Improving CRISPR-Cas9 directed faithful transgene integration outcomes by reducing unwanted random DNA integration.

BACKGROUND: The field of genome editing has been revolutionized by the development of an easily programmable editing tool, the CRISPR-Cas9. Despite its promise, off-target activity of Cas9 posed a great disadvantage for genome editing purposes by causing DNA double strand breaks at off-target locations and causing unwanted editing outcomes. Furthermore, for gene integration applications, which introduce transgene sequences, integration of transgenes to off-target sites could be harmful, hard to detect, and reduce faithful genome editing efficiency. METHOD: Here we report the development of a multicolour fluorescence assay for studying CRISPR-Cas9-directed gene integration at an endogenous locus in human cell lines. We examine genetic integration of reporter genes in transiently transfected cells as well as puromycin-selected stable cell lines to determine the fidelity of multiple CRISPR-Cas9 strategies. RESULT: We found that there is a high occurrence of unwanted DNA integration which tarnished faithful knock-in efficiency. Integration outcomes are influenced by the type of DNA DSBs, donor design, the use of enhanced specificity Cas9 variants, with S-phase regulated Cas9 activity. Moreover, restricting Cas9 expression with a self-cleaving system greatly improves knock-in outcomes by substantially reducing the percentage of cells with unwanted DNA integration. CONCLUSION: Our results highlight the need for a more stringent assessment of CRISPR-Cas9-mediated knock-in outcomes, and the importance of careful strategy design to maximise efficient and faithful transgene integration.

Exploring the use of social network interventions for adults with mental health difficulties: a systematic review and narrative synthesis.

BACKGROUND: People with mental health difficulties often experience social isolation. The importance of interventions to enhance social networks and reduce this isolation is increasingly being recognised. However, the literature has not yet been systematically reviewed with regards to how these are best used. This narrative synthesis aimed to investigate the role of social network interventions for people with mental health difficulties and identify barriers and facilitators to effective delivery. This was undertaken with a view to understanding how social network interventions might work best in the mental health field. METHODS: Systematic searches using combinations of synonyms for mental health difficulties and social network interventions were undertaken across 7 databases (MEDLINE, Embase, PsycINFO, CINAHL, Cochrane Library, Web of Science) and 2 grey literature databases (EThoS and OpenGrey) from their inception to October 2021. We included studies reporting primary qualitative and quantitative data from all study types relating to the use of social network interventions for people with mental health difficulties. The quality of included studies was assessed using the Mixed Methods Appraisal Tool. Data were extracted and synthesised narratively. RESULTS: The review included 54 studies, reporting data from 6,249 participants. Social network interventions were generally beneficial for people with mental health difficulties but heterogeneity in intervention type, implementation and evaluation made it difficult to draw definitive conclusions. Interventions worked best when they (1) were personalised to individual needs, interests and health, (2) were delivered outside formal health services and (3) provided the opportunity to engage in authentic valued activities. Several barriers to access were identified which, without careful consideration could exacerbate existing health inequalities. Further research is required to fully understand condition-specific barriers which may limit access to, and efficacy of, interventions. CONCLUSIONS: Strategies for improving social networks for people with mental health difficulties should focus on supporting engagement with personalised and supported social activities outside of formal mental health services. To optimise access and uptake, accessibility barriers should be carefully considered within implementation contexts and equality, diversity and inclusion should be prioritised in intervention design, delivery and evaluation and in future research.

Creating positive experiences of involvement in mental health research.

The importance of patient and public involvement (PPI) in mental health research is increasingly acknowledged by funders, researchers, and patients. However, the impact of PPI on those who bring their own lived experiences to research environments is underexplored. A retrospective reflective approach was undertaken collaboratively by four people bringing lived experiences of mental health difficulties to a study adapting a social network intervention for mental health services. Authors considered their experiences of involvement and how these affected them personally. We identified six characteristics of involvement that benefit not only research quality, but also people participating in PPI activities: reframing painful memories, recognising value, practising reciprocity, bridging gaps, countering stigma, and challenging established narratives. When designing and conducting research, it is important to engage empathetically with how involvement is experienced by different people. Values should be translated collaboratively into action so that unintended harms might be avoided. This Personal View offers reflections and recommendations to support this process.

