Epicardial adipose tissue dispersion at CT and recurrent atrial fibrillation after pulmonary vein isolation.

OBJECTIVES: Epicardial adipose tissue (EAT) remodeling is associated with atrial fibrillation (AF). Left atrial (LA) EAT dispersion on cardiac CT is a non-invasive imaging biomarker reflecting EAT heterogeneity. We aimed to investigate the association of LA EAT dispersion with AF recurrence after pulmonary vein isolation (PVI). METHODS: In a prospective registry of consecutive patients undergoing first PVI, mean EAT attenuation values were measured on contrast-enhanced cardiac CT scans in Hounsfield units (HU) within low (- 195 to - 45 HU) and high (- 44 to - 15 HU) threshold EAT compartments around the left atrium (LA). EAT dispersion was defined as the difference between the mean HU values within the two EAT compartments. Continuous variables were compared between groups using the Mann-Whitney U test and cox proportional hazard models were used to calculate hazard ratios of predictors of 1-year AF recurrence. RESULTS: A total of 208 patients were included, 135 with paroxysmal AF and 73 with persistent AF. LA EAT dispersion was significantly larger in patients with persistent compared to paroxysmal AF (52.6 HU vs. 49.9 HU; p = 0.001). After 1 year of follow-up, LA EAT dispersion above the mean (> 50.8 HU) was associated with a higher risk of AF recurrence (HR 2.3, 95% CI 1.5-3.6; p < 0.001). It retained its predictive value when corrected for age, sex, body mass index, LA volume, and AF type (HR 2.8, 95% CI 1.6-4.6; p < 0.001). CONCLUSION: A larger LA EAT dispersion on contrast-enhanced cardiac CT scans, reflecting EAT heterogeneity, is independently associated with AF recurrence after PVI. CLINICAL RELEVANCE STATEMENT: Based on LA EAT dispersion assessment, a more accurate risk stratification and patient selection may be possible based on a pre-procedural cardiac CT when planning PVI. KEY POINTS: • Epicardial adipose tissue (EAT) remodeling is associated with atrial fibrillation (AF). • A larger left atrial EAT dispersion in a pre-procedural cardiac CT was associated with a higher 1-year AF recurrence risk after pulmonary vein isolation. • A pre-procedural cardiac CT with left atrial EAT dispersion assessment may provide a more accurate risk stratification and patient selection for PVI.

A Novel MIP-1-Expressing Macrophage Subtype in BAL Fluid from Healthy Volunteers.

Tissue availability remains an important limitation of single-cell genomic technologies for investigating cellular heterogeneity in human health and disease. BAL represents a minimally invasive approach to assessing an individual's lung cellular environment for diagnosis and research. However, the lack of high-quality, healthy lung reference data is a major obstacle to using single-cell approaches to study a plethora of lung diseases. Here, we performed single-cell RNA sequencing on over 40,000 cells isolated from the BAL of four healthy volunteers. Of the six cell types or lineages we identified, macrophages were consistently the most numerous across individuals. Our analysis confirmed the expression of marker genes defining cell types despite background signals because of the ambient RNA found in many single-cell studies. We assessed the variability of gene expression across macrophages and defined a distinct subpopulation of cells expressing a set of genes associated with Macrophage Inflammatory Protein 1 (MIP-1). RNA in situ hybridization and reanalysis of published lung single-cell data validated the presence of this macrophage subpopulation. Thus, our study characterizes lung macrophage heterogeneity in healthy individuals and provides a valuable resource for future studies to understand the lung environment in health and disease.

Pancreas and Islet Transplantation: Comparative Outcome Analysis of a Single-centre Cohort Over 20-years.

