Citations

Background: Calcium release channel deficiency syndrome (CRCDS) is caused by biogenic or biophysical loss-of-function (LOF) pathogenic variants in the RYR2 -encoded ryanodine receptor (RyR2), a key intracellular Ca 2+ release channel. Previously, we identified a novel homozygous duplication involving the promoter and exons 1-4 of RYR2 , leading to 80% RyR2 protein loss and exertion-related sudden death in the young. Here, we generated a RYR2 knockout (RYR2-KO) induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) model to explore intracellular and electrophysiological compensatory mechanisms that overcome this extreme loss of RyR2 protein. Methods: Using CRISPR/Cas9 gene editing, a homozygous c.163delT variant (p.S55Pfs*46) was inserted into a normal iPSC line (isogenic control) to create a homozygous RYR2-KO iPSC line. After re-engineering the lines into ventricular-like cardiomyocytes (iPSC-CMs), intracellular Ca 2+ handling was assessed by Fluo-4 AM cell imaging (0.5 Hz stimulation). Electrical remodeling in the L-type Ca 2+ current (I CaL ) was assessed using the whole-cell patch clamp technique. Results: Significant differences were observed in Ca 2+ transient parameters between RYR2-KO and isogenic control iPSC-CMs. Biogenic RyR2 loss significantly reduced Ca 2+ transient peak amplitude (CTA: 0.16 ± 0.01 ΔF/F0, p<0.0001) and upstroke velocity (CTV: 0.42 ± 0.06 (ΔF/F0)/t, p<0.0001), and prolonged Ca 2+ transient duration (CTD 90 : 1.59 ± 0.03 s, p=0.01) as compared to isogenic control (CTA: 0.48 ± 0.04 ΔF/F0; CTV: 1.30 ± 0.15 (ΔF/F0)/t; CTD 90 : 1.46 ± 0.05 s). Additionally, RyR2 loss abolished SR Ca 2+ leak (0.9 ± 0.9 % versus 35.1 ± 15.5 %, p=0.03). Lastly, a significant reduction in I CaL density was observed in RYR2-KO iPSC-CMs as compared to isogenic control iPSC-CMs (at 0 mV, RYR2-KO: -8.54 ± 1.60 pA/pF, control: -17.45 ± 3.69 pA/pF, p=0.0004). These data indicate that I CaL reduction may contribute to the reduced Ca 2+ transient peak. Conclusions: Complete loss of RyR2 in iPSC-CMs profoundly disrupts intracellular Ca 2+ handling, abolishes Ca 2+ sparks frequency, and secondarily down-regulates the sarcolemmal L-type Ca 2+ channel.

Background: A blanking period allowing for atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) has historically been standardized to 90 days. With the recent introduction of pulsed field ablation (PFA) for PVI and emerging in vitro data suggesting a shorter inflammatory timeframe, it remains unclear whether recurrences during this 90-days period reflect incomplete procedural success or merely transient inflammatory changes. Research Question: In patients undergoing PVI with PFA, do early AF recurrences at 30, 60, and 90 days predict late AF recurrences beyond the standardized 90-day blanking period? Methods: Patients undergoing PFA for AF were retrospectively included. Procedures were performed under general anesthesia, and high-density (HD) mapping, with PVI and additional ablation lines applied at the operator’s discretion. PFA catheters included Farawave, PulseSelect, and Sphere-9. AF recurrences were defined as documented episodes on 12-lead ECG or cardiac monitoring devices, confirmed by interpretation from an experienced cardiologist. Survival analyses were conducted based on the occurrence of early recurrences at 30, 60, and 90 days post-ablation. Kaplan-Meier curves and hazard ratios were reported. This study was approved by our institutional review board. Results: To the best of our knowledge, this is the largest real-world study reporting outcomes of PFA for AF in the United States. A total of 1,214 patients were included in the analysis. Mean age was 66.4 years; 31.9% were female, and 22.4% underwent redo PVI. Six-month AF recurrence-free survival was 79% (95% CI, 75–83%) for the overall cohort. Patients experiencing early recurrence at 30, 60, and 90 days had a significantly higher risk of AF recurrence beyond the standardized 90-day blanking period (HR 4.0, 95% CI 2.7–5.9, P < 0.01; HR 5.0, 95% CI 3.6–7.1, P < 0.01; and HR 6.9, 95% CI 4.9–9.6, P < 0.01, respectively). Conclusion: Early recurrences at 30, 60, and 90 days post-ablation are strongly associated with atrial fibrillation recurrence beyond the 90-day blanking period. These findings challenge the traditional concept of blanking period after PFA and suggest that early recurrence may indicate incomplete procedural success rather than transient inflammation.

