John P. Vavalle

Staring, a Novel E3 Ubiquitin-Protein Ligase That Targets Syntaxin 1 for Degradation*

Syntaxin 1 is an essential component of the neurotransmitter release machinery, and regulation of syntaxin 1 expression levels is thought to contribute to the mechanism underlying learning and memory. However, the molecular events that control the degradation of syntaxin 1 remain undefined. Here we report the identification and characterization of a novel RING finger protein, Staring, that interacts with syntaxin 1. Staring is expressed throughout the brain, where it exists in both cytosolic and membrane-associated pools. Staring binds and recruits the brain-enriched E2 ubiquitin-conjugating enzyme UbcH8 to syntaxin 1 and facilitates the ubiquitination and proteasome-dependent degradation of syntaxin 1. These findings suggest that Staring is a novel E3 ubiquitin-protein ligase that targets syntaxin 1 for degradation by the ubiquitin-proteasome pathway.

SNIP, a novel SNAP-25-interacting protein implicated in regulated exocytosis.

Synaptosome-associated protein of 25 kDa (SNAP-25) is a presynaptic membrane protein that has been clearly implicated in membrane fusion in both developing and mature neurons, although its mechanisms of action are unclear. We have now identified a novel SNAP-25-interacting protein named SNIP. SNIP is a hydrophilic, 145-kDa protein that comprises two predicted coiled-coil domains, two highly charged regions, and two proline-rich domains with multiple PPXY and PXXP motifs. SNIP is selectively expressed in brain where it co-distributes with SNAP-25 in most brain regions. Biochemical studies have revealed that SNIP is tightly associated with the brain cytoskeleton. Subcellular fractionation and immunofluorescence localization studies have demonstrated that SNIP co-localizes with SNAP-25 as well as the cortical actin cytoskeleton, suggesting that SNIP serves as a linker protein connecting SNAP-25 to the submembranous cytoskeleton. By using deletion analysis, we have mapped the binding domains of SNIP and SNAP-25, and we have demonstrated that the SNIP-SNAP-25 association is mediated via coiled-coil interactions. Moreover, we have shown that overexpression of SNIP or its SNAP-25-interacting domain inhibits Ca2+-dependent exocytosis from PC12 cells. These results indicate that SNIP is involved in regulation of neurosecretion, perhaps via its interaction with SNAP-25 and the cytoskeleton.

A Phase 2, randomized, partially blinded, active-controlled study assessing the efficacy and safety of variable anticoagulation reversal using the REG1 system in patients with acute coronary syndromes: results of the RADAR trial

AIMS We sought to determine the degree of anticoagulation reversal required to mitigate bleeding, and assess the feasibility of using pegnivacogin to prevent ischaemic events in acute coronary syndrome (ACS) patients managed with an early invasive approach. REG1 consists of pegnivacogin, an RNA aptamer selective factor IXa inhibitor, and its complementary controlling agent, anivamersen. REG1 has not been studied in invasively managed patients with ACS nor has an optimal level of reversal allowing safe sheath removal been defined. METHODS AND RESULTS Non-ST-elevation ACS patients (n = 640) with planned early cardiac catheterization via femoral access were randomized 2:1:1:2:2 to pegnivacogin with 25, 50, 75, or 100% anivamersen reversal or heparin. The primary endpoint was total ACUITY bleeding through 30 days. Secondary endpoints included major bleeding and the composite of death, myocardial infarction, urgent target vessel revascularization, or recurrent ischaemia. Enrolment in the 25% reversal arm was suspended after 41 patients. Enrolment was stopped after three patients experienced allergic-like reactions. Bleeding occurred in 65, 34, 35, 30, and 31% of REG1 patients with 25, 50, 75, and 100% reversal and heparin. Major bleeding occurred in 20, 11, 8, 7, and 10% of patients. Ischaemic events occurred in 3.0 and 5.7% of REG1 and heparin patients, respectively. CONCLUSION At least 50% reversal is required to allow safe sheath removal after cardiac catheterization. REG1 appears a safe strategy to anticoagulate ACS patients managed invasively and warrants further investigation in adequately powered clinical trials of patients who require short-term high-intensity anticoagulation.

