Phosphorylation of the receptor protein Pex5p modulates import of proteins into peroxisomes.

Peroxisomes are organelles with vital functions in metabolism and their dysfunction is associated with human diseases. To fulfill their multiple roles, peroxisomes import nuclear-encoded matrix proteins, most carrying a peroxisomal targeting signal (PTS) 1. The receptor Pex5p recruits PTS1-proteins for import into peroxisomes; whether and how this process is posttranslationally regulated is unknown. Here, we identify 22 phosphorylation sites of Pex5p. Yeast cells expressing phospho-mimicking Pex5p-S507/523D (Pex5p2D) show decreased import of GFP with a PTS1. We show that the binding affinity between a PTS1-protein and Pex5p2D is reduced. An in vivo analysis of the effect of the phospho-mimicking mutant on PTS1-proteins revealed that import of most, but not all, cargos is affected. The physiological effect of the phosphomimetic mutations correlates with the binding affinity of the corresponding extended PTS1-sequences. Thus, we report a novel Pex5p phosphorylation-dependent mechanism for regulating PTS1-protein import into peroxisomes. In a broader view, this suggests that posttranslational modifications can function in fine-tuning the peroxisomal protein composition and, thus, cellular metabolism.

Left Atrial Appendage Occlusion in Nonagenarians.

BACKGROUND: Nonagenarians constitute a fast-growing and high-risk segment of the population, with scarce data on specific outcomes for percutaneous left atrial appendage occlusion (LAAO). The aim of the present paper was to assess the outcomes of nonagenarian patients undergoing LAAO from the prospective global Amplatzer Amulet observational study. Overall, 1088 subjects were prospectively included in the study. Among them, 9 (1%) were nonagenarians. Amulet device implant success was achieved in all patients and the only major procedural adverse event was a pseudoaneurysm. During the 2-year follow-up after LAAO, no ischemic strokes or transient ischemic attacks were reported. Further studies will be necessary to confirm the favorable LAAO outcomes in this growing segment of the atrial fibrillation population.

Length of stay following percutaneous left atrial appendage occlusion: Data from the prospective, multicenter Amplatzer Amulet Occluder Observational Study.

AIMS: To evaluate factors influencing the length of stay in patients undergoing percutaneous left atrial appendage occlusion (LAAO). METHODS AND RESULTS: Patient characteristics, procedural data and the occurrence of serious adverse events were analyzed from the AmplatzerTM AmuletTM Occluder Observational Study. Patients were divided into three groups: same day (S, 0day, n = 60, 5.6%) early (E, 1day, n = 526, 48.9%), regular (R, 2-3days, n = 338, 31.4%) and late (L, ≥4days, n = 152, 14.1%) discharge and followed up for 60 days. Procedure and device related SAE during the in-hospital stay (S: 0.0% vs. E: 1.0% vs. R: 2.1% vs. L: 23%, p<0.0001) were a major trigger for a prolonged in-hospital stay. Of the 37 subjects in the late discharge group with an SAE prior to discharge, cardiac or bleeding complications were the most common underlying conditions, occurring in 26 subjects. Multinomial logistic analysis only identified HAS-BLED score as an independent influencing factor (p = 0.04) for a late discharge. After 60 days, mortality tended to be greatest in the late discharge group (S: 0.0% vs. E: 1.0% vs. R: 1.2% vs. L: 3.3%, p = 0.1066). CONCLUSION: Over half of the subjects receiving an Amplatzer Amulet occluder were discharged within 1 day of the implant procedure. Serious adverse events were a major trigger for a late discharge after LAAO. Increased HAS-BLED score was associated with a prolonged in-hospital stay.

Gender difference in left atrial appendage occlusion outcomes: Results from the Amplatzer™ Amulet™ Observational Study.