OBJECTIVE: To provide the largest single-center analysis of islet (ITx) and pancreas (PTx) transplantation. SUMMARY BACKGROUND DATA: Studies describing long-term outcomes with ITx and PTx are scarce. METHODS: We included adults undergoing ITx (n=266) and PTx (n=146) at the University of Alberta from January 1999 to October 2019. Outcomes include patient and graft survival, insulin independence, glycemic control, procedure-related complications, and hospital readmissions. Data are presented as medians (interquartile ranges, IQR) and absolute numbers (percentages, %) and compared using Mann-Whitney and χ2 tests. Kaplan-Meier estimates, Cox proportional hazard models and mixed main effects models were implemented. RESULTS: Crude mortality was 9.4% and 14.4% after ITx and PTx, respectively ( P= 0.141). Sex-adjusted and age-adjusted hazard-ratio for mortality was 2.08 (95% CI, 1.04-4.17, P= 0.038) for PTx versus ITx. Insulin independence occurred in 78.6% and 92.5% in ITx and PTx recipients, respectively ( P= 0.0003), while the total duration of insulin independence was 2.1 (IQR 0.8-4.6) and 6.7 (IQR 2.9-12.4) year for ITx and PTx, respectively ( P= 2.2×10 -22 ). Graft failure ensued in 34.2% and 19.9% after ITx and PTx, respectively ( P =0.002). Glycemic control improved for up to 20-years post-transplant, particularly for PTx recipients (group, P= 7.4×10 -7 , time, P =4.8×10 -6 , group*time, P= 1.2×10 -7 ). Procedure-related complications and hospital readmissions were higher after PTx ( P =2.5×10 -32 and P= 6.4×10 -112 , respectively). CONCLUSIONS: PTx shows higher sex-adjusted and age-adjusted mortality, procedure-related complications and readmissions compared with ITx. Conversely, insulin independence, graft survival and glycemic control are better with PTx. This study provides data to balance risks and benefits with ITx and PTx, which could improve shared decision-making.

Acute and long-term outcomes of quadripolar IS-4 versus bipolar IS-1 left ventricular leads in cardiac resynchronization therapy: A retrospective registry study.

BACKGROUND: The implantation procedure of left ventricular (LV) leads and the management of cardiac resynchronization therapy (CRT) patients can be challenging. The IS-4 standard for CRT offers additional pacing vectors compared to bipolar leads (IS-1). IS-4 leads improve procedural outcome and may also result in lower adverse events during follow-up (FU) and improve clinical outcome in CRT patients. Further long-term FU data comparing the two lead designs are necessary. METHODS: In this retrospective, single-center study we included adult patients implanted with a CRT-Defibrillator (CRT-D) or CRT-Pacemaker (CRT-P) with a quadripolar (IS-4 group) or bipolar (IS-1 group) LV lead and with available ≥3 years clinical FU. The combined primary endpoint was a combination of predefined, lead-related adverse events. Secondary endpoints were all single components of the primary endpoint. RESULTS: Overall, 133 patients (IS-4 n = 66; IS-1 n = 67) with a mean FU of 4.03 ± 1.93 years were included. Lead-related adverse events were less frequent in patients with an IS-4 lead than with an IS-1 lead (n = 8, 12.1% vs. n = 23, 34.3%; p = .002). The secondary outcomes showed a lower rate of LV lead deactivation/explantation and LV lead dislodgement/dysfunction (4.5% vs. 22.4%; p = .003; 4.5% vs. 17.9%; p = .015, respectively) in the IS-4 patient group. Less patients suffered from unresolved phrenic nerve stimulation with an IS-4 lead (3.0% vs. 13.4%; p = .029). LV lead-related re-interventions were fewer in case of an IS-4 lead (6.1% vs. 17.9%; p = .036). CONCLUSION: In this retrospective analysis, the IS-4 LV lead is associated with lower lead-related complication rates than the IS-1 lead at long-term FU.

The Relationship between Enhancing Left Atrial Adipose Tissue at CT and Recurrent Atrial Fibrillation.

Background The association of epicardial adipose tissue (EAT) and its metabolic activity with atrial fibrillation (AF) is an area of active investigation. Left atrial (LA) enhancing EAT (e-EAT) at cardiac CT may be a noninvasive surrogate marker for the metabolic activity of EAT. Purpose To determine the relationship between LA e-EAT and recurrence after AF ablation. Materials and Methods In a secondary analysis of a prospective registry of consecutive patients (from July 2018 to December 2019) undergoing first AF ablation, total and LA EAT were segmented on preprocedural noncontrast- and contrast-enhanced cardiac CT scans. LA e-EAT volume fraction was defined as the LA EAT volume difference between the noncontrast- and contrast-enhanced scan divided by the total LA EAT volume on the noncontrast-enhanced scan (threshold values, -15 HU to -195 HU). Continuous variables were compared between groups by using the Mann-Whitney U test. Cox proportional hazard models were used to calculate hazard ratios of predictors of 1-year AF recurrence. Results A total of 212 patients (mean age, 64 years; 159 men) who underwent a first AF ablation were included (paroxysmal AF, 64%; persistent AF, 36%). The LA EAT volume was higher in patients with persistent versus paroxysmal AF (50 cm3 [IQR, 37-72] vs 37 [IQR, 27-49]; P < .001), but no difference was found for LA e-EAT (P = .09). After 1 year of follow-up, AF recurrence rate was 77 of 212 (36%). LA e-EAT above the mean (>33%) was associated with a higher risk of AF recurrence (hazard ratio [HR], 2.1; 95% CI: 1.3, 3.3; P < .01). In a multivariable Cox regression analysis, LA e-EAT retained its predictive value when corrected for sex, age, AF phenotype, LA volume index, and LA EAT volume (HR, 1.9; 95% CI: 1.1, 3.1; P = .02). Conclusion Left atrial enhancing epicardial adipose tissue was independently associated with recurrence after atrial fibrillation ablation. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Stojanovska in this issue.

