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Digoxin is used in children with heart failure and tachyarrhythmia. Its use in patients with single ventricle anatomy has increased following evidence of improved interstage survival after the Norwood procedure. Digoxin has a narrow therapeutic window and may alter serum potassium balance, inducing arrhythmias. We hypothesized digoxin use in the setting of abnormal serum potassium levels is associated with arrhythmias. We reviewed all patients ≤ 18 years who received digoxin while admitted at our institution from 2014 to 2021. Admissions < 2 nights were excluded. We compared patients with a hemodynamically significant arrhythmia to those without. We performed adjusted mixed-effects logistic regression with arrhythmia as the outcome variable and potassium status as the predictor variable; adjusting for weight, route of digoxin administration, digoxin indication, serum creatinine, and number of interacting drugs prescribed. Abnormal potassium was defined as serum levels < 3.5 mmol/L or > 6.0 mmol/L. There were 268 encounters in 171 patients. Potassium levels were abnormal in 75.5% of patients who experienced an arrhythmia during digoxin administration, compared to 42.6% who did not (p < 0.001). Odds of arrhythmia was 138% higher in patients with abnormal potassium receiving digoxin (AOR = 2.38, 95% CI 1.07–5.29, p = 0.03). Receiving intravenous digoxin was also associated with a 7.35 odds of cardiac arrhythmia (AOR 7.35, p = 0.006, 95% CI 1.79–30.26). Odds of arrhythmia is increased during digoxin administration when pediatric patients have abnormal potassium levels. Vigilant attention to potassium levels is essential to prevent adverse outcomes during digoxin therapy. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most persistent arrhythmia today, with its prevalence increasing exponentially with the rising age of the population. Particularly at elevated heart rates, a functional abnormality known as cardiac alternans can occur prior to the onset of lethal arrhythmias. Cardiac alternans are a beat-to-beat oscillation of electrical activity and the force of cardiac muscle contraction. Extensive evidence has demonstrated that microvolt T-wave alternans can predict ventricular fibrillation vulnerability and the risk of sudden cardiac death. The majority of our knowledge of the mechanisms of alternans stems from studies of ventricular electrophysiology, although recent studies offer promising evidence of the potential of atrial alternans in predicting the risk of AF. Exciting preclinical and clinical studies have demonstrated a link between atrial alternans and the onset of atrial tachyarrhythmias. Here, we provide a comprehensive review of the clinical utility of atrial alternans in identifying the risk and guiding treatment of AF.

Background: Systemic inflammation has been associated with atherosclerotic cardiovascular diseases (ASCVD) and arrhythmia occurrence in rheumatologic conditions such as rheumatoid arthritis. Polymyositis and dermatomyositis (PD) are rare rheumatologic conditions characterized by symmetrical proximal muscle weakness and, in the case of dermatomyositis, cutaneous eruption. Although there is literature associating PD with ASCVD, no population-level studies have analyzed arrhythmia risk in PD.Objective: The purpose of this study was to assess the prevalence of arrhythmia and its subtypes by age and sex in patients with PD and to determine associations between arrhythmia and PD.Methods: This retrospective cohort study included adults for whom hospitalizations had been recorded in the National Inpatient Sample database in the United States between 2016 and 2018. Patients with PD were matched (1:10) by age to patients without PD. Prevalence of arrhythmia was calculated in the 2 groups and compared by sex and age groups. Associations between PD and arrhythmia were determined after adjustment for common arrhythmia risk factors.Results: From 107,001,355 hospitalizations, 32,085 adults with PD were matched to 320,850 controls. Patients with PD aged <70 years had a higher prevalence of arrhythmia and higher adjusted odds of arrhythmia compared with controls. This increased risk was only seen for supraventricular arrhythmias. Adults with PD had increased odds of in-hospital mortality if they had an arrhythmia diagnosis (odds ratio 3.3; 95% confidence interval 2.5-4.5; P <.001).Conclusion: We found a higher prevalence and odds of arrhythmias, particularly supraventricular arrhythmias, in young and middle-aged patients with PD compared with matched controls. Arrhythmias were associated with significant mortality among patients with PD. [ABSTRACT FROM AUTHOR]

Background: Sudden death accounts for approximately 10% of deaths among working-age adults and is associated with poor air quality. Objectives: To identify high-risk groups and potential modifiers and mediators of risk, we explored previously established associations between fine particulate matter (PM 2.5 ) and sudden death stratified by potential risk factors., Methods: Sudden death victims in Wake County, NC, from 1 March 2013 to 28 February 2015 were identified by screening Emergency Medical Systems reports and adjudicated ( n  = 399). Daily PM 2.5 concentrations for Wake County from the Air Quality Data Mart were linked to event and control periods. Potential modifiers included greenspace metrics, clinical conditions, left ventricular hypertrophy (LVH), and neutrophil-to-lymphocyte ratio (NLR). Using a case-crossover design, conditional logistic regression estimated the OR (95%CI) for sudden death for a 5 μg/m 3 increase in PM 2.5 with a 1-day lag, adjusted for temperature and humidity, across risk factor strata., Results: Individuals having LVH or an NLR above 2.5 had PM 2.5 associations of greater magnitude than those without [with LVH OR: 1.90 (1.04, 3.50); NLR > 2.5: 1.25 (0.89, 1.76)]. PM 2.5 was generally less impactful for individuals living in areas with higher levels of greenspace., Conclusion: LVH and inflammation may be the final step in the causal pathway whereby poor air quality and traditional risk factors trigger arrhythmia or myocardial ischemia and sudden death. The combination of statistical evidence with clinical knowledge can inform medical providers of underlying risks for their patients generally, while our findings here may help guide interventions to mitigate the incidence of sudden death., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Rappazzo, Egerstrom, Wu, Capone, Joodi, Keen, Cascio and Simpson.)

