Evidence for a Heritable Contribution to Atrial Fibrillation Associated With Fibrosis

High-fat stimulation induces atrial structural remodeling via the TPM1/P53/SHISA5 Axis

BACKGROUND

Atrial structural remodeling plays a central role in the development and progression of atrial fibrillation (AF) and significantly influences its course. Hyperlipidemia, a potential contributor to AF, affects cardiac function through multiple pathways. This study aimed to investigate the underlying mechanisms by which high lipid levels promote AF progression.

METHODS

In vitro cell models were established using palmitic acid (PA) stimulation, and in vivo rat models were generated by feeding a high-fat diet (HFD). Proteomic and transcriptomic sequencing analyses were conducted to identify differentially expressed proteins and genes. Extracellular vesicles (EVs) were isolated and characterized by differential centrifugation. Cell proliferation was assessed using EdU incorporation and flow cytometry, while transmission electron microscopy (TEM) was used to observe autophagy. Protein expression was analyzed by immunoblotting, immunohistochemistry, and immunofluorescence.

RESULTS

High lipid stimulation significantly increased the expression of tropomyosin 1 (TPM1) in cardiomyocytes, which was transferred to cardiac fibroblasts via EVs, activating the P53/SHISA5 signaling axis and inducing endoplasmic reticulum (ER) stress and autophagy, thereby promoting atrial structural remodeling. Activation of P53 and overexpression of SHISA5 in human cardiac fibroblast (HCF) cells reduced ER stress, autophagy, and fibrosis. Furthermore, ER stress and autophagy markers were significantly elevated in the atrial tissues of HFD-fed rats, while SHISA5 overexpression mitigated these effects.

CONCLUSION

High-fat stimulation may induce atrial fibrosis through the TPM1/P53/SHISA5 axis by modulating the ER stress-autophagy pathway.

Diverticulitis Familiality: A Statewide Case-Control Study

BACKGROUND

The etiology of diverticulitis is multifactorial and poorly understood. We estimated the familiality of diverticulitis using the Utah Population Database, a statewide database linking medical records with genealogy data.

STUDY DESIGN

We identified patients with diverticulitis diagnosed between 1998 and 2018 and age- and sex-matched controls in the Utah Population Database. Risk of diverticulitis in family members of patients and controls was calculated using multivariable Poisson models. We performed exploratory analyses to determine the association of familial diverticulitis with severity of disease and age of onset.

RESULTS

The study population included 9,563 diverticulitis patients (with 229,647 relatives) and 10,588 controls (with 265,693 relatives). Relatives of patients were more likely to develop diverticulitis (incidence rate ratio [IRR] 1.5, 95% CI 1.4 to 1.6) compared with relatives of controls. There was an elevated risk of diverticulitis among first-degree (IRR 2.6, 95% CI 2.3 to 3.0), second-degree (IRR 1.5, 95% CI 1.3 to 1.6), and third-degree relatives of patients (IRR 1.3, 95% CI 1.2 to 1.4). Complicated diverticulitis was more common among relatives of patients compared with relatives of controls (IRR 1.6, 95% CI 1.4 to 1.8). Age at diverticulitis diagnosis was similar between groups (relatives of patients 0.2 years older than relatives of controls, 95% CI -0.5 to 0.9).

CONCLUSIONS

Our results indicate that the first-, second-, and third-degree relatives of diverticulitis patients are at elevated risk of developing diverticulitis. This information may aid surgeons in counseling patients and family members about diverticulitis risk and can inform the development of future risk-stratification tools. Further work is needed to clarify the causal role and relative contribution of various genetic, lifestyle, and environmental factors in the development of diverticulitis.

The Association Between Family History and Diverticulitis Recurrence: A Population-Based Study

BACKGROUND

After initial nonoperative management of diverticulitis, individuals with a family history of diverticulitis may have increased risk of recurrent disease.

OBJECTIVE

This study measured the association between family history and recurrent diverticulitis in a population-based cohort.

DESIGN

This is a retrospective, population-based cohort study.

SETTINGS

The cohort was identified from the Utah Population Database, a statewide resource linking hospital and genealogy records.

PATIENTS

Individuals evaluated in an emergency department or hospitalized between 1998 and 2018 for nonoperatively managed diverticulitis were included.

