrhythmogenic right ventricular cardiomyopathy patients presenting for VT ablation. METHODS AND RESULTS: Twenty-one patients underwent right ventricular endocardial EAM, whereas 17 underwent epicardial EAM, to detect dense scar (<0.5 mV) as well as CMR study within 12 months. Quantitative regional strain analysis was performed in all 21 patients, although the presence of LGE was visually examined in 17 patients. Strain was lower in segments with dense scar on endocardial and epicardial EAM (-9.7±4.1 versus -7.3±4.0, and -9.8±2.8 versus -7.6±3.8; P<0.05), in segments with LGE scar (-9.9±4.4 versus -6.0±3.6; P=0.001), and at VT culprit sites (-7.4±3.7 versus -10.1±4.1; P<0.001), compared with the rest of right ventricular. On patient-clustered analysis, a unit increase in strain was associated with 21% and 18% decreased odds of scar on endocardial and epicardial EAM, respectively, 17% decreased odds of colocalizing VT culprit site, and 43% decreased odds of scar on LGE-CMR ( P<0.05 for all). LGE and EAM demonstrated poor agreement with κ=0.18 (endocardial, n=17) and κ=0.06 (epicardial, n=13). Only 8 (15%) VT termination sites exhibited LGE. CONCLUSIONS: Regional myocardial strain on cine CMR improves detection of arrhythmogenic VT substrate compared with LGE. This may enhance diagnostic accuracy of CMR in arrhythmogenic right ventricular cardiomyopathy without the need for invasive procedures and facilitate the planning of VT ablation procedures.