Implantable cardioverter defibrillator use in arrhythmogenic right ventricular cardiomyopathy in North America and Europe.

BACKGROUND AND AIMS: Implantable cardioverter-defibrillators (ICDs) are critical for preventing sudden cardiac death (SCD) in arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aims to identify cross-continental differences in utilization of primary prevention ICDs and survival free from sustained ventricular arrhythmia (VA) in ARVC. METHODS: This was a retrospective analysis of ARVC patients without prior VA enrolled in clinical registries from 11 countries throughout Europe and North America. Patients were classified according to whether they received treatment in North America or Europe and were further stratified by baseline predicted VA risk into low- (<10%/5 years), intermediate- (10%-25%/5 years), and high-risk (>25%/5 years) groups. Differences in ICD implantation and survival free from sustained VA events (including appropriate ICD therapy) were assessed. RESULTS: One thousand ninety-eight patients were followed for a median of 5.1 years; 554 (50.5%) received a primary prevention ICD, and 286 (26.0%) experienced a first VA event. After adjusting for baseline risk factors, North Americans were more than three times as likely to receive ICDs {hazard ratio (HR) 3.1 [95% confidence interval (CI) 2.5, 3.8]} but had only mildly increased risk for incident sustained VA [HR 1.4 (95% CI 1.1, 1.8)]. North Americans without ICDs were at higher risk for incident sustained VA [HR 2.1 (95% CI 1.3, 3.4)] than Europeans. CONCLUSIONS: North American ARVC patients were substantially more likely than Europeans to receive primary prevention ICDs across all arrhythmic risk strata. A lower rate of ICD implantation in Europe was not associated with a higher rate of VA events in those without ICDs.

Impact of stress on cardiac phenotypes in mice harboring an ankyrin-B disease variant.

Encoded by ANK2, ankyrin-B (AnkB) is a multifunctional adapter protein critical for the expression and targeting of key cardiac ion channels, transporters, cytoskeletal-associated proteins, and signaling molecules. Mice deficient for AnkB expression are neonatal lethal, and mice heterozygous for AnkB expression display cardiac structural and electrical phenotypes. Human ANK2 loss-of-function variants are associated with diverse cardiac manifestations; however, human clinical 'AnkB syndrome' displays incomplete penetrance. To date, animal models for human arrhythmias have generally been knock-out or transgenic overexpression models and thus the direct impact of ANK2 variants on cardiac structure and function in vivo is not clearly defined. Here, we directly tested the relationship of a single human ANK2 disease-associated variant with cardiac phenotypes utilizing a novel in vivo animal model. At baseline, young AnkBp.E1458G+/+ mice lacked significant structural or electrical abnormalities. However, aged AnkBp.E1458G+/+ mice displayed both electrical and structural phenotypes at baseline including bradycardia and aberrant heart rate variability, structural remodeling, and fibrosis. Young and old AnkBp.E1458G+/+ mice displayed ventricular arrhythmias following acute (adrenergic) stress. In addition, young AnkBp.E1458G+/+ mice displayed structural remodeling following chronic (transverse aortic constriction) stress. Finally, AnkBp.E1458G+/+ myocytes harbored alterations in expression and/or localization of key AnkB-associated partners, consistent with the underlying disease mechanism. In summary, our findings illustrate the critical role of AnkB in in vivo cardiac function as well as the impact of single AnkB loss-of-function variants in vivo. However, our findings illustrate the contribution and in fact necessity of secondary factors (aging, adrenergic challenge, pressure-overload) to phenotype penetrance and severity.

Flecainide Is Associated With a Lower Incidence of Arrhythmic Events in a Large Cohort of Patients With Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: In severely affected patients with catecholaminergic polymorphic ventricular tachycardia, beta-blockers are often insufficiently protective. The purpose of this study was to evaluate whether flecainide is associated with a lower incidence of arrhythmic events (AEs) when added to beta-blockers in a large cohort of patients with catecholaminergic polymorphic ventricular tachycardia. METHODS: From 2 international registries, this multicenter case cross-over study included patients with a clinical or genetic diagnosis of catecholaminergic polymorphic ventricular tachycardia in whom flecainide was added to beta-blocker therapy. The study period was defined as the period in which background therapy (ie, beta-blocker type [beta1-selective or nonselective]), left cardiac sympathetic denervation, and implantable cardioverter defibrillator treatment status, remained unchanged within individual patients and was divided into pre-flecainide and on-flecainide periods. The primary end point was AEs, defined as sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter defibrillator shock, and arrhythmic syncope. The association of flecainide with AE rates was assessed using a generalized linear mixed model assuming negative binomial distribution and random effects for patients. RESULTS: A total of 247 patients (123 [50%] females; median age at start of flecainide, 18 years [interquartile range, 14-29]; median flecainide dose, 2.2 mg/kg per day [interquartile range, 1.7-3.1]) were included. At baseline, all patients used a beta-blocker, 70 (28%) had an implantable cardioverter defibrillator, and 21 (9%) had a left cardiac sympathetic denervation. During a median pre-flecainide follow-up of 2.1 years (interquartile range, 0.4-7.2), 41 patients (17%) experienced 58 AEs (annual event rate, 5.6%). During a median on-flecainide follow-up of 2.9 years (interquartile range, 1.0-6.0), 23 patients (9%) experienced 38 AEs (annual event rate, 4.0%). There were significantly fewer AEs after initiation of flecainide (incidence rate ratio, 0.55 [95% CI, 0.38-0.83]; P=0.007). Among patients who were symptomatic before diagnosis or during the pre-flecainide period (n=167), flecainide was associated with significantly fewer AEs (incidence rate ratio, 0.49 [95% CI, 0.31-0.77]; P=0.002). Among patients with ≥1 AE on beta-blocker therapy (n=41), adding flecainide was also associated with significantly fewer AEs (incidence rate ratio, 0.25 [95% CI, 0.14-0.45]; P<0.001). CONCLUSIONS: For patients with catecholaminergic polymorphic ventricular tachycardia, adding flecainide to beta-blocker therapy was associated with a lower incidence of AEs in the overall cohort, in symptomatic patients, and particularly in patients with breakthrough AEs while on beta-blocker therapy.

