Environmental Exposome and Atrial Fibrillation: Emerging Evidence and Future Directions.

There has been increased awareness of the linkage between environmental exposures and cardiovascular health and disease. Atrial fibrillation is the most common sustained cardiac arrhythmia, affecting millions of people worldwide and contributing to substantial morbidity and mortality. Although numerous studies have explored the role of genetic and lifestyle factors in the development and progression of atrial fibrillation, the potential impact of environmental determinants on this prevalent condition has received comparatively less attention. This review aims to provide a comprehensive overview of the current evidence on environmental determinants of atrial fibrillation, encompassing factors such as air pollution, temperature, humidity, and other meteorologic conditions, noise pollution, greenspace, and the social environment. We discuss the existing evidence from epidemiological and mechanistic studies, critically evaluating the strengths and limitations of these investigations and the potential underlying biological mechanisms through which environmental exposures may affect atrial fibrillation risk. Furthermore, we address the potential implications of these findings for public health and clinical practice and identify knowledge gaps and future research directions in this emerging field.

The Global Burden of premature cardiovascular disease, 1990-2019.

Aims: Premature cardiovascular disease (pCVD) definition varies in literature, with age cut-offs ranging from 50-65 years. While there is some literature available on pCVD in North America, comprehensive data on its global burden is still lacking which hinders the development of efficient strategies for early detection and prevention. In this study we aimed to investigate the global trends in pCVD related morbidity and mortality from 1990 to 2019. Methods: The 1990-2019 Global Burden of Disease (GBD) database was utilized to examine global trends in cardiovascular disease-related total mortality, mortality rates, and Disability-Adjusted Life Years (DALYs) within individuals aged 15-49 years. The findings were further analyzed based on factors such as age, sex, and Socio-Demographic Index (SDI). Results: From 1990 to 2019, the number of global annual pCVD deaths increased by 25%, from 992,067 (95% UI 1,042,261 - 946,383) to 1,241,484 (95% UI 1,339,193 -1,146,252). The rate of associated mortality decreased by 13%. Metabolic conditions were the most significant risk factors for pCVD mortality. Ischemic heart disease and stroke are the leading causes of death across all age groups. pCVD mortality presented progressive widening between high and low SDI regions. Additionally, sex-specific disparities in CVD mortality were significantly greater in the premature age group as compared to all-age groups. Conclusion: pCVD is an increasingly significant global cause of morbidity and mortality that disproportionately affects males and individuals living in less privileged regions. Furthermore, ischemic heart disease and stroke were identified as the main drivers of pCVD global burden.

Novel functional atrial fibrillation risk genes and pathways identified from coexpression analyses in human left atria.

BACKGROUND: Genomewide association studies have associated >100 genetic loci with atrial fibrillation (AF), but establishing causal genes contributing to AF remains challenging. OBJECTIVE: The purpose of this study was to determine candidate novel causal genes and mechanistic pathways associated with AF risk loci by incorporating gene expression and coexpression analyses and to provide a resource for functional studies and targeting of AF-associated genes. METHODS: Cis-expression quantitative trait loci were identified for candidate genes near AF risk variants in human left atrial tissues. Coexpression partners were identified for each candidate gene. Weighted gene coexpression network analysis (WGCNA) identified modules and modules with overrepresentation of candidate AF genes. Ingenuity pathway analysis (IPA) was applied to the coexpression partners of each candidate gene. IPA and gene set over representation analysis were applied to each WGCNA module. RESULTS: One hundred sixty-six AF-risk single nucleotide polymorphisms were located in 135 loci. Eighty-one novel genes not previously annotated as putative AF risk genes were identified. IPA identified mitochondrial dysfunction, oxidative stress, epithelial adherens junction signaling, and sirtuin signaling as the most frequent significant pathways. WGCNA characterized 64 modules (candidate AF genes overrepresented in 8), represented by cell injury, death, stress, developmental, metabolic/mitochondrial, transcription/translation, and immune activation/inflammation regulatory pathways. CONCLUSION: Candidate gene coexpression analyses suggest significant roles for cellular stress and remodeling in AF, supporting a dual risk model for AF: Genetic susceptibility to AF may not manifest until later in life, when cellular stressors overwhelm adaptive responses. These analyses also provide a novel resource to guide functional studies on potential causal AF genes.

