14 research outputs found

    Methodologie der Parametrisierung von Large-Scale-Netzwerk-Simulationen

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    Network providers are confronted with the optimisation or extension of existing networks. This leads to new challenges for simulation-based network dimensioning. The first challenge is the realistic simulation of the existing network, where topology information and traffic measurements have to be considered. The second challenge is to predict how changes of the existing network will affect its performance: link capacities, queue management algorithms etc. are subject to changes to adapt the network to changing traffic requirements. The best strategy for enhancing or extending the network under consideration can be found by comparing the resulting benefits and disadvantages between the existing network and new alternatives. The simulation of existing networks is an inverse problem: (i) the network description and some measurements are given from the network provider; (ii) the number and the behaviour of clients must be derived from the given parameters. Considering this problem was motivated by an industry project "ERNANI" funded by the "Deutsches Forschungsnetz" (DFN) and the German Telekom. The author proposes a new methodology to solve the inverse problem. First, an algorithm for the allocation of clients is proposed. This algorithm efficiently controls the average traffic intensity. Second, a method is developed for matching higher-order moments of the simulated traffic to measurements made in existing networks. Two higher moment parameters were selected, that are of major importance in network engineering: the coefficient of variation and the Hurst parameter. Realistic network simulations are characterised by high complexity because internal states of protocols must be stored for each connection. Therefore, memory requirements and simulation speed are major issues in such simulations. One solution for this problem is to reduce the number of clients by increasing the activity of each client in order to keep the traffic characteristics unchanged. To asses the applicability and performance of this solution, critical network parameters are estimated as a function of the number of clients. The parameters considered are: average link load, loss probability, coefficient of variation of the packet inter-arrival times, Hurst parameter and average end-to-end delay. It is shown in this work that the number of clients, as well as the required memory, could be reduced by a factor of 4-8 without significant impact on the studied parameters. Reducing the number of clients by a factor of 8 the simulation speed increased by approximately 33 %. This work represents a major step towards realistic modelling and simulation of existing networks. The simulation results based on the presented methodology are very promising. The successful increase of the simulation efficiency represents one step towards the realistic simulation of current and future multi-Gbit networks.Netzwerkbetreiber werden mit der Optimierung und Erweiterung von existierenden Netzwerken konfrontiert. Dies führt zu neuen Herausforderungen für die simulations-basierte Netzwerkdimensionierung: Die erste Herausforderung ist die realistische Simulation des existierenden Netzes unter Berücksichtigung der Topologie und der Verkehrsmessungen. Die zweite Herausforderung ist die Vorhersage, wie sich Veränderungen im existierenden Netz auf die Leistungsfähigkeit auswirken: die Kapazitäten der Verbindungsleitungen, die Algorithmen der Warteschlangen etc. können verändert werden, um den sich verändernden Anforderungen zu genügen. Der Vergleich der resultierenden Vor- und Nachteile zwischen dem existierenden Netz und den Alternativen dient der Entscheidungsfindung für das zukünftige Netzwerk. Die Simulation von existierenden Netzen ist ein inverses Problem: (i) die Netzwerk-Beschreibung und einige Messwerte sind bekannt; (ii) die Anzahl und das Verhalten der Benutzer muss jedoch von den bekannten Parametern abgeleitet werden. Die Behandlung dieses Problems wurde durch das Industrieprojekt "ERNANI" angeregt, gefördert durch Deutsches Forschungsnetz (DFN) und Telekom. Der Autor stellt in dieser Arbeit eine neue Methodologie vor, um das inverse Problem zu lösen. Es wird ein Algorithmus vorgeschlagen, der die mittlere Netzlast effizient über die Anzahl und Verteilung der Nutzer kontrolliert. Im weiteren wird eine Methode vorgestellt, mit der höhere Momente der Verkehrsstatistik, hier der Variationskoeffizient und der Hurst Parameter, gemessenen Werten angepasst werden können. Realistische Netzwerk-Simulationen zeichnen sich durch eine hohe Komplexität aus, da die Protokollzustände für jede Verbindung gespeichert werden müssen. Der Speicherbedarf und die Simulationsgeschwindigkeit überschreiten daher leicht kritische Grenzen. Als Lösung wird die Reduktion der Anzahl der Nutzer durch Steigerung ihrer Aktivität vorgeschlagen. Zur Leistungsbewertung wurden folgende kritische Netzparameter in Abhängigkeit von der Anzahl der Nutzer untersucht: mittlere Last, Verlustwahrscheinlichkeit, Variationskoeffizient der Zwischenankunftszeiten und Hurst Parameter. Die Anzahl der Nutzer, und damit der Speicherbedarf, konnte ohne signifikanten Einfluss auf die untersuchten Parameter um den Faktor 4-8 reduziert werden, wobei die Simulationsgeschwindigkeit um bis zu 33 % zunahm. Diese Arbeit repräsentiert einen wesentlichen Schritt in Richtung der realistischen Modellierung und Simulation von existierenden Netzen. Die Simulationsergebnisse basierend auf den hier vorgestellten Methoden sind vielversprechend. Die erfolgreiche Steigerung der Effizienz der Simulationen bedeutet einen Schritt in Richtung der realistischen Simulation von existierenden und zukünftigen Hochgeschwindigkeitsnetzen