Estimation of Early Graft Function Using the BETA-2 Score Following Clinical Islet Transplantation.

Little is known about how early islet graft function evolves in the clinical setting. The BETA-2 score is a validated index of islet function that can be calculated from a single blood sample and lends itself to frequent monitoring of graft function. In this study, we characterized early graft function by calculating weekly BETA-2 score in recipients who achieved insulin independence after single transplant (group 1, n = 8) compared to recipients who required a second transplant before achieving insulin independence (group 2, n = 7). We also determined whether graft function 1-week post-transplant was associated with insulin independence in individuals who received initial transplant between 2000-2017 (n = 125). Our results show that graft function increased rapidly reaching a plateau 4-6 weeks post-transplant. The BETA-2 score was higher in group 1 compared to group 2 as early as 1-week post-transplant (15 + 3 vs. 9 + 2, p = 0.001). In an unselected cohort, BETA-2 at 1-week post-transplant was associated with graft survival as defined by insulin independence during median follow up of 12 months (range 2-119 months) with greater survival among those with BETA-2 score >10 (p < 0.001, log-rank test). These findings suggest that primary graft function is established within 4-6 weeks post-transplant and graft function at 1-week post-transplant predicts long-term transplant outcomes.

Efficacy and safety of ethanol infusion into the vein of Marshall for mitral isthmus ablation.

INTRODUCTION: Chemical ablation by retrograde infusion of ethanol into the vein of Marshall (VOM-EI) can facilitate the achievement of mitral isthmus block. This study sought to describe the efficacy and safety of this technique. METHODS AND RESULTS: Twenty-two consecutive patients (14 males, median age 71 years) with attempted VOM-EI for mitral isthmus ablation were included in the study. VOM-EI was successfully performed with a median of 4 ml of 96% ethanol in 19 patients (86%) and the mitral isthmus was successfully blocked in all (100%). Touch up endocardial and/or epicardial ablation after VOM-EI was necessary for 12 patients (63%). Perimitral flutter was present in 12 patients (63%) during VOM-EI and terminated or slowed by VOM-EI in 4 and 3 patients, respectively. The low-voltage area of the mitral isthmus region increased from 3.1 cm2 (interquartile range [IQR] 0-7.9) before to 13.2 cm2 (IQR: 8.2-15.0) after VOM-EI and correlated significantly with the volume of ethanol injected (p = .03). Median high-sensitive cardiac troponin-T increased significantly from 330 ng/L (IQR: 221-516) the evening of the procedure to 598 ng/L (IQR: 382-769; p = .02) the following morning. A small pericardial effusion occurred in three patients (16%), mild pericarditis in one (5%), and uneventful VOM dissection in two (11%). After a median follow-up of 3.5 months (IQR: 3.0-11.0), 10 of 18 patients (56%) with VOM-EI and available follow-up had arrhythmia recurrence. Repeat ablation was performed in five patients (50%) and peri-mitral flutter diagnosed in three (60%). CONCLUSION: VOM-EI is feasible, safe, and effective to achieve acute mitral isthmus block.

Ultralow temperature cryoablation: Safety and efficacy of preclinical atrial and ventricular lesions.

