Epidemiology and modifiable risk factors for atrial fibrillation

Association of Cardiac CT-Derived Epicardial Adipose Tissue With Atrial Fibrillation in Patients Without Left Atrial Fibrosis as Defined by Endocardial Voltage Mapping

INTRODUCTION

Epicardial adipose tissue (EAT) is often associated with atrial fibrosis, and both can provide the substrate for atrial fibrillation (AF). However, most AF patients have no evidence of left atrial (LA) fibrosis based on bipolar voltage mapping. We determined whether EAT differs in AF patients without LA fibrosis compared to matched controls without AF.

METHODS

Patients undergoing cardiac CT before first-time AF catheter ablation were prospectively enrolled. LA bipolar voltage mapping was performed, and patients were divided into -LVZ (LA low voltage zones < 5% of LA surface area; no fibrosis) and +LVZ (LA low voltage zones ≥ 5%; fibrosis). A control group without AF was matched to -LVZ patients. EAT was quantified on CT using standard signal thresholding to quantify total and regional volumes. AF patients were followed for 1-year postablation to assess atrial arrhythmia (AA) recurrence.

RESULTS

-LVZ (n = 50) had higher total EAT volumes than matched controls (n = 48) (79 [58-109] vs. 51 [37-73] cm³, p < 0.001), higher LA EAT (9 [6.3-12] vs. 4.2 [2.9-5.8] cm³, p < 0.001), higher posterior LA EAT (9.7 [6.4-12] vs. 5.9 [2.8-7.2] cm³, p < 0.001) and higher right atrial EAT (7.3 [5.1-9.9] vs. 4.8 [3.2-6.5] cm³, p < 0.001). These differences remained even after correcting EAT for BMI and LA volumes. There were no significant differences in EAT volumes between -LVZ and +LVZ (n = 25). There was no significant association between EAT and AF recurrence postablation.

CONCLUSION

EAT volume is greater in AF patients without evidence of LA fibrosis compared to matched controls without AF. These findings support an association of EAT with AF pathogenesis even in the absence of LA fibrosis.

Obesity modifies the association between abnormal glucose metabolism and atrial fibrillation in older adults: A community-based longitudinal and prospective cohort study

PURPOSE

To investigate the modifying role of obesity in the association between abnormal glucose metabolism and atrial fibrillation (AF) risk in older individuals.

METHODS

From April 2007 to November 2011, 11663 participants aged ≥60 years were enrolled in Shandong area. Glucose metabolic status were determined using fasting plasma glucose and hemoglobin A1c levels, obesity determined using body mass index (BMI), waist-to-hip ratio (WHR), and visceral fat area (VFA). Obesity-associated metabolic activities were assessed using adiponectin-to-leptin ratio (ALR), galectin-3, and triglyceride-glucose index (TyG). New-onset AF was diagnosed by ICD-10.

RESULTS

During an average of 11.1 years of follow-up, 1343 participants developed AF. AF risks were higher in those with prediabetes, uncontrolled diabetes, and well-controlled diabetes than with normoglycemia. The hazard ratios were decreased by 14.79%, 40.29%, and 25.23% in those with prediabetes, 31.44%, 53.56%, and 41.90% in those with uncontrolled diabetes, and 21.16%, 42.38%, and 27.59% in those with well-controlled diabetes after adjusting for BMI, WHR, and VFA, respectively. The population attributable risk percentage of general obesity, central obesity, and high VFA for new-onset AF were 10.43%, 34.78%, and 31.30%, respectively. ALR, galectin-3, and TyG significantly mediated the association of BMI, WHR, and VFA with AF risk (all Padj. <0.001).

CONCLUSIONS

Obesity mediates the association between abnormal glucose metabolism and AF risk in older individuals. WHR is an effective modifier than BMI and VFA for moderating the association. ALR, TyG, and galectin-3 mediate the moderating effect of obesity on the association between abnormal glucose metabolism and AF risk.

Associations of socioeconomic status and chronic stress with incident atrial fibrillation among older adults: A prospective cohort study from the UK biobank

BACKGROUND

This study aimed to assess the relationship between socioeconomic status (SES) and chronic stress on the incidence of atrial fibrillation (AF) in older adults, and the potential role of chronic stress in the association.

METHODS

This study included 122,494 UK Biobank participants aged ≥60 years without AF at baseline. Latent class analysis was used to define the SES of participants. Chronic stress was measured using allostatic load (AL), and participants were categorized into low, medium and high AL groups. The Cox proportional hazards model, mediation, and interaction analyses were conducted to investigate the associations between SES, AL, and AF risk.

RESULTS

Low SES (hazard ratio [HR]: 1.10; 95 % confidence interval [CI]: 1.04-1.15) and high AL (HR: 1.37; 95 % CI: 1.30-1.45) were associated with an increased risk of AF, respectively. Individuals in the low SES and high AL groups exhibited the highest risk of AF compared to those in the high SES and low AL groups (HR: 1.46; 95 % CI: 1.32-1.61). We identified additive and multiplicative interactions in the low SES and high AL groups (relative risk due to interaction: 0.12 (95 % CI: 0.02-0.22); P for interaction = 0.0385). AL also exerted a partial mediating effect on the association between SES and the incidence of AF (mediation proportion: 17.3 %; 95 % CI: 5.9-28.7 %).

CONCLUSIONS

Our study revealed significant associations between SES, chronic stress, and the incidence of AF in older adults. Chronic stress was also shown to partially mediate the association.

MASLD Is Associated With an Increased Long-Term Risk of Atrial Fibrillation: An Updated Systematic Review and Meta-Analysis

BACKGROUND

Studies have reported an association between metabolic dysfunction-associated steatotic liver disease (MASLD) and an increased risk of developing atrial fibrillation (AF). However, the magnitude of the risk and whether this risk varies with the severity of MASLD remains uncertain.

METHODS

In this systematic review and meta-analysis, we searched three large electronic databases using predefined keywords to identify cohort studies (published up to 30 September 2024) in which MASLD was diagnosed by liver biopsy, imaging methods, International Classification of Diseases (ICD) codes, or blood-based scores. The primary outcome was the occurrence of AF based on ICD codes, medical records, or electrocardiograms. Meta-analysis was performed using random-effects modelling.

RESULTS

We identified 16 retrospective cohort studies with aggregate data on ~19.5 million individuals followed for a median of 7.2 years. MASLD was significantly associated with an increased risk of developing incident AF (random-effects hazard ratio 1.20, 95% CI 1.10-1.32; I2 = 92%). This risk did not appear to further increase with the severity of liver fibrosis (n = 3 studies; random-effects hazard ratio 1.22, 95% CI 1.18-1.26; I2 = 10%). The risk of AF remained significant even after adjusting for age, sex, body mass index, hypertension, Type 2 diabetes or other cardiometabolic risk factors. Sensitivity analyses did not modify these findings. The funnel plot and Egger's test showed no significant publication bias.

CONCLUSIONS

This updated and comprehensive meta-analysis provides evidence that MASLD is significantly associated with an increased long-term risk of developing incident AF. Further research is required to better decipher the link between MASLD and increased AF incidence.

Empagliflozin protects the heart from atrial fibrillation in rats through inhibiting the NF-κB/HIF-1α regulatory axis and atrial remodeling

Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia. The current study aimed to investigate the potential of empagliflozin (EMPA) to protect against acetylcholine (ACh)/calcium chloride (CaCl2)-induced AF in rats and elucidate the possible underlying mechanism of action. Rats were randomly assigned to five groups, as follows: CTRL group: received 1 ml/kg isotonic saline; AF group: received 1 ml/kg induction mixture of ACh/CaCl2 (60 µg ACh and 10 mg CaCl2 per ml); EMPA group: received 30 mg/kg EMPA; AF + EMPA10 group: received the induction mixture concurrent with 10 mg/kg EMPA; AF + EMPA30 group: received the induction mixture concurrent with 30 mg/kg EMPA. Our results showed that EMPA administration inhibited the AF-related electrocardiographic abnormalities and decreased the serum brain natriuretic peptide levels. EMPA treatment maintained the cardiac redox balance, as indicated by reduced levels of the lipid peroxidation biomarker malonaldehyde while enhancing the antioxidant glutathione levels. Moreover, EMPA markedly repressed ACh/CaCl2-induced C-reactive protein, tumor necrosis factor, and interleukin-6 production. Interestingly, EMPA administration strongly suppressed cardiac transforming growth factor beta1, collagen type I, and alpha-smooth muscle actin expression levels in the AF rats. These results were consistent with our histopathological findings, which revealed the ameliorative effect of EMPA on AF-induced inflammatory and fibrotic lesions. Mechanistically, EMPA dose-dependently downregulated nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor (HIF)-1α expressions. Besides, it attenuated the pro-apoptotic active caspase-3 while augmenting the anti-apoptotic B-cell lymphoma 2 expressions. Furthermore, EMPA dose-dependently suppressed cardiac phosphatidylinositol 3-kinase (PI3K)/Akt signaling. In conclusion, this study demonstrates that EMPA intervention, within AF induction, protects against ACh/CaCl2-induced AF in rats, exerting powerful antioxidant, anti-inflammatory, anti-fibrotic, and anti-apoptotic effects. These effects are mainly mediated through the targeting of the NF-κB/HIF-1α regulatory axis in a dose-dependent manner.