    Cardiac myosin activation with omecamtiv mecarbil in systolic heart failure

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    BACKGROUND The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown. METHODS We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.5 mg, or 50 mg twice daily) or placebo, in addition to standard heart-failure therapy. The primary outcome was a composite of a first heart-failure event (hospitalization or urgent visit for heart failure) or death from cardiovascular causes. RESULTS During a median of 21.8 months, a primary-outcome event occurred in 1523 of 4120 patients (37.0%) in the omecamtiv mecarbil group and in 1607 of 4112 patients (39.1%) in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.86 to 0.99; P = 0.03). A total of 808 patients (19.6%) and 798 patients (19.4%), respectively, died from cardiovascular causes (hazard ratio, 1.01; 95% CI, 0.92 to 1.11). There was no significant difference between groups in the change from baseline on the Kansas City Cardiomyopathy Questionnaire total symptom score. At week 24, the change from baseline for the median N-terminal pro-B-type natriuretic peptide level was 10% lower in the omecamtiv mecarbil group than in the placebo group; the median cardiac troponin I level was 4 ng per liter higher. The frequency of cardiac ischemic and ventricular arrhythmia events was similar in the two groups. CONCLUSIONS Among patients with heart failure and a reduced ejection, those who received omecamtiv mecarbil had a lower incidence of a composite of a heart-failure event or death from cardiovascular causes than those who received placebo. (Funded by Amgen and others; GALACTIC-HF ClinicalTrials.gov number, NCT02929329; EudraCT number, 2016 -002299-28.)

    Rationale, design, and baseline characteristics in Evaluation of LIXisenatide in Acute Coronary Syndrome, a long-term cardiovascular end point trial of lixisenatide versus placebo

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    Background: Cardiovascular (CV) disease is the leading cause of morbidity and mortality in patients with type 2 diabetes mellitus (T2DM). Furthermore, patients with T2DM and acute coronary syndrome (ACS) have a particularly high risk of CV events. The glucagonlike peptide 1 receptor agonist, lixisenatide, improves glycemia, but its effects on CV events have not been thoroughly evaluated. Methods: ELIXA (www.clinicaltrials.gov no. NCT01147250) is a randomized, double-blind, placebo-controlled, parallelgroup, multicenter study of lixisenatide in patients with T2DM and a recent ACS event. The primary aim is to evaluate the effects of lixisenatide on CV morbidity and mortality in a population at high CV risk. The primary efficacy end point is a composite of time to CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. Data are systematically collected for safety outcomes, including hypoglycemia, pancreatitis, and malignancy. Results: Enrollment began in July 2010 and ended in August 2013; 6,068 patients from 49 countries were randomized. Of these, 69% are men and 75% are white; at baseline, the mean ± SD age was 60.3 ± 9.7 years, body mass index was 30.2 ± 5.7 kg/m2, and duration of T2DM was 9.3±8.2 years. The qualifying ACS wasamyocardial infarctionin83% and unstableangina in 17%. The study will continue until the positive adjudication of the protocol-specified number of primary CV events. Conclusion: ELIXA will be the first trial to report the safety and efficacy of a glucagon-like peptide 1 receptor agonist in people with T2DM and high CV event risk

    Relation of Lipoprotein(a) Levels to Incident Type 2 Diabetes and Modification by Alirocumab Treatment

