Conformational Activation Promotes CRISPR-Cas12a Catalysis and Resetting of the Endonuclease Activity.

Cas12a, also known as Cpf1, is a type V-A CRISPR-Cas RNA-guided endonuclease that is used for genome editing based on its ability to generate specific dsDNA breaks. Here, we show cryo-EM structures of intermediates of the cleavage reaction, thus visualizing three protein regions that sense the crRNA-DNA hybrid assembly triggering the catalytic activation of Cas12a. Single-molecule FRET provides the thermodynamics and kinetics of the conformational activation leading to phosphodiester bond hydrolysis. These findings illustrate why Cas12a cuts its target DNA and unleashes unspecific cleavage activity, degrading ssDNA molecules after activation. In addition, we show that other crRNAs are able to displace the R-loop inside the protein after target DNA cleavage, terminating indiscriminate ssDNA degradation. We propose a model whereby the conformational activation of the enzyme results in indiscriminate ssDNA cleavage. The displacement of the R-loop by a new crRNA molecule will reset Cas12a specificity, targeting new DNAs.

Structures of the Cmr-ß Complex Reveal the Regulation of the Immunity Mechanism of Type III-B CRISPR-Cas.

Cmr-ß is a type III-B CRISPR-Cas complex that, upon target RNA recognition, unleashes a multifaceted immune response against invading genetic elements, including single-stranded DNA (ssDNA) cleavage, cyclic oligoadenylate synthesis, and also a unique UA-specific single-stranded RNA (ssRNA) hydrolysis by the Cmr2 subunit. Here, we present the structure-function relationship of Cmr-ß, unveiling how binding of the target RNA regulates the Cmr2 activities. Cryoelectron microscopy (cryo-EM) analysis revealed the unique subunit architecture of Cmr-ß and captured the complex in different conformational stages of the immune response, including the non-cognate and cognate target-RNA-bound complexes. The binding of the target RNA induces a conformational change of Cmr2, which together with the complementation between the 5' tag in the CRISPR RNAs (crRNA) and the 3' antitag of the target RNA activate different configurations in a unique loop of the Cmr3 subunit, which acts as an allosteric sensor signaling the self- versus non-self-recognition. These findings highlight the diverse defense strategies of type III complexes.

Molecular basis of cyclic tetra-oligoadenylate processing by small standalone CRISPR-Cas ring nucleases.

Standalone ring nucleases are CRISPR ancillary proteins, which downregulate the immune response of Type III CRISPR-Cas systems by cleaving cyclic oligoadenylates (cA) second messengers. Two genes with this function have been found within the Sulfolobus islandicus (Sis) genome. They code for a long polypeptide composed by a CARF domain fused to an HTH domain and a short polypeptide constituted by a CARF domain with a 40 residue C-terminal insertion. Here, we determine the structure of the apo and substrate bound states of the Sis0455 enzyme, revealing an insertion at the C-terminal region of the CARF domain, which plays a key role closing the catalytic site upon substrate binding. Our analysis reveals the key residues of Sis0455 during cleavage and the coupling of the active site closing with their positioning to proceed with cA4 phosphodiester hydrolysis. A time course comparison of cA4 cleavage between the short, Sis0455, and long ring nucleases, Sis0811, shows the slower cleavage kinetics of the former, suggesting that the combination of these two types of enzymes with the same function in a genome could be an evolutionary strategy to regulate the levels of the second messenger in different infection scenarios.

Structure of the Cpf1 endonuclease R-loop complex after target DNA cleavage.

Cpf1 is an RNA-guided endonuclease that is emerging as a powerful genome-editing tool. Here we provide insight into its DNA-targeting mechanism by determining the structure of Francisella novicida Cpf1 with the triple-stranded R-loop generated after DNA cleavage. The structure reveals the machinery involved in DNA unwinding to form a CRISPR RNA (crRNA)-DNA hybrid and a displaced DNA strand. The protospacer adjacent motif (PAM) is recognized by the PAM-interacting domain. The loop-lysine helix-loop motif in this domain contains three conserved lysine residues that are inserted in a dentate manner into the double-stranded DNA. Unzipping of the double-stranded DNA occurs in a cleft arranged by acidic and hydrophobic residues facilitating the crRNA-DNA hybrid formation. The PAM single-stranded DNA is funnelled towards the nuclease site through a mixed hydrophobic and basic cavity. In this catalytic conformation, the PAM-interacting domain and the helix-loop-helix motif in the REC1 domain adopt a 'rail' shape and 'flap-on' conformations, respectively, channelling the PAM strand into the cavity. A steric barrier between the RuvC-II and REC1 domains forms the 'septum', separating the displaced PAM strand and the crRNA-DNA hybrid, avoiding DNA re-annealing. Mutations in key residues reveal a mechanism linking the PAM and DNA nuclease sites. Analysis of the Cpf1 structures proposes a singular working model of RNA-guided DNA cleavage, suggesting new avenues for redesign of Cpf1.