INTERVENTION

The primary predictor was a positive family history of diverticulitis, defined as diverticulitis in a first-, second-, or third-degree relative.

MAIN OUTCOME MEASURES

This study measured the adjusted association between family history and the primary outcome of recurrent diverticulitis. A secondary outcome was elective surgery for diverticulitis. Additional analyses evaluated risk by degree of relation of the affected family member.

RESULTS

The cohort included 4426 individuals followed for a median of 71 months. Median age was 64 years and 45% were male; 17% had complicated disease, 11% had recurrence, and 15% underwent elective surgery. After adjustment, individuals with a family history of diverticulitis had a similar risk of recurrence when compared to those without a family history (HR 1.0; 95% CI 0.8-1.2). However, individuals with a family history of diverticulitis were more likely to undergo elective surgery (HR 1.4; 95% CI 1.1-1.6). This effect was most pronounced in those with an affected first-degree family member (HR 1.7; 95% CI 1.4-2.2).

LIMITATIONS

The use of state-specific data may limit generalizability.

CONCLUSIONS

In this population-based analysis, individuals with a family history of diverticulitis were more likely to undergo elective surgery than those without a family history, despite similar risks of recurrence and complicated diverticulitis. Further work is necessary to understand the complex social, environmental, and genetic factors that influence diverticulitis treatment and outcomes. See Video Abstract at http://links.lww.com/DCR/B876 .

ASOCIACIN ENTRE LOS ANTECEDENTES FAMILIARES Y LA RECURRENCIA DE LA DIVERTICULITIS UN ESTUDIO POBLACIONAL

ANTECEDENTES:Después del tratamiento inicial no quirúrgico de la diverticulitis, las personas con antecedentes familiares de diverticulitis pueden tener un mayor riesgo de enfermedad recurrente.OBJETIVO:Este estudio midió la asociación entre antecedentes familiares y diverticulitis recurrente en una cohorte poblacional.DISEÑO:Este es un estudio de cohorte retrospectivo de la población.ENTORNO CLÍNICO:La cohorte se identificó a partir de la Base de datos de población de Utah, un recurso estatal que vincula los registros hospitalarios y genealógicos.PACIENTES:Se incluyeron individuos evaluados en un departamento de emergencias u hospitalizados entre 1998 y 2018 por diverticulitis manejada de forma no quirúrgica.INTERVENCIÓN:El predictor principal fue un historial familiar positivo de diverticulitis, definida como diverticulitis en un familiar de primer, segundo o tercer grado.PRINCIPALES MEDIDAS DE VALORACIÓN:Este estudio midió la asociación ajustada entre los antecedentes familiares y el resultado primario de diverticulitis recurrente. Un resultado secundario fue la cirugía electiva por diverticulitis. Análisis adicionales evaluaron el riesgo por grado de parentesco del familiar afectado.RESULTADOS:La cohorte incluyó a 4.426 individuos seguidos durante una mediana de 71 meses. La mediana de edad fue de 64 años y el 45% eran varones. El 17% tenía enfermedad complicada, el 11% recidiva y el 15% se sometió a cirugía electiva. Después del ajuste, los individuos con antecedentes familiares de diverticulitis tenían un riesgo similar de recurrencia en comparación con aquellos sin antecedentes familiares (HR 1,0; IC del 95%: 0,8-1,2). Sin embargo, las personas con antecedentes familiares de diverticulitis tenían más probabilidades de someterse a una cirugía electiva (HR 1,4; IC del 95%: 1,1-1,6). Este efecto fue más pronunciado en aquellos con un familiar de primer grado afectado (HR 1,7; IC del 95%: 1,4-2,2).LIMITACIONES:El uso de datos específicos del estado puede limitar la generalización.CONCLUSIONES:En este análisis poblacional, los individuos con antecedentes familiares de diverticulitis tenían más probabilidades de someterse a una cirugía electiva que aquellos sin antecedentes familiares, a pesar de riesgos similares de recurrencia y diverticulitis complicada. Es necesario seguir trabajando para comprender los complejos factores sociales, ambientales y genéticos que influyen en el tratamiento y los resultados de la diverticulitis. Consulte Video Resumen en http://links.lww.com/DCR/B876 . (Traducción-Dr. Ingrid Melo ).