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    OBJECTIVE: In observational data, lower levels of lipoprotein(a) have been associated with greater prevalence of type 2 diabetes. Whether pharmacologic lowering of lipoprotein(a) influences incident type 2 diabetes is unknown. We determined the relationship of lipoprotein(a) concentration with incident type 2 diabetes and effects of treatment with alirocumab, a PCSK9 inhibitor. RESEARCH DESIGN AND METHODS: In the ODYSSEY OUTCOMES trial alirocumab was compared with placebo in patients with acute coronary syndrome. Incident diabetes was determined from laboratory, medication, and adverse event data. RESULTS: Among 13,480 patients without diabetes at baseline, 1,324 developed type 2 diabetes over a median 2.7 years. Median baseline lipoprotein(a) was 21.9 mg/dL. With placebo, 10 mg/dL lower baseline lipoprotein(a) was associated with hazard ratio 1.04 (95% CI 1.02-1.06, P < 0.001) for incident type 2 diabetes. Alirocumab reduced lipoprotein(a) by a median 23.2% with greater absolute reductions from higher baseline levels and no overall effect on incident type 2 diabetes (hazard ratio 0.95, 95% CI 0.85-1.05). At low baseline lipoprotein(a) levels, alirocumab tended to reduce incident type 2 diabetes, while at high baseline lipoprotein(a) alirocumab tended to increase incident type 2 diabetes compared with placebo (treatment-baseline lipoprotein(a) interaction P = 0.006). In the alirocumab group, a 10 mg/dL decrease in lipoprotein(a) from baseline was associated with hazard ratio 1.07 (95% CI 1.03-1.12; P = 0.0002) for incident type 2 diabetes. CONCLUSIONS: In patients with acute coronary syndrome, baseline lipoprotein(a) concentration associated inversely with incident type 2 diabetes. Alirocumab had neutral overall effect on incident type 2 diabetes. However, treatment-related reductions in lipoprotein(a), more pronounced from high baseline levels, were associated with increased risk of incident type 2 diabetes. Whether these findings pertain to other therapies that reduce lipoprotein(a) is undetermined

    Cardiac myosin activation with omecamtiv mecarbil in systolic heart failure

    No full text
    Background: The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown. Methods: We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.5 mg, or 50 mg twice daily) or placebo, in addition to standard heart-failure therapy. The primary outcome was a composite of a first heart-failure event (hospitalization or urgent visit for heart failure) or death from cardiovascular causes. Results: During a median of 21.8 months, a primary-outcome event occurred in 1523 of 4120 patients (37.0%) in the omecamtiv mecarbil group and in 1607 of 4112 patients (39.1%) in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.86 to 0.99; P=0.03). A total of 808 patients (19.6%) and 798 patients (19.4%), respectively, died from cardiovascular causes (hazard ratio, 1.01; 95% CI, 0.92 to 1.11). There was no significant difference between groups in the change from baseline on the Kansas City Cardiomyopathy Questionnaire total symptom score. At week 24, the change from baseline for the median N-terminal pro–B-type natriuretic peptide level was 10% lower in the omecamtiv mecarbil group than in the placebo group; the median cardiac troponin I level was 4 ng per liter higher. The frequency of cardiac ischemic and ventricular arrhythmia events was similar in the two groups. Conclusions: Among patients with heart failure and a reduced ejection, those who received omecamtiv mecarbil had a lower incidence of a composite of a heart-failure event or death from cardiovascular causes than those who received placebo. (Funded by Amgen and others; GALACTIC-HF ClinicalTrials.gov number, NCT02929329. opens in new tab; EudraCT number, 2016-002299-28. opens in new tab.

    Safety of the PCSK9 inhibitor alirocumab: insights from 47 296 patient-years of observation /

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    The ODYSSEY OUTCOMES trial, comprising over 47 000 patient-years of placebo-controlled observation, demonstrated important reductions in the risk of recurrent ischaemic cardiovascular events with the monoclonal antibody to proprotein convertase subtilisin/kexin type 9 alirocumab, as well as lower all-cause death. These benefits were observed in the context of substantial and persistent lowering of low-density lipoprotein cholesterol with alirocumab compared with that achieved with placebo. The safety profile of alirocumab was indistinguishable from matching placebo except for a ∼1.7% absolute increase in local injection site reactions. Further, the safety of alirocumab compared with placebo was evident in vulnerable groups identified before randomization, such as the elderly and those with diabetes mellitus, previous ischaemic stroke, or chronic kidney disease. The frequency of adverse events and laboratory-based abnormalities was generally similar to that in placebo-treated patients. Thus, alirocumab appears to be a safe and effective lipid-modifying treatment over a duration of at least 5 years

    Lipoprotein(a) and benefit of PCSK9 inhibition in patients with nominally controlled LDL cholesterol