A phase I, randomized, double-blind, placebo-controlled, ascending single- and multiple-dose study of the pharmacokinetics, safety, and tolerability of oral ceftibuten in healthy adult subjects.

This was a phase I, randomized, double-blind, placebo-controlled, ascending single- and multiple-dose study of oral ceftibuten to describe the pharmacokinetics (PK) of cis-ceftibuten (administered form) and trans-ceftibuten (metabolite), and to describe safety and tolerability at higher than licensed doses. Subjects received single 400, 600, or 800 mg doses of ceftibuten on Days 1 and 4, followed by 7 days of twice-daily dosing from Days 4 to 10. Non-compartmental methods were used to describe parent drug and metabolite PK in plasma and urine. Dose proportionality was examined using C max, AUC0-12, and AUC0-INF. Accumulation was calculated as the ratio of AUC0-12 on Days 4 and 10. Adverse events (AEs) were monitored throughout the study. Following single ascending doses, mean cis- and trans-ceftibuten C max were 17.6, 24.1, and 28.1 mg/L, and 1.1, 1.5, and 2.2 mg/L, respectively; cis-ceftibuten urinary recovery accounted for 64.3%-86.9% of the administered dose over 48 h. Following multiple ascending doses, mean cis- and trans-ceftibuten C max were 21.7, 28.1, and 38.8 mg/L, and 1.4, 1.9, and 2.8 mg/L, respectively; cis-ceftibuten urinary recovery accounted for 72.2%-96.4% of the administered dose at steady state. The exposure of cis- and trans-ceftibuten increased proportionally with increasing doses. Cis- and trans-ceftibuten accumulation factor was 1.14-1.19 and 1.28-1.32. The most common gastrointestinal treatment emergent AEs were mild and resolved without intervention. Ceftibuten was well tolerated. Dose proportionality and accumulation of cis- and trans-ceftibuten were observed. These results support the ongoing development of ceftibuten at doses up to 800 mg twice-daily. (The study was registered at ClinicalTrials.gov under the identifier NCT03939429.).

Population pharmacokinetics of fluconazole in critically ill patients receiving extracorporeal membrane oxygenation and continuous renal replacement therapy: an ASAP ECMO study.

This multicenter study describes the population pharmacokinetics (PK) of fluconazole in critically ill patients receiving concomitant extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) and includes an evaluation of different fluconazole dosing regimens for achievement of target exposure associated with maximal efficacy. Serial blood samples were obtained from critically ill patients on ECMO and CRRT receiving fluconazole. Total fluconazole concentrations were measured in plasma using a validated chromatographic assay. A population PK model was developed and Monte Carlo dosing simulations were performed using Pmetrics in R. The probability of target attainment (PTA) of various dosing regimens to achieve fluconazole area under the curve to minimal inhibitory concentration ratio (AUC0-24/MIC) >100 was estimated. Eight critically ill patients receiving concomitant ECMO and CRRT were included. A two-compartment model including total body weight as a covariate on clearance adequately described the data. The mean (±standard deviation, SD) clearance and volume of distribution were 2.87 ± 0.63 L/h and 15.90 ± 13.29 L, respectively. Dosing simulations showed that current guidelines (initial loading dose of 12 mg/kg then 6 mg/kg q24h) achieved >90% of PTA for a MIC up to 1 mg/L. None of the tested dosing regimens achieved 90% of PTA for MIC above 2 mg/L. Current fluconazole dosing regimen guidelines achieved >90% PTA only for Candida species with MIC <1 mg/L and thus should be only used for Candida-documented infections in critically ill patients receiving concomitant ECMO and CRRT. Total body weight should be considered for fluconazole dose.

What are the optimal pharmacokinetic/pharmacodynamic targets for ß-lactamase inhibitors? A systematic review.