Erratum: Structure of the Cpf1 endonuclease R-loop complex after target DNA cleavage.

This corrects the article DOI: 10.1038/nature22398.

Structural basis of cyclic oligoadenylate degradation by ancillary Type III CRISPR-Cas ring nucleases.

Type III CRISPR-Cas effector systems detect foreign RNA triggering DNA and RNA cleavage and synthesizing cyclic oligoadenylate molecules (cA) in their Cas10 subunit. cAs act as a second messenger activating auxiliary nucleases, leading to an indiscriminate RNA degradation that can end in cell dormancy or death. Standalone ring nucleases are CRISPR ancillary proteins which downregulate the strong immune response of Type III systems by degrading cA. These enzymes contain a CRISPR-associated Rossman-fold (CARF) domain, which binds and cleaves the cA molecule. Here, we present the structures of the standalone ring nuclease from Sulfolobus islandicus (Sis) 0811 in its apo and post-catalytic states. This enzyme is composed by a N-terminal CARF and a C-terminal wHTH domain. Sis0811 presents a phosphodiester hydrolysis metal-independent mechanism, which cleaves cA4 rings to generate linear adenylate species, thus reducing the levels of the second messenger and switching off the cell antiviral state. The structural and biochemical analysis revealed the coupling of a cork-screw conformational change with the positioning of key catalytic residues to proceed with cA4 phosphodiester hydrolysis in a non-concerted manner.

Evolution of interventional imaging in structural heart disease.

Treatments for structural heart diseases (SHD) have been considerably evolved by the widespread of transcatheter approach in the last decades. The progression of transcatheter treatments for SHD was feasible due to the improvement of devices and the advances in imaging techniques. In this setting, the cardiovascular imaging is pivotal not only for the diagnosis but even for the treatment of SHD. With the aim of fulfilling these tasks, a multimodality imaging approach with new imaging tools for pre-procedural planning, intra-procedural guidance, and follow-up of SHD was developed. This review will describe the current state-of-the-art imaging techniques for the most common percutaneous interventions as well as the new imaging tools. The imaging approaches will be addressed describing the use in pre-procedural planning, intra-procedural guidance, and follow-up.

Myocardial injury in patients with SARS-CoV-2 pneumonia: Pivotal role of inflammation in COVID-19.

AIMS: Infection by SARS-CoV-2 may result in a systemic disease and a proportion of patients ranging 15%-44% experienced cardiac injury (CI) diagnosed by abnormal troponin levels. The aim of the present study was to analyse the clinical characteristics of a large series of hospitalized patients for COVID-19 in order to identify predisposing and/or protective factors of CI and the outcome. METHODS AND RESULTS: This is an observational, retrospective study on patients hospitalized in two Italian centres (San Raffaele Hospital and Cremona Hospital) for COVID-19 and at least one high-sensitivity cardiac troponin (hs-cTnt) measurement during hospitalization. CI was defined if at least one hs-cTnt value was above the 99th percentile. The primary end-point was the occurrence of CI during hospitalization. We included 750 patients (median age 67, IQR 56-77 years; 69% males), of whom 46.9% had history of hypertension, 14.7% of chronic coronary disease and 22.3% of chronic kidney disease (CKD). Abnormal troponin levels (median troponin 74, IQR 34-147 ng/l) were detected in 390 patients (52%) during the hospitalization. At multivariable analysis age, CKD, cancer, C-reactive protein (CRP) levels were independently associated with CI. Independent predictors of very high troponin levels were chronic kidney disease and CRP levels. Patients with CI showed higher rate of all-cause mortality (40.0% vs. 9.1%, p = 0.001) compared to those without CI. CONCLUSION: This large, multicentre Italian study confirmed the high prevalence of CI and its prognostic role in hospitalized patients with COVID-19, highlighting the leading role of systemic inflammation for the occurrence of CI.

Outcome of left atrial appendage closure using cerebral protection system for thrombosis: no patient left behind.