BACKGROUND: Ultralow temperature cyroablation (ULTC) is designed to create focal, linear, and circumferential lesions. The aim of this study was to assess the safety, efficacy, and durability of atrial and ventricular ULTC lesions in preclinical large animal models. METHODS AND RESULTS: The ULTC system uses nitrogen near its liquid-vapor critical point to cool 11-cm ablation catheters. The catheter can be shaped to specific anatomies using pre-shaped stylets. ULTC was used in 11 swine and four sheep to create atrial (pulmonary vein isolation and linear ablation) and ventricular lesions. Acute and 90-day success were evaluated by intracardiac mapping and histologic examination. Cryoadherence was observed during all ULTC applications, ensuring catheter stability at target locations. Local electrograms were completely eliminated immediately after the first single-shot ULTC application in 49 of 53 (92.5%) atrial and in 31 of 32 (96.9%) ventricular applications. Lesion depth as measured on histology preparations was 1.96 ± 0.8 mm in atrial and 5.61 ± 2.2 mm in ventricular lesions. In all animals, voltage maps and histology demonstrated transmural and durable lesions without gaps, surrounded by intact collagen fibers without injury to surrounding tissues. Transient coronary spasm could be provoked with endocardial ULTC in the left ventricle in close proximity to a coronary artery. CONCLUSIONS: ULTC created effective and efficient atrial and ventricular lesions in vivo without procedural complications in two large animal models. ULTC lesions were transmural, contiguous, and durable over 3 months.

Mitochondrial 8-oxoguanine DNA glycosylase mitigates alveolar epithelial cell PINK1 deficiency, mitochondrial DNA damage, apoptosis, and lung fibrosis.

Alveolar epithelial cell (AEC) apoptosis, arising from mitochondrial dysfunction and mitophagy defects, is important in mediating idiopathic pulmonary fibrosis (IPF). Our group established a role for the mitochondrial (mt) DNA base excision repair enzyme, 8-oxoguanine-DNA glycosylase 1 (mtOGG1), in preventing oxidant-induced AEC mtDNA damage and apoptosis and showed that OGG1-deficient mice have increased lung fibrosis. Herein, we determined whether mice overexpressing the mtOGG1 transgene (mtOgg1tg) are protected against lung fibrosis and whether AEC mtOGG1 preservation of mtDNA integrity mitigates phosphatase and tensin homolog-induced putative kinase 1 (PINK1) deficiency and apoptosis. Compared with wild type (WT), mtOgg1tg mice have diminished asbestos- and bleomycin-induced pulmonary fibrosis that was accompanied by reduced lung and AEC mtDNA damage and apoptosis. Asbestos and H2O2 promote the MLE-12 cell PINK1 deficiency, as assessed by reductions in the expression of PINK1 mRNA and mitochondrial protein expression. Compared with WT, Pink1-knockout (Pink1-KO) mice are more susceptible to asbestos-induced lung fibrosis and have increased lung and alveolar type II (AT2) cell mtDNA damage and apoptosis. AT2 cells from Pink1-KO mice and PINK1-silenced (siRNA) MLE-12 cells have increased mtDNA damage that is augmented by oxidative stress. Interestingly, mtOGG1 overexpression attenuates oxidant-induced MLE-12 cell mtDNA damage and apoptosis despite PINK1 silencing. mtDNA damage is increased in the lungs of patients with IPF as compared with controls. Collectively, these findings suggest that mtOGG1 maintenance of AEC mtDNA is crucial for preventing PINK1 deficiency that promotes apoptosis and lung fibrosis. Given the key role of AEC apoptosis in pulmonary fibrosis, strategies aimed at preserving AT2 cell mtDNA integrity may be an innovative target.

Impedance, power, and current in radiofrequency ablation: Insights from technical, ex vivo, and clinical studies.

BACKGROUND: Radiofrequency (RF) power is routinely considered during RF application. In contrast, impedance has been relatively poorly studied, despite also influencing RF lesion creation. The aim of this study was to examine the influence of electric impedance on RF lesion characteristics and on clinical RF ablation parameters. METHODS AND RESULTS: In the first part of the study, power and impedance were systematically varied and the resulting current was calculated using custom-made software. In the second part of the study, ablation lesions (n = 40) were analyzed in a porcine ex vivo model. RF applications were delivered in cardiac muscle preparations with systematically varied values of electric impedance using a contact force ablation catheter. In the third part of the study, n = 3378 clinical RF applications were analyzed, power, impedance, and current data were exported and correlated with clinical patient data. 20 ± 3 W/80 Ω, 30 ± 3 W/120 Ω, 40 ± 3 W/160 Ω, and 50 ± 3 W/200 Ω RF applications resulted in 498 ± 40, 499 ± 26, 500 ± 20, and 500 ± 16 mA RF current, which were not significantly different (p = .32). Ablation lesions were significantly different in depth and diameter when applied with the same power but different impedances (p < .01); lesion sizes decreased when increasing impedance. In clinical data, a large range of delivered current (e.g., 39-40 W: 530-754 mA) was measured, due to variations in impedance. CONCLUSIONS: RF lesion creation is determined by current rather than by power. During clinical RF ablation procedures, impedance significantly influences current delivery and varies considerably between patients. Impedance and current are clinically relevant parameters that should be considered during RF ablation.