Background: Long QT syndrome (LQTS) is a potentially lethal cardiac channelopathy that stems primarily from pathogenic variants in KCNQ1 (LQT1), KCNH2 (LQT2), or SCN5A (LQT3) and is characterized by prolongation of the cardiac action potential duration (APD) at the cellular level. Despite current therapeutic options, there is a pressing need for novel, precision medicine-based, effective pharmacological therapies for LQTS, particularly for LQT2 and LQT3. Goal: To develop a high-throughput drug screening platform to identify novel therapeutics for LQTS using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Methods: iPSC-CMs were made for patients with LQT2 (p.G604S) or LQT3 (p.P1332L). Voltage dye assays were performed using a kinetic image cytometer (KIC) in a 96 well format. The APD at 90% repolarization (APD90) was measured in treated/untreated iPSC-CMs. Cyteseer image analysis software was used for optical APD analysis. SCN5A-P1332L iPSC-CMs were treated with 10 uM mexiletine (MEX) as a positive control. 114 compounds from a commercially available library of FDA-approved drugs were tested in triplicate to assess their APD shortening efficacy. Whole-cell patch clamp was used to confirm the lead compound’s effect in KCNH2-G604S iPSC-CMs. Results: MEX significantly shortened the APD90 of SCN5A-P1332L iPSC-CMs by 13% (669 ± 5 to 586 ± 10 ms; p<0.0001; n=50). Of the 114 tested compounds, 6 shortened the APD90 of SCN5A-P1332L iPSC-CMs by greater than 20%. The lead compound shortened the APD90 of SCN5A-P1332L iPSC-CMs by 32% (571 ± 2 ms; n=314, to 387 ± 4 ms; n=80; p<0.0001). All 6 candidate compounds also shortened the APD90 of KCNH2-G604S iPSC-CMs by greater than 20% in KIC screening assays. Whole-cell patch clamp confirmed APD shortening by the lead compound in KCNH2-G604S iPSC-CMs (759 ± 35 ms; n=13, to 599 ± 89 ms; n=9; p<0.03). Conclusion: The high-throughput KIC screen confirmed mexiletine’s APD shortening effects in SCN5A-P1332L iPSC-CMs, validating the assay's potential for efficient, large-scale drug screening. In a pilot screen, we identified 6 novel LQTS drug candidates which shortened the APD90 in SCN5A-P1332L (LQT3) and KCNH2-G604S (LQT2) iPSC-CMs more than mexiletine. The lead compound’s APD shortening effects in KCNH2-G604S iPSC-CMs were confirmed with whole cell patch clamp. The KIC platform offers a robust method for identifying novel QT shortening compounds by enabling reproducible APD measurements in a high-throughput format.

Background: Patients with cardiac implantable electronic devices (CIEDs) undergoing radiation therapy face potential risks of device malfunction. Proton beam therapy (PBT), with its reduced neutron scatter, has emerged as a potentially safer alternative, yet real-world safety data remain scarce. Methods: We conducted a retrospective cohort study of 100 patients with CIEDs (76 pacemakers, 24 ICDs) who underwent PBT from 2016 to 2023 at a quaternary center. Baseline and serial device interrogations were performed before, during, and after treatment to assess lead impedance, capture thresholds, battery function, and arrhythmic events. Patients were stratified by pacemaker dependence and monitored accordingly. Primary outcomes included device malfunction and new-onset arrhythmias during treatment. Secondary outcomes included device parameter changes, one-year arrhythmia incidence, and cardiac-related hospitalizations. Results: No treatment-related deaths or major device failures occurred. Device malfunction was rare (2 pacemaker patients, 2.6%), with no malfunctions in ICD recipients. Transient, non-clinically significant changes in lead impedance and capture thresholds were observed. Arrhythmias during treatment occurred in 26% of pacemaker and 25% of ICD patients, but only 4% developed new arrhythmias. At one year, device-related complications and cardiac outcomes remained comparable across groups. Independent predictors of arrhythmias during treatment included a higher radiation dose per fraction (OR 1.45; p=0.001), a longer treatment duration (OR 1.12; p=0.04), and a higher number of fractions (OR 1.20; p=0.01). Conclusion: Proton beam therapy appears safe in patients with CIEDs, with a low incidence of clinically significant device malfunctions or arrhythmias. These findings support the integration of PBT into routine practice for this population and underscore the importance of structured monitoring protocols and prospective guideline refinement.