Adapting a social network intervention for use in secondary mental health services using a collaborative approach with service users, carers/supporters and health professionals in the United Kingdom.

BACKGROUND: Social integration, shared decision-making and personalised care are key elements of mental health and social care policy. Although these elements have been shown to improve service user and service-level outcomes, their translation into practice has been inconsistent and social isolation amongst service users persists. AIM: To co-adapt, with service users, carers/supporters and health professionals, a web-based social network intervention, GENIE™, for use in secondary mental health services. The intervention is designed to support social activity and preference discussions between mental healthcare professionals and service users as a means of connecting individuals to local resources. METHODS: In Phase 1 (LEARN), we completed two systematic reviews to synthesise the existing evidence relating to the i) effectiveness and ii) the implementation of social network interventions for people with mental health difficulties. We undertook semi-structured interviews with a convenience sample of 15 stakeholders previously involved in the implementation of the intervention in physical healthcare settings. Interviews were also conducted with 5 national key stakeholders in mental health (e.g., policy makers, commissioners, third sector leads) to explore wider implementation issues. In Phase 2 (ADAPT), we worked iteratively with eight service users, nine carers, six professionals/volunteers and our patient and public advisory group. We drew on a framework for experience-based co-design, consisting of a series of stakeholder consultation events, to discuss the use of the social network intervention, in mental health services. Participants also considered factors that could serve as enablers, barriers, and challenges to local implementation. RESULTS: Across the stakeholder groups there was broad agreement that the social network intervention had potential to be useful within mental health services. In terms of appropriate and effective implementation, such an intervention was predicted to work best within the care planning process, on discharge from hospital and within early intervention services. There were indications that the social connection mapping and needs assessment components were of most value and feasible to implement which points to the potential utility of a simplified version compared to the one used in this study. The training provided to facilitators was considered to be more important than their profession and there were indications that service users should be offered the opportunity to invite a carer, friend, or family member to join them in the intervention. CONCLUSION: The GENIE™ intervention has been co-adapted for use in mental health services and a plan for optimal implementation has been co-produced. The next phase of the programme of work is to design and implement a randomised controlled trial to evaluate clinical and cost effectiveness of a simplified version of the intervention.

Detecting endogenous TRIB2 protein expression by flow cytometry and Western blotting.

Protein kinases catalyze the transfer of a phosphate group thereby activating proteins and initiating signaling cascades. Their cousins, the pseudokinases, are enzymatically nonactive counterparts of protein kinases that can be considered zombie enzymes. Interestingly, pseudokinases, which constitute about 10% of the human kinome, have been implicated in many cancers, despite their sequences predicting a lack of catalytic activity. Owing to recent research, it has been demonstrated that dysregulation of many pseudokinases triggers changes in cell signaling, proliferation, and drug resistance. This review is aimed at describing methods that can be used for detection of Tribbles family of pseudokinases, specifically TRIB2. We describe intracellular staining by flow cytometry and Western blotting techniques for the detection of endogenous TRIB2 protein.

Assessing the effectiveness of social network interventions for adults with a diagnosis of mental health problems: a systematic review and narrative synthesis of impact.