Troponin-T as predictor of mortality in patients attending the emergency department with atrial fibrillation

BACKGROUND

High-sensitive Troponin-T (hsTnT) is often increased in acute illness and may be of prognostic importance in patients with atrial fibrillation (AF). The aim of this study was to analyse the characteristics and data of patients attending the emergency department (ED) with AF to determine whether age-adjusted hsTnT levels can predict mortality.

METHODS

This retrospective, single centre, register-based cohort study included all patients ≥ 18 years attending the emergency department during 2018 and 2020 with a primary diagnosis at the ED of AF and sampled for hsTnT. Symptoms, comorbidities, lab results, and characteristics were registered. Patients were divided into groups based on hsTnT level (< 15, 15-50, and > 50 ng/L).

PRIMARY OUTCOMES

30-day and 1-year mortality.

RESULTS

A total of 625 patients were included (median age 72, and 45% female). All-cause mortality was 2% at 30 days and 8% at 1-year. The hazard ratio (HR) for 30-day mortality was 4.17 (95% confidence interval (CI) 0.49-35.79, p = 0.192) for hsTnT 15-50 ng/L and 9.64 (95% CI 0.98-95.30, p = 0.053) for hsTnT > 50 ng/L compared to hsTnT < 15 ng/L when adjusted for age. The HR for 1-year mortality was 4.82 (95% CI 1.81-12.82, p = 0.002) for hsTnT 15-50 ng/L and 9.70 (95% CI 3.27-28.74, p < 0.001) for hsTnT > 50 ng/L compared to hsTnT < 15 ng/L when adjusted for age.

CONCLUSIONS

Elevated hsTnT levels increase the risk for 30-day and 1-year mortality independently of age. Both mild and major elevation of hsTnT levels is associated with increased risk for 1-year mortality regardless of age.

Coffee consumption and adverse cardiovascular events in patients with atrial fibrillation

BACKGROUND

There is some evidence of reduced major cardiovascular event (MACE) rates associated with moderate coffee consumption in the general population. However, there is concern about the potential risks of coffee consumption in patients with atrial fibrillation (AF). Therefore, we aimed to investigate the association between coffee consumption and MACE in AF patients.

METHODS

Data of patients with documented AF enrolled in two large prospective observational multicenter cohort studies (Swiss-AF and Beat-AF) were analyzed. Follow-up information was obtained on a yearly basis. Coffee consumption was categorized into two main groups: "daily" and "not-daily" coffee consumers as well as additional subcategories. The primary endpoint was MACE, defined as a composite of stroke or systemic embolism, myocardial infarction, hospitalization for acute heart failure, and cardiovascular mortality. Secondary endpoints were the individual components of MACE and all-cause mortality. We performed time-updated multivariable adjusted Cox regression analyses to investigate the association between coffee consumption and MACE.

RESULTS

The incidence rate for MACE was 5.09 per 100 person-years (py) in daily and 7.49 per 100 py in not-daily consumers (median follow-up duration: 4.7 years). After adjustment for pre-selected confounding variables, daily coffee consumption was associated with a 23% lower hazard for MACE compared to not-daily consumption (hazard ratio (HR) (95% confidence interval (CI)) 0.77 (0.66; 0.89)). Patients with moderate coffee consumption (2-3 cups/day) had the lowest hazard for MACE compared to patients with not-daily coffee consumption (HR (95% CI) 0.74 (0.63; 0.87)).

CONCLUSIONS

In a population of AF patients, daily coffee consumption was associated with a reduced risk for MACE, hospitalization for acute heart failure, and all-cause mortality. The results were inconclusive for stroke or systemic embolism, myocardial infarction, and cardiovascular death. In this analysis, we found no evidence of an unfavourable association of daily coffee consumption in AF Patients with adverse outcome events.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02105844.

Clinical outcomes, management, healthcare resource utilization, and cost according to the CHA2DS2-VASc scores in Asian patients with nonvalvular atrial fibrillation

BACKGROUND

The prognosis among non-valvular atrial fibrillation (NVAF) patients with different CHA2DS2-VASc scores in the contemporary Asian population remains unclear. Additionally, there is a lack of research examining the disparities in management patterns, healthcare resource utilization (HCRU), and cost among these patients.

METHODS AND RESULTS

This retrospective cohort study assessed patients diagnosed with NVAF between January 2018 and July 2022. Patients were stratified into 3 cohorts by CHA2DS2-VASc scores: low-risk, intermediate-risk, and high-risk. One-year incidence rates and cumulative incidence of clinical outcomes (including ischemic stroke [IS], transient ischemic attack [TIA], arterial embolism [AE], and major bleeding [MB]) were calculated. Management patterns, HCRU, and cost were analyzed descriptively. Among 419,490 NVAF patients (mean age: 75.2 years, 45.1 % female), 16,541 (3.9 %) were classified as low-risk, 38,494 (9.2 %) as intermediate-risk, and 364,455 (86.9 %) as high-risk. The one-year incidence rates for IS, TIA, AE, and MB were 12.4 (95 % CI, 12.3-12.5), 1.1 (95 % CI, 1.0-1.1), 0.5 (95 % CI, 0.5-0.5), and 3.1 per 100 person-years (95 % CI, 3.1-3.2), with an increasing trend from the low-risk to the high-risk group, respectively. During follow-up, 16.4 % and 11.1 % of patients in the low-risk and high-risk cohorts received oral anticoagulants (OACs), respectively. In addition, significant differences in HCRU and cost were observed in these three cohorts.

CONCLUSION

This study demonstrates that contemporary Asian NVAF patients with higher CHA2DS2-VASc scores experience higher incidence of adverse outcomes and increased hospital resource consumption. Additionally, suboptimal management was present across all CHA2DS2-VASc score groups.

Bioinspired balloon catheter integrated with stretchable "flounder" electrodes under high voltage for uniform pulsed field ablation

Atrial fibrillation leads to severe diseases such as heart failure and strokes. While catheter ablation is prevalent for the treatment, existing techniques hardly can achieve both tissue selectivity and ablation uniformity. Here, we propose a bioinspired strategy for balloon-based pulsed field ablation (PFA) systems based on "flounder" electrodes. Inspired by a flounder skeleton and citrus peels, the microfabricated electrodes are ultrathin, stretchable, and have a scattered configuration, withstanding large balloon deformation (87% compression), high voltage (1200 volts), and owning exceptional tissue conformability (720° twists). Mechanical-electrical coupled stimulation optimizes balloon electrodes with hemispherical electric field uniformity. A water lily-inspired transfer printing method enables one-step integration of multielectrodes with the balloon. A comprehensive PFA system is complemented, achieving ablation depths of 3.8 millimeters (potato), 3.1 millimeters (rabbit), and 2.3 millimeters (swine) with good uniformity and electrophysiological isolation. These results shed light on the quantitative design of PFA systems, with high potential for more precise, safe, and effective catheter ablation therapies.

A Titin Missense Variant Causes Atrial Fibrillation

Rare and common genetic variants contribute to the risk of atrial fibrillation (AF). Although ion channels were among the first AF candidate genes identified, rare loss-of-function variants in structural genes such as TTN have also been implicated in AF pathogenesis partly by the development of an atrial myopathy, but the underlying mechanisms are poorly understood. While TTN truncating variants (TTNtvs) have been causally linked to arrhythmia and cardiomyopathy syndromes, the role of missense variants (mvs) remains unclear. We report that rare TTNmvs are associated with adverse clinical outcomes in AF patients and we have identified a mechanism by which a TTNmv (T32756I) causes AF. Modeling the TTN-T32756I variant using human induced pluripotent stem cell-derived atrial cardiomyocytes (iPSC-aCMs) revealed that the mutant cells display aberrant contractility, increased activity of a cardiac potassium channel (KCNQ1, Kv7.1), and dysregulated calcium homeostasis without compromising the sarcomeric integrity of the atrial cardiomyocytes. We also show that a titin-binding protein, the Four-and-a-Half Lim domains 2 (FHL2), has increased binding with KCNQ1 and its modulatory subunit KCNE1 in the TTN-T32756I-iPSC-aCMs, enhancing the slow delayed rectifier potassium current (I ks). Suppression of FHL2 in mutant iPSC-aCMs normalized the I ks, supporting FHL2 as an I ks modulator. Our findings demonstrate that a single amino acid change in titin not only affects function but also causes ion channel remodeling and AF. These findings emphasize the need for high-throughput screening to evaluate the pathogenicity of TTNmvs and establish a mechanistic link between titin, potassium ion channels, and sarcomeric proteins that may represent a novel therapeutic target.

Factors Correlated with Anticoagulation Choice in Primary Care Patients with Atrial Fibrillation and High Stroke Risk

BACKGROUND

The available data on anticoagulation therapy in real-world primary care settings for atrial fibrillation (AF) patients at high risk of stroke is limited.

OBJECTIVE

To evaluate anticoagulation therapy and elucidate the factors associated with the selection between direct oral anticoagulants (DOACs) and warfarin.

DESIGN AND PARTICIPANTS

This is a retrospective cohort study that included patients ≥ 18 years old at a large primary care outpatient group, a network of twenty clinics in the northeast United States between January 4, 2021 - January 4, 2023.

MAIN MEASURES

Oral anticoagulation therapy in AF patients with high risk of stroke (CHA2DS2-VASc score of ≥ 2 in men or ≥ 3 in women).