Background: The optimal management of chronic severe primary degenerative mitral regurgitation (MR) is to repair the valve but identification of the optimal timing of surgery remains challenging. Current guidelines suggest 'watchful waiting' until the onset of symptoms or left ventricular (LV) dysfunction but these have been challenged as promoting 'rescue surgery'. Better predictors are required to inform decision-making in relation to the necessity and timing of surgery. Chronic volume overload is a stimulus for adverse adaptive LV remodelling. Subclinical reduction in LV strain before mitral repair predicts a fall in LV ejection fraction following surgery and is thought to reflect the development of myocardial fibrosis in response to chronic volume overload. Myocardial fibrosis can be detected non-invasively using cardiac magnetic resonance (CMR) imaging techniques as an expansion of the extracellular volume (ECV).Methods/design: This study investigates whether: 1) patients with above median ECV will have smaller reduction in end-systolic volume index (as a measure of the degree of reverse LV remodelling) on CMR following mitral valve repair, compared to those with below median ECV; and 2) higher ECV on CMR, validated through histology, adversely impacts upon post-operative complications and symptomatic improvement following surgery. This is a multi-centre, prospective, cross-sectional comparison of patients prior to and 9 months following surgery for chronic severe primary degenerative MR. To establish the natural history of ECV in MR, an additional cohort of patients with asymptomatic MR who do not wish to consider early repair will be followed. Investigations include CMR, cardiopulmonary exercise test, stress echocardiography, signal-averaged electrocardiogram, 24-h electrocardiogram monitoring, laboratory tests and patient-reported outcome measures. Patients undergoing surgery will have cardiac biopsies performed at the time of mitral valve repair for histological quantification of fibrosis.Discussion: This study will advance our understanding of ventricular remodelling in MR, its impact on patient symptoms and ventricular response following surgery. Establishing the link between myocardial fibrosis (measured on CMR and validated through histology), with early ventricular dysfunction, will offer physicians a novel non-invasive biomarker that can further inform the timing of surgery.Trial Registration: This trial was registered at ClinicalTrials.gov ( NCT02355418 ) on 30th November 2015. [ABSTRACT FROM AUTHOR]

Background: The optimal management of chronic severe primary degenerative mitral regurgitation (MR) is to repair the valve but identification of the optimal timing of surgery remains challenging. Current guidelines suggest 'watchful waiting' until the onset of symptoms or left ventricular (LV) dysfunction but these have been challenged as promoting 'rescue surgery'. Better predictors are required to inform decision-making in relation to the necessity and timing of surgery. Chronic volume overload is a stimulus for adverse adaptive LV remodelling. Subclinical reduction in LV strain before mitral repair predicts a fall in LV ejection fraction following surgery and is thought to reflect the development of myocardial fibrosis in response to chronic volume overload. Myocardial fibrosis can be detected non-invasively using cardiac magnetic resonance (CMR) imaging techniques as an expansion of the extracellular volume (ECV)., Methods/design: This study investigates whether: 1) patients with above median ECV will have smaller reduction in end-systolic volume index (as a measure of the degree of reverse LV remodelling) on CMR following mitral valve repair, compared to those with below median ECV; and 2) higher ECV on CMR, validated through histology, adversely impacts upon post-operative complications and symptomatic improvement following surgery. This is a multi-centre, prospective, cross-sectional comparison of patients prior to and 9 months following surgery for chronic severe primary degenerative MR. To establish the natural history of ECV in MR, an additional cohort of patients with asymptomatic MR who do not wish to consider early repair will be followed. Investigations include CMR, cardiopulmonary exercise test, stress echocardiography, signal-averaged electrocardiogram, 24-h electrocardiogram monitoring, laboratory tests and patient-reported outcome measures. Patients undergoing surgery will have cardiac biopsies performed at the time of mitral valve repair for histological quantification of fibrosis., Discussion: This study will advance our understanding of ventricular remodelling in MR, its impact on patient symptoms and ventricular response following surgery. Establishing the link between myocardial fibrosis (measured on CMR and validated through histology), with early ventricular dysfunction, will offer physicians a novel non-invasive biomarker that can further inform the timing of surgery., Trial Registration: This trial was registered at ClinicalTrials.gov ( NCT02355418 ) on 30th November 2015.