DNA-encoded library-enabled discovery of proximity-inducing small molecules.

Small molecules that induce protein-protein associations represent powerful tools to modulate cell circuitry. We sought to develop a platform for the direct discovery of compounds able to induce association of any two preselected proteins, using the E3 ligase von Hippel-Lindau (VHL) and bromodomains as test systems. Leveraging the screening power of DNA-encoded libraries (DELs), we synthesized ~1 million DNA-encoded compounds that possess a VHL-targeting ligand, a variety of connectors and a diversity element generated by split-and-pool combinatorial chemistry. By screening our DEL against bromodomains in the presence and absence of VHL, we could identify VHL-bound molecules that simultaneously bind bromodomains. For highly barcode-enriched library members, ternary complex formation leading to bromodomain degradation was confirmed in cells. Furthermore, a ternary complex crystal structure was obtained for our most enriched library member with BRD4BD1 and a VHL complex. Our work provides a foundation for adapting DEL screening to the discovery of proximity-inducing small molecules.

Activation of human STING by a molecular glue-like compound.

Stimulator of interferon genes (STING) is a dimeric transmembrane adapter protein that plays a key role in the human innate immune response to infection and has been therapeutically exploited for its antitumor activity. The activation of STING requires its high-order oligomerization, which could be induced by binding of the endogenous ligand, cGAMP, to the cytosolic ligand-binding domain. Here we report the discovery through functional screens of a class of compounds, named NVS-STGs, that activate human STING. Our cryo-EM structures show that NVS-STG2 induces the high-order oligomerization of human STING by binding to a pocket between the transmembrane domains of the neighboring STING dimers, effectively acting as a molecular glue. Our functional assays showed that NVS-STG2 could elicit potent STING-mediated immune responses in cells and antitumor activities in animal models.

Safety of ventricular arrhythmia radiofrequency ablation with half-normal saline irrigation.

AIMS: Failure of radiofrequency (RF) ablation of ventricular arrhythmias is often due to inadequate lesion size. Irrigated RF ablation with half-normal saline (HNS) has the potential to increase lesion size and reduce sodium delivery to the patient if the same volume of RF irrigant were used for normal saline (NS) and HNS but could increase risks related to steam pops and lesion size. This study aims to assess periprocedural complications and acute ablation outcome of ventricular arrhythmias ablation with HNS. METHODS AND RESULTS: Prospective assessment of outcomes was performed in 1024 endocardial and/or epicardial RF ablation procedures in 935 consecutive patients (median age 64 years, 71.2% men, 73.4% cardiomyopathy, 47.2% sustained ventricular tachycardia). Half-normal saline was selected at the discretion of the treating physician. Radiofrequency ablation power was generally titrated to a ≤15â€…Ω impedance fall with intracardiac echocardiography monitoring. Half-normal saline was used in 900 (87.9%) and NS in 124 (12.1%) procedures. Any adverse event within 30 days occurred in 13.0% of patients treated with HNS RF ablation including 4 (0.4%) strokes/transient ischaemic attacks and 34 (3.8%) pericardial effusions requiring treatment (mostly related to epicardial access). Two steam pops with perforation required surgical repair (0.2%). Patients who received NS irrigation had less severe disease and arrhythmias. In multivariable models, adverse events and acute success of the procedure were not related to the type of irrigation. CONCLUSION: Half-normal saline irrigation RF ablation with power guided by impedance fall and intracardiac echocardiography has an acceptable rate of complications and acute ablation success while administering half of the saline load expected for NS irrigation.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Durable pulmonary vein isolation with diffuse posterior left atrial ablation using low-flow, median power, short-duration strategy.

INTRODUCTION: To target posterior wall isolation (PWI) in atrial fibrillation (AF) ablation, diffuse ablation theoretically confers a lower risk of conduction recovery compared to box set. We sought to assess the safety and efficacy of diffuse PWI with low-flow, medium-power, and short-duration (LF-MPSD) ablation, and evaluate the durability of pulmonary vein isolation (PVI) and PWI among patients undergoing repeat ablations. METHODS: We retrospectively studied patients undergoing LF-MPSD ablation for AF (PVI + diffuse PWI) between August 2017 and December 2019. Clinical characteristics were collected. Kaplan-Meier survival analysis was performed to study AF/atrial flutter (AFL) recurrence. Ablation data were analyzed in patients who underwent a repeat AF/AFL ablation. RESULTS: Of the 463 patients undergoing LF-MPSD AF ablation (PVI alone, or PVI + diffuse PWI), 137 patients had PVI + diffuse PWI. Acute PWI with complete electrocardiogram elimination was achieved in 134 (97.8%) patients. Among the 126 patients with consistent follow-up, 38 (30.2%) patients had AF/AFL recurrence during a median duration of 14 months. Eighteen patients underwent a repeat AF/AFL ablation after PVI + diffuse PWI, and 16 (88.9%) patients had durable PVI, in contrast to 10 of 45 (23.9%) patients who had redo ablation after LF-MPSD PVI alone. Seven patients (38.9%) had durable PWI, while 11 patients had partial electrical recovery at the posterior wall. The median percentage of area without electrical activity at the posterior wall was 70.7%. Conduction block across the posterior wall was maintained in 16 (88.9%) patients. CONCLUSION: There was a high rate of PVI durability in patients undergoing diffuse PWI and PVI. Partial posterior wall electrical recovery was common but conduction block across the posterior wall was maintained in most patients.

