Manganese-Based Tunnel-Type Cathode Materials for Secondary Li-Ion and K-Ion Batteries.

The rational design of novel cathode materials remains a key pursuit in the development of (post) Li-ion batteries. Considering the relative ionic and Stokes radii and open frameworks with large tunnels, Na-based compounds can act as versatile cathodes for monovalent Li-ion and post-Li-ion batteries. Here, tunnel-type sodium insertion material Na0.44MnO2 is demonstrated as an intercalation host for Li-ion and K-ion batteries. The rod-shaped Na0.44MnO2 was synthesized by a solution combustion method assuming an orthorhombic structure (space group Pbam), which led to Na0.11K0.27MnO2 (NKMO) and Na0.18Li0.51MnO2 (NLMO) cathodes for K-ion batteries and Li-ion batteries, respectively, via facile electrochemical ion exchange from Na0.44MnO2. These new compositions, NKMO and NLMO, exhibited capacities of ∼74 and 141 mAh g-1, respectively (at a rate of C/20), with excellent cycling stability. The underlying mechanistic aspects (structural changes and charge storage mechanism) in these cathode compositions were probed by combining ex situ structural, spectroscopy, and electrochemical tools. Tunnel-type Na0.44MnO2 forms a versatile cathode material for non-aqueous alkali-ion batteries.

Systolic dysfunction in patients with methamphetamine use and heart failure with preserved ejection fraction.

BACKGROUND: We aimed to evaluate for occult systolic dysfunction and the effect of methamphetamine cessation among patients with methamphetamine use (MU) and heart failure with preserved ejection fraction (HFpEF). METHODS: A retrospective cohort of patients with HFpEF with serial echocardiograms was stratified by MU and evaluated using myocardial strain analysis on echocardiograms at baseline and 1 year to measure global longitudinal strain (GLS). Contemporaneous controls with an ICD diagnosis of HF within 3 days of an MU case were chosen. RESULTS: Patients with MU (n = 31) were younger (49 ± 10 vs 59 ± 16 years, p < 0.01) and more frequently male (55% vs 26%, p = 0.04) than controls (n = 23). There was no baseline difference in ejection fraction (EF) (median 66% [IQR 58,71%] vs 62% [56,69%], p = 0.33) or GLS (-13.0% [-16.3,-10.9%] vs -14.8% [-16.0,-11.3%], p = 0.40). At one-year follow-up, MU cessation (n = 15) was associated with improvement in GLS (absolute change -4.4% [-6.5,-1.7%], p < 0.01), while no absolute change was observed with continued MU (n = 16) (0.74% [-1.2,2.8%], p = 0.22) or controls without MU (-0.6% [-2.1,2.8%], p = 0.78). Of those with abnormal baseline GLS, normalization was observed in 46% with MU cessation, none with continued MU, and 5% of controls (p < 0.001). Among MU patients, improvement in GLS was associated with decreased HF admissions per year [HR 0.74 per 1% change in GLS, 95% CI 0.55,0.98, p = 0.04]. CONCLUSIONS: Patients with MU and HFpEF may have occult systolic dysfunction as demonstrated by abnormal GLS, and MU cessation at 1 year is associated with improvement in GLS and a reduction in risk of HF admissions.

Characteristics and outcomes of recurrent atrial fibrillation after prior failed pulmonary vein isolation.

BACKGROUND: The mechanisms for atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) catheter ablation are unclear. Non-PV organized atrial arrhythmias (PAC, AT, macro-reentrant AFL) are possible contributors; however the prevalence and effect of their ablation on recurrent AF are unknown. We hypothesize that the identification and ablation of non-PV organized atrial arrhythmias were associated with less AF recurrence. METHODS: Patients who underwent repeat ablation for recurrent AF after prior PVI were retrospectively enrolled. The prevalence and characteristics of PV reconnections and non-PV organized atrial arrhythmias were identified. The outcomes of time to clinical AF recurrence, heart failure (HF) hospitalization, and mortality were analyzed in patients using multivariable adjusted Cox regression. RESULTS: In 74 patients with recurrent AF (age 66 ± 9 years, left atrial volume index 38 ± 10 ml/m2, 59% persistent AF), PV reconnections were found in 46 patients (61%), macro-reentrant atrial flutter in 27 patients (36%), and focal tachycardia in 12 patients (16%). Mapping and ablation of non-PV organized atrial arrhythmias were associated with a reduced recurrence of late clinical AF (adjusted HR 0.26, CI 0.08-0.85, p = 0.03) and the composite outcome of recurrence of late AF, HF hospitalization, and mortality (adjusted HR 0.38, CI 0.17-0.85, p = 0.02), with median follow-up of 1.6 (IQR 0.7-6.3) years. The presence of PV reconnections or empiric linear ablation was not associated with reduction in clinical AF or composite endpoints. CONCLUSION: The ablation of non-PV organized atrial arrhythmias resulted in a reduction of late clinical AF recurrence and composite outcome. In this challenging population, alternate mechanisms beyond PV reconnections need to be considered. Prospective studies are needed.

Association of chronic kidney disease and end-stage renal disease with procedural complications and in-hospital outcomes from left atrial appendage occlusion device implantation in patients with atrial fibrillation: Insights from the national inpatient sample of 36,065 procedures.

BACKGROUND: Left atrial appendage occlusion (LAAO) has emerged as an alternative strategy to oral anticoagulation for mitigating ischemic stroke risk in selected patients with atrial fibrillation (AF), but safety data in patients with significant kidney disease are limited. OBJECTIVE: To determine the association of chronic kidney disease (CKD) and end-stage renal disease (ESRD) with procedural complications and in-hospital outcomes after LAAO in AF patients. METHODS: Data were extracted from National Inpatient Sample for calendar years 2015-2018. Watchman implantations were identified on the basis of International Classification of Diseases, 9th and 10th Revision, Clinical Modification codes of 37.90 and 02L73DK. The outcomes assessed in our study included complications, inpatient mortality, and resource utilization with LAAO. RESULTS: A total of 36,065 Watchman recipients were included in the final analysis. CKD (9.8%, n = 3545) and ESRD (3%, n = 1155) were associated with a higher prevalence of major complications and mortality in crude analysis compared to no CKD. After multivariate adjustment for potential confounders, CKD was associated with length of stay (LOS) >1 day (adjusted odds ratio [aOR] 1.355; 95% confidence interval [CI] 1.234-1.488), median cost >$24,663 (aOR 1.267; 95% CI 1.176-1.365), and acute kidney injury (aOR 4.134; 95% CI 3.536-4.833), while ESRD was associated with in-patient mortality (aOR 7.156; 95% CI 3.294-15.544). CONCLUSION: The prevalence of CKD and ESRD was approximately 13% in AF patients undergoing Watchman LAAO implantations. CKD was independently associated with prolonged LOS, higher hospitalization costs, and acute kidney injury, while ESRD was independently associated with in-patient mortality.

Na2MnP2O7 polymorphs as efficient bifunctional catalysts for oxygen reduction and oxygen evolution reactions.

In order to design earth-abundant low cost electrocatalysts, this communication exploits polymorphism in Na2MnP2O7 pyrophosphate sodium insertion materials. Two polymorphs of Na2MnP2O7 have been prepared with a short annealing duration of 30 minutes. These scalable materials exhibit efficient bifunctional electrocatalytic activity stemming from the Mn redox centre and robust structural framework.