BACKGROUND: Pharmacokinetic/pharmacodynamic (PK/PD) indices are widely used for the selection of optimum antibiotic doses. For ß-lactam antibiotics, fT>MIC, best relates antibiotic exposure to efficacy and is widely used to guide the dosing of ß-lactam/ß-lactamase inhibitor (BLI) combinations, often without considering any PK/PD exposure requirements for BLIs. OBJECTIVES: This systematic review aimed to describe the PK/PD exposure requirements of BLIs for optimal microbiological efficacy when used in combination with ß-lactam antibiotics. METHODS: Literature was searched online through PubMed, Embase, Web of Science, Scopus and Cochrane Library databases up to 5 June 2023. Studies that report the PK/PD index and threshold concentration of BLIs approved for clinical use were included. Narrative data synthesis was carried out to assimilate the available evidence. RESULTS: Twenty-three studies were included. The PK/PD index that described the efficacy of BLIs was fT>CT for tazobactam, avibactam and clavulanic acid and fAUC0-24/MIC for relebactam and vaborbactam. The optimal magnitude of the PK/PD index is variable for each BLI based on the companion ß-lactam antibiotics, type of bacteria and ß-lactamase enzyme gene transcription levels. CONCLUSIONS: The PK/PD index that describes the efficacy of BLIs and the exposure measure required for their efficacy is variable among inhibitors; as a result, it is difficult to make clear inference on what the optimum index is. Further PK/PD profiling of BLI, using preclinical infection models that simulate the anticipated mode(s) of clinical use, is warranted to streamline the exposure targets for use in the optimization of dosing regimens.

Current practices and challenges of outpatient parenteral antimicrobial therapy: a narrative review.

Extended hospitalization for infection management increases inpatient care costs and the risk of healthcare-associated adverse events, including infections. The growing global demand for healthcare, the diminishing availability of hospital beds and an increasing patient preference for care within their own home have been the primary drivers of the expansion of hospital-in-the-home programmes. Such programmes include the use of IV antimicrobials in outpatient settings, known as outpatient parenteral antimicrobial therapy (OPAT). However, OPAT practices vary globally. This review article aims to describe the current OPAT practices and challenges worldwide. OPAT practice begins with patient evaluation and selection using eligibility criteria, which requires collaboration between the interdisciplinary OPAT team, patients and caregivers. Depending on care requirements, eligible patients may be enrolled to various models of care, receiving medication by healthcare professionals at outpatient infusion centres, hospital clinics, home visits or through self-administration. OPAT can be used for the management of many infections where an effective oral treatment option is lacking. Various classes of parenteral antimicrobials, including ß-lactams, aminoglycosides, glycopeptides, fluoroquinolones and antifungals such as echinocandins, are used globally in OPAT practice. Despite its benefits, OPAT has numerous challenges, including complications from medication administration devices, antimicrobial side effects, monitoring requirements, antimicrobial instability, patient non-adherence, patient OPAT rejection, and challenges related to OPAT team structure and administration, all of which impact its outcome. A negative outcome could include unplanned hospital readmission. Future research should focus on mitigating these challenges to enable optimization of the OPAT service and thereby maximize the documented benefits for the healthcare system, patients and healthcare providers.

Population pharmacokinetics of posaconazole in allogeneic haematopoietic stem cell transplant patients.

BACKGROUND: Invasive fungal disease (IFD) in the early post-allogeneic HSCT (alloHCT) period is associated with increased likelihood of catastrophic outcomes. The utility of oral modified release (MR) posaconazole tablets is limited by reduced drug absorption from gastrointestinal toxicity induced by cytotoxic chemotherapy, necessitating a switch to the IV posaconazole formulation. OBJECTIVES: To describe the population pharmacokinetics of posaconazole for oral MR and IV formulations in alloHCT patients and determine dosing regimens likely to achieve therapeutic exposures. METHODS: We performed a prospective observational pharmacokinetic study in adult patients in the early post-alloHCT period requiring a change in posaconazole formulation (oral to IV). Samples were analysed using a validated LC-MS/MS method. Population pharmacokinetic analysis and Monte Carlo simulations (n = 1000) were performed using Pmetrics for R. RESULTS: Twenty patients aged between 21 and 70 years were included in the study. A two-compartment model, incorporating mucositis/diarrhoea to modify the bioavailability for oral administration best described the data. To achieve ≥90% PTA, simulations showed that higher than currently recommended doses of oral MR posaconazole were required for prophylaxis Cmin targets (≥0.5 and ≥0.7 mg/L), while increased doses of both formulations were required for IFD treatment PK/PD targets, with patients experiencing oral mucositis/diarrhoea unlikely to achieve these. CONCLUSIONS: Increased doses of posaconazole should be considered for both prophylaxis and treatment of IFD to increase the proportion of alloHCT patients achieving therapeutic exposures, particularly the oral formulation in patients with mucositis and/or diarrhoea. Posaconazole therapeutic drug monitoring should be considered for all formulations in this setting.

Population pharmacokinetics and dosing simulations of total and unbound temocillin in the plasma and CSF of neurocritically ill patients with external ventricular drain-related cerebral ventriculitis.