KEY RESULTS

Among the 3,118 adult patients with AF and high risk of stroke (median age 77.90, IQR 71.66-84.50 years; male 57.6%), we found that older age (aOR 1.40, p = 0.003), greater BMI (25-29.9: aOR 1.32, p = 0.048; ≥ 30 aOR 1.42, p = 0.010), and taking more than five medications (aOR 2.28, p < 0.001) were more likely to be on an oral anticoagulant. Among those taking an OAC, having Medicare as the sole coverage (aOR 0.53, p = 0.032), male gender (aOR 0.69, p = 0.011), worse renal function (aOR 0.80, p = 0.021), and higher CHA2DS2-VASc score (aOR 0.88, p = 0.024) are more likely to be on warfarin than a DOAC. Patients taking more than five medications daily (6-10 medications: aOR 1.92, p = 0.013; ≥ 16: aOR = 2.10, p = 0.006) were more likely to be on an anticoagulant and may receive a DOAC over warfarin.

CONCLUSIONS

AF with high stroke risk adult patients are more likely to be on an oral anticoagulant if they are older, having BMI ≥ 25, or taking more than five medications. Medicare as the sole coverage, male gender, worse renal function, and higher CHA2DS2-VASc scores are factors associated with greater warfarin usage, while patients taking over five daily medications are more likely to be prescribed DOACs.

Circ_0079480 facilitates proliferation, migration and fibrosis of atrial fibroblasts in atrial fibrillation by sponing miR-338-3p to activate the THBS1/TGF-β1/Smad3 signaling

BACKGROUND

Atrial fibrosis is associated with the pathogenesis of atrial fibrillation (AF). This study aims to discuss the function of circ_0079480 in atrial fibrosis and its underlying mechanism.

METHODS

In vitro and in vivo models of atrial fibrosis were established by using angiotensin II (Ang II) to treat human atrial fibroblasts (HAFs) and C57/B6J mice. qRT-PCR and western blot were used to examine the mRNA and protein expression levels. CCK-8, EdU, cell strach, and transwell assays were performed to determine the proliferation and migration of HAFs. Dual-luciferase reporter and RIP/RNA pull-down assays were explored to identify the interaction of miR-338-3p and circ_0079480/THBS1. HE and Masson's trichrome staining experiments were performed to analyze the histopathological change in mice atrial tissues.

RESULTS

Circ_0079480 expression was increased in AF patients' atrial tissues and Ang II-treated HAFs. Silencing circ_0079480 inhibited cell proliferation and migration and reduced fibrosis-associated gene expression in Ang II-treated HAFs. Circ_0079480 could target miR-338-3p to repress its expression. MiR-338-3p inhibitor blocked the inhibitory effects of circ_0079480 knockdown on HAFs proliferation, migration, and fibrosis. Thrombospondin-1 (THBS1) was confirmed as a downstream target of miR-338-3p, and circ_0079480 could sponge miR-338-3p to upregulate THBS1 expression. Moreover, silencing THBS1 suppressed Ang II-induced proliferation, migration, and fibrosis in HAFs. More importantly, depletion of circ_0079480 inactivated the THBS1/TGF-β1/Smad3 signaling by upregulating miR-338-3p. Mice experiments also confirmed the suppression of circ_0079480 knockdown on atrial fibrosis.

CONCLUSION

Circ_0079480 acts as a sponge of miR-338-3p to upregulate THBS1 expression and activate the TGF-β1/Smad3 signaling, finally promoting Ang II-induced atrial fibrosis.

Raw photoplethysmogram waveforms versus peak-to-peak intervals for machine learning detection of atrial fibrillation: Does waveform matter?

BACKGROUND

Machine learning-based analysis can accurately detect atrial fibrillation (AF) from photoplethysmograms (PPGs), however the computational requirements for analyzing raw PPG waveforms can be significant. The analysis of PPG-derived peak-to-peak intervals may offer a more feasible solution for smartphone deployment, provided the diagnostic utility is comparable.

AIMS

To compare raw PPG waveforms and PPG-derived peak-to-peak intervals as input signals for machine learning detection of AF.

METHODS

We developed specialized neural networks for raw waveform and peak-to-peak interval analyses and trained them on 7,704 PPGs from 106 patients from the TeleCheck-AF project. We evaluated the neural networks on 48,912 PPGs from 416 patients from the VIRTUAL-SAFARI project. We recorded computational requirements, sensitivity, positive predictive value (PPV), and F1 score.

RESULTS

With 1.6 million trainable parameters, the waveform model was more than 100 times as complex as the interval model (15,513 parameters) and required 19 times more computational power. In external validation, metrics were comparable between the interval and waveform models. For the interval model vs. the waveform model, sensitivity was 91.7 % vs. 81.9 % (p=0.4), PPV was 80.5 % vs. 84.5 % (p=0.3), and F1 score was 85.6 % vs. 81.3 % (p=0.5), respectively.

CONCLUSION

PPG-derived peak-to-peak intervals and PPG waveforms were equivalent as input signals to neural networks in terms of accurate AF detection. The reduced computational requirements of the interval model make it a more suitable option for deployment on digital end-user devices such as smartphones.

Serum Homocysteine and Atrial Fibrillation Recurrence after Catheter Ablation: A Meta-Analysis of 11 Cohort Studies Involving 2147 Patients

The relationship between serum homocysteine (Hcy) levels and atrial fibrillation (AF) recurrence following catheter ablation remains unclear. This meta-analysis aims to investigate this association. Comprehensive searches in PubMed, Web of Science, Embase, Wanfang, and China National Knowledge Infrastructure (CNKI) databases identified relevant studies published up to May 25, 2024. Cohort studies that measured pre-ablation serum Hcy levels and reported AF recurrence post-ablation were included. Data were analyzed using random-effects models by incorporating the potential influence of heterogeneity, with odds ratios (ORs) and 95% confidence intervals (CIs) calculated for the association between serum Hcy levels and AF recurrence. Eleven retrospective cohort studies involving 2147 patients with AF who underwent catheter ablation were analyzed. Higher pre-ablation serum Hcy levels were associated with an increased risk of AF recurrence (OR for per 1 μmol/l increment of Hcy: 1.22, 95% CI: 1.17 to 1.28, p<0.001; I²=0%). Additionally, studies that categorized Hcy levels also found a higher risk of AF recurrence in patients with elevated Hcy (OR for patients with a high versus a low serum Hcy: 2.75, 95% CI: 2.02 to 3.75, p <0.001; I²=0%). Funnel plots and Egger's regression test indicated low risks of publication bias. In conclusions, elevated pre-ablation serum Hcy levels are significantly associated with an increased risk of AF recurrence post-catheter ablation. These findings suggest that Hcy could be a valuable biomarker for predicting AF recurrence and may inform pre-ablation risk stratification. Further prospective studies are warranted to confirm these results.

Association of induced atrial fibrillation in the electrophysiology laboratory with endothelial dysfunction and documented atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) is a common arrhythmia that increases morbidity and mortality, as well as healthcare costs. The induction of AF (IAF) during programmed atrial pacing in an electrophysiological study (EPS) is a prevalent phenomenon that has been underappreciated by electrophysiologists. Despite extensive research on AF, only a few studies have focused on this phenomenon. The aim of our study was to investigate the association between history of AF and IAF and the underlying pathophysiological factors such as arterial stiffness, subclinical atherosclerosis, and impaired endothelial function.

METHODS

This cross-sectional and observational study included 87 patients who had palpitations and were scheduled for EPS. Patients underwent biochemical investigations, transthoracic echocardiography, carotid ultrasound, carotid-femoral artery pulse wave velocity (PWV), and flow-mediated dilatation (FMD) measurements before EPS. Patients were divided into two groups, AF-induced and non-induced in EPS, for further statistical analysis.

RESULTS

AF was induced in 16 of 87 patients (18.3%) included in the analysis. The FMD (%) was significantly lower (16.01 ± 10.1 vs. 8.7 ± 5.7, P = 0.022) and, remarkably, the proportion of patients with a history of AF was significantly higher (2.8% vs. 37.5%, P < 0.001) in the IAF group. ROC analysis showed that a documented AF and FMD predicted IAF, with AUC of 0.741 (p = 0.012) and 0.740 (p = 0.001), respectively. Logistic regression analysis revealed that FMD and history of AF were strong predictors of IAF (odds ratio [OR], 0.853; 95% confidence interval [CI] 0.737-0.988; P = 0.034, OR: 10.1, 95% CI 4.9-20.5; P = 0.003, respectively).

CONCLUSION

Endothelial dysfunction and documented AF were associated with IAF during EPS.

Androgen receptor pathway inhibitors and drug-drug interactions in prostate cancer

Prostate cancer represents a major global health challenge, necessitating efficacious therapeutic strategies. Androgen receptor pathway inhibitors (ARPIs) have become central to prostate cancer treatment, demonstrating significant effectiveness in both metastatic and non-metastatic contexts. Abiraterone acetate, by inhibiting androgen synthesis, deprives cancer cells androgens necessary for growth, while second-generation androgen receptor (AR) antagonists disrupt AR signaling by blocking AR binding, thereby impeding tumor progression. Given the predominance of prostate cancer in the elderly, who often present with multiple comorbidities requiring complex pharmacological regimens, the potential for drug-drug interactions with ARPIs is a critical concern. These interactions, particularly through pathways like CYP2D6 inhibition by abiraterone and CYP3A4 induction by enzalutamide and apalutamide, necessitate a thorough understanding to optimize therapeutic outcomes and minimize adverse effects. This review aims to delineate the efficacy of ARPIs in prostate cancer management and elucidate their interaction with common medications, highlighting the importance of vigilant drug management to optimize patient care.