CPSF3-dependent pre-mRNA processing as a druggable node in AML and Ewing's sarcoma.

The post-genomic era has seen many advances in our understanding of cancer pathways, yet resistance and tumor heterogeneity necessitate multiple approaches to target even monogenic tumors. Here, we combine phenotypic screening with chemical genetics to identify pre-messenger RNA endonuclease cleavage and polyadenylation specificity factor 3 (CPSF3) as the target of JTE-607, a small molecule with previously unknown target. We show that CPSF3 represents a synthetic lethal node in a subset of acute myeloid leukemia (AML) and Ewing's sarcoma cancer cell lines. Inhibition of CPSF3 by JTE-607 alters expression of known downstream effectors in AML and Ewing's sarcoma lines, upregulates apoptosis and causes tumor-selective stasis in mouse xenografts. Mechanistically, it prevents the release of newly synthesized pre-mRNAs, resulting in read-through transcription and the formation of DNA-RNA hybrid R-loop structures. This study implicates pre-mRNA processing, and specifically CPSF3, as a druggable target providing an avenue to therapeutic intervention in cancer.

Author Correction: CPSF3-dependent pre-mRNA processing as a druggable node in AML and Ewing's sarcoma.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Left atrial appendage morphology predicts the formation of left atrial appendage thrombus.

BACKGROUND: Nonchicken wing left atrial appendage (LAA) morphology is associated with higher risk for stroke in patients with atrial fibrillation (AF) than chicken wing (CW) morphology. OBJECTIVE: Assess whether LAA morphology predicts the formation of LAA thrombus independent of age, sex, presenting rhythm, left ventricular ejection fraction (LVEF), or anticoagulant use. METHODS: A cross-sectional analysis was performed on patients prospectively enrolled in the Vanderbilt LAA Registry or presenting for transesophageal echocardiogram (TEE) between January 1, 2015, and November 1, 2017 (n = 306). Two physicians independently reviewed TEEs interpreted as having LAA thrombus. Determination of LAA morphology, ejection velocity, and presence of thrombus (n = 102) were based on 0°, 45°, 90°, and 135° TEE views. The control cohort (n = 204) included consecutive AF patients undergoing TEE without LAA thrombus. RESULTS: LAA morphology in patients with LAA thrombus was: 35% windsock, 47% broccoli, and 12% CW. Windsock (odds ratio [OR], 4.0; 95% confidence interval [CI]: 1.7-9.3, p = .001) and broccoli (OR, 6.6; 95% CI: 2.6-16.6; p < .001) morphology were higher risk for thrombus compared to CW. Female sex predicted higher-odds for LAA thrombus (OR, 2.6; 95% CI: 1.4-4.8; p = .002) as did LAA-EV < 20 cm/s (OR, 11.12; 95% CI: 5.6-22.1). Anticoagulation use (OR, 0.5; 95% CI: 0.3-0.9; p = .03) and higher LVEF (OR, 0.95; 95% CI: 0.93-0.98; p < .001) were associated with lower risk. In patients with a CW morphology who had LAA thrombus, 4 of the 7 had an LAA-EV < 20 cm/s and acute systolic heart failure with LVEF < 30% or active malignancy. In multivariable linear regression analysis controlling for presenting rhythm, anticoagulant use, age, sex, and LVEF, CW morphology appears relatively protective from LAA thrombus (p = .001). CONCLUSION: CW LAA morphology appears relatively protective against the formation of LAA thrombus.

A small-molecule inhibitor of C5 complement protein.

The complement pathway is an important part of the immune system, and uncontrolled activation is implicated in many diseases. The human complement component 5 protein (C5) is a validated drug target within the complement pathway, as an anti-C5 antibody (Soliris) is an approved therapy for paroxysmal nocturnal hemoglobinuria. Here, we report the identification, optimization and mechanism of action for the first small-molecule inhibitor of C5 complement protein.