Atrial tachycardia circuits include low voltage area from index atrial fibrillation ablation relationship between RF ablation lesion and AT.

BACKGROUND: No study to date has used high-density mapping to investigate the relationship between prior radiofrequency (RF) lesions for persistent atrial fibrillation (PsAF) ablation and subsequent atrial tachycardias (ATs). METHODS: From 41 consecutive patients who underwent AT ablation at a second procedure using an ultrahigh-density mapping system, 22 patients (38 ATs) were included as they also had complete maps with a multipolar catheter and three-dimensional (3D) mapping system at the time of the first PsAF ablation procedure. We, therefore, compared voltage maps from the first AF ablation procedure to those from the subsequent AT ablation procedure, as well as the lesion sets used for AF ablation vs the activation patterns in AT during the second procedure. RESULTS: In the 38 ATs, 211 of 285 analyzed atrial areas displayed low voltage area (LVA) (74%). Eighteen percent (38/211) existed before the index ablation for AF while 82% (173/211) were newly identified as LVA during the second procedure. Ninety-nine percent (172/173) of the newly developed LVA colocalized with RF lesions delivered for PsAF. Of the 38 ATs, 89.5% (34/38) AT circuits were associated with newly developed LVA due to RF lesions whilst 10.5% (4/38) AT circuits were associated with pre-existing LVA observed at the index procedure. No AT circuit was completely independent from index RF lesions in this series. CONCLUSIONS: Analysis of detailed 3D electroanatomical mapping demonstrates that most ATs after PsAF ablation are involving LVAs due to index RF lesions.

In silico analysis of the relation between conventional and high-power short-duration RF ablation settings and resulting lesion metrics.

BACKGROUND: Use of lesion metric indices is a proposed strategy to support pulmonary vein isolation procedures and these indices show good correlations with lesion sizes. The aim of this in silico study is to provide a detailed analysis of radiofrequency (RF) settings, including high-power short-duration (HPSD) settings, and resulting lesion metric indices. METHODS AND RESULTS: A software program was designed which simulated virtual RF ablations. Lesion metric indices (Ablation index: AI, Lesion size index: LSI) were calculated based on underlying RF settings (contact force [CF], power, duration). In series of calculations, the applied settings were varied within defined ranges (CF: 1-80 g, power: 1-60 W, duration: 1-60 seconds). Overall, n = 388 000 virtual ablations were calculated. The resulting lesion metric indices were compared with each other and analyzed in relation to respective RF settings. Increasing contact force from 1 to 10 g resulted in a 4.4-fold LSI value, whilst increasing contact force from 10 to 20g resulted in a 1.5-fold value (P < .01). When RF power was increased by 10 W, lesion metric indices increased between 1.3- and 1.6-fold. A prolongation of RF duration by 10 seconds resulted in a 1.2-to-1.3-fold increase of lesion metric indices. HPSD RF applications of 50 W, 11 to 13 seconds, and 60 W, 8 to 10 seconds resulted in equivalent lesion metric indices when compared with 30 W, 30 seconds conventional ablations. CONCLUSIONS: The findings support the clinical use of contact forces within a 10 to 20 g range. AI is more sensitive to RF duration, whereas LSI is more sensitive to contact force. HPSD RF settings can successfully be derived from lesion metric indices.

Assessment of Risks and Benefits of Beta Cell Replacement Versus Automated Insulin Delivery Systems for Type 1 Diabetes.