BACKGROUND: Social connections have been linked to the genesis and amelioration of mental health problems and thus have potential therapeutic value. PURPOSE: To identify the current evidence base, assess risk of bias and synthesise findings on the effectiveness of social network interventions for people with mental health problems. METHODS: Electronic databases (MEDLINE, Embase, PsycINFO, CINAHL, Cochrane Library, Web of Science, Scopus) and grey literature databases were systematically searched from inception to October 2021 using free text syntax combining synonyms for 'mental health problems' and 'social network interventions'. Articles were eligible for inclusion if they reported data from randomised controlled trials on the effectiveness of interventions designed to improve social networks for adults (18+) with mental health problems. Papers were independently reviewed for inclusion with conflicts resolved through consensus. Included papers were quality assessed and data extracted and synthesized narratively. Risk of bias was assessed using the Cochrane Risk of Bias Tool. RESULTS: Nine studies randomising 2226 participants were included. Four focused on those with a diagnosis of schizophrenia or psychosis, one on major depressive disorder and four included all types of mental health diagnoses. The current evidence base is of unclear quality. However, interventions which focused on supporting social activities appear to hold the most promise for enhancing social networks. Data on cost-effectiveness and research acceptability were limited, but suggest the potential economic feasibility of and acceptability for evaluating these interventions. CONCLUSION: There is emerging evidence that social network interventions can be effective in improving social connections for people with mental health problems. However, further evaluations with robust methodological approaches are required to inform evidence-based recommendations for health services.

CRISPR Gene Editing of Murine Blood Stem and Progenitor Cells Induces MLL-AF9 Chromosomal Translocation and MLL-AF9 Leukaemogenesis.

Chromosomal rearrangements of the mixed lineage leukaemia (MLL, also known as KMT2A) gene on chromosome 11q23 are amongst the most common genetic abnormalities observed in human acute leukaemias. MLL rearrangements (MLLr) are the most common cytogenetic abnormalities in infant and childhood acute myeloid leukaemia (AML) and acute lymphocytic leukaemia (ALL) and do not normally acquire secondary mutations compared to other leukaemias. To model these leukaemias, we have used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing to induce MLL-AF9 (MA9) chromosomal rearrangements in murine hematopoietic stem and progenitor cell lines and primary cells. By utilizing a dual-single guide RNA (sgRNA) approach targeting the breakpoint cluster region of murine Mll and Af9 equivalent to that in human MA9 rearrangements, we show efficient de novo generation of MA9 fusion product at the DNA and RNA levels in the bulk population. The leukaemic features of MA9-induced disease were observed including increased clonogenicity, enrichment of c-Kit-positive leukaemic stem cells and increased MA9 target gene expression. This approach provided a rapid and reliable means of de novo generation of Mll-Af9 genetic rearrangements in murine haematopoietic stem and progenitor cells (HSPCs), using CRISPR/Cas9 technology to produce a cellular model of MA9 leukaemias which faithfully reproduces many features of the human disease in vitro.

Pseudokinases: a tribble-edged sword.

Advances in the understanding of the Tribbles family of pseudokinases (TRIB1, TRIB2 and TRIB3) reveal these proteins as potentially valuable biomarkers of disease diagnosis, prognosis, prediction and clinical strategy. In their role as signalling mediators and scaffolding proteins, TRIBs lead to changes in protein stability and activity, which impact on diverse cellular processes such as proliferation, differentiation, cell cycle and cell death. We review the role of TRIB proteins as promising therapeutic targets, with an emphasis on their role in cancer, and as biomarkers, with potential application across diverse pathological processes.

Pulmonary vein measurements on pre-procedural CT/MR imaging can predict difficult pulmonary vein isolation and phrenic nerve injury during cryoballoon ablation for paroxysmal atrial fibrillation.