BACKGROUND: Percutaneous LAAO represents an alternative for stroke prevention in patients not tolerating anticoagulation. While women are at higher risk of complications during percutaneous coronary or valvular interventions, the impact of gender on LAAO outcomes is not well characterized. The current study assessed potential gender-related differences in procedural and long-term outcomes following left atrial appendage occlusion (LAAO). METHODS: 1088 AF patients were enrolled in the prospective, multicenter, Amplatzer™ Amulet™ Observational Study and followed for 2 years with scheduled adverse event assessments. The prespecified primary outcome was ischemic stroke, systemic embolism or cardiovascular (CV) death at 2 years. We also compared the rate of procedural success, device-related thrombus (DRT) and major bleeding between genders. RESULTS: 702 men and 386 women underwent LAAO. Implant successwas high, and similar between men and women (98.9 vs 99.5%, p = 0.58). Similarly, no difference was observed in the primary outcome (12.0 vs 12.5%, p = 0.82). Compared to the CHA2DS2-VASc predicted rate, we observed a numerically greater absolute risk reduction of ischemic stroke in women (from 7.6 to 2.1%/year) than men (from 6.2 to 2.2%/year). DRT through 2 years was similar between groups (1.6%, p = 0.96). We found no significant gender difference in terms of periprocedural or long-term (7.1 vs 7.6%/year) major bleeding. CONCLUSIONS: In this large group of patients undergoing LAAO using the Amplatzer™ Amulet™ device we found no significant gender difference in terms of procedural or long-term clinical outcomes. Similarly to oral anticoagulation, device-based LAA occlusion renders AF-related stroke risk similar in women and men. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT02447081.https://clinicaltrials.gov/ct2/show/NCT02447081.

Clinical outcomes of patients undergoing percutaneous left atrial appendage occlusion in general anaesthesia or conscious sedation: data from the prospective global Amplatzer Amulet Occluder Observational Study.

OBJECTIVE: To evaluate the safety and efficacy of percutaneous left atrial appendage occlusion (LAAO) using conscious sedation (CS). BACKGROUND: Several percutaneous structural heart disease interventions are safely and efficiently performed using CS instead of general anaesthesia (GA). This concept has not been evaluated in a large multicenter cohort of patients undergoing LAAO. METHODS: Patients from the prospective, global Amplatzer Amulet Occluder Observational Study were divided into two groups (GA vs CS). Baseline information, periprocedural and postprocedural efficacy and complications, as well as outcomes through 7 days post implant were compared. RESULTS: Patients undergoing transesophageal-guided implants were categorised by GA (n=607, 64%) or CS (n=342, 36%) usage. Mean age was 75 years in both groups. LAAO technical success was achieved in 99% of both groups. The procedure duration (GA: 35±22 min vs CS: 27±19 min, p<0.001), total amount of contrast medium (GA: 105±81 mL vs CS: 86±66 mL, p<0.001) and fluoroscopic time (GA: 13±9 min vs CS: 12±13 min, p<0.001) were less in CS cases. Procedure-related or device-related serious adverse events during the first 7 days were numerically higher in the CS group (GA: 4.9% vs CS: 7.6%, p=0.114). Peridevice residual flow was absent or ≤5 mm 1-3 months after the procedure in 99.7% of the GA and in 100% of the CS group (p=1.000). CONCLUSIONS: In a large global study, LAAO with the Amplatzer Amulet occluder is safe and feasible using CS. Procedure duration and total amount of contrast were less with CS than GA cases. TRIAL REGISTRATION NUMBER: NCT02447081; Results.

Incidence and clinical impact of major bleeding following left atrial appendage occlusion: insights from the Amplatzer Amulet Observational Post-Market Study.