BACKGROUND: Cerebral ventriculitis might be caused by Gram-negative bacteria, including ESBL producers. Temocillin may be a useful treatment option in this scenario; however, no consistent data are available regarding its penetration into the CSF. OBJECTIVES: To describe the population pharmacokinetics of temocillin in plasma and CSF and to determine the probability for different simulated dosing regimens to achieve pharmacokinetic/pharmacodynamic (PK/PD) targets in the CSF. METHODS: Ten post-neurosurgical critically ill adult patients requiring continuous drainage of CSF were included in this monocentric, prospective, open-label, non-randomized study. They received 2 g loading dose temocillin over 30 min IV infusion, followed by a 6 g continuous infusion over 24 h. Total and unbound concentrations were measured in plasma (n = 88 and 86) and CSF (n = 88 and 88) samples and used to build a population PK model. Monte Carlo simulations were performed to estimate the PTA at 100% Css>MIC (steady state concentration above the MIC) in CSF. RESULTS: All patients were infected with Enterobacterales with temocillin MICs ≤8 mg/L. The median (min-max) temocillin penetration in CSF was 12.1% (4.3-25.5) at steady state. Temocillin unbound plasma pharmacokinetics were best described by a one-compartment model. PTA for the applied dosing regimen was >90% for bacteria with MIC ≤ 4 mg/L. CONCLUSIONS: The currently approved dose of 6 g by continuous infusion may be adequate for the treatment of ventriculitis by Enterobacterales with MIC ≤ 4 mg/L if considering 100% Css>MIC as the PK/PD target to reach. Higher maintenance doses could help covering higher MICs, but their safety would need to be assessed.

Understanding the nebulisation of antibiotics: the key role of lung microdialysis studies.

BACKGROUND: Nebulisation of antibiotics is a promising treatment for ventilator-associated pneumonia (VAP) caused by multidrug-resistant organisms. Ensuring effective antibiotic concentrations at the site of infection in the interstitial space fluid is crucial for clinical outcomes. Current assessment methods, such as epithelial lining fluid and tissue homogenates, have limitations in providing longitudinal pharmacokinetic data. MAIN BODY: Lung microdialysis, an invasive research technique predominantly used in animals, involves inserting probes into lung parenchyma to measure antibiotic concentrations in interstitial space fluid. Lung microdialysis offers unique advantages, such as continuous sampling, regional assessment of antibiotic lung concentrations and avoidance of bronchial contamination. However, it also has inherent limitations including the cost of probes and assay development, the need for probe calibration and limited applicability to certain antibiotics. As a research tool in VAP, lung microdialysis necessitates specialist techniques and resource-intensive experimental designs involving large animals undergoing prolonged mechanical ventilation. However, its potential impact on advancing our understanding of nebulised antibiotics for VAP is substantial. The technique may enable the investigation of various factors influencing antibiotic lung pharmacokinetics, including drug types, delivery devices, ventilator settings, interfaces and disease conditions. Combining in vivo pharmacokinetics with in vitro pharmacodynamic simulations can become feasible, providing insights to inform nebulised antibiotic dose optimisation regimens. Specifically, it may aid in understanding and optimising the nebulisation of polymyxins, effective against multidrug-resistant Gram-negative bacteria. Furthermore, lung microdialysis holds promise in exploring novel nebulisation therapies, including repurposed antibiotic formulations, bacteriophages and immunomodulators. The technique's potential to monitor dynamic biochemical changes in pneumonia, such as cytokines, metabolites and inflammation/infection markers, opens avenues for developing theranostic tools tailored to critically ill patients with VAP. CONCLUSION: In summary, lung microdialysis can be a potential transformative tool, offering real-time insights into nebulised antibiotic pharmacokinetics. Its potential to inform optimal dosing regimen development based on precise target site concentrations and contribute to development of theranostic tools positions it as key player in advancing treatment strategies for VAP caused by multidrug-resistant organisms. The establishment of international research networks, exemplified by LUMINA (lung microdialysis applied to nebulised antibiotics), signifies a proactive step towards addressing complexities and promoting multicentre experimental studies in the future.

Antimicrobial Exposures in Critically Ill Patients Receiving Extracorporeal Membrane Oxygenation.

Rationale: Data suggest that altered antimicrobial concentrations are likely during extracorporeal membrane oxygenation (ECMO). Objectives: The primary aim of this analysis was to describe the pharmacokinetics (PKs) of antimicrobials in critically ill adult patients receiving ECMO. Our secondary aim was to determine whether current antimicrobial dosing regimens achieve effective and safe exposure. Methods: This study was a prospective, open-labeled, PK study in six ICUs in Australia, New Zealand, South Korea, and Switzerland. Serial blood samples were collected over a single dosing interval during ECMO for 11 antimicrobials. PK parameters were estimated using noncompartmental methods. Adequacy of antimicrobial dosing regimens were evaluated using predefined concentration exposures associated with maximal clinical outcomes and minimal toxicity risks. Measurements and Main Results: We included 993 blood samples from 85 patients. The mean age was 44.7 ± 14.4 years, and 61.2% were male. Thirty-eight patients (44.7%) were receiving renal replacement therapy during the first PK sampling. Large variations (coefficient of variation of ⩾30%) in antimicrobial concentrations were seen leading to more than fivefold variations in all PK parameters across all study antimicrobials. Overall, 70 (56.5%) concentration profiles achieved the predefined target concentration and exposure range. Target attainment rates were not significantly different between modes of ECMO and renal replacement therapy. Poor target attainment was observed across the most frequently used antimicrobials for ECMO recipients, including for oseltamivir (33.3%), piperacillin (44.4%), and vancomycin (27.3%). Conclusions: Antimicrobial PKs were highly variable in critically ill patients receiving ECMO, leading to poor target attainment rates. Clinical trial registered with the Australian New Zealand Clinical Trials Registry (ACTRN12612000559819).