BACKGROUND: Left atrial appendage (LAA) thrombosis increases the risk of stroke and its management has to be assessed. The aim of the present study is to evaluate short and long-term safety and efficacy of a standardized approach of percutaneous LAA closure (LAAC) routinely using a cerebral protection device (CPD) in patients with LAA thrombosis or sludge (LAAT). METHODS: We prospectively enrolled 14 consecutive patients with atrial fibrillation complicated by LAAT presenting in a high-volume tertiary center. In seven patients (50%) LAAT was found after anticoagulant withdrawal for severe bleedings and in the remaining half LAAT was found despite appropriate anticoagulant therapy. All patients were treated with a standardized interventional approach of LAAC routinely using a CPD and guided by transoesophageal echocardiography. RESULTS: Mean age was 68 ± 14 years and nine patients (64%) were male. Mean CHA2 DS2 -VASc and HAS-BLED scores were 3.3 ± 1.6 and 2.3 ± 1.1, respectively. Six patients (42.8%) presented organized thrombi while eight LAA sludge (57.1%). In 13 patients (92.8%) CPD was positioned through a right radial arterial access. Procedural success was achieved in all patients. In one patient we assisted to embolization of the thrombus during deployment of the device in the absence of neurological consequences. During a mean follow up of 426 ± 307 days, one patient died for non-cardiac cause while no embolic event or major bleeding were reported. CONCLUSION: In an unselected cohort, LAAC with the systematic use of CPD was a feasible, safe and effective therapeutic option for LAAT both acutely and after long-term follow-up.

Use of edge-to-edge percutaneous mitral valve repair for severe mitral regurgitation in cardiogenic shock: A multicenter observational experience (MITRA-SHOCK study).

OBJECTIVES: The aim of this study was to evaluate the impact of edge-to-edge PMVR on short and mid-term clinical outcomes in patients with CS and severe MR. BACKGROUND: Severe mitral regurgitation (MR) in the setting of cardiogenic shock (CS) is associated with three times higher risk of 1-year mortality. In refractory CS, edge-to-edge percutaneous mitral valve repair (PMVR) can be a potential therapeutic option. METHODS: We retrospectively included consecutive patients with refractory CS and concomitant severe MR treated with MitraClip® system. CS was defined according to the criteria used in the SHOCK trial and procedural success according to Mitral Valve Academic Research Consortium (MVARC) criteria. The 30-day and 6-month mortality were the primary and secondary endpoints respectively. RESULTS: Thirty-one patients (median age 73 years [interquartile range, IQR 66-78], 25.8% female), STS mortality score 37.9 [IQR 30.4-42.4]), with CS and concomitant severe MR treated with edge-to-edge PMVR were retrospectively enrolled. Procedural success was 87.1%. Thirty-day and 6-month survival rates were 78.4 and 45.2% respectively. Univariate Cox Regression Model analysis showed that procedural success was a predictor of both 30-day (HR = 0.12, 95% CI 0.03-0.55, p < .01) and 6-month survival (HR = 0.22, 95% CI 0.06-0.84, p = .027). CONCLUSIONS: Edge-to-edge PMVR in patients with CS and concomitant severe MR was associated with good procedural safety and success with acceptable short and mid-term survival rates. It could be considered a bailout option in this setting of patients.

Subclinical myocardial dysfunction in patients recovered from COVID-19.

BACKGROUND: Myocardial injury (MI) can be detected during the acute phase of Coronavirus disease 19 (COVID-19) and is associated with a dismal prognosis. Recent imaging studies described the persistence of cardiac abnormalities after the recovery. The aim of the study was to investigate the spectrum of cardiac abnormalities at mid-term follow-up in patients recovered from COVID-19 using clinical assessment, laboratory tests, and imaging evaluation with comprehensive echocardiography. METHODS: This is an observational, cross-sectional study assessing an unselected cohort of consecutive patients recovered from COVID-19. MI was defined by elevated plasma levels of high sensitive troponin T (hsTnT). At the follow-up, a complete examination including echocardiography was performed. RESULTS: The 123 patients included were divided into two groups according to the presence of MI during hospitalization: group A (without MI) and group B (with MI). After a median of 85 days, group B patients were more frequently symptomatic for dyspnea and had significantly higher values of hsTnT and N-Terminal prohormone of Brain Natriuretic Peptide (NT-proBNP), compared to Group A. No differences between the two groups in left nor right ventricle dimension and ejection fraction were found. However, in group B a significant reduction of mean left ventricle global longitudinal strain was observed (-15.7±.7 vs -18.1± .3 in group A, p < 0.001), together with higher frequency of impaired diastolic function and higher values of pulmonary pressure. CONCLUSIONS: In patients recovered from COVID-19, echocardiography with speckle-tracking analysis may be an useful imaging tool to identify subclinical myocardial dysfunction and potentially guide management strategies.