OBJECTIVE: We tested the hypothesis that pulmonary vein (PV) measurements on pre-procedural CT/MR imaging can predict difficulty in isolation and phrenic nerve (PN) injury during cryoballoon ablation for paroxysmal atrial fibrillation (AF). METHODS: Consecutive patients with paroxysmal AF who had pre-procedural CT/MRI and underwent cryoballoon ablation as part of a randomized trial were studied. Imaging was anonymized for blinded analysis of: (1) maximum ostial diameter, (2) minimum ostial diameter, (3) ostial area and (4) ratio of maximum over minimum ostial diameter (eccentricity index). Veins that required more than 2 freezes of at least 200 s duration to isolate or not isolated were defined as difficult to isolate. Loss of PN pacing during right-sided ablation was defined as PN injury. Logistic regression was used to analyze the predictive effect of the measurements on the 2 outcomes. RESULTS: 148 PVs in 38 patients (aged 60 ± 11 years, 76% male) were analyzed. Left inferior PV (LIPV) was most difficult to isolate with 23 out of 37 PVs (62%), and PN injury occurred in 3 of 38 (8%) right superior PV (RSPV). Greater eccentricity index predicted difficulty in isolating LIPV, OR 40.33 (95% CI 1.40 to 1160, p = 0.03) and smaller eccentricity index predicted PN injury in RSPV, OR 0.01 (95% CI 0.01-0.16, p = 0.001). CONCLUSIONS: Eccentricity index measured from pre-procedural CT/MR imaging can predict difficulty of PV isolation and PN injury during cryoballoon ablation for paroxysmal AF.

Point-by-Point Radiofrequency Ablation Versus the Cryoballoon or a Novel Combined Approach: A Randomized Trial Comparing 3 Methods of Pulmonary Vein Isolation for Paroxysmal Atrial Fibrillation (The Cryo Versus RF Trial).

INTRODUCTION: Catheter ablation of paroxysmal AF using the Cryoballoon (CRYO) has yielded similar success rates to conventional wide encirclement using radiofrequency catheter ablation (RFCA), but randomized data are lacking. Pilot data suggested a high success rate with a combined approach (COMBINED) using wide encirclement with RFCA followed by 2 CRYO applications to each vein. We compared these 3 strategies in a randomized controlled trial. METHODS AND RESULTS: Patients undergoing first time paroxysmal AF ablation were randomized to RFCA, CRYO, or COMBINED. Patients were followed up at 3, 6, and 12 months with 7 days of ambulatory ECG monitoring. Success was defined as freedom from arrhythmia without antiarrhythmic drugs after a single procedure. A total of 237 patients were randomized. Success at 1 year was achieved in 47% in the RFCA group, 67% in the CRYO group, and 76% in the COMBINED group (P < 0.001 for RFCA vs. CRYO, P<0.001 for RFCA vs. COMBINED, and P = 0.220 for CRYO vs. COMBINED). Procedure time was 211 (IQR 174-256) minutes for RFCA compared to 167 (136-202) minutes for CRYO and 278 (243-327) minutes for COMBINED (P < 0.001 for RFCA vs. COMBINED, RFCA vs. CRYO, and CRYO vs. COMBINED groups). CONCLUSIONS: Pulmonary vein isolation for paroxysmal AF is faster with CRYO and results in a higher single procedure success rate than conventional point by point RFCA. The COMBINED approach was not superior to CRYO alone.

Randomized trial comparing robotic to manual ablation for atrial fibrillation.

BACKGROUND: Catheter ablation of atrial fibrillation (AF) is a physically demanding procedure for the operator, involving radiation exposure, and has limited success rates. Remote robotic navigation (RRN) may offer benefit to the procedure, though only 1 previous small randomized trial has assessed this. OBJECTIVE: This study aimed to investigate the impact of RRN on 1-year single-procedure success rates. METHODS: RRN was compared to manual ablation in a randomized control trial setting by using an intention-to-treat analysis. RESULTS: A total of 157 patients underwent ablation (116/157 (74%) persistent AF; 67/116 (58%) of these long-standing persistent AF). There were no significant differences between the RRN and manual groups with respect to 1-year single-procedure success rates (19/78 (24%) and 26/78 (33%), respectively; P = .29), acute wide area circumferential ablation reconnection rates, complication rates, or procedure times. On multivariable analysis, fluoroscopy times were significantly shorter in the RRN group. The number of catheter displacements during ablation was lower in the RRN group, as was subjectively assessed operator fatigue. The crossover rate from RRN to manual ablation was 11/78 (14%), mainly secondary to technical problems with the RRN system. A learning curve was evident for RRN ablation: the fluoroscopy and procedure times were significantly lower after the first 10 cases in an operator's experience. CONCLUSION: This randomized trial showed no difference in the success rate for catheter ablation of AF between a RRN and manual approach. The results highlight the learning curve for RRN ablation and suggest that the use of this technology leads to an improvement in fluoroscopy times, catheter stability, and operator fatigue.