BACKGROUND: Major bleeding (MB) events are independent predictors of mortality after cardiac interventional procedures. The clinical relevance of MB following left atrial appendage occlusion (LAAO) remains unclear. AIMS: This study aimed to investigate the incidence and clinical impact of MB after LAAO in a real-world population at high risk for bleeding and contraindicated to anticoagulation. METHODS: The two-year results of the Amplatzer Amulet Observational Post-Market Study were analysed. An independent committee adjudicated MBs according to the Bleeding Academic Research Consortium scale. Cox proportional hazards regression identified variables associated with MB events and mortality. RESULTS: The MB rate was 7.2%/year, with a rate of 10.1%/year during year one, decreasing to 4.0%/year over year two. The most common bleeding location was gastrointestinal, accounting for 48% of MBs. Pre-LAAO MB was associated with an increased risk for post-LAAO MB (HR 2.34, 95% CI: 1.37-3.99). The occurrence of post-LAAO MB was associated with increased mortality (37.3% vs 12.7%; p<0.0001), driven mainly by events occurring beyond the periprocedural period. The annualised rate of ischaemic stroke or TIA was similar in patients with and without MB (2.3% vs 3.3%; p=0.446). MB post LAAO was a strong independent predictor of mortality (HR 3.07, 95% CI: 2.15-4.40). CONCLUSIONS: In real-world patients at high bleeding risk, MB following LAAO was not uncommon and associated with a significant increase in mortality, without increasing the risk of stroke. ClinicalTrials.gov Identifier: NCT02447081. https://clinicaltrials.gov/ct2/show/NCT02447081.

Comparative data on left atrial appendage occlusion efficacy and clinical outcomes by age group in the Amplatzer™ Amulet™ Occluder Observational Study.

AIMS: Left atrial appendage occlusion (LAAO) may be considered for patients with non-valvular atrial fibrillation (NVAF) and a relative/formal contraindication to anticoagulation. This study aimed to summarize the impact of aging on LAAO outcomes at short and long-term follow-up. METHODS AND RESULTS: We compared subjects aged <70, ≥70 and <80, and ≥80 years old in the prospective, multicentre Amplatzer™ Amulet™ Occluder Observational Study (Abbott, Plymouth, MN, USA). Serious adverse events (SAEs) were reported from implant through a 2-year post-LAAO visit and adjudicated by an independent clinical events committee. Overall, 1088 subjects were prospectively enrolled. There were 265 subjects (24.4%) <70 years old, 491 subjects (45.1%) ≥70 and <80 years old, and 332 subjects (30.5%) ≥80 years old, with the majority (≥80%) being contraindicated to anticoagulation. As expected, CHA2DS2-VASc and HAS-BLED Scores increased with age. Implant success was high (≥98.5%) across all groups, and the proportion of subjects with a procedure- or device-related SAE was similar between groups. At follow-up, the observed ischaemic stroke rate was not significantly different between groups, and corresponding risk reductions were 62, 56, and 85% when compared with predicted rates for subjects <70, ≥70 and <80, and ≥80 years old, respectively. Major bleeding and mortality rates increased with age, while the incidence of device-related thrombus tended to increase with age. CONCLUSIONS: Despite the increased risk for ischaemic stroke with increasing age in AF patients, LAAO reduced the risk for ischaemic stroke compared with the predicted rate across all age groups without differences in procedural SAEs.

The Impact of CHA2DS2-VASc and HAS-BLED Scores on Clinical Outcomes in the Amplatzer Amulet Study.