PURPOSE OF REVIEW: Current approaches to insulin replacement in type 1 diabetes are unable to achieve optimal levels of glycemic control without substantial risk of hypoglycemia and substantial burden of self-management. Advances in biology and technology present beta cell replacement and automated insulin delivery as two alternative approaches. Here we discuss current and future prospects for the relative risks and benefits for biological and psychosocial outcomes from the perspective of researchers, clinicians, and persons living with diabetes. RECENT FINDINGS: Beta cell replacement using pancreas or islet transplant can achieve insulin independence but requires immunosuppression. Although insulin independence may not be sustained, time in range of 80-90%, minimal glycemic variability and abolition of hypoglycemia is routine after islet transplantation. Clinical trials of potentially unlimited supply of stem cell-derived beta cells are showing promise. Automated insulin delivery (AID) systems can achieve 70-75% time in range, with reduced glycemic variability. Impatient with the pace of commercially available AID, users have developed their own algorithms which appear to be at least equivalent to systems developed within conventional regulatory frameworks. The importance of psychosocial factors and the preferences and values of persons living with diabetes are emerging as key elements on which therapies should be evaluated beyond their impact of biological outcomes. Biology or technology to deliver glucose dependent insulin secretion is associated with substantial improvements in glycemia and prevention of hypoglycemia while relieving much of the substantial burden of diabetes. Automated insulin delivery, currently, represents a more accessible bridge to a biologic cure that we expect future cellular therapies to deliver.

Arrhythmia exacerbation after post-infarction ventricular tachycardia ablation: prevalence and prognostic significance.

AIMS: Catheter ablation is an effective treatment for post-infarction ventricular tachycardia (VT). However, some patients may experience a worsened arrhythmia phenotype after ablation. We aimed to determine the prevalence and prognostic impact of arrhythmia exacerbation (AE) after post-infarction VT ablation. METHODS AND RESULTS: A total of 1187 consecutive patients (93% men, median age 68 years, median ejection fraction 30%) who underwent post-infarction VT ablation at six centres were included. Arrhythmia exacerbation was defined as post-ablation VT storm or incessant VT in patients without prior similar events. During follow-up (median 717 days), 426 (36%) patients experienced VT recurrence. Events qualifying as AE occurred in 67 patients (6%). Median times to VT recurrence with and without AE were 238 [interquartile range (IQR) 35-640] days and 135 (IQR 22-521) days, respectively (P = 0.25). Almost half of the patients (46%) who experienced AE experienced it within 6 months of the index procedure. Patients with AE had had longer ablation times during the ablation procedures compared to the rest of the patients (median 42 vs. 34 min, P = 0.02). Among patients with VT recurrence, the risk of death or heart transplantation was significantly higher in patients with than without AE (hazard ratio 1.99, 95% CI 1.28-3.10; P = 0.002) after adjusting for age, gender, ejection fraction, cardiac resynchronization therapy, post-ablation non-inducibility, and post-ablation amiodarone use. CONCLUSION: Arrhythmia exacerbation after ablation of infarct-related VT is infrequent but is independently associated with an adverse long-term outcome among patients who experience a VT recurrence. The mechanisms and mitigation strategies of AE after catheter ablation require further investigation.

Leadless pacemaker implantation quality: importance of the operator's experience.

AIMS: Leadless cardiac pacemaker (PM) implantation differs from conventional PM implantation. While the procedure has been considered safe, recent real-world data raised concerns about the learning curve of new operators and their implantation quality. The goal of this study was to investigate the influence of the first operator's experience on leadless PM implantation quality and procedural efficiency. METHODS AND RESULTS: We performed a bicentric analysis of all Micra TPS™ implantations in two large tertiary referral hospitals. We assessed both leadless PM implantation quality based on the absence of complications (requiring intervention or prolonged hospitalization), good electrical performance (pacing threshold ≤ 1.5 V/0.24 ms, R-wave amplitude > 5 mV), and acceptable fluoroscopy duration (<10 min) as well as procedural efficiency in relation to the operator's experience. Univariate and multivariate logistic regression analyses were performed to identify predictors for implantation quality and procedural efficiency. Leadless PM implantation was successful in 106/111 cases (95.5%). Three patients (2.7%) experienced acute complications (one cardiac tamponade, one femoral bleeding, one posture-related PM exit block). Multivariate analysis showed that implantation quality of more experienced first operators was higher [odds ratio 1.09 (95% confidence interval 1.00-1.19), P = 0.05]. Procedural efficiency increased with operator experience as evidenced by an inverse correlation of procedure time, time to the first deployment, fluoroscopy time, and the number of procedures performed (all P < 0.05). CONCLUSION: The operator's learning curve is a critical factor for leadless PM implantation quality and procedural efficiency.

Acute and mid-term outcome of ethanol infusion of vein of Marshall for the treatment of perimitral flutter.