Aortic valve surgery and survival in patients with moderate or severe aortic stenosis and left ventricular dysfunction

AIMS We aimed to determine the frequency of aortic valve surgery (AVR) with or without coronary artery bypass grafting (CABG), among patients with moderate/severe aortic stenosis (AS) and left ventricular systolic dysfunction (LVSD), and its relationship with survival. METHODS AND RESULTS The Duke Echocardiographic Database (N = 132 804) was queried for patients with mean gradient ≥25 mmHg and/or peak velocity ≥3 m/s and LVSD (left ventricular ejection fraction ≤50%) from 1 January 1995-28 February 2014. For analyses purposes, AS was defined both by mean gradient and calculated aortic valve area (AVA) criteria. Time-dependent indicators of AVR in multivariable Cox models were used to assess the relationship of AVR and all-cause mortality. A total of 1634 patients had moderate (N = 1090, 67%) or severe (N = 544, 33%) AS by mean gradient criteria. Overall, 287 (26%) patients with moderate AS and 263 (48%) patients with severe AS underwent AVR within 5 years of the qualifying echo. There were 863 (53%) deaths observed up to 5 years following index echo. After multivariable adjustment in an inverse probability weighted regression model, AVR was associated with higher 5-year survival amongst patients with moderate AS and severe AS whether classified by AVA or mean gradient criteria. Over all, AVR ± CABG compared with medical therapy was associated with significantly lower mortality [hazard ratio, HR = 0.49 (0.38, 0.62), P < 0.0001]. Compared with CABG alone, CABG + AVR was associated with better survival [HR = 0.18 (0.12, 0.27), P < 0.0001]. CONCLUSIONS In patients with moderate/severe AS and LVSD, mortality is substantial and amongst those selected for surgery, AVR with or without CABG is associated with higher survival. Research is required to understand factors contributing to current practice patterns and the possible utility of transcatheter approaches in this high-risk cohort.

The systemic inflammatory response syndrome in patients with ST-segment elevation myocardial infarction.

Objectives:To assess whether systemic inflammatory response syndrome is associated with morbidity and mortality in ST-elevation myocardial infarction. Design and Setting:Secondary analysis of multicenter randomized controlled trials. Patients:Complement and reduction of infarct size after angioplasty or lytics project patients (n = 1,903) with ST-elevation myocardial infarction undergoing fibrinolysis or mechanical reperfusion. Interventions:None Measurements and Main Results:The prevalence of systemic inflammatory response syndrome was described in the 1,186 patients (64.4%) with data available for all systemic inflammatory response syndrome criteria. Using multiple imputations for the 1,843 patients (96.8%) with available endpoints, we compared the 90-day prevalence of death, shock, heart failure, or stroke between patients with and without systemic inflammatory response syndrome at presentation and at 24 hours post admission. Systemic inflammatory response syndrome was defined as ≥ 2 of 1) heart rate > 90 beats/min, 2) respiratory rate > 20 breaths/min, 3) body temperature > 38 or < 36°C, or 4) leukocyte count > 12 or < 4 × 109/L. At presentation, 25.0% of patients met systemic inflammatory response syndrome criteria; at 24 hours, 8.1% of patients met systemic inflammatory response syndrome criteria. The primary outcome was more frequent among patients with systemic inflammatory response syndrome at presentation (31.0% vs 16.7%; adjusted hazard ratio, 1.78 [95% CI, 1.35–2.34]; p < 0.001) and at 24 hours (36.7% vs 11.1%; adjusted hazard ratio, 2.84 [95% CI, 2.03–3.97]; p < 0.001). Mortality at 90 days was also higher among patients with systemic inflammatory response syndrome at either time point. Each additional systemic inflammatory response syndrome criterion was independently associated with 90-day outcomes at the time of presentation (adjusted hazard ratio, 1.41 per systemic inflammatory response syndrome criteria [95% CI, 1.24–1.61]; p < 0.001) and at 24 hours (adjusted hazard ratio, 1.72 per systemic inflammatory response syndrome criteria [95% CI, 1.47–2.01]; p < 0.001). Conclusion:The diagnosis of systemic inflammatory response syndrome and the cumulative number of systemic inflammatory response syndrome criteria were independently associated with 90-day clinical outcomes in a population of patients with ST-elevation myocardial infarction. The independent association of this simple composite measure of the inflammatory response with outcomes underscores the importance of the clinical inflammatory response in ST-elevation myocardial infarction.

Prognostic significance of bleeding location and severity among patients with acute coronary syndromes.