Background: Syncope is a leading cause of transient loss of consciousness, especially in older adults. Post-syncopal driving restrictions are widely recommended, but the required duration varies by state. The impact of these policies on motor vehicle crash outcomes remains unclear. Methods: We conducted a cross-sectional analysis of 45 U.S. states, comparing crash and fatality data between states requiring < 6 months vs. ≥ 6 months of driving restriction following a syncopal episode. Data were obtained from Fatality Analysis Reporting System, National Highway Traffic Safety Administration, state Department of Motor Vehicles, and medical boards. Crash rates were normalized by licensed drivers and population. Statistical comparisons were made using Welch’s t-tests. Results: States with ≥ 6-month restrictions had significantly lower crash rates among older drivers (0.0171 vs. 0.0256, p = 0.0076). Relative crash ratios comparing older to younger drivers were also lower (0.220 vs. 0.306, p = 0.067). Overall crash rates trended lower in states with ≥ 6-month restrictions in both per licensed driver ( p = 0.054) and per population ( p = 0.099). No significant differences were observed in fatality rates. Conclusions: Longer post-syncope driving restriction durations (≥ 6 months) are associated with reduced crash risk among older drivers and a narrowing of age-related disparities in crash rates. These findings suggest potential public health value in adopting more uniform, evidence-based restriction policies following syncopal events for older drivers.

Background: The comparable long-term benefits of coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI) in patients with multivessel disease remains limited in underrepresented populations, particularly in patients with multivessel coronary artery disease and heart failure with severely reduced left ventricular ejection fraction (LVEF <35%). Research Question: Among patients with HF and LVEF < 35% which revascularization strategy (CABG or PCI) provides superior long-term clinical outcomes? Methods: We conducted a systematic review and meta-analysis of observational studies involving patients with ischemic heart disease (IHD), HF and LVEF < 35% undergoing PCI or CABG with a minimum follow-up duration of five years. PubMed, Embase, and Cochrane databases were searched for studies published up to April 15, 2025. We computed hazard ratios (HR) from propensity score matched results. We used Cochrane Review Manager version 9.2.1 for statistical analysis. The primary endpoints of interest included all-cause mortality at 5 to 10 years, repeat revascularization, and all-cause mortality at 10 or more years. Results: We included 8 studies with 12,697 patients (6,187 PCI vs 6,510 CABG). Median follow-up duration ranged from 3.8 to 5.2 years, with the longest reported follow-up up to 13 years. The cumulative, propensity adjusted, incidence of all-cause mortality was significantly lower in the CABG group compared to PCI in 5 to 10 years of follow-up (HR 0.61; 95% CI 0.54-0.69; p<0.001) and ≥ 10 years (HR 0.63; 95% CI 0.53-0.74; p<0.001). Additionally, CABG was associated with a reduced need for repeat revascularization in the 5 to 10 year time frame, with a HR of 0.42 (95% CI 0.22-0.81; p=0.01). Conclusion: In this systematic review and meta-analysis of patients with IHD and an ejection fraction ≤ 35% undergoing revascularization, CABG was associated with a reduction in all-cause mortality at ≥ 5 and ≥ 10 years of follow-up, as compared to PCI.