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    BACKGROUND Guidelines recommend nonstatin lipid-lowering agents in patients at very high risk for major adverse cardiovascular events (MACE) if low-density lipoprotein cholesterol (LDL-C) remains >= 70 mg/dL on maximum tolerated statin treatment. It is uncertain if this approach benefits patients with LDL-C near 70 mg/dL. Lipoprotein(a) levels may influence residual risk.OBJECTIVES In a post hoc analysis of the ODYSSEY Outcomes (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) trial, the authors evaluated the benefit of adding the proprotein subtilisin/kexin type 9 inhibitor alirocumab to optimized statin treatment in patients with LDL-C levels near 70 mg/dL. Effects were evaluated according to concurrent lipoprotein(a) levels.METHODS ODYSSEY Outcomes compared alirocumab with placebo in 18,924 patients with recent acute coronary syndromes receiving optimized statin treatment. In 4,351 patients (23.0%), screening or randomization LDL-C was = 70 mg/dL (median 94.0 mg/dL; interquartile range: 83.2-111.0 mg/dL).RESULTS In the lower LDL-C subgroup, MACE rates were 4.2 and 3.1 per 100 patient-years among placebo-treated patients with baseline lipoprotein(a) greater than or less than or equal to the median (13.7 mg/dL). Corresponding adjusted treatment hazard ratios were 0.68 (95% confidence interval [CI]: 0.52-0.90) and 1.11 (95% CI: 0.83-1.49), with treatment-lipoprotein(a) interaction on MACE (P-interaction = 0.017). In the higher LDL-C subgroup, MACE rates were 4.7 and 3.8 per 100 patient-years among placebo-treated patients with lipoprotein(a) >13.7 mg/dL or <= 13.7 mg/dL; corresponding adjusted treatment hazard ratios were 0.82 (95% CI: 0.72-0.92) and 0.89 (95% CI: 0.75-1.06), with P-interaction = 0.43.CONCLUSIONS In patients with recent acute coronary syndromes and LDL-C near 70 mg/dL on optimized statin therapy, proprotein subtilisin/kexin type 9 inhibition provides incremental clinical benefit only when lipoprotein(a) concentration is at least mildly elevated. (ODYSSEY Outcomes: Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab; NCT01663402) (C) 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.Cardiolog

    Apolipoprotein B, Residual Cardiovascular Risk After Acute Coronary Syndrome, and Effects of Alirocumab.

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    Apolipoprotein B (apoB) provides an integrated measure of atherogenic risk. Whether apoB levels and apoB lowering hold incremental predictive information on residual risk after acute coronary syndrome beyond that provided by low-density lipoprotein cholesterol is uncertain.The ODYSSEY OUTCOMES trial (Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab) compared the proprotein convertase subtilisin/kexin type 9 inhibitor alirocumab with placebo in 18 924 patients with recent acute coronary syndrome and elevated atherogenic lipoproteins despite optimized statin therapy. Primary outcome was major adverse cardiovascular events (MACE; coronary heart disease death, nonfatal myocardial infarction, fatal/nonfatal ischemic stroke, hospitalization for unstable angina). Associations between baseline apoB or apoB at 4 months and MACE were assessed in adjusted Cox proportional hazards and propensity score-matched models.Median follow-up was 2.8 years. In proportional hazards analysis in the placebo group, MACE incidence increased across increasing baseline apoB strata (3.2 [95% CI, 2.9-3.6], 4.0 [95% CI, 3.6-4.5], and 5.5 [95% CI, 5.0-6.1] events per 100 patient-years in strata &lt;75, 75-&lt;90, ≥90 mg/dL, respectively; Ptrend&lt;0.0001) and after adjustment for low-density lipoprotein cholesterol (Ptrend=0.035). Higher baseline apoB stratum was associated with greater relative (Ptrend&lt;0.0001) and absolute reduction in MACE with alirocumab versus placebo. In the alirocumab group, the incidence of MACE after month 4 decreased monotonically across decreasing achieved apoB strata (4.26 [95% CI, 3.78-4.79], 3.09 [95% CI, 2.69-3.54], and 2.41 [95% CI, 2.11-2.76] events per 100 patient-years in strata ≥50, &gt;35-&lt;50, and ≤35 mg/dL, respectively). Compared with propensity score-matched patients from the placebo group, treatment hazard ratios for alirocumab also decreased monotonically across achieved apoB strata. Achieved apoB was predictive of MACE after adjustment for achieved low-density lipoprotein cholesterol or non-high-density lipoprotein cholesterol but not vice versa.In patients with recent acute coronary syndrome and elevated atherogenic lipoproteins, MACE increased across baseline apoB strata. Alirocumab reduced MACE across all strata of baseline apoB, with larger absolute reductions in patients with higher baseline levels. Lower achieved apoB was associated with lower risk of MACE, even after accounting for achieved low-density lipoprotein cholesterol or non-high-density lipoprotein cholesterol, indicating that apoB provides incremental information. Achievement of apoB levels as low as ≤35 mg/dL may reduce lipoprotein-attributable residual risk after acute coronary syndrome.URL: https://www.gov; Unique identifier: NCT01663402