A Type III-B Cmr effector complex catalyzes the synthesis of cyclic oligoadenylate second messengers by cooperative substrate binding.

Recently, Type III-A CRISPR-Cas systems were found to catalyze the synthesis of cyclic oligoadenylates (cOAs), a second messenger that specifically activates Csm6, a Cas accessory RNase and confers antiviral defense in bacteria. To test if III-B CRISPR-Cas systems could mediate a similar CRISPR signaling pathway, the Sulfolobus islandicus Cmr-α ribonucleoprotein complex (Cmr-α-RNP) was purified from the native host and tested for cOA synthesis. We found that the system showed a robust production of cyclic tetra-adenylate (c-A4), and that c-A4 functions as a second messenger to activate the III-B-associated RNase Csx1 by binding to its CRISPR-associated Rossmann Fold domain. Investigation of the kinetics of cOA synthesis revealed that Cmr-α-RNP displayed positively cooperative binding to the adenosine triphosphate (ATP) substrate. Furthermore, mutagenesis of conserved domains in Cmr2α confirmed that, while Palm 2 hosts the active site of cOA synthesis, Palm 1 domain serves as the primary site in the enzyme-substrate interaction. Together, our data suggest that the two Palm domains cooperatively interact with ATP molecules to achieve a robust cOA synthesis by the III-B CRISPR-Cas system.

Aortic valve area calculation using 3D transesophageal echocardiography: Implications for aortic stenosis severity grading.

AIMS: Aortic stenosis (AS) grading by 2D-transthoracic echocardiography (2D-TTE) aortic valve area (AVA) calculation is limited by left ventricular outflow tract (LVOT) area underestimation. The combination of Doppler parameters with 3D LVOT area obtained by multidetector computed tomography (MDCT) can improve AS grading, reconciling discordant 2D-TTE findings. This study aimed to systematically evaluate the role of 3D-transesophageal echocardiography (3D-TEE) in AS grading using MDCT as reference standard. METHODS AND RESULTS: 288 patients (81 ± 6.3 years, 52.4% female) with symptomatic AS underwent 2D-TTE, 3D-TEE, and MDCT for transcatheter aortic valve implantation. Doppler parameters were combined with 3D LVOT areas measured by manual and semi-automated software 3D-TEE and by MDCT to calculate AVA, reassessing AS severity. Both 3D-TEE modalities demonstrated good correlation with MDCT, with excellent intra-observer and inter-observer variability. Compared to MDCT, 3D-TEE measurements significantly underestimated AVA (PANOVA  < .0001), although the difference was clinically acceptable. Compared to 2D-TTE, 3D-TEE manual and semi-automated software reclassified severe AS in 21.9% and 25.2% of cases, respectively (P < .0001), overcame grading parameters discordance in more than 40% of cases in patients with low-gradient AS (P < .0001) and reduced the proportion of low-flow states in nearly 75% of cases when combined to stroke volume index assessment (P < .0001). 3D-TEE imaging modalities showed a reduction in the proportion of patients with low-gradient and pathological AVA as defined by 2D-TTE, and improved AVA and mean pressure gradient agreement with current guidelines cutoff values. CONCLUSION: 3D-TEE AVA calculation is a reliable tool for AS grading with excellent reproducibility and good correlation with MDCT measurements.

Percutaneous left atrial appendage occlusion with the Amulet device: The impact of device disc position upon periprocedural and long-term outcomes.

OBJECTIVE: To investigate the effect of left atrial appendage (LAA) occlusion device positioning upon periprocedural and long-term outcomes. BACKGROUND: The Amulet device is designed to cover the ostium of the LAA. Prolapse of the device into the neck of the LAA is not uncommon resulting in incomplete coverage of the ostium. The clinical consequences of this remain uncertain. METHODS: Outcomes of 87 patients with successful LAA closure were analyzed according to Amulet disc position: group A (n = 45) had complete LAA ostium coverage; group B (n = 42) had incomplete ostium coverage because of disc prolapse. Periprocedural major adverse events (MAE) (composite of all cause death, tamponade, device/air embolization, cerebrovascular events, myocardial infarction, and major bleeding not related to vascular access complications) and total device-related periprocedural adverse events (defined as MAE and pericardial effusion) were evaluated. All patients were followed up longitudinally with long-term events defined as a composite of: cardiovascular death, cerebrovascular events, systemic embolization, and major bleeding requiring transfusion or intervention. RESULTS: Median follow-up was 234 days (IQR 150-436 days). There was a trend toward more periprocedural MAE in group B (P = 0.07) with deep implantation of the Amulet device associated with significantly more periprocedural adverse events (P = 0.03). There were no differences in reposition attempts (P = 0.9) or long-term events (P = 0.57). CONCLUSIONS: Our data suggest that suboptimal device positioning may be associated with worse periprocedural outcomes but no difference in long-term clinical outcomes. The results of this relatively small cohort does not seem to be affected by repositioning attempts during the index procedure.