OBJECTIVES: The aim of this study was to evaluate the impact of CHA2DS2-VASc and HAS-BLED scores on ischemic and bleeding events of patients enrolled in the Amplatzer Amulet Observational Study. BACKGROUND: Baseline CHA2DS2-VASc and HAS-BLED scores have been validated in atrial fibrillation patients to guide about anticoagulation but not in patients treated by left atrial appendage occlusion (LAAO). METHODS: Subjects were stratified according to CHA2DS2-VASc and HAS-BLED scores. Clinical outcomes were collected through 2 years and adjudicated by an independent committee. RESULTS: Subjects were considered at low (n = 156), moderate (n = 715), and high (n = 215) risk for ischemic stroke, corresponding to CHA2DS2-VASc scores of <3, 3 to 5, and ≥6, respectively. The annual rates of ischemic stroke were 1.1%, 2.0%, and 3.5%, respectively. When compared with the predicted rate, LAAO reduced the risk of ischemic stroke by 56%, 69%, and 68%. Device-related thrombus occurred in 0.7%, 1.5%, and 3.0% of subjects at low, moderate, and high risk for ischemic stroke, respectively. The HAS-BLED score was ≤3 in 629 subjects and >3 in 456 subjects, respectively. Non-peri-procedural major bleeding was reduced by 11% and 9% compared with predicted rates in the low and high bleeding risk groups, respectively. CONCLUSIONS: LAAO with the Amplatzer Amulet reduced the risk of ischemic stroke compared with the predicted rate, with a greater magnitude among patients at high thromboembolic risk without increasing the bleeding risk. (Amplatzer™Amulet™ Post-Market Study [Amulet™PMS]; NCT02447081).

Incidence, Characterization, and Clinical Impact of Device-Related Thrombus Following Left Atrial Appendage Occlusion in the Prospective Global AMPLATZER Amulet Observational Study.

OBJECTIVES: This study sought to report the incidence, characteristics, and clinical impact of device-related thrombus (DRT) following left atrial appendage occlusion (LAAO) with the AMPLATZER Amulet device (Abbott, Plymouth, Minnesota). BACKGROUND: DRT is a potential serious complication of LAAO, but the incidence and clinical impact of DRTs in a real-world setting are not well characterized. METHODS: A total of 1,088 patients were enrolled in a multicenter prospective study and followed for 1 year. All events were adjudicated by an independent committee, including the presence of DRT. Patients with DRT were reviewed for suboptimal device implantation and characterization of DRT formation. Multiple Cox regression was performed to identify predictors of DRT formation. RESULTS: Device implantation was successful in 1,078 (99%) patients, with 1-year follow-up completed in 96.3% of patients. A total of 18 DRTs occurred in 17 patients (1.7%/year), as a second DRT developed following complete resolution of an initial DRT in 1 patient. The left upper pulmonary vein ridge was not covered by the Amulet disc in 82% of DRT patients, indicating suboptimal implantation, with most thrombus developing in the untrabeculated area of the LAA ostium between the pulmonary vein ridge and the upper edge of the disc. Three (18%) DRT patients had an ischemic stroke, all within 3 months of DRT diagnosis. Patients with a DRT were at a greater risk for ischemic stroke or transient ischemic attack compared with non-DRT patients (hazard ratio: 5.27; 95% confidence interval: 1.58 to 17.55; p = 0.007). Larger LAA orifice width was a predictor of DRT formation (hazard ratio: 1.09; 95% confidence interval: 1.00 to 1.19; p = 0.04). CONCLUSIONS: Following LAAO with the AMPLATZER Amulet device, DRT was observed infrequently. Although the presence of DRT was associated with an increased rate of ischemic stroke or transient ischemic attack as compared with patients without DRT, the large majority of DRT patients (82%) did not experience any ischemic neurologic events.

Comparison of interscalene block, general anesthesia, and intravenous analgesia for out-patient shoulder reduction.