Research Priorities for Atrial Fibrillation in Australia: A Statement From the Australian Cardiovascular Alliance Clinical Arrhythmia Theme

Atrial fibrillation (AF) is highly prevalent in the Australian community, ranking amongst the highest globally. The consequences of AF are significant. Stroke, dementia and heart failure risk are increased substantially, hospitalisations are amongst the highest for all cardiovascular causes, and Australians living with AF suffer from substantial symptoms that impact quality of life. Australian research has made a significant impact at the global level in advancing the care of patients living with AF. However, new strategies are required to reduce the growing incidence of AF and its associated healthcare demand. The Australian Cardiovascular Alliance (ACvA) has led the development of an arrhythmia clinical theme with the objective of tackling major research priorities to achieve a reduction in AF burden across Australia. In this summary, we highlight these research priorities with particular focus on the strengths of Australian research and the strategies needed to move forward in reducing incident AF and improving outcomes for those who live with this chronic condition.

Identification and Functional Investigation of SOX4 as a Novel Gene Underpinning Familial Atrial Fibrillation

Background: Atrial fibrillation (AF) signifies the most prevalent supraventricular arrhythmia in humans and may lead to cerebral stroke, cardiac failure, and even premature demise. Aggregating strong evidence points to genetic components as a cornerstone in the etiopathogenesis of familial AF. However, the genetic determinants for AF in most patients remain elusive. Methods: A 4-generation pedigree with idiopathic AF and another cohort of 196 unrelated patients with idiopathic AF as well as 278 unrelated healthy volunteers were recruited from the Chinese population of Han ethnicity. A family-based whole-exome sequencing examination followed by a Sanger sequencing assay in all research subjects was implemented. The functional impacts of the identified SOX4 mutations were explored via a dual-reporter assay. Results: Two new heterozygous SOX4 mutations, NM_003107.3: c.211C>T; p.(Gln71*) and NM_003107.3: c.290G>A; p.(Trp97*), were observed in the family and 1 of 196 patients with idiopathic AF, respectively. The two mutations were absent in the 278 control individuals. The biochemical measurements revealed that both Gln71*- and Trp97*-mutant SOX4 failed to transactivate GJA1 (Cx43). Moreover, the two mutations nullified the synergistic activation of SCN5A by SOX4 and TBX5. Conclusions: The findings first indicate SOX4 as a gene predisposing to AF, providing a novel target for antenatal genetic screening, individualized prophylaxis, and precision treatment of AF.

Translation of pathophysiological mechanisms of atrial fibrosis into new diagnostic and therapeutic approaches

Atrial fibrosis is one of the main manifestations of atrial cardiomyopathy, an array of electrical, mechanical and structural alterations associated with atrial fibrillation (AF), stroke and heart failure. Atrial fibrosis can be both a cause and a consequence of AF and, once present, it accelerates the progression of AF. The pathophysiological mechanisms leading to atrial fibrosis are diverse and include stretch-induced activation of fibroblasts, systemic inflammatory processes, activation of coagulation factors and fibrofatty infiltrations. Importantly, atrial fibrosis can occur in different forms, such as reactive and replacement fibrosis. The diversity of atrial fibrosis mechanisms and patterns depends on sex, age and comorbidity profile, hampering the development of therapeutic strategies. In addition, the presence and severity of comorbidities often change over time, potentially causing temporal changes in the mechanisms underlying atrial fibrosis development. This Review summarizes the latest knowledge on the molecular and cellular mechanisms of atrial fibrosis, its association with comorbidities and the sex-related differences. We describe how the various patterns of atrial fibrosis translate into electrophysiological mechanisms that promote AF, and critically appraise the clinical applicability and limitations of diagnostic tools to quantify atrial fibrosis. Finally, we provide an overview of the newest therapeutic interventions under development and discuss relevant knowledge gaps related to the association between clinical manifestations and pathological mechanisms of atrial fibrosis and to the translation of this knowledge to a clinical setting.

Kidney function, uric acid, and risk of atrial fibrillation: experience from the AMORIS cohort

BACKGROUND

Uric acid closely relates to both kidney disease and atrial fibrillation (AF), yet the extent to which it influences the kidney-AF association remains uncertain. We examined the relationship between kidney function and risk of AF, accounting for uric acid levels.

METHODS

A total of 308,509 individuals in the Swedish Apolipoprotein-Related Mortality Risk (AMORIS) cohort were included and their serum creatinine and uric acid were measured during 1985-1996. Ten-year incident AF was identified via linkage with the national registers. Glomerular filtration rate (eGFR) (ml/min/1.73 m2) was calculated with the 2009 Chronic Kidney Disease Epidemiology Collaboration equation. Hyperuricemia was defined as > 420 µmol/L for men and > 360 µmol/L for women.

RESULTS

Over a mean follow-up of 9.4 years, 10,007 (3.2%) incident AF cases occurred. After adjusting for age, sex, cardiovascular diseases, total cholesterol, triglycerides, and glucose, individuals with low eGFR (< 30 and 30-59 ml/min/1.73 m2 ) had a higher risk of AF compared to those with normal eGFR (60-89) (hazard ratio (HR) = 1.72, 95% confidence interval (CI):1.29-2.30; HR = 1.10, 95% CI: 1.03-1.18, respectively). After further adjusting for uric acid levels, the association disappeared (HR = 0.97, 95% CI: 0.72-1.30; HR = 0.93, 95% CI: 0.86-1.00, respectively). When stratifying by hyperuricemia yes/no, eGFR < 30 ml/min/1.73 m2 was associated with higher AF risk in a small group of individuals without hyperuricemia (HR = 2.58, 95% CI: 1.64-4.07).

CONCLUSION

Uric acid largely accounted for the relationship between eGFR and AF in this study. However, in individuals without hyperuricemia, eGFR in the lowest range (< 30 ml/min/1.73 m2) was still associated with increased risk of AF.

Improvements in Cardiopulmonary Exercise Test Results in Atrial Fibrillation Patients After Radiofrequency Ablation in Kazakhstan

This prospective study evaluates the impact of radiofrequency ablation (RFA) on cardiorespiratory indicators in patients with long-standing persistent atrial fibrillation admitted to the Heart Center UMC between January 2022 and April 2024 in Astana, Kazakhstan. The study aims to assess the functional cardiac benefits of RFA. Out of 717 registered atrial fibrillation patients, 104 were examined before and 3 months after ablation, focusing on cardiorespiratory parameters. A before-and-after analysis using linear mixed models was applied to evaluate changes in cardiorespiratory parameters post-RFA. Significant improvements were noted across various measures. VO2 max increased from 11.5 ± 4.4 mL/kg/min to 18.0 ± 4.5 mL/kg/min (p < 0.001). Oxygen uptake improved from 7.2 ± 2.6 mL/beat to 11.0 ± 3.4 mL/beat (p < 0.001). The 6-min walking test distance rose from 306 ± 82 m to 400 ± 48 m (p < 0.001). METs increased from 4.4 ± 1.6 to 8.0 ± 1.3 (p < 0.001). Heart rate at peak exercise decreased from 175.5 ± 18.6 to 147.2 ± 12.3 beats per minute (p < 0.001). NT-proBNP levels decreased from 1357 ± 1182 to 415 ± 339 pg/mL (p < 0.001). Patients with persistent atrial fibrillation undergoing RFA showed functional improvements in CPET indicators such as VO2 max, METs, O2 pulse, heart rate, and the 6-min walking test. Improvements were also seen in Nt-proBNP analysis. These results emphasize the need for longitudinal follow-up to optimize outcomes and minimize medical risks.

Diet and risk of atrial fibrillation: a systematic review

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia. Comprehensive modification of established AF risk factors combined with dietary interventions and breaking deleterious habits has been shown to reduce AF burden and recurrence. Numerous AF risk factors, such as diabetes, obesity or hypertension can be partially related to dietary and lifestyle choices. Therefore, dietary interventions may have potential as a therapeutic approach in AF. Based on available data, current guidelines recommend alcohol abstinence or reduction to decrease AF symptoms, burden, and progression, and do not indicate the need for caffeine abstention to prevent AF episodes (unless it is a trigger for AF symptoms). Uncertainty persists regarding harms or benefits of other dietary factors including chocolate, fish, salt, polyunsaturated and monounsaturated fatty acids, vitamins, and micronutrients. This article provides a systematic review of the association between AF and both dietary patterns and components. Additionally, it discusses potentially related mechanisms and introduces different strategies to assess patients' nutrition patterns, including mobile health solutions and diet indices. Finally, it highlights the gaps in knowledge requiring future investigation.

Pleiotropic Effects of Resveratrol on Aging-Related Cardiovascular Diseases-What Can We Learn from Research in Dogs?

Resveratrol (RES) is a polyphenol with natural anti-inflammatory and antioxidant properties. It is found in abundance in plants, i.e., grapes and mulberry fruit. In addition, synthetic forms of RES exist. Since the discovery of its specific biological properties, RES has emerged as a candidate substance not only with modeling effects on the immune response but also as an important factor in preventing the onset and progression of cardiovascular disease (CVD). Previous research provided strong evidence of the effects of RES on platelets, mitochondria, cardiomyocytes, and vascular endothelial function. In addition, RES positively affects the coagulation system and vasodilatory function and improves blood flow. Not only in humans but also in veterinary medicine, cardiovascular diseases have one of the highest incidence rates. Canine and human species co-evolved and share recent evolutionary selection processes, and interestingly, numerous pathologies of companion dogs have a human counterpart. Knowledge of the impact of RES on the cardiovascular system of dogs is becoming clearer in the literature. Dogs have long been recognized as valuable animal models for the study of various human diseases as they share many physiological and genetic similarities with humans. In this review, we aim to shed light on the pleiotropic effects of resveratrol on cardiovascular health in dogs as a translational model for human cardiovascular diseases.