Background: Transvenous lead extraction (TLE) is the standard of care for cardiac implantable electronic device (CIED) infections. Data regarding the optimal timing of CIED reimplantation after TLE are not well established. Objective: This study aims to assess the 5-year outcomes of early (≤7 days) versus non-early (>7 days) CIED reimplantation following TLE for CIED infection using a multi-national database. Methods: Using the TriNetX Analytics Research Network, we included patients aged ≥18 years who underwent TLE for CIED infection between 1/1/2014 and 1/1/2020. Patients were further categorized into two groups: early CIED reimplantation (≤7 days from TLE) and non-early CIED reimplantation. Propensity score matching (PSM) was performed by including patient demographics, LVEF, cardiac comorbidities and medications. The study outcomes included all-cause mortality and cardiac adverse events during a 5-year study period. Results: A total of 1668 patients in the early CIED reimplantation group and 1550 in the non-early group were identified. After PSM, 1327 patients in each group were analyzed. Compared to non-early group, early CIED reimplantation group was associated with significantly higher odds of all-cause hospitalization (odds ratio [OR]: 1.837, 95% confidence interval [CI]: 1.532-2.203) and repeated device infection (OR: 1.569, 95% CI: 1.314-1.873) at 5-year follow-up. However, no significant differences were observed in all-cause mortality (OR: 0.927, 95% CI: 0.778-1.104), HF exacerbation (OR: 1.021, 95% CI: 0.855-1.218), cardiac arrest (OR:0.924, 95% CI: 0.739-1.157), stroke (OR: 1.169, 95% CI: 0.915-1.494), cardiac thrombus (OR: 1.163, 95% CI: 0.749-1.808), major bleeding (OR: 1.079, 95% CI: 0.857-1.358) and venous thromboembolism (OR: 0.923, 95% CI: 0.759-1.123) between the two groups. Conclusion: Early reimplantation of CIED following TLE of infected devices was associated with worse outcomes in all-cause hospitalization and repeated device infection. Further large prospective studies are needed to define the optimal timing of device reimplantation.

Abstract Objective: The National Institutes of Health (NIH) Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER) is a validated laptop-based battery of executive functioning tests. A modified tablet version of the EXAMINER was developed on the UCSF Tablet-based Cognitive Assessment Tool (TabCAT-EXAMINER). Here we describe the battery and investigate the reliability and validity of a composite score. Methods: A diagnostically heterogeneous sample of 2135 individuals (mean age = 65.58, SD = 16.07), including controls and participants with a variety of neurodegenerative syndromes, completed the TabCAT-EXAMINER. A composite score was developed using confirmatory factor analysis and item response theory. Validity was evaluated via linear regressions that tested associations with neuropsychological tests, demographics, clinical diagnosis, and disease severity. Replicability of cross-sectional results was tested in a separate sample of participants ( n = 342) recruited from a frontotemporal dementia study. As this separate sample also collected longitudinal TabCAT-EXAMINER measures, we additionally assessed test-retest reliability and associations between baseline disease severity and changes in TabCAT-EXAMINER scores. Results: The TabCAT-EXAMINER score was normally distributed, demonstrated high test-retest reliability, and was associated in the expected directions with independent tests of executive functioning, demographics, disease severity, and diagnosis. Greater baseline disease severity was associated with more rapid longitudinal TabCAT-EXAMINER decline. Conclusions: The TabCAT-EXAMINER is a tablet-based executive functioning battery developed for observational research and clinical trials. Performance can be summarized as a single composite score, and results of this study support its reliability and validity in cognitive aging and neurodegenerative disease cohorts.

ABSTRACT Suicidality contributes substantially to global morbidity and mortality, yet despite its heritability, its biological etiology remains largely elusive. We conducted multi-ancestry genome-wide association study meta-analyses of suicidal ideation (259,747 cases), suicide attempt (64,993 cases), suicide death (9,197 cases), and suicidal behavior (suicide attempt/ death, 75,300 cases), across 54 cohorts (e.g., the Psychiatric Genomics Consortium, Million Veteran Program, UK Biobank). We identified 77 significant loci across meta-analyses, including 59 previously unreported for suicidality. SNP-based heritability ranged from 2.0-6.7% and there were strong, yet incomplete, genetic correlations between suicidality phenotypes (0.70-0.88). Fine-mapping prioritized putative causal SNPs and 20 credible genes. Enrichment analyses implicated synaptic pathways and neuronal populations predominantly in subcortical brain regions (e.g., amygdala excitatory, medium spiny, hippocampal CA1-3). Together, these findings establish suicidality as a polygenic set of traits with both shared and distinct genetic influences, providing a foundation for future studies of suicide biology and etiology.