Our approach to persistent atrial fibrillation in the setting of pulmonary vein isolation.

In patients with persistent atrial fibrillation (AF) despite durable pulmonary vein isolation, there are a variety of approaches to further ablation. Here we summarize our strategy in this population. In brief, our approach is to isolate the posterior wall, ablate the coronary sinus musculature and left lateral ridge, complete a lateral mitral line, and achieve cavotricuspid isthmus block. Subsequently, we target organized atrial flutters and if AF persists, we ablate areas of long, fractionated electrograms within scarred regions. We administer isuprel in patients with a presentation consistent with triggered atrial fibrillation (low scar burden, paroxysms of AF).

Outcomes in patients with cardiac amyloidosis and implantable cardioverter-defibrillator.

AIMS: Cardiac amyloidosis (CA) is associated with increased mortality due to arrhythmias, heart failure, and electromechanical dissociation. However, the role of an implantable cardioverter-defibrillator (ICD) remains unclear. We conducted case-control study to assess survival in CA patients with and without a primary prevention ICD and compared outcomes to an age, sex, and device implant year-matched non-CA group with primary prevention ICD. METHODS AND RESULTS: There were 91 subjects with CA [mean age= 71.2 ± 10.2, female 22.0%, 49 AL with Mayo Stage 2.9 ± 1.0, 41 transthyretin amyloidosis (ATTR), 1 other] followed by Vanderbilt Amyloidosis centre. Patients with ICD (n = 23) were compared with those without (n = 68) and a non-amyloid group with ICD (n = 46). All subjects with ICD had implantation for primary prevention. Mean left ventricular ejection fraction was 36.2% ± 14.4% in CA with ICD, 41.0% ± 10.6% in CA without ICD, and 33.5% ± 14.4% in non-CA patients. Over 3.5 ± 3.1 years, 6 (26.1%) CA, and 12 (26.1%) non-CA subjects received ICD therapies (P = 0.71). Patients with CA had a significantly higher mortality (43.9% vs. 17.4%, P = 0.002) compared with the non-CA group. Mean time from device implantation to death was 21.8 months in AL and 22.8 months in ATTR patients. There was no significant difference in mortality between CA patients who did and did not receive an ICD (39.0% vs. 46.0%, P = 0.59). CONCLUSIONS: Despite comparable event rates patients with CA had a significantly higher mortality and ICDs were not associated with longer survival. With the emergence of effective therapy for AL amyloidosis, further study of ICD is needed in this group.

Recognition of the iso-ADP-ribose moiety in poly(ADP-ribose) by WWE domains suggests a general mechanism for poly(ADP-ribosyl)ation-dependent ubiquitination.

Protein poly(ADP-ribosyl)ation and ubiquitination are two key post-translational modifications regulating many biological processes. Through crystallographic and biochemical analysis, we show that the RNF146 WWE domain recognizes poly(ADP-ribose) (PAR) by interacting with iso-ADP-ribose (iso-ADPR), the smallest internal PAR structural unit containing the characteristic ribose-ribose glycosidic bond formed during poly(ADP-ribosyl)ation. The key iso-ADPR-binding residues we identified are highly conserved among WWE domains. Binding assays further demonstrate that PAR binding is a common function for the WWE domain family. Since many WWE domain-containing proteins are known E3 ubiquitin ligases, our results suggest that protein poly(ADP-ribosyl)ation may be a general mechanism to target proteins for ubiquitination.

Esophageal Injury and Atrioesophageal Fistula Caused by Ablation for Atrial Fibrillation.

Esophageal perforation is a dreaded complication of atrial fibrillation ablation that occurs in 0.1% to 0.25% of atrial fibrillation ablation procedures. Delayed diagnosis is associated with the development of atrial-esophageal fistula (AEF) and increased mortality. The relationship between the esophagus and the left atrial posterior wall is variable, and the esophagus is most susceptible to injury where it is closest to areas of endocardial ablation. Esophageal ulcer seems to precede AEF development, and postablation endoscopy documenting esophageal ulcer may identify patients at higher risk for AEF. AEF has been reported with all modalities of atrial fibrillation ablation despite esophageal temperature monitoring. Despite the name AEF, fistulas functionally act 1 way, esophageal to atrial, which accounts for the observed symptoms and imaging findings. Because of the rarity of AEF, evaluation and validation of strategies to reduce AEF remain challenging. A high index of suspicion is recommended in patients who develop constitutional symptoms or sudden onset chest pain that start days or weeks after atrial fibrillation ablation. Early detection by computed tomography scan with oral and intravenous contrast is safe and feasible, whereas performance of esophageal endoscopy in the presence of AEF may result in significant neurological injury resulting from air embolism. Outcomes for esophageal stenting are poor in AEF. Aggressive intervention with skilled cardiac and thoracic surgeons may improve chances of stroke-free survival for all types of esophageal perforation.