AIMS: We hypothesized that an epicardial approach using ethanol infusion in the vein of Marshall (EIVOM) may improve the result of ablation for perimitral flutter (PMF). METHODS AND RESULTS: We studied 103 consecutive patients with PMF undergoing high-resolution mapping. The first 71 were treated with radiofrequency (RF) ablation alone (RF-group), and the next 32 underwent EIVOM followed by RF on the endocardial and epicardial mitral isthmus (EIVOM/RF-group). Contact force was not measured during ablation. Acute and 1-year outcomes were compared. Flutter termination rates were similar between the RF-group (63/71, 88.7%) and EIVOM/RF-group (31/32, 96.8%, P = 0.27). Atrial tachycardia (AT) terminated with EIVOM alone in 22/32 (68.6%) in the EIVOM/RF-group. Bidirectional block of mitral isthmus was always achieved in the EIVOM/RF-group, but significantly less frequently achieved in the RF-group (62/71, 87.3%; P = 0.05). Median RF duration for AT termination/conversion was shorter [0 (0-6) s in the EIVOM/RF-group than 312 (55-610) s in the RF-group, P < 0.0001], as well as for mitral isthmus block in the EIVOM/RF-group [246 (0-663) s] than in the RF-group [900 (525-1310) s, P < 0.0001]. Pericardial effusion was observed in 1/32 (3.2%) in EIVOM/RF-group and 5/71 (7.0%) in RF-group (P = 0.66); two in RF-group required drainage and one of them developed subsequent ischaemic stroke. One-year follow-up demonstrated fewer recurrences in the EIVOM/RF-group [6/32 (18.8%)] than in the RF-group [29/71 (40.8%), P = 0.04]. By multivariate analysis, only EIVOM was significantly associated with less AT recurrence (hazard ratio = 0.35, P = 0.018). CONCLUSION: Ethanol infusion in the vein of Marshall may reduce RF duration required for PMF termination as well as for mitral isthmus block without severe complications, and the mid-term outcome may be improved by this approach.

High incidence of diaphragmatic myopotential oversensing by a specific implantable cardioverter defibrillator.

INTRODUCTION: Diaphragmatic myopotential oversensing (dMPO) by implantable cardioverter defibrillators (ICDs) is thought to be a rare condition that can be misdiagnosed as lead failure and lead to unnecessary lead replacement. We observed several cases of dMPO in patients with Sorin/LivaNova ICDs (MicroPort Sci.). We sought to systematically assess the incidence of dMPO in patients with Sorin/LivaNova ICDs. METHODS AND RESULTS: A predefined number of 100 consecutive patients with Sorin/LivaNova ICDs were prospectively included in the device clinic of our center. Stored arrhythmia episodes were checked for spontaneous dMPO. In addition, we performed provocation maneuvers by Valsalva. At least one episode of spontaneous or provoked dMPO was seen in 12 (12%) of the 100 patients included in the study (86% males, median age: 66 years). Nine of 89 patients (10%) with true bipolar and 3 of 11 patients (27%) with integrated bipolar sensing configuration were affected. Spontaneous dMPO was observed in 7 of 58 patients (12%) with sensitivity programmed to 0.4 mV and in 2 of 42 patients (5%) with sensitivity programmed to 0.6 mV (not significant). In three patients, dMPO could be provoked with no spontaneous episodes recorded. In two nonpacemaker-dependent patients with a CRT-D, ventricular pacing was temporarily inhibited. No antitachycardia therapy was triggered by dMPO in any patient. CONCLUSIONS: DMPO is frequent in patients with Sorin/LivaNova ICDs, especially with sensitivity programmed to 0.4 mV. It also frequently occurs with true bipolar sensing configuration. DMPO should not be misinterpreted as lead failure to avoid unnecessary lead replacement.

Single-Cell Transcriptomic Analysis of Human Lung Provides Insights into the Pathobiology of Pulmonary Fibrosis.

