464 research outputs found
Thermodynamics and Universality for Mean Field Quantum Spin Glasses
We study aspects of the thermodynamics of quantum versions of spin glasses.
By means of the Lie-Trotter formula for exponential sums of operators, we adapt
methods used to analyze classical spin glass models to answer analogous
questions about quantum models.Comment: 17 page
Theory of Two-Dimensional Quantum Heisenberg Antiferromagnets with a Nearly Critical Ground State
We present the general theory of clean, two-dimensional, quantum Heisenberg
antiferromagnets which are close to the zero-temperature quantum transition
between ground states with and without long-range N\'{e}el order. For
N\'{e}el-ordered states, `nearly-critical' means that the ground state
spin-stiffness, , satisfies , where is the
nearest-neighbor exchange constant, while `nearly-critical' quantum-disordered
ground states have a energy-gap, , towards excitations with spin-1,
which satisfies . Under these circumstances, we show that the
wavevector/frequency-dependent uniform and staggered spin susceptibilities, and
the specific heat, are completely universal functions of just three
thermodynamic parameters. Explicit results for the universal scaling functions
are obtained by a expansion on the quantum non-linear sigma model,
and by Monte Carlo simulations. These calculations lead to a variety of
testable predictions for neutron scattering, NMR, and magnetization
measurements. Our results are in good agreement with a number of numerical
simulations and experiments on undoped and lightly-doped .Comment: 81 pages, REVTEX 3.0, smaller updated version, YCTP-xxx
Gut microbiota‐dependent trimethylamine N‐oxide and cardiovascular outcomes in patients with prior myocardial infarction: A nested case control study from the PEGASUS‐TIMI 54 trial
Background
Trimethylamine N‐oxide (TMAO) may have prothrombotic properties. We examined the association of TMAO quartiles with major adverse cardiovascular events (MACE) and the effect of TMAO on the efficacy of ticagrelor.
Methods and Results
PEGASUS‐TIMI 54 (Prevention of Cardiovascular Events in Patients With Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin ‐ Thrombolysis in Myocardial Infarction 54) randomized patients with prior myocardial infarction to ticagrelor or placebo (median follow‐up 33 months). Baseline plasma concentrations of TMAO were measured in a nested case‐control study of 597 cases with cardiovascular death, myocardial infarction, or stroke (MACE) and 1206 controls matched for age, sex, and estimated glomerular filtration rate [eGFR]. Odds ratios (OR) were used for the association between TMAO quartiles and MACE, adjusting for baseline clinical characteristics (age, sex, eGFR, region, body mass index, hypertension, hypercholesterolemia, diabetes mellitus, smoking, peripheral artery disease, index event, aspirin dosage and treatment arm), and cardiovascular biomarkers (hs‐TnT [high‐sensitivity troponin T], hs‐CRP [high‐sensitivity C‐reactive protein], NT‐proBNP [N‐terminal‐pro‐B‐type natriuretic peptide]). Higher TMAO quartiles were associated with risk of MACE (OR for quartile 4 versus quartile 1, 1.43, 95% CI, 1.06–1.93, P trend=0.015). The association was driven by cardiovascular death (OR 2.25, 95% CI, 1.28–3.96, P trend=0.003) and stroke (OR 2.68, 95% CI, 1.39–5.17, P trend<0.001). After adjustment for clinical factors, the association persisted for cardiovascular death (ORadj 1.89, 95% CI, 1.03–3.45, P trend=0.027) and stroke (ORadj 2.01, 95% CI, 1.01–4.01, P trend=0.022), but was slightly attenuated after adjustment for cardiovascular biomarkers (cardiovascular death: ORadj 1.74, 95% CI, 0.88–3.45, P trend=0.079; and stroke: ORadj 1.82, 95% CI, 0.88–3.78, P trend=0.056). The reduction in MACE with ticagrelor was consistent across TMAO quartiles (P interaction=0.92).
Conclusions
Among patients with prior myocardial infarction, higher TMAO levels were associated with cardiovascular death and stroke but not with recurrent myocardial infarction. The efficacy of ticagrelor was consistent regardless of TMAO levels.