Avoiding misclassification of acute kidney injury: Timing is everything.

Accurate detection of acute kidney injury (AKI) in clinical trials is important. Using a 'baseline' creatinine from trial enrolment may not be ideal for understanding a participant's true baseline kidney function. We aimed to determine if a 'pre-trial baseline creatinine' resulted in comparable creatinine concentrations to a 'trial baseline creatinine', and how the timing of baseline creatinine affected the incidence of AKI in the Combination Antibiotic therapy for MEthicillin Resistant Staphylococcus aureus (CAMERA2) randomised trial. Study sites retrospectively collected a pre-trial baseline creatinine from up to 1 year before CAMERA2 trial enrolment ideally when the patient was medically stable. Baseline creatinine from CAMERA2 (the 'trial baseline creatinine'), was the highest creatinine measurement in the 24 h preceding trial randomisation. We used Wilcoxon sign rank test to compare pre-trial and trial baseline creatinine concentrations. We included 217 patients. The median pre-trial baseline creatinine was significantly lower than the median trial baseline creatinine (82 µmol/L [IQR 65-104 µmol/L] versus 86 µmol/L [IQR 66-152 µmol/L] p = <0.001). Using pre-trial baseline creatinine, 48 of 217 patients (22%) met criteria for an AKI at CAMERA2 enrolment and only 5 of these patients met criteria for an AKI using the CAMERA2 study protocol (using baseline creatinine from trial entry). Using a baseline creatinine from the time of trial enrolment failed to detect many patients with AKI. Trial protocols should consider the optimal timing of baseline creatinine and the limitations of using a baseline creatinine during an acute illness.

RyR2 C-terminal truncating variants identified in patients with arrhythmic phenotypes exert a dominant negative effect through formation of wildtype-truncation heteromers.

Gain-of-function missense variants in the cardiac ryanodine receptor (RyR2) are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT), whereas RyR2 loss-of-function missense variants cause Ca2+ release deficiency syndrome (CRDS). Recently, truncating variants in RyR2 have also been associated with ventricular arrhythmias (VAs) and sudden cardiac death. However, there are limited insights into the potential clinical relevance and in vitro functional impact of RyR2 truncating variants. We performed genetic screening of patients presenting with syncope, VAs, or unexplained sudden death and in vitro characterization of the expression and function of RyR2 truncating variants in HEK293 cells. We identified two previously unknown RyR2 truncating variants (Y4591Ter and R4663Ter) and one splice site variant predicted to result in a frameshift and premature termination (N4717 + 15Ter). These 3 new RyR2 truncating variants and a recently reported RyR2 truncating variant, R4790Ter, were generated and functionally characterized in vitro. Immunoprecipitation and immunoblotting analyses showed that all 4 RyR2 truncating variants formed heteromers with the RyR2-wildtype (WT) protein. Each of these C-terminal RyR2 truncations was non-functional and suppressed [3H]ryanodine binding to RyR2-WT and RyR2-WT mediated store overload induced spontaneous Ca2+ release activity in HEK293 cells. The expression of these RyR2 truncating variants in HEK293 cells was markedly reduced compared with that of the full-length RyR2 WT protein. Our data indicate that C-terminal RyR2 truncating variants are non-functional and can exert a dominant negative impact on the function of the RyR2 WT protein through formation of heteromeric WT/truncation complex.

Atrial Fibrillation Recurrence in Patients With Transient New-Onset Atrial Fibrillation Detected During Hospitalization for Noncardiac Surgery or Medical Illness : A Matched Cohort Study.