A randomized controlled trial of catheter ablation versus medical treatment of atrial fibrillation in heart failure (the CAMTAF trial).

BACKGROUND: Restoring sinus rhythm in patients with heart failure (HF) and atrial fibrillation (AF) may improve left ventricular (LV) function and HF symptoms. We sought to compare the effect of a catheter ablation strategy with that of a medical rate control strategy in patients with persistent AF and HF. METHODS AND RESULTS: Patients with persistent AF, symptomatic HF, and LV ejection fraction <50% were randomized to catheter ablation or medical rate control. The primary end-point was the difference between groups in LV ejection fraction at 6 months. Baseline LV ejection fraction was 32±8% in the ablation group and 34±12% in the medical group. Twenty-six patients underwent catheter ablation, and 24 patients were rate controlled. Freedom from AF was achieved in 21/26 (81%) at 6 months off antiarrhythmic drugs. LV ejection fraction at 6 months in the ablation group was 40±12% compared with 31±13% in the rate control group (P=0.015). Ablation was associated with better peak oxygen consumption (22±6 versus 18±6 mL/kg per minute; P=0.014) and Minnesota living with HF questionnaire score (24±22 versus 47±22; P=0.001) compared with rate control. CONCLUSIONS: Catheter ablation is effective in restoring sinus rhythm in selected patients with persistent AF and HF, and can improve LV function, functional capacity, and HF symptoms compared with rate control. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT01411371.

A biogenic amine and a neuropeptide act identically: tyramine signals through calcium in Drosophila tubule stellate cells.

Insect osmoregulation is subject to highly sophisticated endocrine control. In Drosophila, both Drosophila kinin and tyramine act on the Malpighian (renal) tubule stellate cell to activate chloride shunt conductance, and so increase the fluid production rate. Drosophila kinin is known to act through intracellular calcium, but the mode of action of tyramine is not known. Here, we used a transgenically encoded GFP::apoaequorin translational fusion, targeted to either principal or stellate cells under GAL4/UAS control, to demonstrate that tyramine indeed acts to raise calcium in stellate, but not principal cells. Furthermore, the EC(50) tyramine concentration for half-maximal activation of the intracellular calcium signal is the same as that calculated from previously published data on tyramine-induced increase in chloride flux. In addition, tyramine signalling to calcium is markedly reduced in mutants of NorpA (a phospholipase C) and itpr, the inositol trisphosphate receptor gene, which we have previously shown to be necessary for Drosophila kinin signalling. Therefore, tyramine and Drosophila kinin signals converge on phospholipase C, and thence on intracellular calcium; and both act to increase chloride shunt conductance by signalling through itpr. To test this model, we co-applied tyramine and Drosophila kinin, and showed that the calcium signals were neither additive nor synergistic. The two signalling pathways thus represent parallel, independent mechanisms for distinct tissues (nervous and epithelial) to control the same aspect of renal function.

Improved electrogram attenuation during ablation of paroxysmal atrial fibrillation with the Hansen robotic system.