Registration
URL: https://www.clinicaltrials.gov; Unique identifiers: PEGASUS‐TIMI 54, NCT01225562
Effect of alirocumab on major adverse cardiovascular events according to renal function in patients with a recent acute coronary syndrome: Prespecified analysis from the ODYSSEY OUTCOMES randomized clinical trial
Aims Statins reduce cardiovascular risk in patients with acute coronary syndrome (ACS) and normal-to-moderately impaired renal function. It is not known whether proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors provide similar benefit across a range of renal function. We determined whether effects of the PCSK9 inhibitor alirocumab to reduce cardiovascular events and death after ACS are influenced by renal function. ................................................................................................................................................................................................... Methods ODYSSEY OUTCOMES compared alirocumab with placebo in patients with recent ACS and dyslipidaemia despite and results intensive statin treatment. Estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m was exclusionary. In 18 918 patients, baseline eGFR was 82.8 ± 17.6 mL/min/1.73 m , and low-density lipoprotein cholesterol (LDL-C) was 92 ± 31 mg/dL. At 36 months, alirocumab decreased LDL-C by 48.5% vs. placebo but did not affect eGFR (P = 0.65). Overall, alirocumab reduced risk of the primary outcome (coronary heart disease death, non-fatal myocardial infarction, ischaemic stroke, or unstable angina requiring hospitalization) with fewer deaths. There was no interaction between continuous eGFR and treatment on the primary outcome or death (P = 0.14 and 0.59, respectively). Alirocumab reduced primary outcomes in patients with eGFR >_90 mL/min/1.73 m (n = 7470; hazard ratio 0.784, 95% confidence interval 0.670–0.919; P = 0.003) and 60 to <90 (n = 9326; 0.833, 0.731–0.949; P = 0.006), but not in those with eGFR < 60 (n = 2122; 0.974, 0.805–1.178; P = 0.784). Adverse events other than local injection-site reactions were similar in both groups across all categories of eGFR. ................................................................................................................................................................................................... Conclusions In patients with recent ACS, alirocumab was associated with fewer cardiovascular events and deaths across the range of renal function studied, with larger relative risk reductions in those with eGFR > 60 mL/min/1.73 m 2 2 2 2The trial was funded by Sanofi and Regeneron Pharmaceuticals, Inc
The effect of glucagon-like peptide-1 receptor agonists liraglutide and semaglutide on cardiovascular and renal outcomes across baseline blood pressure categories: Analysis of the LEADER and SUSTAIN 6 trials
It is unknown if the cardioprotective and renal effects of glucagon-like peptide-1 receptor agonists are consistent across blood pressure (BP) categories in patients with type 2 diabetes and at high risk of cardiovascular events. Using data from the LEADER (9340 patients) and SUSTAIN 6 (3297 patients) trials, we evaluated post hoc the cardiorenal effect of liraglutide and semaglutide on major adverse cardiovascular events (MACE) and nephropathy by baseline BP categories using a Cox proportional hazards model (treatment and subgroup as factors; adjusted for cardiorenal risk factors). Data from the two trials were analysed separately. In the LEADER and SUSTAIN 6 trials, the prevalence of stage 1 hypertension was 30% and 31%, respectively, and of stage 2 hypertension 41% and 43%, respectively. There was no statistical heterogeneity across the BP categories for the effects of liraglutide (P =.06 for MACE; P =.14 for nephropathy) or semaglutide (P =.40 for MACE; P =.27 for nephropathy) versus placebo. This implies that liraglutide and semaglutide may be beneficial for patients with type 2 diabetes, irrespective of their baseline BP
Integrating coronary atherosclerosis burden and progression with coronary artery disease risk factors to guide therapeutic decision making