PURPOSE: Shoulder dislocation is often associated with intense pain, and requires urgent pain therapy and reduction. Interscalene block, general anesthesia, or intravenous analgesia alone are applied procedures that facilitate shoulder reduction by the surgeon and ease patients' pain. This study was conducted to compare procedure times, patient satisfaction, side-effects, and clinical outcome of these clinical procedures. METHODS: Retrospective chart analysis was performed for all patients treated at the Emergency Department of a primary care hospital. In addition, standardized telephone interviews were conducted. Subjective clinical outcome and patient satisfaction (SF-36, Quick-DASH, ZUF-8) were measured with the standardized questionnaires. RESULTS: The shortest overall procedure time [67.5 min (48.8-93.5 min), P = 0.003] was found in patients with interscalene block. The advantage of general anesthesia was the shortest anesthesia induction time [10 min (7.8-10 min), P < 0.0001]; reduction time [6 min (4.3-6 min), P = 0.039]; and time to discharge [90 min (67.5-123.8 min), P = 0.0001] were significantly prolonged in comparison to interscalene block [5 min (1-5 min) and 45 min (2-67.5 min)]. The longest reduction time [11 min (10-13.5 min), P = 0.0008] was seen in patients in the intravenous analgesia group. Overall, patient satisfaction was greater in patients with regional as compared to general anesthesia [measured by ZUF-8: 12 (9-15) vs. 17 (12-24), P = 0.03]. Subjective clinical outcome (SF-36, DASH) was comparable among the three groups. There was one immediately identified esophageal intubation in the general anesthesia group. CONCLUSIONS: Out-patient shoulder reduction can be accomplished no matter whether general anesthesia, regional anesthesia, or intravenous analgesia alone was administered. Clinical outcome as measured by SF-36 and DASH was comparable among the three groups, but the shortest overall procedure time and greater patient satisfaction were found in patients with interscalene block.

Defining the Mammalian Peroxisomal Proteome.

The current view on peroxisomes has changed dramatically from being human cell oddities to vital organelles that host several key metabolic pathways. To fulfil over 50 different enzymatic functions, human peroxisomes host either unique peroxisomal proteins or dual-localized proteins. The identification and characterization of the complete peroxisomal proteome in humans is important for diagnosis and treatment of patients with peroxisomal disorders as well as for uncovering novel peroxisomal functions and regulatory modules. Hence, here we compiled a comprehensive list of mammalian peroxisomal and peroxisome-associated proteins by curating results of several quantitative and non-quantitative proteomic studies together with entries in the UniProtKB and Compartments knowledge channel databases. Our analysis gives a holistic view on the mammalian peroxisomal proteome and brings to light potential new peroxisomal and peroxisome-associated proteins. We believe that this dataset, represents a valuable surrogate map of the human peroxisomal proteome.

Study of Peroxisomal Protein Phosphorylation by Functional Proteomics.

Reversible protein phosphorylation is a frequently occurring posttranslational modification mediated by protein kinases and phosphatases that plays an essential role in the regulation of a large number of cellular processes. Evidence is accumulating that protein phosphorylation is also an important mechanism governing processes associated with peroxisome biology. For an improved and detailed understanding of these processes and their regulation it is therefore crucial to study phosphorylation of peroxisome-associated proteins and to determine the phosphorylated amino acid(s). To place peroxisome-related processes into a larger, cellular context, it is further required to identify the kinases and phosphatases catalyzing phosphorylation and dephosphorylation events in peroxisomal proteins. We here provide a strategy for the targeted analysis of peroxisomal phosphoproteins of Saccharomyces cerevisiae combining affinity purification of epitope-tagged peroxisomal proteins with Phos-tag SDS-PAGE and high-resolution mass spectrometry (MS) for the identification and precise localization of in vivo phosphosites. Furthermore, we describe a protocol for an MS-based in vitro kinase assay using recombinant peroxisomal proteins and a selected kinase facilitating the site-resolved analysis of kinase-substrate relationships.

Pex17p-dependent assembly of Pex14p/Dyn2p-subcomplexes of the peroxisomal protein import machinery.