BACKGROUND: Robotic catheter ablation aims to improve outcomes after ablation of atrial fibrillation (AF) through improved lesion quality. This study examined electrogram attenuation as a measure of efficacy in response to robotic (ROB) and manual (MAN) ablation. METHODS: Patients with paroxysmal AF undergoing ablation as part of an ongoing randomized controlled trial were studied (Clinical Trials Registration NCT01037296). Patients underwent pulmonary vein isolation using NavX (St. Jude Medical, St. Paul, MN, USA). Patients were randomized to MAN or ROB catheter ablation using a 3.5-mm irrigated-tip catheter with standardized ablation settings. Bipolar electrogram voltage was measured at 0, 5, 10, 20, and 30 seconds after ablation onset. Distance from ablation lesion to the left atrial surface on NavX were calculated. RESULTS: Similar ablation energy was delivered in ROB and MAN groups, achieving comparable rates of PV isolation (100% vs 98%). The bipolar voltages of 4,434 electrograms from 303 ablation lesions (146 ROB, 157 MAN) were measured. At 30 seconds, signal attenuation was greater in the ROB group than MAN (mean 65 ± 4% vs 55 ± 4% of baseline voltage, P < 0.01). A total of 2,064 NavX ablation lesions were assessed (906 ROB and 1,158 MAN). ROB lesions were on average 0.52 mm further inside the geometry than MAN (P < 0.0001). CONCLUSIONS: Robotic ablation results in greater signal attenuation in man. This is achieved despite manual lesions being closer to the left atrial surface. Catheter stability and constant energy delivery may be key to achieving signal attenuation, rather than increased contact force.

A randomised comparison of Cartomerge vs. NavX fusion in the catheter ablation of atrial fibrillation: the CAVERN Trial.

PURPOSE: Integration of a 3D reconstruction of the left atrium into cardiac mapping systems can aid catheter ablation of atrial fibrillation (AF). The two most widely used systems are NavX Fusion and Cartomerge. We aimed to compare the clinical efficacy of these systems in a randomised trial. METHODS: Patients undergoing their first ablation were randomised to mapping using either NavX fusion or CartoMerge. Pulmonary vein isolation by wide area circumferential ablation was performed for paroxysmal AF with additional linear and fractionated potential ablation for persistent AF. Seven-day Holter monitoring was used for confirmation of sinus rhythm maintenance at 6 months. RESULTS: Ninety-seven patients were randomised and underwent a procedure. There was no difference in the primary endpoint of freedom from arrhythmia at 6 months (51% in the Cartomerge group vs. 48% in the NavX Fusion group, p = 0.76). 3D image registration was faster with Cartomerge (24 vs. 33 min, p = 0.0001), used less fluoroscopic screening (11 vs. 15 min, p = 0.039) with a lower fluoroscopic dose (840 vs. 1,415 mGyCm(2), p = 0.043). There was a strong trend to lower ablation times in the Cartomerge group, overall RF time (3,292 s vs. 4,041, p = 0.07). Distance from 3D lesion to 3D image shell was smaller in the Cartomerge group (2.7 ± 1.9 vs. 3.3 ± 3.7 mm, p < 0.001). CONCLUSIONS: Cartomerge appears to be faster and uses less fluoroscopy to achieve registration than NavX Fusion, but overall procedural times and clinical outcomes are similar.

Maintenance of sinus rhythm with an ablation strategy in patients with atrial fibrillation is associated with a lower risk of stroke and death.