Genetically Based Atrial Fibrillation: Current Considerations for Diagnosis and Management

Atrial fibrillation (AF) is the most common atrial arrhythmia and is subcategorized into numerous clinical phenotypes. Given its heterogeneity, investigations into the genetic mechanisms underlying AF have been pursued in recent decades, with predominant analyses focusing on early onset or lone AF. Linkage analyses, genome wide association studies (GWAS), and single gene analyses have led to the identification of rare and common genetic variants associated with AF risk. Significant overlap with genetic variants implicated in dilated cardiomyopathy syndromes, including truncating variants of the sarcomere protein titin, have been identified through these analyses, in addition to other genes associated with cardiac structure and function. Despite this, widespread utilization of genetic testing in AF remains hindered by the unclear impact of genetic risk identification on clinical outcomes and the high prevalence of variants of unknown significance (VUS). However, genetic testing is a reasonable option for patients with early onset AF and in those with significant family history of arrhythmia. While many knowledge gaps remain, emerging data support genotyping to inform selection of AF therapeutics. In this review we highlight the current understanding of the complex genetic basis of AF and explore the overlap of AF with inherited cardiomyopathy syndromes. We propose a set of criteria for clinical genetic testing in AF patients and outline future steps for the integration of genetics into AF care. This article is protected by copyright. All rights reserved.

The history and geographic distribution of a KCNQ1 atrial fibrillation risk allele

The genetic architecture of atrial fibrillation (AF) encompasses low impact, common genetic variants and high impact, rare variants. Here, we characterize a high impact AF-susceptibility allele, KCNQ1 R231H, and describe its transcontinental geographic distribution and history. Induced pluripotent stem cell-derived cardiomyocytes procured from risk allele carriers exhibit abbreviated action potential duration, consistent with a gain-of-function effect. Using identity-by-descent (IBD) networks, we estimate the broad- and fine-scale population ancestry of risk allele carriers and their relatives. Analysis of ancestral migration routes reveals ancestors who inhabited Denmark in the 1700s, migrated to the Northeastern United States in the early 1800s, and traveled across the Midwest to arrive in Utah in the late 1800s. IBD/coalescent-based allele dating analysis reveals a relatively recent origin of the AF risk allele (~5000 years). Thus, our approach broadens the scope of study for disease susceptibility alleles to the context of human migration and ancestral origins.

Left atrial fibrosis in atrial fibrillation: Mechanisms, clinical evaluation and management

Atrial fibrillation (AF), the commonest arrhythmia, shows associations with various disease conditions. Mounting evidence indicates that atrial fibrosis is an important part of the arrhythmogenic substrate, with an essential function in the generation of conduction abnormalities that underlie the transition from paroxysmal to persistent AF, which in turn contributes to AF perpetuation. Left atrial (LA) fibrosis is considered a possible major factor and predictor in AF treatment. The present review provides insights into LA fibrosis’ association with AF. The information is focused on clinical aspects and mechanisms, clinical evaluating methods that evaluate fibrosis changes and examining possible options for the prevention of atrial fibrosis.

Early-onset atrial fibrillation patients show reduced left ventricular ejection fraction and increased atrial fibrosis

Atrial fibrillation (AF) has traditionally been considered an electrical heart disease. However, genetic studies have revealed that the structural architecture of the heart also play a significant role. We evaluated the functional and structural consequences of harboring a titin-truncating variant (TTNtv) in AF patients, using cardiac magnetic resonance (CMR). Seventeen early-onset AF cases carrying a TTNtv, were matched 1:1 with non-AF controls and a replication cohort of early-onset AF cases without TTNtv, and underwent CMR. Cardiac volumes and left atrial late gadolinium enhancement (LA LGE), as a fibrosis proxy, were measured by a blinded operator. Results: AF cases with TTNtv had significantly reduced left ventricular ejection fraction (LVEF) compared with controls (57 ± 4 vs 64 ± 5%, P < 0.001). We obtained similar findings in early-onset AF patients without TTNtv compared with controls (61 ± 4 vs 64 ± 5%, P = 0.02). We furthermore found a statistically significant increase in LA LGE when comparing early-onset AF TTNtv cases with controls. Using state-of-the-art CMR, we found that early-onset AF patients, irrespective of TTNtv carrier status, had reduced LVEF, indicating that early-onset AF might not be as benign as previously thought.