Treatment of Subclinical Hyperthyroidism and Incident Atrial Fibrillation

CONTEXT

Treating overt hyperthyroidism prevents atrial fibrillation (AF). Though subclinical hyperthyroidism (SH) has been associated with AF, it is unknown whether treating SH prevents AF.

OBJECTIVE

We aimed to identify the association between treating SH and incident AF.

DESIGN

In a pharmacoepidemiologic retrospective cohort study, patients diagnosed with SH between 2000 and 2021 were followed.

PATIENTS

Outpatients ≥ 18 years with biochemical SH and without prior AF, hypothyroidism, thyroid cancer, pituitary disease, or pregnancy were included.

MAIN OUTCOMES

The primary outcome was incident AF. Secondary outcomes were ECG and echocardiographic features associated with AF.

RESULTS

Of 2169 patients screened, 360 (131 treated and 229 untreated) were followed up for a mean of 4.27 years. In the treated and untreated groups, AF occurred in 4 (3.1%) and 15 (6.6%) patients (p = 0.15), and AF incidence was 0.8% and 1.4%/year (p = 0.31), respectively. The hazard ratio (HR) for treatment as a time-dependent variable was 0.60 (95% CI 0.19-1.92; p = 0.39). As some cases of AF were documented nearly simultaneously with SH treatment, a sensitivity analysis was performed reassigning two patients diagnosed with AF < 30 days after starting SH treatment to the untreated group. Here, in the treated and untreated groups, AF occurred in 1.6% and 7.4% (p = 0.02), and AF incidence was 0.4% and 1.8%/year (p = 0.02), respectively. The HR was 0.25 (0.06-1.13; p = 0.07). There were no differences in ECG or echocardiographic features.

CONCLUSION

There was an overall trend towards lower incidence and prevalence of AF following treatment of SH, supporting the need for larger scale studies.

Real-world evidence of early rhythm control in patients with atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

The favorable benefits of early rhythm control (ERC) therapy in newly diagnosed patients with atrial fibrillation (AF) have been demonstrated in the EAST-AFNET 4 trial. However, the generalizability and applicability of ERC in real-world clinical settings remain inconclusive.

METHODS

We conducted a systematic search of the PubMed and Embase databases to identify observational studies published between January 2020 and February 2024 that focused on real-world evidence pertaining to ERC. The effectiveness and safety outcomes in our study were analogous to those evaluated in the EAST-AFNET 4 trial.

RESULTS

A total of 4 observational studies that fulfilled the inclusion criteria of EAST-AFNET 4 were included, involving 130,970 patients with AF, 30.7% of whom received ERC therapy. In our pooled analysis using the fixed-effects model, compared with rate control, ERC significantly decreased the occurrence risk of the primary composite outcome (hazard ratio [HR] 0.86, 95% confidence interval[CI] 0.82-0.91), cardiovascular death (HR 0.87, 95% CI 0.78-0.98), stroke (HR 0.80, 95% CI 0.73-0.87), and hospitalization with worsening heart failure (HR 0.91, 95% CI 0.84-0.99) or acute coronary syndrome (HR 0.72, 95% CI 0.59-0.87). In terms of safety outcomes, there were no differences in the composite safety outcome (HR 1.00, 95% CI 0.95-1.05) and all-cause death (HR 0.93, 95% CI 0.82-1.06) between the two studied groups.

CONCLUSIONS

ERC therapy showed favorable effectiveness outcomes compared with rate control, whereas the safety outcomes between the two therapeutic strategies did not differ significantly, supporting the benefits of ERC therapy over rate control in selected real-world patients with AF.

REGISTRATION

The study protocol was registered to PROSPERO (CRD42023443569).

Metabolic remodelling in atrial fibrillation: manifestations, mechanisms and clinical implications

Atrial fibrillation (AF) is a continually growing health-care burden that often presents together with metabolic disorders, including diabetes mellitus and obesity. Current treatments often fall short of preventing AF and its adverse outcomes. Accumulating evidence suggests that metabolic disturbances can promote the development of AF through structural and electrophysiological remodelling, but the underlying mechanisms that predispose an individual to AF are aetiology-dependent, thus emphasizing the need for tailored therapeutic strategies to treat AF that target an individual's metabolic profile. AF itself can induce changes in glucose, lipid and ketone metabolism, mitochondrial function and myofibrillar energetics (as part of a process referred to as 'metabolic remodelling'), which can all contribute to atrial dysfunction. In this Review, we discuss our current understanding of AF in the setting of metabolic disorders, as well as changes in atrial metabolism that are relevant to the development of AF. We also describe the potential of available and emerging treatment strategies to target metabolic remodelling in the setting of AF and highlight key questions and challenges that need to be addressed to improve outcomes in these patients.

Managing elderly patients with atrial fibrillation and multimorbidity: call for a systematic approach

INTRODUCTION

Atrial fibrillation (AF) is often accompanied by comorbidities. Not only cardiovascular but also non-cardiovascular comorbidities have been associated with AF. Multimorbidity is therefore a common finding in patients with AF, especially in elderly patients. Multimorbidity is associated with adverse outcomes, adds complexity to AF management, and poses a significant burden on healthcare costs. It is expected that the prevalence of elderly patients with multimorbidity will increase significantly. It is therefore crucial to outline implications for clinical practice and guide comprehensive multimorbidity management.

AREAS COVERED

This perspective article outlines multimorbidity in AF and the importance of comprehensive comorbidity management. It addresses current clinical practice guided by international guidelines and the need for integrated care including a patient-centered focus, comprehensive AF management, coordinated multidisciplinary care, and supporting technology. Moreover, it proposes a novel model of care delivery following a systematic approach to multimorbidity management.

EXPERT OPINION

Providing comprehensive care by means of a multidisciplinary team and patient engagement is crucial to provide optimal personalized care for elderly patients with AF and multimorbidity. A systematic integrated care approach seems promising, but further studies are needed to investigate the feasibility of a systematic approach and prioritization of comorbidity management in patients with multimorbidity.

Gene Therapy for Cardiovascular Disease: Clinical Perspectives

Cardiovascular disease (CVD) stands as one of the leading causes of death in the United States, with its prevalence steadily on the rise. Traditional therapeutic approaches, such as pharmacological treatment, cardiovascular intervention, and surgery, have inherent limitations. In response to these challenges, cardiac gene therapy has emerged as a promising alternative for treating CVD patients. However, several obstacles persist, including the low efficiency of gene transduction, immune reactions to vectors or transduced cells, and the occurrence of off-target effects. While preclinical research has demonstrated significant success in various CVD model in both small and large animals, the translation of these findings to clinical applications has, for the most part, yielded disappointing results, except for some early, albeit small, trials. This review aims to provide a comprehensive summary of recent preclinical and clinical studies on gene therapy for various CVDs. Additionally, we discuss the existing limitations and challenges that hinder the widespread clinical application of cardiac gene therapy.

Obstructive Sleep Apnea Characterization: A Multimodal Cross-Recurrence-Based Approach for Investigating Atrial Fibrillation

Obstructive sleep apnea (OSA) is believed to contribute significantly to atrial fibrillation (AF) development in certain patients. Recent studies indicate a rising risk of AF with increasing OSA severity. However, the commonly used apnea-hypopnea index in clinical practice may not adequately account for the potential cardiovascular risks associated with OSA. 1) Objective: to propose and explore a novel method for assessing OSA severity considering potential connection to cardiac arrhythmias. 2) Method: the approach utilizes cross-recurrence features to characterize OSA and AF by considering the relationships among oxygen desaturation, pulse arrival time, and heart-beat intervals. Multinomial logistic regression models were trained to predict four levels of OSA severity and four groups related to heart rhythm issues. The rank biserial correlation coefficient, rrb, was used to estimate effect size for statistical analysis. The investigation was conducted using the MESA database, which includes polysomnography data from 2055 subjects. 3) Results: a derived cross-recurrence-based index showed a significant association with a higher OSA severity (p 0.01) and the presence of AF (p 0.01). Additionally, the proposed index had a significantly larger effect, rrb, than the conventional apnea-hypopnea index in differentiating increasingly severe heart rhythm issue groups: 0.14 0.06, 0.33 0.10, and 0.41 0.07. 4) Significance: the proposed method holds relevance as a supplementary diagnostic tool for assessing the authentic state of sleep apnea in clinical practice.

Impact of Non-Valvular Atrial Fibrillation on Mitral Valve Anatomic Features: A Study of Three-Dimensional Mitral Valve by Transesophageal Echocardiography and Automatic Analysis Software

BACKGROUND/AIM

Mitral regurgitation (MR) is frequently observed in non-valvular atrial fibrillation (NVAF) patients and is a significant risk factor for its progression. This study aims to investigate the three-dimensional anatomical characteristics of the mitral valve (MV) in patients with different types of NVAF to elucidate the underlying mechanisms of MR.