OBJECTIVE: To investigate whether catheter ablation of atrial fibrillation (AF) reduces stroke rate or mortality. METHODS: An international multicentre registry was compiled from seven centres in the U.K. and Australia for consecutive patients undergoing catheter ablation of AF. Long-term outcomes were compared with (1) a cohort with AF treated medically in the Euro Heart Survey, and (2) a hypothetical cohort without AF, age and gender matched to the general population. Analysis of stroke and death was carried out after the first procedure (including peri-procedural events) regardless of success, on an intention-to-treat basis. RESULTS: 1273 patients, aged 58±11 years, 56% paroxysmal AF, CHADS(2) score 0.7±0.9, underwent 1.8±0.9 procedures. Major complications occurred in 5.4% of procedures, including stroke/TIA in 0.7%. Freedom from AF following the last procedure was 85% (76% off antiarrhythmic drugs) for paroxysmal AF, and 72% (60% off antiarrhythmic drugs) for persistent AF. During 3.1 (1.0-9.6) years from the first procedure, freedom from AF predicted stroke-free survival on multivariate analysis (HR=0.30, CI 0.16 to 0.55, p<0.001). Rates of stroke and death were significantly lower in this cohort (both 0.5% per patient-year) compared with those treated medically in the Euro Heart Survey (2.8% and 5.3%, respectively; p<0.0001). Rates of stroke and death were no different from those of the general population (0.4% and 1.0%, respectively). CONCLUSION: Restoration of sinus rhythm by catheter ablation of AF is associated with lower rates of stroke and death compared with patients treated medically.

Characterization of fractionated atrial electrograms critical for maintenance of atrial fibrillation: a randomized, controlled trial of ablation strategies (the CFAE AF trial).

BACKGROUND: Whether ablation of complex fractionated atrial electrograms (CFAE) modifies atrial fibrillation (AF) by eliminating drivers or atrial debulking remains unknown. This randomized study aimed to determine the effect of ablating different CFAE morphologies compared with normal electrograms (ie, debulking normal tissue) on the cycle length of persistent AF (AFCL). METHODS AND RESULTS: After pulmonary vein isolation left and right atrial CFAE were targeted, until termination of AF or abolition of CFAE before DC cardioversion. Ten-second electrograms were classified according to a validated scale, with grade 1 being most fractionated and grade 5 normal. Patients were randomly assigned to have CFAE grades eliminated sequentially, from grade 1 to 5 (group 1) or grade 5 to 1 (group 2). An increase in AFCL (mean of left and right atrial appendage) ≥5 ms after a lesion was regarded as significant. CFAE (n=968) were targeted in 20 patients. AFCL increased after targeting 51±35% of grade 1 CFAE, 30±15% grade 2, 12±5% grade 3, 33±12% grade 4, and 8±15% grade 5 CFAE (P<0.01 for grades 1, 2, and 4 versus 5; 3 versus 5, not significant). The proportion of lesions causing AFCL prolongation was unaffected by the order in which CFAE were targeted. CONCLUSIONS: Targeting CFAE is not simply atrial debulking. Ablating certain grades of CFAE increases AFCL, suggesting they are more important in maintaining AF. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00894400.

Does ventricular dyssynchrony on echocardiography predict response to cardiac resynchronisation therapy? A randomised controlled study.

OBJECTIVE: To determine the value of echocardiography in predicting response to cardiac resynchronisation therapy (CRT). METHODS: This is a prospective randomised study that recruited patients with (group 1) and without (group 2) echocardiographic evidence of mechanical dyssynchrony. 73 heart failure patients (NYHA III-IV) with a requirement for an implantable cardioverter defibrillator, QRS ≥120 ms and LV ejection fraction (EF) <35% were studied. Group 1 patients received CRT-D (26 patients). Group 2 patients were randomised to CRT-D (group 2a: 23 patients) or implantable cardioverter defibrillator (group 2b: 21 patients). MAIN OUTCOME MEASURES: were peak oxygen consumption (VO(2)max), NYHA class, and echocardiography at baseline and at 6 months. RESULTS: 62% of group 1 patients achieved ≥1 ml/kg/min increase in VO(2)max at 6 months versus 50% in group 2a and 21% in group 2b (p=0.04). Group 1 patients showed significant improvements in VO(2)max (15.8±2 to 18.0±4 ml/kg/min, p=0.01), NYHA class (3.1±0.3 to 1.9±0.7, p<0.001) and EF (22±7% to 26±9%, p=0.02). Group 2a showed significant improvement in NYHA class (3.1±0.3 to 2.2±0.7, p<0.001) but no change in EF or VO(2)max. Group 2b showed no change in NYHA class or EF with a decline in VO(2)max (16.4±4 to 14.1±4, p=0.03). A significantly higher proportion of patients in group 2b showed ≥1 ml/kg/min deterioration in VO(2)max compared to group 2a (68% vs 23%, HR for group 2b: 2.4, 95% CI 1.2 to 4.8, p=0.005). CONCLUSIONS: The presence of echocardiographic dyssynchrony identifies patients who derive the most improvement from CRT. Patients without dyssynchrony also show more benefit and less deterioration with CRT than without and should not be denied CRT.