    Effects of alirocumab on cardiovascular and metabolic outcomes after acute coronary syndrome in patients with or without diabetes: a prespecified analysis of the ODYSSEY OUTCOMES randomised controlled trial

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    BACKGROUND: After acute coronary syndrome, diabetes conveys an excess risk of ischaemic cardiovascular events. A reduction in mean LDL cholesterol to 1·4-1·8 mmol/L with ezetimibe or statins reduces cardiovascular events in patients with an acute coronary syndrome and diabetes. However, the efficacy and safety of further reduction in LDL cholesterol with an inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9) after acute coronary syndrome is unknown. We aimed to explore this issue in a prespecified analysis of the ODYSSEY OUTCOMES trial of the PCSK9 inhibitor alirocumab, assessing its effects on cardiovascular outcomes by baseline glycaemic status, while also assessing its effects on glycaemic measures including risk of new-onset diabetes. METHODS: ODYSSEY OUTCOMES was a randomised, double-blind, placebo-controlled trial, done at 1315 sites in 57 countries, that compared alirocumab with placebo in patients who had been admitted to hospital with an acute coronary syndrome (myocardial infarction or unstable angina) 1-12 months before randomisation and who had raised concentrations of atherogenic lipoproteins despite use of high-intensity statins. Patients were randomly assigned (1:1) to receive alirocumab or placebo every 2 weeks; randomisation was stratified by country and was done centrally with an interactive voice-response or web-response system. Alirocumab was titrated to target LDL cholesterol concentrations of 0·65-1·30 mmol/L. In this prespecified analysis, we investigated the effect of alirocumab on cardiovascular events by glycaemic status at baseline (diabetes, prediabetes, or normoglycaemia)-defined on the basis of patient history, review of medical records, or baseline HbA1c or fasting serum glucose-and risk of new-onset diabetes among those without diabetes at baseline. The primary endpoint was a composite of death from coronary heart disease, non-fatal myocardial infarction, fatal or non-fatal ischaemic stroke, or unstable angina requiring hospital admission. ODYSSEY OUTCOMES is registered with ClinicalTrials.gov, number NCT01663402. FINDINGS: At study baseline, 5444 patients (28·8%) had diabetes, 8246 (43·6%) had prediabetes, and 5234 (27·7%) had normoglycaemia. There were no significant differences across glycaemic categories in median LDL cholesterol at baseline (2·20-2·28 mmol/L), after 4 months' treatment with alirocumab (0·80 mmol/L), or after 4 months' treatment with placebo (2·25-2·28 mmol/L). In the placebo group, the incidence of the primary endpoint over a median of 2·8 years was greater in patients with diabetes (16·4%) than in those with prediabetes (9·2%) or normoglycaemia (8·5%); hazard ratio (HR) for diabetes versus normoglycaemia 2·09 (95% CI 1·78-2·46, p<0·0001) and for diabetes versus prediabetes 1·90 (1·65-2·17, p<0·0001). Alirocumab resulted in similar relative reductions in the incidence of the primary endpoint in each glycaemic category, but a greater absolute reduction in the incidence of the primary endpoint in patients with diabetes (2·3%, 95% CI 0·4 to 4·2) than in those with prediabetes (1·2%, 0·0 to 2·4) or normoglycaemia (1·2%, -0·3 to 2·7; absolute risk reduction pinteraction=0·0019). Among patients without diabetes at baseline, 676 (10·1%) developed diabetes in the placebo group, compared with 648 (9·6%) in the alirocumab group; alirocumab did not increase the risk of new-onset diabetes (HR 1·00, 95% CI 0·89-1·11). HRs were 0·97 (95% CI 0·87-1·09) for patients with prediabetes and 1·30 (95% CI 0·93-1·81) for those with normoglycaemia (pinteraction=0·11). INTERPRETATION: After a recent acute coronary syndrome, alirocumab treatment targeting an LDL cholesterol concentration of 0·65-1·30 mmol/L produced about twice the absolute reduction in cardiovascular events among patients with diabetes as in those without diabetes. Alirocumab treatment did not increase the risk of new-onset diabetes. FUNDING: Sanofi and Regeneron Pharmaceuticals.sponsorship: Sanofi and Regeneron Pharmaceuticals. (Sanofi, Regeneron Pharmaceuticals)status: Publishe
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