METHODS

A retrospective analysis was conducted on 82 paroxysmal atrial fibrillation patients (PAF group) and 66 persistent atrial fibrillation patients (PerAF group) who underwent real-time three-dimensional transesophageal echocardiography (RT 3D-TEE) before initial ablation. Additionally, 30 patients undergoing RT 3D-TEE for the assessment of patent foramen ovale were selected as the control group. Basic echocardiographic variables were measured, left atrioventricular volume and strain parameters were calculated using automated software (Dynamic-HeartModel and AutoStrain). MV anatomic features were analyzed using the 4D-MV Assessment software (TomTec Imaging Systems).

RESULTS

The maximum left atrial volume (LAVmax) was highest in the PerAF group, followed by the PAF and control groups, with statistically significant differences (p < 0.01). Left atrial reservoir strain (LASr) showed an opposite trend, being the lowest in the PerAF group (p < 0.01). The proportion of moderate to severe MR was significantly higher in the PerAF group (27.3%) compared to the PAF group (11.0%) (p < 0.01). Compared to controls, the AF groups exhibited mitral annular (MA) dilation, flattening of the MA plane, and increased leaflet area (all p < 0.05). Correlation analysis between effective regurgitant orifice area (EROA) and left atrioventricular structure and function parameters, as well as various annular parameters, showed that EROA was significantly correlated with left ventricular end-diastolic volume (LVEDV), LAVmax, LASr, anterior and posterior diameter, annular area, ratio of annular height to commissural diameter (AH/CD ratio), posterior leaflet area, posterior leaflet length, and the C-shaped annulus length (all p < 0.05).

CONCLUSIONS

Significant remodeling of the MV apparatus occurs in NVAF patients, with more pronounced changes in PerAF patients, contributing to a higher incidence of moderate to severe MR. RT 3D-TEE-based MV automated assessment offers significant advantages in accurately diagnosing MV remodeling and supporting the evaluation of MR in NVAF patients.

Inflammation in liver fibrosis and atrial fibrillation: A prospective population-based proteomic study

Background & Aims

Elevated liver stiffness has been associated with atrial fibrillation (AFib) in the general population. The mechanism underlying this association is unclear.

Methods

Participants were recruited from the general population and prospectively enrolled with follow-up for 5 years. The fibrosis-4 (FIB-4) index was used as a surrogate marker for liver fibrosis. Proteomics analysis was performed using the 92-target Olink inflammation panel. Validation was performed using the NAFLD fibrosis score (NFS), aspartate aminotransferase to platelet index (APRI), and repeat confirmation proteomics.

Results

A sample of 11,509 participants with a mean age of 54.0 ± 11.1 years, 51.3% women, and a median FIB-4 index of 0.85 (0.65/1.12), was used. The FIB-4 index was predictive for prevalent (FIB-4 index adjusted odds ratio (aOR) per SD: 1.100 with 95% CI 1.011-1.196; p = 0.026), but not incident AFib (log[FIB-4 index]) adjusted hazard ratio: 1.125 with 95% CI 0.943-1.342, p = 0.19). Elastic net regularized regression identified CCL20, DNER, and CXCL10 for prevalent AFib, and AXIN1, CXCL10, and Flt3L for the log(FIB-4 index) (per SD) as most important in common regulated proteins. The relationship between the FIB-4 index, the identified proteins, and AFib was relevant and reproduced at the 5-year follow-up for CXCL10 after adjusting for confounders (log[FIB-4 index] per SD - CXCL10 [per SD] adjusted β 0.160 with 95% CI 0.127-0.194, p <0.0001; CXCL10 [per SD] - AFib aOR 1.455 with 95% CI 1.217-1.741, p <0.0001), reproduced using the NFS and APRI, and corresponding to increased serum levels.

Conclusions

CXCL10 is linked to liver fibrosis, as determined by the FIB-4 index, and to prevalent AFib.

Impact and implications

How elevated liver stiffness relates to atrial fibrillation in the general population remains to be clarified. We hypothesized that systemic inflammation against a background of liver fibrosis produced from metabolic dysfunction-associated steatotic liver disease (MASLD), is involved in the pathophysiology of atrial fibrillation. Using large-scale targeted proteomics, we found that CXCL10 is related to both liver fibrosis, as defined by the fibrosis-4 index, and to atrial fibrillation. These results can aid evidence-based drug development for patients with atrial fibrillation and MASLD-related liver fibrosis.

Pathways to precision medicine: deciphering the secrets of physiological and pathological atrial enlargement

Cardiac functional, morphological, and histological analysis, coupled with liquid chromatography and mass spectrometry, of two transgenic mouse models with cardiomyocyte-specific overexpression of insulin-like growth factor 1 receptor (IGF1R) or a dominant-negative PI3K mutant (DCM-dnPI3K) revealed distinctive functional and molecular profiles during physiological (driven by IGF1R overexpression) and pathological (driven by dn-PI3K overexpression) atrial remodeling. The current study confirmed previously reported findings, including ventricular dilatation and enhanced systolic function with no evidence of arrhythmia in IGF1R model, as well as ventricular hypertrophy and decreased systolic function with intermittent atrial fibrillation in DCM-dnPI3K model. Novel findings obtained from the left atrial (LA) characterization of female mice revealed that physiological atrial enlargement resulted from increased atrial myocyte size and was associated with preserved atrial function, as determined by maintained LA ejection fraction (EF). The proteomic profile of IGF1R transgenic (Tg) mice was enriched for metabolic remodeling and showed a protein expression pattern similar to that of healthy human atria; on the other hand, pathological atrial enlargement resulted from increased atrial fibrosis with normal myocyte size and was associated with impaired atrial function due to a reduced LA EF. The proteomic profile of DCM-dnPI3K mice was enriched to both metabolic and structural remodeling and showed a protein expression pattern similar to that of human AF atria.

A Crowdsourced AI Framework for Atrial Fibrillation Detection in Apple Watch and Kardia Mobile ECGs

Background: Atrial fibrillation (AFib) detection via mobile ECG devices is promising, but algorithms often struggle to generalize across diverse datasets and platforms, limiting their real-world applicability. Objective: This study aims to develop a robust, generalizable AFib detection approach for mobile ECG devices using crowdsourced algorithms. Methods: We developed a voting algorithm using random forest, integrating six open-source AFib detection algorithms from the PhysioNet Challenge. The algorithm was trained on an AliveCor dataset and tested on two disjoint AliveCor datasets and one Apple Watch dataset. Results: The voting algorithm outperformed the base algorithms across all metrics: the average of sensitivity (0.884), specificity (0.988), PPV (0.917), NPV (0.985), and F1-score (0.943) on all datasets. It also demonstrated the least variability among datasets, signifying its highest robustness and effectiveness in diverse data environments. Moreover, it surpassed Apple's algorithm on all metrics and showed higher specificity but lower sensitivity than AliveCor's Kardia algorithm. Conclusions: This study demonstrates the potential of crowdsourced, multi-algorithmic strategies in enhancing AFib detection. Our approach shows robust cross-platform performance, addressing key generalization challenges in AI-enabled cardiac monitoring and underlining the potential for collaborative algorithms in wearable monitoring devices.

Altered ventricular repolarisation dynamic: the missing link between obstructive sleep apnoea and sudden death?

Research is needed to explore the broader links between oxygen desaturation episodes, ventricular repolarisation instability and genesis of malignant arrhythmic events https://bit.ly/3WeQNHy.

Atrial Fibrillation and Heart Failure With Reduced Ejection Fraction: New Assessment of an Old Problem

Atrial fibrillation (AF) and heart failure (HF)-specifically, heart failure with reduced ejection fraction (HFrEF)-often coexist, and each contributes to the propagation of the other. This relationship extends from the mechanistic and physiological to clinical syndromes, quality of life, and long-term cardiovascular outcomes. The risk factors for AF and HF overlap and create a critical opportunity to prevent adverse outcomes among patients at greatest risk for either condition. Increasing recognition of the linkages between AF and HF have led to widespread interest in designing diagnostic, predictive, and interventional strategies targeting all aspects of disease, from identifying genetic predisposition to addressing social determinants of health. Advances across this spectrum culminated in updated multisociety guidelines for management of AF, which includes specific consideration of comorbid AF and HF. This review expands on these guidelines by further highlighting relevant clinical trial findings and providing additional context for the evolving recommendations for management in this important and growing population.

Will Factor XI Inhibitors Replace Current Anticoagulants for Stroke Prevention in Atrial Fibrillation?

PURPOSE OF REVIEW

This review provides an overview of the factor XI (FXI) inhibitor hypothesis for the development of novel anticoagulants which may be safer to those currently used in clinical practice and describes preliminary clinical data from phase 2 dose-ranging studies of patients with atrial fibrillation.

RECENT FINDINGS

Recent data from phase 2 dose ranging studies demonstrate substantial reductions in bleeding with FXI pathway inhibition compared with currently approved anticoagulants. However, larger studies are necessary to demonstrate efficacy of FXI inhibition for stroke prevention in atrial fibrillation. FXI pathway inhibition holds great promise for revolutionizing the landscape of anticoagulation for atrial fibrillation, primarily by reducing bleeding risk; however, further data are necessary to demonstrate efficacy.