OBJECTIVES This study sought to determine if there is an association between bleed location and clinical outcomes in acute coronary syndromes (ACS) patients. BACKGROUND The prognostic significance of bleeding location among ACS patients undergoing cardiac catheterization is not well known. METHODS We analyzed in-hospital bleeding events among 9,978 patients randomized in the SYNERGY (Superior Yield of the New Strategy of Enoxaparin, Revascularization, and Glycoprotein IIb/IIIa Inhibitors) study. Bleeding events were categorized by location as access site, systemic, surgical, or superficial, and severity was graded using the GUSTO (Global Use of Strategies to Open Occluded Coronary Arteries) definition. We assessed the association of each bleeding location and severity with 6-month risk of death or myocardial infarction using a multicovariate-adjusted Cox proportional hazard model. RESULTS A total of 4,900 bleeding events were identified among 3,694 ACS patients with in-hospital bleeding. Among 4,679 GUSTO mild/moderate bleeding events, only surgical and systemic bleeds were associated with an increased risk of 6-month death or myocardial infarction (adjusted hazard ratio [HR]: 2.52 [95% confidence interval (CI): 2.16 to 2.94, and 1.40 [95% CI: 1.16 to 1.69], respectively). Mild/moderate superficial and access-site bleeds were not associated with downstream risk (adjusted HR: 1.17 [95% CI: 0.97 to 1.40], and 0.96 [95% CI: 0.82 to 1.12], respectively). Among 221 GUSTO severe bleeds, surgical bleeds were associated with the highest risk (HR: 5.27 [95% CI: 3.80 to 7.29]), followed by systemic (HR: 4.48 [95% CI: 2.98 to 6.72]), and finally access-site bleeds (HR: 3.57 [95% CI: 2.35 to 5.40]). CONCLUSIONS Among ACS patients who develop in-hospital bleeding, systemic and surgical bleeding are associated with the highest risks of adverse outcomes regardless of bleeding severity. Although the most frequent among bleeds, GUSTO mild/moderate access-site bleeding is not associated with increased risk. These data underscore the importance of strategies to minimize overall bleeding risk beyond vascular access site management.

Transcatheter versus surgical aortic valve replacement in intermediate risk patients: a meta-analysis

BACKGROUND Transcatheter aortic valve replacement (TAVR) has been approved in patients with high or prohibited surgical risk for surgery for treatment of severe symptomatic aortic stenosis. Prospective studies examining the benefits of TAVR in intermediate risk patients are ongoing. Other smaller studies including lower risk patients have been conducted, but further meta-analysis of these studies is required to draw more broad comparisons. METHODS A Medline search was conducted using standard methodology to search for clinical trials and observational studies including intermediate risk patients. We limited our meta-analysis to studies matching patient populations by propensity scores or randomization and examined clinical outcomes between TAVR and surgical aortic valve replacement (SAVR). RESULTS Analysis of the TAVR and SAVR cohorts revealed no significant differences in the outcomes of 30-day [OR (95% CI): 0.85 (0.57, 1.26)] or 1-year mortality [OR (95% CI): 0.96 (0.75, 1.23)]. A trend towards benefit with TAVR was noted in terms of neurological events and myocardial infarction (MI) without statistical significance. A statistically significant decrease in risk of post-procedural acute renal failure in the TAVR group [OR (95% CI): 0.52 (0.27, 0.99)] was observed, but so was a significantly higher rate of pacemaker implantations for the TAVR group [OR (95% CI): 6.51 (3.23, 13.12)]. CONCLUSIONS We conclude that in intermediate risk patients undergoing aortic valve replacement, the risk of mortality, neurological outcomes, and MI do not appear to be significantly different between TAVR and SAVR. However, there appears to be a significant reduction in risk of acute renal failure at the expense of an increased risk of requiring a permanent pacemaker in low and intermediate risk patients undergoing TAVR compared to SAVR.

Use of the REG1 anticoagulation system in patients with acute coronary syndromes undergoing percutaneous coronary intervention: results from the phase II RADAR-PCI study.