The genome editing revolution: A CRISPR-Cas TALE off-target story.

In the last 10 years, we have witnessed a blooming of targeted genome editing systems and applications. The area was revolutionized by the discovery and characterization of the transcription activator-like effector proteins, which are easier to engineer to target new DNA sequences than the previously available DNA binding templates, zinc fingers and meganucleases. Recently, the area experimented a quantum leap because of the introduction of the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) system (clustered regularly interspaced short palindromic sequence). This ribonucleoprotein complex protects bacteria from invading DNAs, and it was adapted to be used in genome editing. The CRISPR ribonucleic acid (RNA) molecule guides to the specific DNA site the Cas9 nuclease to cleave the DNA target. Two years and more than 1000 publications later, the CRISPR-Cas system has become the main tool for genome editing in many laboratories. Currently the targeted genome editing technology has been used in many fields and may be a possible approach for human gene therapy. Furthermore, it can also be used to modifying the genomes of model organisms for studying human pathways or to improve key organisms for biotechnological applications, such as plants, livestock genome as well as yeasts and bacterial strains.

Echocardiographic features of post-transcatheter aortic valve implantation thrombosis and endocarditis.

BACKGROUND: Transcatheter heart valve thrombosis (THV-t) and endocarditis (THV-e) are relevant complications after transcatheter aortic valve implantation (TAVI). Transcatheter heart valve (THV) dysfunction definition is mostly based on Doppler (stenosis/regurgitation) without considering leaflets characteristics. PURPOSE: To evaluate the additional diagnostic value of leaflets echocardiographic features over Doppler when prosthetic valve complication is suspected. METHODS: Among 621 post-TAVI patients, 128 cases with probable valve complication were identified. THV-t was finally diagnosed in 13 patients (10%) and THV-e in 8 (6%), while the remaining 107 (84%) had no definitive diagnosis of thrombosis/endocarditis (THV-no). We analyzed at 2 time points (baseline and follow-up) both traditional Doppler parameters and leaflets morpho-functional features. RESULTS: Both Doppler and leaflets parameters showed high sensitivity (sensitivity 92%) and low specificity (ranging from specificity 32% to 74%) in detecting THV-t. Interestingly, the combination of mean aortic pressure gradient ≥20 mm Hg and leaflet thickening significantly improved the specificity of echocardiography for diagnosis of THV thrombosis (specificity 94%). On the other hand, echocardiographic diagnosis of THV endocarditis remained limited by very low sensitivity despite showing high specificity. CONCLUSIONS: The combination of Doppler and leaflets parameters can improve the echocardiographic diagnosis of THV thrombosis in post-TAVI patients with suspicious symptoms, via a significant increase in the overall test specificity. This would potentially allow more rational gatekeeping to more expensive/invasive diagnostic examinations (eg, CT scan) or therapeutic trials (eg, unnecessary anticoagulation).

The shape of the DNA minor groove directs binding by the DNA-bending protein Fis.

The bacterial nucleoid-associated protein Fis regulates diverse reactions by bending DNA and through DNA-dependent interactions with other control proteins and enzymes. In addition to dynamic nonspecific binding to DNA, Fis forms stable complexes with DNA segments that share little sequence conservation. Here we report the first crystal structures of Fis bound to high- and low-affinity 27-base-pair DNA sites. These 11 structures reveal that Fis selects targets primarily through indirect recognition mechanisms involving the shape of the minor groove and sequence-dependent induced fits over adjacent major groove interfaces. The DNA shows an overall curvature of approximately 65 degrees , and the unprecedented close spacing between helix-turn-helix motifs present in the apodimer is accommodated by severe compression of the central minor groove. In silico DNA structure models show that only the roll, twist, and slide parameters are sufficient to reproduce the changes in minor groove widths and recreate the curved Fis-bound DNA structure. Models based on naked DNA structures suggest that Fis initially selects DNA targets with intrinsically narrow minor grooves using the separation between helix-turn-helix motifs in the Fis dimer as a ruler. Then Fis further compresses the minor groove and bends the DNA to generate the bound structure.