Peroxisomal matrix protein import is facilitated by cycling receptors that recognize their cargo proteins in the cytosol by peroxisomal targeting sequences (PTS). In the following, the assembled receptor-cargo complex is targeted to the peroxisomal membrane where it docks to the docking-complex as part of the peroxisomal translocation machinery. The docking-complex is composed of Pex13p, Pex14p and in yeast also Pex17p, whose function is still elusive. In order to characterize the function of Pex17p, we compared the composition and size of peroxisomal receptor-docking complexes from wild-type and pex17Δ cells. Our data demonstrate that the deficiency of Pex17p affects the stoichiometry of the constituents of an isolated 600kDa complex and that pex17Δ cells lack a high molecular weight complex (>900kDa) of unknown function. We identified the dynein light chain protein Dyn2p as an additional core component of the Pex14p/Pex17p-complex. Both, Pex14p and Pex17p interact directly with Dyn2p, but in vivo, Pex17p turned out to be prerequisite for an association of Dyn2p with Pex14p. Finally, like pex17Δ also dyn2Δ cells lack the high molecular weight complex. As dyn2Δ cells also display reduced peroxisomal function, our data indicate that Dyn2p-dependent formation of the high molecular weight Pex14p-complex is required to maintain peroxisomal function on wild-type level.

Monopolizing Sanctioning Power under Noise Eliminates Perverse Punishment But Does Not Increase Cooperation.

We run several experiments which allow us to compare cooperation under perfect and imperfect information in a centralized and decentralized punishment regime. Under perfect and extremely noisy information, aggregate behavior does not differ between institutions. Under intermediate noise, punishment escalates in the decentralized peer-to-peer punishment regime which badly affects efficiency while sustaining cooperation for longer. Only decentralized punishment is often directed at cooperators (perverse punishment). We report several, sometimes subtle, differences in punishment behavior, and how contributions react.

Structural insights into cargo recognition by the yeast PTS1 receptor.

The peroxisomal matrix protein import is facilitated by cycling import receptors that shuttle between the cytosol and the peroxisomal membrane. The import receptor Pex5p mediates the import of proteins harboring a peroxisomal targeting signal of type I (PTS1). Purified recombinant Pex5p forms a dimeric complex with the PTS1-protein Pcs60p in vitro with a KD of 0.19 µm. To analyze the structural basis for receptor-cargo recognition, the PTS1 and adjacent amino acids of Pcs60p were systematically scanned for Pex5p binding by an in vitro site-directed photo-cross-linking approach. The cross-linked binding regions of the receptor were subsequently identified by high resolution mass spectrometry. Most cross-links were found with TPR6, TPR7, as well as the 7C-loop of Pex5p. Surface plasmon resonance analysis revealed a bivalent interaction mode for Pex5p and Pcs60p. Interestingly, Pcs60p lacking its C-terminal tripeptide sequence was efficiently cross-linked to the same regions of Pex5p. The KD value of the interaction of truncated Pcs60p and Pex5p was in the range of 7.7 µm. Isothermal titration calorimetry and surface plasmon resonance measurements revealed a monovalent binding mode for the interaction of Pex5p and Pcs60p lacking the PTS1. Our data indicate that Pcs60p contains a second contact site for its receptor Pex5p, beyond the C-terminal tripeptide. The physiological relevance of the ancillary binding region was supported by in vivo import studies. The bivalent binding mode might be explained by a two-step concept as follows: first, cargo recognition and initial tethering by the PTS1-receptor Pex5p; second, lock-in of receptor and cargo.

Reduction of inappropriate ICD therapies in patients with primary prevention of sudden cardiac death: DECREASE study.

BACKGROUND: A significant number of patients with an implantable cardioverter/defibrillator (ICD) for primary prevention receive inappropriate shocks. Previous studies have reported a reduction of inappropriate therapies with simple modifications of ICD detection settings, however, inclusion criteria and settings varied markedly between studies. Our aim was to investigate the effect of raising the ICD detection zone in the entire primary prevention ICD population. METHODS AND RESULTS: 543 patients receiving an ICD for primary prevention were randomized to either conventional or progressive ICD programming. The detection rate was programmed at 171 bpm for ventricular tachycardia (VT) and 214 bpm for ventricular fibrillation (VF) in the Conventional group and 187 bpm for VT and 240 bpm for VF in the Progressive group. 43 % of patients received single-chamber and 57 % dual-chamber detection devices (DDD-ICD 19 %; CRT-D 38 %). The primary endpoint consisted of inappropriate therapies and untreated VT/VF. The primary endpoint was reached in 35 patients (13 %) in the Conventional group and 17 patients (6 %) in the Progressive group (p = 0.004). Progressive ICD programming led to significantly fewer amount of patients with ICD therapies (26 vs. 14 %; p < 0.001) and shocks (11 vs. 5 %; p = 0.023) compared to conventional ICD programming. Sub-analyses showed the greatest reduction of inappropriate therapies and shocks in dual-chamber detection devices with progressive compared to single-chamber detection devices with conventional ICD programming (p < 0.001). CONCLUSIONS: Progressive ICD programming reduces the number of inappropriate therapies and shocks in a broad primary prevention ICD population particularly in combination with dual-chamber detection algorithms. CLINICAL TRIAL REGISTRATION: http://clinicaltrials.gov ; ClinicalTrials.gov identifier NCT01217528.