Temporal trends in safety and complication rates of catheter ablation for atrial fibrillation.

INTRODUCTION: Atrial fibrillation (AF) ablation is increasingly common, but is associated with potential major complications. Technology, experience, and protocols have evolved significantly in recent times, and may have impacted procedural safety. We sought to compare AF ablation safety profiles, including complication rates and fluoroscopy times in a "modern" versus "historical" cohort. METHODS AND RESULTS: We evaluated consecutive patients undergoing AF ablation from a modern cohort (MC) from 2014 to 2015 and a historic cohort (HC) from 2009 to 2011 for complications. Major complications were categorized according to Heart Rhythm Society guidelines. We included 1,425 patients, 726 in the HC and 699 in the MC. The MC was older, had more OSA and less valvular AF. Fifty-two (3.5%) procedures suffered major complications across the cohorts, with significantly fewer in the MC (5.0% vs. 2.3%, P  =  0.007). The largest reductions were seen in vascular, hemorrhagic, ischemic stroke, and perforation/tamponade related complications. Periprocedural antiplatelets drugs (aHR 2.1 [95 CI 1.1-3.9], P  =  0.02) and force-sensing catheters (aHR 0.4 [95 CI 0.2-0.9], P  =  0.03) were independently related to major complication rates. Direct oral anticoagulants and uninterrupted anticoagulation were not associated with complications. There was a decrease in both fluoroscopy (-17.4 minutes [95 CI 19.2-15.6], P < 0.0001) and radiofrequency ablation times (-561 seconds [95CI -750 to -371], P < 0.0001). CONCLUSIONS: The safety profile of AF ablation has improved significantly in less than a decade.

Downstream overdrive pacing and intracardiac concealed fusion to guide rapid identification of atrial tachycardia after atrial fibrillation ablation.

Aims: Atrial tachycardia (AT) related to atrial fibrillation (AF) ablation frequently poses a diagnostic challenge. Downstream overdrive pacing (DOP) can be used to rapidly detect reentry and assess proximity of a pacing site to an AT circuit or focus. We hypothesized that systematic DOP using multielectrode catheters would facilitate AT mapping. Methods and results: DOP identified constant fusion when the post-pacing interval (PPI)-tachycardia cycle length (TCL) <40 ms and stimulus to adjacent upstream atrial electrogram interval >75% of TCL. Mapping was performed as follows: (i) CS DOP, (ii) DOP at left atrial (LA) roof, (iii) DOP at selected LA sites based on prior DOP attempts, and (iv) mapping and ablation at regions of fractionated electrograms in region of AT. Activation mapping was performed at operator discretion. AT diagnosis was confirmed by successful ablation or additional mapping when ablation was unsuccessful. Fifty consecutive patients with sustained AT underwent mapping of 68 ATs, of whom 42 (62%) were macroreentrant, 19 were locally reentrant (28%), and 7 (10%) were focal. AT was correctly identified with a median of three DOP attempts. All macroreentrant ATs were identified with ≤6 DOP attempts. One AT (1.6%) was terminated by DOP, and three ATs (4.8%) required activation mapping. Intracardiac concealed fusion was seen in 26 ATs (38%), each of which was successfully ablated. Conclusion: Reentry could be demonstrated in a substantial majority of AF ablation-related AT. A stepwise diagnostic approach using DOP and recognition of intracardiac concealed fusion can be used to rapidly identify and ablate reentrant AT.

Family history of atrial fibrillation as a predictor of atrial substrate and arrhythmia recurrence in patients undergoing atrial fibrillation catheter ablation.