Impact of variant pulmonary vein anatomy and image integration on long-term outcome after catheter ablation for atrial fibrillation.

AIMS: To investigate the impact of variant pulmonary vein (PV) anatomy and the use of three-dimensional image integration (3D-II) on long-term efficacy of catheter ablation for atrial fibrillation (AF). METHODS: Consecutive procedures from 2002 to 2007 were analysed from a prospective database. All patients underwent wide area circumferential ablation, with linear lesions added and complex fractionated electrograms targeted for persistent AF. Imaging was segmented on Carto to assess PV anatomy. RESULTS: Three hundred and fifty patients underwent 1.9 ± 0.9 procedures. The mean age was 57 ± 11 years, 73% males, and 55% paroxysmal AF. Freedom from AF/atrial tachycardia was 42% for paroxysmal AF and 20% for persistent AF at 3.1 years after the first procedure, or 86 and 66%, respectively, at 2.5 years after the last procedure. The Kaplan-Meier analysis showed a trend towards improved single-procedure efficacy with 3D-II (8.9% difference, P = 0.087) and a reduction in the number of procedures per patient from 2.1 ± 1.1 to 1.8 ± 0.9 (P < 0.0001). The use of 3D-II improved single-procedure efficacy with Carto (13.3% difference, P = 0.018), but not with Ensite NavX. Variant PV anatomy was identified in 28% and was associated with a lower single-procedure efficacy (10.0% difference, P = 0.024) but with no effect on final outcome. Multivariate analysis confirmed the impact of 3D-II [hazard ratio (HR) for recurrence of AF 0.67, P = 0.020] and variant PV anatomy (HR 1.37, P = 0.044). CONCLUSION: The use of 3D-II improves single-procedure efficacy of PV isolation for AF. Variant PV anatomy was associated with a lower single-procedure success rate.

A prospective comparison of echocardiography and device algorithms for atrioventricular and interventricular interval optimization in cardiac resynchronization therapy.

AIMS: Echocardiographic optimization of atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) is costly, time-consuming, and requires skill and expertise so is usually undertaken only in 'non-responder' patients. An algorithm in St Jude Medical CRT devices (QuickOpt) claims to optimize these settings automatically. The aim of this study was to compare the two optimization techniques. METHODS AND RESULTS: Optimization of AV and VV intervals was performed a month after CRT device implantation in 26 patients with heart failure, first by echocardiography then by QuickOpt. The left ventricular outflow tract (LVOT) velocity-time integral (VTI) was measured after optimization by each method. Agreement between the optimization methods was assessed by the Bland-Altman analysis and correlation by Pearson's correlation coefficient. There was good correlation between the LVOT VTI following optimization by both methods (R2 = 0.77, P < 0.001). However, agreement between the two methods was poor, with 15 of 26 and 10 of 26 patients having a >20 ms difference in the optimal AV and VV interval values, respectively. Left ventricular outflow tract VTI was significantly better (22 of 26 patients; P < 0.001) in patients optimized by echocardiography than by QuickOpt. CONCLUSION: There is a poor agreement in optimal AV and VV intervals determined by echocardiography and QuickOpt, with echocardiographic optimization giving a superior haemodynamic outcome.