Catheter Ablation of Ventricular Tachycardia in Patients With MitraClip Device: Preliminary Findings.

INTRODUCTION: Patients with mitral regurgitation are increasingly treated by percutaneous implantation of a MitraClip device (Abbott Park, IL, USA). We investigate the feasibility and safety of the transmitral catheter route for catheter ablation of ventricular tachycardia (VT) in these patients. METHODS: The mitral valve with the MitraClip in situ was crossed under transesophageal 3-dimensional echocardiographic and fluoroscopic guidance using a steerable sheath for ablation of the left ventricle. RESULTS: Five patients (all males, median age 74.0 ± 16.0 years) who had previously a MitraClip implanted were referred for catheter ablation of VT. The left ventricular ejection fraction was 29.0% ± 24.0%. One patient had both an atrial septal defect and a left atrial appendage occluder device in addition to a MitraClip. The duration between MitraClip implantation and ablation was 1019.0 ± 783.0 days. After transseptal puncture, ablation catheter was successfully steered through the mitral valve with the use of fluoroscopy. A complete high-density map of the substrate in sinus rhythm could be obtained in all patients using multipolar mapping catheters. In 1 patient, mapping was carried out using a mini-basket catheter. Procedural endpoints, noninducibility of all VTs, and abolition of all late potentials were achieved in all patients. Procedure time was 255.0 ± 52.5 minute, fluoroscopy time was 23.0 ± 7.3, and the radiation dose was 61.0 ± 37.5 Gycm2 . No mitral insufficiency or worsening of regurgitation was documented after the procedure. CONCLUSIONS: This is the first report demonstrating the feasibility and safety of VT ablation in patients with a MitraClip device using the anterograde transmitral catheter route.

Left atrial appendage closure: A single center experience and comparison of two contemporary devices.

OBJECTIVES: To compare indications and clinical outcomes of two contemporary left atrial appendage (LAA) percutaneous closure systems in a "real-world" population. BACKGROUND: Percutaneous LAA occlusion is an emerging therapeutic option for stroke prevention in atrial fibrillation. Some questions however remain unanswered, such as the applicability of results of randomized trials to current clinical practice. Moreover, currently available devices have never been directly compared. METHODS: We retrospectively analyzed consecutive patients who underwent LAA closure at San Raffaele Hospital, Milan, Italy between 2009 and 2015. Clinical indications and device selection were left to operators' decision; routine clinical and transesophageal echocardiography (TEE) follow-up was performed. RESULTS: One-hundred and sixty-five patients were included in the study, of which 99 were treated with the Amplatzer Cardiac Plug (ACP) and 66 with the Watchman system. During the follow-up period (median 15 months, interquartile range 6-26 months) five patients died. The incidence of ischemic events was low, with one patient suffering a transient ischemic attack and no episodes recorded of definitive strokes. Twenty-six leaks ≥1 mm were detected (23%); leaks were less common with the ACP and with periprocedural three-dimensional TEE evaluation, but were not found to correlate with clinical events. Clinical outcomes were comparable between the two devices. CONCLUSIONS: Our data show excellent safety and efficacy of LAA closure, irrespectively of the device utilized, in a population at high ischemic and hemorrhagic risk. The use of ACP and 3D-TEE minimized the incidence of residual leaks; however, the clinical relevance of small peri-device flow warrants further investigation. © 2016 Wiley Periodicals, Inc.

Young Patient with Advanced Heart Failure No Longer a Candidate for Heart Transplantation after MitraClip® Procedure.

In Europe, mitral regurgitation (MR) is the second most common form of valvular heart disease requiring surgical treatment. The case is presented of a 36-year-old woman with end-stage heart failure secondary to chemotherapy-induced cardiotoxicity, complicated by severe MR. She was listed for heart transplantation and underwent percutaneous MitraClip® implantation in order to preclude further clinical deterioration while awaiting a suitable donor. The one-year follow-up showed a strong improvement of symptoms and mostly reverse left ventricular remodelling, with consequent removal from the heart transplantation list. Video 1: Four-chamber view at baseline. Video 2: Four-chamber view at one-year follow up. Video 3: Tricuspid regurgitation and right ventricle at baseline. Video 4: Tricuspid regurgitation and right ventricle at one-year follow up.