A dynamic network model of mTOR signaling reveals TSC-independent mTORC2 regulation.

The kinase mammalian target of rapamycin (mTOR) exists in two multiprotein complexes (mTORC1 and mTORC2) and is a central regulator of growth and metabolism. Insulin activation of mTORC1, mediated by phosphoinositide 3-kinase (PI3K), Akt, and the inhibitory tuberous sclerosis complex 1/2 (TSC1-TSC2), initiates a negative feedback loop that ultimately inhibits PI3K. We present a data-driven dynamic insulin-mTOR network model that integrates the entire core network and used this model to investigate the less well understood mechanisms by which insulin regulates mTORC2. By analyzing the effects of perturbations targeting several levels within the network in silico and experimentally, we found that, in contrast to current hypotheses, the TSC1-TSC2 complex was not a direct or indirect (acting through the negative feedback loop) regulator of mTORC2. Although mTORC2 activation required active PI3K, this was not affected by the negative feedback loop. Therefore, we propose an mTORC2 activation pathway through a PI3K variant that is insensitive to the negative feedback loop that regulates mTORC1. This putative pathway predicts that mTORC2 would be refractory to Akt, which inhibits TSC1-TSC2, and, indeed, we found that mTORC2 was insensitive to constitutive Akt activation in several cell types. Our results suggest that a previously unknown network structure connects mTORC2 to its upstream cues and clarifies which molecular connectors contribute to mTORC2 activation.

Clinical efficacy of left ventricular pacing vector programmability in cardiac resynchronization therapy defibrillator patients for management of phrenic nerve stimulation and/or elevated left ventricular pacing thresholds: insights from the Efface Phrenic Stim study.

AIMS: Elevated left ventricular (LV) pacing thresholds or phrenic nerve stimulation (PNS) might be possible reasons for absence of continuous and effective biventricular stimulation. This study investigated the benefit and clinical efficacy of the ability to choose one out of three different LV pacing vectors for the management of suboptimal LV pacing thresholds and PNS. METHODS AND RESULTS: This prospective, observational multicentre study enrolled 132 patients (Pts) implanted with a cardiac resynchronization therapy defibrillator, that offers three LV pacing vectors: (i) Bipolar; (ii) LVtip ↔ RVcoil; (iii) LVring ↔ RVcoil (RV = right ventricular). Left ventricular pacing thresholds and PNS thresholds were obtained in sitting and left lateral body position for all programmable LV pacing vectors at hospital discharge and follow up (FU). In 97%, a bipolar transvenous LV lead was successfully implanted. In 87% of Pts at least one acceptable pacing vector could be identified that provides good pacing threshold (≤ 2.5 V at 5 ms) and acceptable margin to PNS (≥ 2:1). This is an increase of 18% compared with conventional bipolar systems (74%) with two LV vectors and of 25% compared with unipolar systems (70%). The LVtip ↔ RVcoil vector provided the best LV pacing thresholds, but the highest rate of PNS. CONCLUSIONS: The programmability of LV pacing vectors is a powerful feature to avoid PNS and obtain acceptable LV pacing thresholds. In order to retain reprogramming options for LV vectors during FU, LV pacing leads with at least two electrodes should be chosen whenever possible.