Rationale: The contributions of diverse cell populations in the human lung to pulmonary fibrosis pathogenesis are poorly understood. Single-cell RNA sequencing can reveal changes within individual cell populations during pulmonary fibrosis that are important for disease pathogenesis. Objectives: To determine whether single-cell RNA sequencing can reveal disease-related heterogeneity within alveolar macrophages, epithelial cells, or other cell types in lung tissue from subjects with pulmonary fibrosis compared with control subjects. Methods: We performed single-cell RNA sequencing on lung tissue obtained from eight transplant donors and eight recipients with pulmonary fibrosis and on one bronchoscopic cryobiospy sample from a patient with idiopathic pulmonary fibrosis. We validated these data using in situ RNA hybridization, immunohistochemistry, and bulk RNA-sequencing on flow-sorted cells from 22 additional subjects. Measurements and Main Results: We identified a distinct, novel population of profibrotic alveolar macrophages exclusively in patients with fibrosis. Within epithelial cells, the expression of genes involved in Wnt secretion and response was restricted to nonoverlapping cells. We identified rare cell populations including airway stem cells and senescent cells emerging during pulmonary fibrosis. We developed a web-based tool to explore these data. Conclusions: We generated a single-cell atlas of pulmonary fibrosis. Using this atlas, we demonstrated heterogeneity within alveolar macrophages and epithelial cells from subjects with pulmonary fibrosis. These results support the feasibility of discovery-based approaches using next-generation sequencing technologies to identify signaling pathways for targeting in the development of personalized therapies for patients with pulmonary fibrosis.

The Sphingosine Kinase 1 Inhibitor, PF543, Mitigates Pulmonary Fibrosis by Reducing Lung Epithelial Cell mtDNA Damage and Recruitment of Fibrogenic Monocytes.

Idiopathic pulmonary fibrosis (IPF) is a chronic disease for which novel approaches are urgently required. We reported increased sphingosine kinase 1 (SPHK1) in IPF lungs and that SPHK1 inhibition using genetic and pharmacologic approaches reduces murine bleomycin-induced pulmonary fibrosis. We determined whether PF543, a specific SPHK1 inhibitor post bleomycin or asbestos challenge mitigates lung fibrosis by reducing mitochondrial (mt) DNA damage and pro-fibrotic monocyte recruitment-both are implicated in the pathobiology of pulmonary fibrosis. Bleomycin (1.5 U/kg), crocidolite asbestos (100 µg/50 µL) or controls was intratracheally instilled in Wild-Type (C57Bl6) mice. PF543 (1 mg/kg) or vehicle was intraperitoneally injected once every two days from day 7-21 following bleomycin and day 14-21 or day 30-60 following asbestos. PF543 reduced bleomycin- and asbestos-induced pulmonary fibrosis at both time points as well as lung expression of profibrotic markers, lung mtDNA damage, and fibrogenic monocyte recruitment. In contrast to human lung fibroblasts, asbestos augmented lung epithelial cell (MLE) mtDNA damage and PF543 was protective. Post-exposure PF543 mitigates pulmonary fibrosis in part by reducing lung epithelial cell mtDNA damage and monocyte recruitment. We reason that SPHK1 signaling may be an innovative therapeutic target for managing patients with IPF and other forms of lung fibrosis.

Ethanol infusion for Marshall bundle epicardial connections in Marshall bundle-related atrial tachycardias following atrial fibrillation ablation: The accessibility and success rate of ethanol infusion by using a femoral approach.

BACKGROUND: Ethanol infusion of the vein of Marshall (VOM) may be effective to treat Marshall bundle-related atrial tachycardia (MB-AT). However, methods and clinical results of ethanol infusion for MB-AT have been not established. OBJECTIVE: To assess the accessibility of the VOM and the success rate of ethanol infusion using a femoral approach for MB-AT. METHODS: A single-center observational study included consecutive patients who had MB-AT and in whom we attempted to treat MB-AT during AT by ethanol infusion. When the VOM was able to be cannulated following VOM venogram using a femoral approach, we systematically performed ethanol infusion with selective balloon occlusion of the VOM. We analyzed in detail the efficacy of ethanol infusion of VOM in patients who were in MB-AT during ethanol infusion. RESULTS: We enrolled 54 consecutive patients in whom we attempted to treat MB-AT by ethanol infusion. Of those, the VOM was accessible in 92.5% of patients (50 of 54). Of the 50 patients treated by ethanol infusion during MB-AT, AT was successfully terminated in 56% percent of the patients (28 of 50) by solo treatment of ethanol infusion without RF ablation. The remainder required additional RF application to terminate the MB-AT. A mean of 6.2 ± 2.8 mL of ethanol was infused resulting in the low-voltage area significantly larger than that before ethanol infusion (12.7 ± 8.3 vs 6.6 ± 5.3 cm2 , P < .001). CONCLUSION: The present study demonstrated that the VOM was highly accessible and MB-AT was amenable to treatment by ethanol infusion by using a femoral approach.