Aims: A commonly held notion is that patients with a family history of atrial fibrillation (AF) have worse atrial substrate and higher rates of arrhythmia recurrence following ablation. We sought to examine differences in atrial substrate and catheter ablation outcomes in patients with a 1st degree family member with paroxysmal or persistent AF (PeAF) compared to those without. Methods and results: A total of 256 consecutive patients undergoing their 1st ablation for AF (123 paroxysmal, 133 persistent) with >1 year follow up were included. The presence of one 1st-degree family relative was defined as a 'positive family history'. Clinical characteristics, electroanatomic map findings, ablation characteristics and outcomes were compared in patients with and without a positive family history of AF. Patients with paroxysmal fibrillation with a positive family history (n = 57; 46%) had similar clinical characteristics and arrhythmia recurrence after catheter ablation as those without. Of those that recurred, patients with a positive family history were more likely to have progressed to PeAF (P = 0.05). Patients with PeAF with a positive family history (n = 75; 56%) had similar clinical characteristics, electroanatomic mapping findings and ablation characteristics, but worse long term arrhythmia free survival (P = 0.04). Conclusion: The presence of a 1st-degree family member with AF does not impact the clinical outcomes of catheter ablation for paroxysmal AF. However, a positive family history is associated with worse arrhythmia free survival in patients with PeAF. This finding is not explained by differences in clinical characteristics, atrial substrate assessed by voltage maps or ablation characteristics.

Uninterrupted direct oral anticoagulants vs. uninterrupted vitamin K antagonists during catheter ablation of non-valvular atrial fibrillation: a systematic review and meta-analysis of randomized controlled trials.

Aims: To assess the incremental benefit of uninterrupted direct oral anticoagulants (DOACs) vs. uninterrupted vitamin K antagonists (VKA) for catheter ablation (CA) of non-valvular atrial fibrillation (NVAF) on three primary outcomes: major bleeding, thrombo-embolic events, and minor bleeding. A secondary outcome was post-procedural silent cerebral infarction (SCI) as detected by brain magnetic resonance imaging. Methods and results: A systematic review of Medline, Cochrane, and Embase was done to find all randomized controlled trials (RCTs) in which uninterrupted DOACs were compared against uninterrupted VKA for CA of NVAF. A fixed-effect model was used, with the exception of the analysis regarding major bleeding events (I2 > 25), for which a random effects model was used. The benefit of uninterrupted DOACs over VKA was analysed from four RCTs that enrolled a total of 1716 patients (male: 71.2%) with NVAF. Of these, 1100 patients (64.1%) had paroxysmal atrial fibrillation. No significant benefit was seen in major bleeding events [risk ratio (RR) 0.54, 95% confidence interval (95% CI) 0.29-1.00; P = 0.05]. No significant differences were found in minor bleeding events (RR 1.11, 95% CI 0.82-1.52; P = 0.50), thrombo-embolic events (RR 0.74, 95% CI 0.26-2.11; P = 0.57), or post-procedural SCI (RR 1.06, 95% CI 0.74-1.53; P = 0.74). Conclusion: An uninterrupted DOACs strategy for CA of NVAF appears to be as safe as uninterrupted VKA without a significantly increased risk of minor or major bleeding events. There was a trend favouring DOACs in terms of major bleeding. Given their ease of use, fewer drug interactions and a similar security and effectiveness profile, DOACs should be considered first line therapy in patients undergoing CA for NVAF.

Benefit of left atrial appendage electrical isolation for persistent and long-standing persistent atrial fibrillation: a systematic review and meta-analysis.

Aims: The long-term outcomes of left atrial appendage electrical isolation (LAAEI) in patients with non-paroxysmal atrial fibrillation (AF) have corroborated the significant role of the LAA in this arrhythmia. We sought to investigate the incremental benefit of LAAEI in patients undergoing catheter ablation for persistent AF or long-standing persistent AF (LSPAF). Methods and results: A systematic review of Medline, Cochrane, and Embase for all the clinical studies in which assessment LAAEI in non-paroxysmal AF patients was performed. The benefit of LAAEI in patients with AF was analysed from seven studies that enrolled a total of 930 patients [mean age 63 ± 5 years; male: 69%]. All studies included patients with either persistent AF or LSPAF or the combination of them. The overall freedom from all-arrhythmia recurrence at 12 months of follow-up off antiarrhythmic medications in patients who underwent LAAEI was 75.5% vs. 43.9% in those in whom only standard ablation was performed [56% relative reduction and 31.6% absolute reduction; risk ratio (RR) 0.44, 95% confidence interval (95% CI) 0.31-0.64; P < 0.0001]. The rate of ischaemic stroke in the LAAEI group was 0.4% and in the control group 2.1% at 12 months follow-up (RR 0.40, 95% CI 0.12-1.30; P = 0.13). Acute complications rates were identical between groups [LAAEI 5.5%, control 5.5% (RR 0.99, 95% CI 0.46-2.16; P = 0.99)]. Conclusion: Left atrial appendage electrical isolation in addition to standard ablation appears to have a substantial incremental benefit to achieve freedom from ALL atrial arrhythmias in patients with persistent AF and LSPAF without increasing acute procedural complications and without raising the risk of ischaemic stroke.