BACKGROUND: Atrial fibrillation (AF) is often detected for the first time in patients who are hospitalized for another reason. Long-term risks for AF recurrence in these patients are unclear. OBJECTIVE: To estimate risk for AF recurrence in patients with new-onset AF during a hospitalization for noncardiac surgery or medical illness compared with a matched population without AF. DESIGN: Matched cohort study. (ClinicalTrials.gov: NCT03221777). SETTING: Three academic hospitals in Hamilton, Ontario, Canada. PARTICIPANTS: The study enrolled patients hospitalized for noncardiac surgery or medical illness who had transient new-onset AF. For each participant, an age- and sex-matched control participant with no history of AF from the same hospital ward was recruited. All participants left the hospital in sinus rhythm. MEASUREMENTS: 14-day electrocardiographic (ECG) monitor at 1 and 6 months and telephone assessment at 1, 6, and 12 months. The primary outcome was AF lasting at least 30 seconds on the monitor or captured by ECG 12-lead during routine care at 12 months. RESULTS: Among 139 participants with transient new-onset AF (70 patients with medical illness and 69 surgical patients) and 139 matched control participants, the mean age was 71 years (SD, 10), the mean CHA2DS2-VASc score was 3.0 (SD, 1.5), and 59% were male. The median duration of AF during the index hospitalization was 15.8 hours (IQR, 6.4 to 49.6 hours). After 1 year, recurrent AF was detected in 33.1% (95% CI, 25.3% to 40.9%) of participants in the transient new-onset AF group and 5.0% (CI, 1.4% to 8.7%) of matched control participants; after adjustment for the number of ECG monitors worn and for baseline clinical differences, the adjusted relative risk was 6.6 (CI, 3.2 to 13.7). After exclusion of participants who had electrical or pharmacologic cardioversion during the index hospitalization (n = 40) and their matched control participants and limiting to AF events detected by the patch ECG monitor, recurrent AF was detected in 32.3% (CI, 23.1% to 41.5%) of participants with transient new-onset AF and 3.0% (CI, 0% to 6.4%) of matched control participants. LIMITATIONS: Generalizability is limited, and the study was underpowered to evaluate subgroups and clinical predictors. CONCLUSION: Among patients who have transient new-onset AF during a hospitalization for noncardiac surgery or medical illness, approximately 1 in 3 will have recurrent AF within 1 year. PRIMARY FUNDING SOURCE: Peer-reviewed grants.

Continuous vs Intermittent ß-Lactam Antibiotic Infusions in Critically Ill Patients With Sepsis: The BLING III Randomized Clinical Trial.

Importance: Whether ß-lactam antibiotics administered by continuous compared with intermittent infusion reduces the risk of death in patients with sepsis is uncertain. Objective: To evaluate whether continuous vs intermittent infusion of a ß-lactam antibiotic (piperacillin-tazobactam or meropenem) results in decreased all-cause mortality at 90 days in critically ill patients with sepsis. Design, Setting, and Participants: An international, open-label, randomized clinical trial conducted in 104 intensive care units (ICUs) in Australia, Belgium, France, Malaysia, New Zealand, Sweden, and the United Kingdom. Recruitment occurred from March 26, 2018, to January 11, 2023, with follow-up completed on April 12, 2023. Participants were critically ill adults (≥18 years) treated with piperacillin-tazobactam or meropenem for sepsis. Intervention: Eligible patients were randomized to receive an equivalent 24-hour dose of a ß-lactam antibiotic by either continuous (n = 3498) or intermittent (n = 3533) infusion for a clinician-determined duration of treatment or until ICU discharge, whichever occurred first. Main Outcomes and Measures: The primary outcome was all-cause mortality within 90 days after randomization. Secondary outcomes were clinical cure up to 14 days after randomization; new acquisition, colonization, or infection with a multiresistant organism or Clostridioides difficile infection up to 14 days after randomization; ICU mortality; and in-hospital mortality. Results: Among 7202 randomized participants, 7031 (mean [SD] age, 59 [16] years; 2423 women [35%]) met consent requirements for inclusion in the primary analysis (97.6%). Within 90 days, 864 of 3474 patients (24.9%) assigned to receive continuous infusion had died compared with 939 of 3507 (26.8%) assigned intermittent infusion (absolute difference, -1.9% [95% CI, -4.9% to 1.1%]; odds ratio, 0.91 [95% CI, 0.81 to 1.01]; P = .08). Clinical cure was higher in the continuous vs intermittent infusion group (1930/3467 [55.7%] and 1744/3491 [50.0%], respectively; absolute difference, 5.7% [95% CI, 2.4% to 9.1%]). Other secondary outcomes were not statistically different. Conclusions and Relevance: The observed difference in 90-day mortality between continuous vs intermittent infusions of ß-lactam antibiotics did not meet statistical significance in the primary analysis. However, the confidence interval around the effect estimate includes the possibility of both no important effect and a clinically important benefit in the use of continuous infusions in this group of patients. Trial Registration: ClinicalTrials.gov Identifier: NCT03213990.

Prolonged vs Intermittent Infusions of ß-Lactam Antibiotics in Adults With Sepsis or Septic Shock: A Systematic Review and Meta-Analysis.