Predictors of successful same-day discharge and 1-year outcomes after left atrial appendage closure.

BACKGROUND: Same-day discharge (SDD) following left atrial appendage closure (LAAC) is increasingly common but predictors of successful SDD and 1-year clinical outcomes have not been described. OBJECTIVE: The purpose of this study was to explore predictors of successful SDD and report 1-year outcomes in patients undergoing LAAC with SDD. METHODS: A prospective analysis was performed over a 20-month period of 225 consecutive patients that underwent LAAC in a large, academic hospital. All patients included in the study underwent a SDD protocol. Baseline characteristics and 1-year outcomes of patients discharged same day of the procedure versus those that required at least one overnight stay were compared. Adverse events, procedural success, and procedure times were evaluated. RESULTS: One hundred and sixty-one patients (72%) of patients were discharged the same day and 64 patients (28%) required at least an overnight stay (non-SDD: NSDD). NSDD patients were older and more often female. Procedure time was also longer in the NSDD group than in the SDD (63.4 vs. 55.1 min; p = 0.01). While overall procedural success rates were similar between the SDD and NSDD groups (99.4% vs. 98.4%; p = 0.39), NSDD patients had more complications (9.4% vs. 0%; p = 0.01) and higher number of devices per procedure (1.2 vs. 1.0; p = 0.01) as compared to SDD. At 1 year, there were no significant difference between the SDD and NSDD groups in stroke (1.1% vs. 0%; log-rank p = 0.44) and all-cause mortality (3.9% vs. 4.7%; log-rank p = 0.70). CONCLUSION: In this single-center LAAC experience, female sex, older age, and longer procedure duration were associated with higher likelihood for need of overnight stay. At 1-year follow-up, there were no significant differences in stroke events and death rates between SDD and NSDD groups.

Atrial fibrillation rhythm is associated with marked changes in metabolic and myofibrillar protein expression in left atrial appendage.

Atrial fibrillation (AF) is strongly associated with risk of stroke and heart failure. AF promotes atrial remodeling that increases risk of stroke due to left atrial thrombogenesis, and increases energy demand to support high rate electrical activity and muscle contraction. While many transcriptomic studies have assessed AF-related changes in mRNA abundance, fewer studies have assessed proteomic changes. We performed a proteomic analysis on left atrial appendage (LAA) tissues from 12 patients with a history of AF undergoing elective surgery; atrial rhythm was documented at time of surgery. Proteomic analysis was performed using liquid chromatography with mass spectrometry (LC/MS-MS). Data-dependent analysis identified 3090 unique proteins, with 408 differentially expressed between sinus rhythm and AF. Ingenuity Pathway Analysis of differentially expressed proteins identified mitochondrial dysfunction, oxidative phosphorylation, and sirtuin signaling among the most affected pathways. Increased abundance of electron transport chain (ETC) proteins in AF was accompanied by decreased expression of ETC complex assembly factors, tricarboxylic acid cycle proteins, and other key metabolic modulators. Discordant changes were also evident in the contractile unit with both up and downregulation of key components. Similar pathways were affected in a comparison of patients with a history of persistent vs. paroxysmal AF, presenting for surgery in sinus rhythm. Together, these data suggest that while the LAA attempts to meet the energetic demands of AF, an uncoordinated response may reduce ATP availability, contribute to tissue contractile and electrophysiologic heterogeneity, and promote a progression of AF from paroxysmal episodes to development of a substrate amenable to persistent arrhythmia.