AIMS We sought to determine the feasibility of conducting percutaneous coronary intervention (PCI) in high-risk acute coronary syndrome (ACS) patients utilising the REG1 system consisting of pegnivacogin, an aptameric factor IXa inhibitor, and its controlling agent anivamersen. METHODS AND RESULTS In RADAR, ACS patients were randomised to pegnivacogin 1 mg/kg with 25%, 50%, 75%, or 100% anivamersen reversal or unfractionated heparin. Of the 640 patients randomised, 388 (61%) underwent PCI. Major modified ACUITY 30-day bleeding rates were 18% (25% reversal), 12% (50% reversal), 9% (75% reversal), and 7% (100% reversal), compared with 11% with heparin. The corresponding total bleeding rates were 68%, 39%, 35%, 34%, and 38% (heparin). Ischaemic events were less frequent in those receiving pegnivacogin versus heparin (4.4% vs. 7.3%, p=0.3). Thirty-day urgent TVR (1.1% vs. 0.9%, p=1.0), myocardial infarction (4.0% vs. 6.4%, p=0.3), and angiographic complication (11.2% and 10.8%, p=0.9) rates were similar with pegnivacogin and heparin. There were no incidences of clot formation on guidewires or catheters. CONCLUSIONS High-level factor IXa inhibition in ACS patients undergoing PCI, with at least 50% reversal, has a favourable bleeding profile and appears effective at suppressing ischaemic events and thrombotic complications. Larger phase trials in PCI are warranted. CLINICAL TRIALS REGISTRATION ClinicalTrials.gov NCT00932100.

Transcatheter Versus Surgical Aortic Valve Replacement in Patients With Lower Surgical Risk Scores: A Systematic Review and Meta-Analysis of Early Outcomes

BACKGROUND The results from the PARTNER 2 trial showed the feasibility of transcatheter aortic valve replacement (TAVR) in intermediate surgical risk patients. Although low risk clinical trials will take time to conclude, some data has emerged comparing TAVR with surgical aortic valve replacement (SAVR) in lower risk patients. METHODS A Medline search was conducted using standard methodology to search for studies reporting results comparing TAVR and SAVR. Studies were included if the overall mean Society of Thoracic Surgeons Score was less than 4% (or equivalent Euroscore). A meta-analysis comparing the 30-day risk of clinical outcomes between TAVR and SAVR in the lower surgical risk population was conducted. RESULTS A total of four studies, including one clinical trial and three propensity-matched cohort studies met the inclusion criteria. Compared to SAVR, TAVR had a lower risk of 30-day mortality (RR 0.67, 95% CI 0.41, 1.10), stroke (RR 0.60, 95% CI 0.30, 1.22), bleeding complications (RR 0.51, 95% CI 0.40, 0.67) and acute kidney injury (RR 0.66, 95% CI 0.47, 0.94). However, a higher risk of vascular complications (RR 11.72, 95% CI 3.75, 36.64), moderate or severe paravalvular leak (RR 5.04, 95% CI 3.01, 8.43), and permanent pacemaker implantations (RR 4.62, 95% CI 2.63, 8.12) was noted for TAVR. CONCLUSION Among lower risk patients, TAVR and SAVR appear to be comparable in short term outcomes. Additional high quality studies among patients classified as low risk are needed to further explore the feasibility of TAVR in all surgical risk patients.

Renal failure in patients with ST-segment elevation acute myocardial infarction treated with primary percutaneous coronary intervention: Predictors, clinical and angiographic features, and outcomes

BACKGROUND Among patients presenting with ST-segment elevation myocardial infarction (STEMI) for primary percutaneous coronary intervention (PCI), the associations between clinical outcomes and both baseline renal function and the development of acute kidney injury (AKI) have not been reported in a trial population with unselected baseline renal function. METHODS Patients enrolled in the APEX-AMI trial who underwent primary PCI for the treatment of STEMI were categorized according to (a) baseline renal function and (b) the development of AKI. Patient characteristics, clinical outcomes, and treatment patterns were analyzed according to baseline renal function and the development of AKI. A prediction model for AKI after primary PCI for STEMI was also developed. RESULTS A total of 5,244 patients were included in this analysis and stratified according to baseline estimated glomerular filtration rate (eGFR) (milliliters per minute per 1.73 m(2)) of >90, 60 to 90, 30 to 59, or <30 or as dialysis dependent. Patients with lower eGFR were older, more often female, and less often treated with evidence-based medicines and had worse angiographic outcomes and higher mortality. The rates of AKI for patients with a baseline eGFR of >90, 60 to 90, 30 to 59, and <30 were 2.5%, 4.1%, 8.1%, and 1.6%, respectively (P < .0001). The strongest predictors of AKI were age and presenting in Killip class III or IV. CONCLUSIONS Among patients undergoing primary PCI for STEMI, impaired renal function at presentation and development of post-PCI AKI were highly associated with worse clinical and angiographic outcomes, including death. The risk of developing AKI was low and only modestly associated with baseline renal function.