Minimal extracorporeal circulation and off-pump compared to conventional cardiopulmonary bypass in coronary surgery.

OBJECTIVES: Although minimal extracorporeal circulation (MECC) and off-pump surgery are equal or better alternatives to conventional cardiopulmonary bypass (CCPB) regarding perioperative morbidity, use of blood and blood products and completeness of revascularization, CCPB is still being used in the majority of coronary artery bypass grafting (CABG) operations. METHODS AND RESULTS: We investigated 1472 CABG operations in our center. A total of 1143 CABG operations were performed using CCPB, 220 using MECC and 109 were performed as off-pump coronary artery bypass (OPCAB). All patients were recorded prospectively. Perioperative follow-up was focused on the occurrence of arrhythmia, neurocognitive disorders and the need of blood and blood products. Operative mortality rates were comparable in all three groups. The mean number of distal anastomoses was 3.2+/-0.6 in the MECC group, 3.4+/-0.7 in the CCPB group and 1.9+/-0.8 in the OPCAB group (P=0.01). Arrhythmia occurred in 25% of the MECC group and in 35.6% of the CCPB group (P=0.05). Arrhythmia occurred in 21.7% of the OPCAB group. Seven patients (3%) of the MECC group suffered neurocognitive disorders perioperatively compared to 74 (7%) patients of the CCPB group (P=0.05) and three patients of the OPCAB group (3%). The median number of blood transfusions per patient was 0.8 in the MECC group, 1.8 in the CCPB group and 0.8 in the OPCAB group (P<0.0001). CONCLUSIONS: Perioperative morbidity of MECC and OPCAB is comparable to or even less in comparison to CCPB. MECC allows CABG surgery in cardiac arrest so that completeness of revascularization is being warranted and longer patency rates can be guaranteed. Furthermore, the use of blood and blood products is significantly less in MECC surgery so that MECC should be considered first choice in CABG surgery over CCPB and OPCAB.

Electrical performance and automatic capture characteristics of a 3.5-mm(2) passive fixation lead during 1-year follow-up.

BACKGROUND: Bipolar low polarization electrodes are recommended for a regular AutoCapture (St. Jude Medical, Inc., Sylmar, CA, USA) function in order to effectively detect the evoked response (ER) signal. The objective of this national multicenter registry was to evaluate the electrical performance and the AutoCapture characteristics of the bipolar ventricular pacing lead IsoFlex S, model 1636T or 1646T (St. Jude Medical), in combination with single- and dual-chamber pacemakers. METHODS: Ventricular pacing and sensing thresholds, lead impedance, ER amplitude, and polarization signals were measured at discharge and routine follow-up visits after 1, 3, 6, 9, and 12 months. AutoCapture activation was recommended based on the results of the ER sensitivity test. RESULTS: Of the 252 patients initially included, 109 (43%) have completed the follow-up. The mean ventricular pacing threshold was 0.43 +/- 0.19 V at discharge and 0.68 +/- 0.32 V at 12 months postimplant. The values for the ventricular sensing threshold were between 9.51 +/- 4.12 and 9.99 +/- 4.09 mV at discharge and at the 12-month follow-up. The unipolar lead impedance decreased from 533 +/- 94 to 476 +/- 73 ohms during the follow-up. The mean ER amplitude was 16.47 +/- 6.70 mV at discharge and 17.42 +/- 7.43 mV after 12 months, and the corresponding mean polarization signals were 0.59 +/- 1.00 and 0.74 +/- 1.24 mV, respectively. AutoCapture activation was recommended in at least 95% of the patients investigated over the 12-month follow-up. CONCLUSION: The bipolar ventricular pacing lead IsoFlex S 1636/1646T shows a good electrical performance and is mostly compatible with the AutoCapture algorithm.