Atrial Fibrillation in Hypertrophic Cardiomyopathy

Atrial fibrillation (AF) is common among patients with hypertrophic cardiomyopathy (HCM) with a prevalence greater than 25%. AF in HCM is associated with a high risk of stroke and can be a marker of more advanced cardiomyopathy. Although, it frequently results in cardiac hemodynamic changes which are poorly tolerated, it can be subclinical. Thus, prompt diagnosis and adequate management of AF are essential to minimizing AF-related adverse outcomes in HCM. All HCM patients should be screened for AF regularly, and those with high-risk features should be screened more frequently preferably with extended ambulatory monitoring. Once AF is detected, oral anticoagulation should be initiated. Both general and HCM-specific modifiable risk factors should be addressed and assessment for cardiomyopathy progression should be performed. Although no randomized controlled studies have compared rate versus rhythm control in HCM, early rhythm control could be considered to prevent further LA remodeling.

Atrial cardiopathy biomarkers and atrial fibrillation in the ARCADIA trial

BACKGROUND

ARCADIA compared apixaban to aspirin for secondary stroke prevention in patients with cryptogenic stroke and atrial cardiopathy. One possible explanation for the neutral result is that biomarkers used did not optimally identify atrial cardiopathy. We examined the relationship between biomarker levels and subsequent detection of AF, the hallmark of atrial cardiopathy.

METHODS

Patients were randomized if they met criteria for atrial cardiopathy, defined as P-wave terminal force >5000 μV*ms in ECG lead V1 (PTFV1), NT-proBNP >250 pg/mL, or left atrial diameter index (LADI) ⩾3 cm/m2. For this analysis, the outcome was AF detected per routine care.

RESULTS

Of 3745 patients who consented to screening for atrial cardiopathy, 254 were subsequently diagnosed with AF; 96 before they could be randomized and 158 after randomization. In unadjusted analyses, ln(NT-proBNP) (RR per SD, 1.99; 95% CI, 1.85-2.13), PTFV1 (RR per SD, 1.15; 95% CI, 1.03-1.28) and LADI (RR per SD, 1.34; 95% CI, 1.20-1.50) were associated with AF. In a model containing all 3 biomarkers, demographics, and AF risk factors, age (RR per 10 years, 1.24; 95% CI, 1.09-1.41), ln(NT-proBNP) (RR per SD, 1.88; 95% CI, 1.67-2.11) and LADI (RR per SD, 1.25; 95% CI, 1.14-1.37) were associated with AF. These three variables together had a c-statistic of 0.82 (95% CI, 0.79-0.85) but only modest calibration. Discrimination was attenuated in sensitivity analyses of patients eligible for randomization who may have been more closely followed for AF.

CONCLUSIONS

Biomarkers used to identify atrial cardiopathy in ARCADIA were moderately predictive of subsequent AF.

Transcriptomic analysis of epicardial adipose tissue reveals the potential crosstalk genes and immune relationship between type 2 diabetes mellitus and atrial fibrillation

BACKGROUND

The complex relationship between atrial fibrillation (AF) and type 2 diabetes mellitus (T2DM) suggests a potential role for epicardial adipose tissue (EAT) that requires further investigation. This study employs bioinformatics and experimental approaches to clarify EAT's role in linking T2DM and AF, aiming to unravel the biological mechanisms involved.

METHOD

Bioinformatics analysis initially identified common differentially expressed genes (DEGs) in EAT from T2DM and AF datasets. Pathway enrichment and network analyses were then performed to determine the biological significance and network connections of these DEGs. Hub genes were identified through six CytoHubba algorithms and subsequently validated biologically, with further in-depth analyses confirming their roles and interactions. Experimentally, db/db mice were utilized to establish a T2DM model. AF induction was executed via programmed transesophageal electrical stimulation and burst pacing, focusing on comparing the incidence and duration of AF. Frozen sections and Hematoxylin and Eosin (H&E) staining illuminated the structures of the heart and EAT. Moreover, quantitative PCR (qPCR) measured the expression of hub genes.

RESULTS

The study identified 106 DEGs in EAT from T2DM and AF datasets, underscoring significant pathways in energy metabolism and immune regulation. Three hub genes, CEBPZ, PAK1IP1, and BCCIP, emerged as pivotal in this context. In db/db mice, a marked predisposition towards AF induction and extended duration was observed, with HE staining verifying the presence of EAT. Additionally, qPCR validated significant changes in hub genes expression in db/db mice EAT. In-depth analysis identified 299 miRNAs and 33 TFs as potential regulators, notably GRHL1 and MYC. GeneMANIA analysis highlighted the hub genes' critical roles in stress responses and leukocyte differentiation, while immune profile correlations highlighted their impact on mast cells and neutrophils, emphasizing the genes' significant influence on immune regulation within the context of T2DM and AF.

CONCLUSION

This investigation reveals the molecular links between T2DM and AF with a focus on EAT. Targeting these pathways, especially EAT-related ones, may enable personalized treatments and improved outcomes.

Improved Proteinuria May Attenuate the Risk of Atrial Fibrillation: A Nationwide Population-Based Cohort Study

Background/Objectives: Proteinuria is documented as a risk factor for atrial fibrillation (AF) and can manifest in either reversible or continued forms. Our objective was to examine the relationship between the change in status for proteinuria and the risk of AF in a longitudinal cohort study on the general population nationwide. Methods: We included participants (n = 1,708,103) who underwent repetitive health examinations. The presence of proteinuria was determined by dipstick urinalysis results. The outcome was the occurrence of AF (International Classification of Diseases-10 code: I48). Results: All included participants, 1,666,111 (97.5%), 17,659 (1.0%), 19,696 (1.2%), and 4637 (0.3%), were categorized into groups of proteinuria-free, improved, progressed, and persistent, respectively. During a median follow-up of 14.5 years, 41,190 (2.4%) cases of AF occurred. In the multivariable analysis, the risk of AF was increased as the initial severity was more severe in the proteinuria-improved and proteinuria-persistent groups (p for trend < 0.001). In a further pairwise comparison, the proteinuria-improved group had a relatively lower risk of AF compared to the proteinuria-persistent group (HR: 0.751, 95% CI: 0.652-0.865, p < 0.001). Conclusions: Our study showed that the risk of AF can change according to alterations in proteinuria status. Notably, recovering from proteinuria can also be considered a modifiable risk factor for AF.

Distinct functional and molecular profiles between physiological and pathological atrial enlargement offer potential new therapeutic opportunities for atrial fibrillation

Atrial fibrillation (AF) remains challenging to prevent and treat. A key feature of AF is atrial enlargement. However, not all atrial enlargement progresses to AF. Atrial enlargement in response to physiological stimuli such as exercise is typically benign and reversible. Understanding the differences in atrial function and molecular profile underpinning pathological and physiological atrial remodelling will be critical for identifying new strategies for AF. The discovery of molecular mechanisms responsible for pathological and physiological ventricular hypertrophy has uncovered new drug targets for heart failure. Studies in the atria have been limited in comparison. Here, we characterised mouse atria from (1) a pathological model (cardiomyocyte-specific transgenic (Tg) that develops dilated cardiomyopathy [DCM] and AF due to reduced protective signalling [PI3K]; DCM-dnPI3K), and (2) a physiological model (cardiomyocyte-specific Tg with an enlarged heart due to increased insulin-like growth factor 1 receptor; IGF1R). Both models presented with an increase in atrial mass, but displayed distinct functional, cellular, histological and molecular phenotypes. Atrial enlargement in the DCM-dnPI3K Tg, but not IGF1R Tg, was associated with atrial dysfunction, fibrosis and a heart failure gene expression pattern. Atrial proteomics identified protein networks related to cardiac contractility, sarcomere assembly, metabolism, mitochondria, and extracellular matrix which were differentially regulated in the models; many co-identified in atrial proteomics data sets from human AF. In summary, physiological and pathological atrial enlargement are associated with distinct features, and the proteomic dataset provides a resource to study potential new regulators of atrial biology and function, drug targets and biomarkers for AF.

Dietary interventions in the management of atrial fibrillation

Atrial fibrillation (AF) represents the most common cardiac arrhythmia with significant morbidity and mortality implications. It is a common cause of hospital admissions, significantly impacts quality of life, increases morbidity and decreases life expectancy. Despite advancements in treatment options, prevalence of AF remains exceptionally high. AF is a challenging disease to manage, not just clinically but also financially. Evidence suggests lifestyle modification, including dietary changes, plays a significant role in the treatment of AF. This review aims to analyze the existing literature on the effects of dietary modifications on the incidence, progression, and outcomes of atrial fibrillation. It examines various dietary components, including alcohol, caffeine, omega-3 polyunsaturated fatty acids and minerals, and their impact on AF incidence, progression, and outcomes. The evidence surrounding the effects of dietary patterns, such as the Mediterranean and low carbohydrate diets, on AF is also evaluated. Overall, this review underscores the importance of dietary interventions as part of a comprehensive approach to AF management and highlights the need for further research in this emerging field.