Importance: There is uncertainty about whether prolonged infusions of ß-lactam antibiotics improve clinically important outcomes in critically ill adults with sepsis or septic shock. Objective: To determine whether prolonged ß-lactam antibiotic infusions are associated with a reduced risk of death in critically ill adults with sepsis or septic shock compared with intermittent infusions. Data Sources: The primary search was conducted with MEDLINE (via PubMed), CINAHL, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov from inception to May 2, 2024. Study Selection: Randomized clinical trials comparing prolonged (continuous or extended) and intermittent infusions of ß-lactam antibiotics in critically ill adults with sepsis or septic shock. Data Extraction and Synthesis: Data extraction and risk of bias were assessed independently by 2 reviewers. Certainty of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluation approach. A bayesian framework was used as the primary analysis approach and a frequentist framework as the secondary approach. Main Outcomes and Measures: The primary outcome was all-cause 90-day mortality. Secondary outcomes included intensive care unit (ICU) mortality and clinical cure. Results: From 18 eligible randomized clinical trials that included 9108 critically ill adults with sepsis or septic shock (median age, 54 years; IQR, 48-57; 5961 men [65%]), 17 trials (9014 participants) contributed data to the primary outcome. The pooled estimated risk ratio for all-cause 90-day mortality for prolonged infusions of ß-lactam antibiotics compared with intermittent infusions was 0.86 (95% credible interval, 0.72-0.98; I2 = 21.5%; high certainty), with a 99.1% posterior probability that prolonged infusions were associated with lower 90-day mortality. Prolonged infusion of ß-lactam antibiotics was associated with a reduced risk of intensive care unit mortality (risk ratio, 0.84; 95% credible interval, 0.70-0.97; high certainty) and an increase in clinical cure (risk ratio, 1.16; 95% credible interval, 1.07-1.31; moderate certainty). Conclusions and Relevance: Among adults in the intensive care unit who had sepsis or septic shock, the use of prolonged ß-lactam antibiotic infusions was associated with a reduced risk of 90-day mortality compared with intermittent infusions. The current evidence presents a high degree of certainty for clinicians to consider prolonged infusions as a standard of care in the management of sepsis and septic shock. Trial Registration: PROSPERO Identifier: CRD42023399434.

A Clinical Diagnostic Test for Calcium Release Deficiency Syndrome.

Importance: Sudden death and cardiac arrest frequently occur without explanation, even after a thorough clinical evaluation. Calcium release deficiency syndrome (CRDS), a life-threatening genetic arrhythmia syndrome, is undetectable with standard testing and leads to unexplained cardiac arrest. Objective: To explore the cardiac repolarization response on an electrocardiogram after brief tachycardia and a pause as a clinical diagnostic test for CRDS. Design, Setting, and Participants: An international, multicenter, case-control study including individual cases of CRDS, 3 patient control groups (individuals with suspected supraventricular tachycardia; survivors of unexplained cardiac arrest [UCA]; and individuals with genotype-positive catecholaminergic polymorphic ventricular tachycardia [CPVT]), and genetic mouse models (CRDS, wild type, and CPVT were used to define the cellular mechanism) conducted at 10 centers in 7 countries. Patient tracings were recorded between June 2005 and December 2023, and the analyses were performed from April 2023 to December 2023. Intervention: Brief tachycardia and a subsequent pause (either spontaneous or mediated through cardiac pacing). Main Outcomes and Measures: Change in QT interval and change in T-wave amplitude (defined as the difference between their absolute values on the postpause sinus beat and the last beat prior to tachycardia). Results: Among 10 case patients with CRDS, 45 control patients with suspected supraventricular tachycardia, 10 control patients who experienced UCA, and 3 control patients with genotype-positive CPVT, the median change in T-wave amplitude on the postpause sinus beat (after brief ventricular tachycardia at ≥150 beats/min) was higher in patients with CRDS (P < .001). The smallest change in T-wave amplitude was 0.250 mV for a CRDS case patient compared with the largest change in T-wave amplitude of 0.160 mV for a control patient, indicating 100% discrimination. Although the median change in QT interval was longer in CRDS cases (P = .002), an overlap between the cases and controls was present. The genetic mouse models recapitulated the findings observed in humans and suggested the repolarization response was secondary to a pathologically large systolic release of calcium from the sarcoplasmic reticulum. Conclusions and Relevance: There is a unique repolarization response on an electrocardiogram after provocation with brief tachycardia and a subsequent pause in CRDS cases and mouse models, which is absent from the controls. If these findings are confirmed in larger studies, this easy to perform maneuver may serve as an effective clinical diagnostic test for CRDS and become an important part of the evaluation of cardiac arrest.