Exploring Atrial Fibrillation: Understanding the Complex Relation Between Lifestyle and Genetic Factors

Cardiovascular diseases (CVDs) are the leading cause of death worldwide across diverse ethnic groups. Among these, atrial fibrillation (AF) stands as one of the most prevalent types of arrhythmias and the primary cause of stroke. Risk factors associated with AF include alcohol consumption, aging, high blood pressure, hypertension, inflammation, and genetic factors. A family history of CVD could indicate an increased risk. Consequently, genetic, and genomic testing should be performed to identify the molecular etiology of CVDs and assess at-risk patients. It is important to note that CVDs are the results of the complex interplay of genes and environmental factors, including ethnicity. In this case, the proband's clinic story includes a history of smoking abuse for 10 years (10 cigarettes per day), obesity, hypertension, and an associated familial history. These risk factors, along with genetic variants, could trigger the early onset of AF. In recent years, genetic and genomic studies have significantly advanced our understanding of CVD etiology, given that next-generation sequencing (NGS) allows for the identification of genetic variants that could contribute to these pathologies. Furthermore, NGS facilitates early diagnosis, personalized pharmacological approaches, and identification of novel biomarkers. Thus, NGS is a valuable tool in CVD management. However, such studies are limited in Ecuador, a low- and middle-income country. Several challenges contribute to this gap, encompassing economic, infrastructural, and educational obstacles. Notably, the cost of genetic and genomic studies may also pose a barrier, restricting access to a portion of the population. In this case report, we present a 56-year-old Ecuadorian woman, who has been diagnosed with AF; however, after performing NGS no disease-associated variants were found, despite having strong clinical signs and symptoms. In summary, this case report contributes valuable insights into the complex interplay between genetic and lifestyle factors in the development and management of AF. The case report aims to underscore the potential impact of genetic variants on disease risk, even when classified as variants of uncertain significance, and the importance of an integral approach to patient care that includes genetic screening, lifestyle interventions, and tailored pharmacological treatment.

NAFLD and MAFLD independently increase the risk of major adverse cardiovascular events (MACE): a 20-year longitudinal follow-up study from regional Australia

BACKGROUND AND AIMS

The association between fatty liver disease (FLD) and cardiovascular disease (CVD) in an Australian context has yet to be defined. The primary aim of this study was to investigate the association between FLD and 3-point major adverse cardiovascular events (MACE).

METHODS

This was a longitudinal follow-up study of a randomly sampled adult cohort from regional Australia between 2001 and 2003. Baseline covariates included demographic details, anthropometry, health and lifestyle data, and laboratory tests. Non-alcoholic fatty liver disease (NAFLD) and metabolic-(dysfunction) associated fatty liver disease (MAFLD) were diagnosed in participants with fatty liver index (FLI) ≥ 60 and meeting other standard criteria. ICD-10 codes were used to define clinical outcomes linked to hospitalisations. Three-point MACE defined as non-fatal myocardial infarction (MI) and cerebrovascular accident (CVA) and CVD death.

RESULTS

In total, 1324 and 1444 participants met inclusion criteria for NAFLD and MAFLD analysis, respectively. Over 23,577 and 25,469 person-years follow-up, NAFLD and MAFLD were independent predictors for 3-point MACE, adjusting for demographic covariates and known cardiometabolic risk factors, whilst considering non-CVD death as a competing event (NAFLD: sub-hazard ratio [sHR] 1.56, 95% confidence interval [CI 1.12-2.19]; MAFLD: sHR 1.51, 95% CI 1.11-2.06). The results held true on several sensitivity analyses.

CONCLUSIONS

Both forms of FLD increase the risk for CVD independent of traditional cardiometabolic risk factors.

Practical approach for atrial cardiomyopathy characterization in patients with atrial fibrillation

Atrial fibrillation (AF) causes progressive structural and electrical changes in the atria that can be summarized within the general concept of atrial remodeling. In parallel, other clinical characteristics and comorbidities may also affect atrial tissue properties and make the atria susceptible to AF initiation and its long-term persistence. Overall, pathological atrial changes lead to atrial cardiomyopathy with important implications for rhythm control. Although there is general agreement on the role of the atrial substrate for successful rhythm control in AF, the current classification oversimplifies clinical management. The classification uses temporal criteria and does not establish a well-defined strategy to characterize the individual-specific degree of atrial cardiomyopathy. Better characterization of atrial cardiomyopathy may improve the decision-making process on the most appropriate therapeutic option. We review current scientific evidence and propose a practical characterization of the atrial substrate based on 3 evaluation steps starting with a clinical evaluation (step 1), then assess outpatient complementary data (step 2), and finally include information from advanced diagnostic tools (step 3). The information from each of the steps or a combination thereof can be used to classify AF patients in 4 stages of atrial cardiomyopathy, which we also use to estimate the success on effective rhythm control.

Characteristics and Clinical Outcomes of Patients Hospitalized for Acute Heart Failure Who Develop Atrial Fibrillation or Convert to Sinus Rhythm

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia in acute heart failure (AHF), with a prevalence of approximately 35%. However, little is known about the clinical characteristics and outcomes of in-hospital conversion from AF to sinus rhythm and vice versa.

METHODS

In a post hoc secondary analysis of the randomized, double-blind, placebo-controlled PROTECT trial in patients with AHF, we identified 4 groups of patients: AF at admission and in-hospital conversion to sinus rhythm (n = 44); in-hospital development of AF (n = 31); persistent AF (n = 278); and continuous sinus rhythm (n = 410).

RESULTS

Conversion from AF to sinus rhythm (13.7%) and from sinus rhythm to AF (7.0%) occurred only in a minority of patients. Patients with AF who converted to sinus rhythm were more often classified as being in New York Heart Association class IV, had higher heart rates and higher respiratory rates at hospital admission, whereas patients who developed AF were older, more likely to be female and had the highest ejection fractions compared to continuous sinus rhythm (all P < 0.05). Conversion to sinus rhythm or development of AF occurred mainly within the first 24 hours after hospital admission. Patients with persistent AF and those who developed AF had longer median lengths of hospital stay (8 vs 7 days; P < 0.001 and 9 vs 7 days; P < 0.001, respectively), compared to those with continuous sinus rhythm. In both univariable and multivariable analyses, there was no significant association between the AF groups and the primary clinical outcomes of either 180-day all-cause mortality or 60-day death or readmission for heart failure.

CONCLUSION

In patients hospitalized for AHF, only few converted from AF to sinus rhythm or sinus rhythm to AF. Although development of AF or persistent AF was associated with longer lengths of hospitalization, midterm mortality and readmission rates were similar in the groups.

Patterns of atrial fibrillation, relevant cardiac structural and functional changes predict functional and cognitive outcomes in patients with ischemic stroke and atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) pattern, relevant cardiac changes are important predictors of outcomes in AF, but their impact on patients with ischemic stroke and AF remained unclear. We aimed to explore the impact of AF patterns, cardiac structural and functional markers on long-term functional and cognitive outcomes in ischemic stroke patients with AF.

METHODS

Ischemic stroke patients diagnosed with AF were enrolled in this retrospective cohort study. AF pattern was defined by both traditional and novel classification, in which patients were divided into AF diagnosed after stroke (AFDAS) and known before stroke (KAF). Left atrial (LA) diameter, left ventricular ejection fraction (LVEF), natriuretic peptide (BNP) and cardiac troponin (cTnI) were dichotomized according to the median value. Outcomes include poor functional outcome and cognitive impairment at the 1-year follow-up. Multivariable logistic regression was performed to validate the association between AF pattern, parameters of cardiac change and functional and cognitive outcome.

RESULTS

A total of 377 patients were included. Non-paroxysmal AF patients had a higher risk of poor functional outcome (OR = 3.59, P < 0.0001) and cognitive impairment (OR = 2.38, P = 0.019) than paroxysmal AF patients, while there were no differences between AFDAS and KAF. Lower LVEF (OR = 1.83, P = 0.045) and higher BNP (OR = 2.66, P = 0.001) were associated with poor functional outcome. Lower LVEF (OR = 2.86, P = 0.004), higher LA diameter (OR = 2.72, P = 0.008) and BNP (OR = 2.31, P = 0.023) were associated with cognitive impairment.

CONCLUSIONS

AF type and related cardiac markers can serve as predictors for poor functional and cognitive outcomes. Comprehensive cardiac assessment and monitoring should be strengthened after stroke.

Life's Essential 8, Genetic Susceptibility, and Incident Cardiac Arrhythmias: A Population-Based Prospective Cohort Study

BACKGROUND

Ideal cardiovascular health (CVH) has been associated with reduced cardiovascular disease risk and mortality, but its association with cardiac arrhythmias was still unsettled. In this prospective cohort study, we investigated the relationship between CVH and subsequent arrhythmias risk, including atrial fibrillation (AF)/flutter, ventricular arrhythmias, and bradyarrhythmias.

METHODS

Data from 287,264 participants initially free of arrhythmias in the UK Biobank were included in the analysis. Cox regression models were used to examine the relationship between CVH levels calculated by the American Heart Association's Life's Essential 8 (LE8) metrics, with cardiac arrhythmias risk.

RESULTS

During a median follow-up period of 12.8 years, 16,802 incident AF, 2186 incident ventricular arrhythmias, and 4128 incident bradyarrhythmias were identified. After adjustment for confounding factors, participants with high initial CVH levels had significantly lower risks for AF (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.59-0.68), ventricular arrhythmias (HR, 0.48; 95% CI, 0.40-0.59), and bradyarrhythmias (HR, 0.64; 95% CI, 0.55-0.74) compared with those with low CVH levels. Furthermore, each standard deviation (SD) increase in LE8 scores was associated with a 15% lower risk of AF, 21% for ventricular arrhythmias, and 13% for bradyarrhythmias, respectively. In addition, a significant interaction was observed between CVH levels and the genetic risk of AF (P for interaction, 0.021). The reverse correlation seemed to be more noticeable in individuals with a lower genetic susceptibility to AF.

CONCLUSIONS

We concluded that higher levels of CVH, estimated by the LE8 metrics, were associated with significantly reduced risks of AF, ventricular arrhythmias, and bradyarrhythmias.