An International Multicenter Cohort Study on ß-Blockers for the Treatment of Symptomatic Children With Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: Symptomatic children with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for recurrent arrhythmic events. ß-Blockers decrease this risk, but studies comparing individual ß-blockers in sizeable cohorts are lacking. We aimed to assess the association between risk for arrhythmic events and type of ß-blocker in a large cohort of symptomatic children with CPVT. METHODS: From 2 international registries of patients with CPVT, RYR2 variant-carrying symptomatic children (defined as syncope or sudden cardiac arrest before ß-blocker initiation and age at start of ß-blocker therapy <18 years), treated with a ß-blocker were included. Cox regression analyses with time-dependent covariates for ß-blockers and potential confounders were used to assess the hazard ratio (HR). The primary outcome was the first occurrence of sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter-defibrillator shock, or syncope. The secondary outcome was the first occurrence of any of the primary outcomes except syncope. RESULTS: We included 329 patients (median age at diagnosis, 12 [interquartile range, 7-15] years, 35% females). Ninety-nine (30.1%) patients experienced the primary outcome and 74 (22.5%) experienced the secondary outcome during a median follow-up of 6.7 (interquartile range, 2.8-12.5) years. Two-hundred sixteen patients (66.0%) used a nonselective ß-blocker (predominantly nadolol [n=140] or propranolol [n=70]) and 111 (33.7%) used a ß1-selective ß-blocker (predominantly atenolol [n=51], metoprolol [n=33], or bisoprolol [n=19]) as initial ß-blocker. Baseline characteristics did not differ. The HRs for both the primary and secondary outcomes were higher for ß1-selective compared with nonselective ß-blockers (HR, 2.04 [95% CI, 1.31-3.17]; and HR, 1.99 [95% CI, 1.20-3.30], respectively). When assessed separately, the HR for the primary outcome was higher for atenolol (HR, 2.68 [95% CI, 1.44-4.99]), bisoprolol (HR, 3.24 [95% CI, 1.47-7.18]), and metoprolol (HR, 2.18 [95% CI, 1.08-4.40]) compared with nadolol, but did not differ from propranolol. The HR of the secondary outcome was only higher in atenolol compared with nadolol (HR, 2.68 [95% CI, 1.30-5.55]). CONCLUSIONS: ß1-selective ß-blockers were associated with a significantly higher risk for arrhythmic events in symptomatic children with CPVT compared with nonselective ß-blockers, specifically nadolol. Nadolol, or propranolol if nadolol is unavailable, should be the preferred ß-blocker for treating symptomatic children with CPVT.

Population Pharmacokinetic and Pharmacodynamic Analysis of Valganciclovir for Optimizing Preemptive Therapy of Cytomegalovirus Infections in Kidney Transplant Recipients.

This study aimed to develop a population pharmacokinetic/pharmacodynamic (PK/PD) model of valganciclovir for preemptive therapy of cytomegalovirus (CMV) infection in kidney transplant patients. A population PK/PD model was developed with Monolix. Ganciclovir concentrations and CMV viral loads were obtained retrospectively from kidney transplant patients receiving routine clinical care. Ten thousand Monte Carlo simulations were performed with the licensed dosages adjusted for renal function to assess the probability of attaining a viral load target of ≤290 and ≤137 IU/mL. Fifty-seven patients provided 343 ganciclovir concentrations and 328 CMV viral loads for PK/PD modeling. A one-compartment pharmacokinetic model coupled with an indirect viral turnover growth model with stimulation of viral degradation pharmacodynamic model was devised. Simulations showed that 1- and 2-log10 reduction of CMV viral load mostly occurred between a median of 5 to 6 and 12 to 16 days, respectively. The licensed dosages achieved a probability of reaching the viral load target ≥90% at days 35 to 49 and 42 to 56 for the thresholds of ≤290 and ≤137 IU/mL, respectively. Simulations indicate that in patients with an estimated glomerular filtration rate of 10 to 24 mL/min/1.73m2, a dose increase to 450 mg every 36 h may reduce time to optimal viral load target to days 42 and 49 from a previous time of 49 and 56 days for the thresholds of ≤290 and ≤137 IU/mL, respectively. Currently licensed dosages of valganciclovir for preemptive therapy of CMV infection may achieve a viral load reduction within the first 2 weeks, but treatment should continue for ≥35 days to ensure viral load suppression.

Population Pharmacokinetics of Ganciclovir in Allogeneic Hematopoietic Stem Cell Transplant Patients.

Treatment of cytomegalovirus (CMV) infection in allogeneic hematopoietic stem cell transplantation (alloHCT) patients with ganciclovir is complicated by toxicity and resistance. This study aimed to develop an intravenous ganciclovir population pharmacokinetic model for post-alloHCT patients and to determine dosing regimens likely to achieve suggested therapeutic exposure targets. We performed a prospective observational single-center pharmacokinetic study in adult alloHCT patients requiring treatment with intravenous ganciclovir for CMV viremia or disease. Samples were analyzed using a validated ultraperformance liquid chromatography method. Population pharmacokinetic analysis and Monte Carlo simulations (n = 1000) were performed using Pmetrics for R. Twenty patients aged 18 to 69 years were included in the study. A 2-compartment model with linear elimination from the central compartment and between occasion variability best described the data. Incorporating creatinine clearance (CLCR) estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and presence of continuous renal replacement therapy as covariates for ganciclovir clearance improved the model. Compared to current dosing recommendations, simulations demonstrated loading doses were required to achieve a target AUC24 of 80 to 120 mg.h/L on day 1 of induction therapy. Increased individualization of post-loading induction and maintenance doses based on CLCR is required to achieve the suggested exposures for efficacy (AUC24 >80/>40 mg.h/L for induction/maintenance) while remaining below the exposure thresholds for toxicity (AUC24 <120/<60 mg.h/L for induction/maintenance). Intravenous ganciclovir dosing in alloHCT patients can be guided by CLCR estimated by CKD-EPI. Incorporation of loading doses into induction dosing regimens should be considered for timely achievement of currently suggested exposures.