ImportanceAlthough atherosclerosis represents the primary driver of coronary artery disease, evaluation and treatment approaches have historically relied upon indirect markers of atherosclerosis that include surrogates (cholesterol), signs (angina), and sequelae (ischemia) of atherosclerosis. Direct quantification and characterization of atherosclerosis may encourage a precision heart care paradigm that improves diagnosis, risk stratification, therapeutic decision-making, and longitudinal disease tracking in a personalized fashion.ObservationsThe American College of Cardiology Innovations in Prevention Working Group introduce the Atherosclerosis Treatment Algorithms that personalize medical interventions based upon atherosclerosis findings from coronary computed tomography angiography (CTA) and cardiovascular risk factors. Through integration of coronary CTA-based atherosclerosis evaluation, clinical practice guidelines, and contemporary randomized controlled trial evidence, the Atherosclerosis Treatment Algorithms leverage patient-specific atherosclerosis burden and progression as primary targets for therapeutic intervention. After defining stages of atherosclerosis severity by coronary CTA, Atherosclerosis Treatment Algorithms are described for worsening stages of atherosclerosis for patients with lipid disorders, diabetes, hypertension, obesity, and tobacco use. The authors anticipate a rapid pace of research in the field, and conclude by providing perspectives on future needs that may improve efforts to optimize precision prevention of coronary artery disease. Importantly, the Atherosclerosis Treatment Algorithms are not endorsed by the American College of Cardiology, and should not be interpreted as a statement of American College of Cardiology policy.Conclusions and RelevanceWe describe a precision heart care approach that emphasizes atherosclerosis as the primary disease target for evaluation and treatment. To our knowledge, this is the first proposal to use coronary atherosclerosis burden and progression to personalize therapy selection and therapy changes, respectively.Cardiolog
Generalizability of the REDUCE-IT trial and cardiovascular outcomes associated with hypertriglyceridemia among patients potentially eligible for icosapent ethyl therapy: An analysis of the REduction of Atherothrombosis for Continued Health (REACH) registry
Background: The REDUCE-IT (Reduction of Cardiovascular Events with Icosapent Ethyl–Intervention Trial) trial demonstrated that high-dose icosapent-ethyl reduced the risk of ischemic events in statin-treated patients with elevated triglycerides (TG) and either atherosclerotic cardiovascular disease (ASCVD) or diabetes plus at least one risk factor. Methods and results: Using data from REACH (Reduction of Atherothrombosis for Continued Health), a large international registry of outpatients with or at risk of ASCVD, we evaluated the proportion of patients potentially eligible for enrolment in REDUCE-IT and compared their outcomes to those excluded because of low TG. Among 62,464 patients with either ASCVD or diabetes enrolled in the REACH Registry, 1036/8418 (12.3%) patients in primary prevention and 6049/54046 (11.2%) patients in secondary prevention (11.3% overall) would have been eligible for inclusion in REDUCE-IT. Compared with patients excluded for low TG level, adjusted risk of the primary composite outcome of cardiovascular death, non-fatal myocardial infarction (MI), non-fatal stroke, unstable angina, or coronary revascularization was higher in the REDUCE-IT eligible group (HR:1.06, 95%CI:1.00–1.13, p = 0.04). In addition, unstable angina, non-fatal MI, percutaneous coronary intervention and coronary artery bypass grafting were also more frequent in the REDUCE-IT eligible group (HR:1.17, 95%CI:1.07–1.27, p < 0.001; HR:1.25, 95%CI:1.07–1.45, p < 0.001; HR:1.42, 95%CI:1.27–1.57, p < 0.001; HR:1.43, 95%CI:1.19–1.71, p < 0.001, respectively), whereas the adjusted risk of non-fatal stroke was lower (HR:0.64, 95%CI:0.54–0.75, p < 0.001). Conclusion: In this large international registry of patients with or at high-risk of ASCVD, 11.3% met the REDUCE-IT trial selection criteria. REDUCE-IT eligible patients were found to be at higher risk of cardiac atherothrombotic events, but at lower risk of stroke than trial-ineligible patients with lower TG
Integrating coronary atherosclerosis burden and progression with coronary artery disease risk factors to guide therapeutic decision making (vol 136, page 260, 2023)
Cardiolog
Re-examining the widespread policy of stopping sodium-glucose cotransporter-2 inhibitors during acute illness: A perspective based on the updated evidence
Sodium-glucose cotransporter-2 (SGLT2) inhibitors are now seen as an integral part of therapy in type 2 diabetes to control not only blood glucose but to improve cardiovascular and kidney outcomes. Diabetic ketoacidosis (DKA) is an uncommon but serious complication of type 2 diabetes, which has a high case fatality rate. The absolute risk of DKA in large, prospective randomized clinical trials in people with type 2 diabetes using SGLT2 inhibitors has been low, although the relative risk is higher in those assigned to SGLT2 inhibitors compared with placebo. In those without diabetes but prescribed SGLT2 inhibitors for heart failure or chronic kidney disease, the risk of DKA is similar to placebo. Over the course of the COVID-19 pandemic, cases of DKA have also been reported in cases of COVID-19 hospitalizations. Consensus guidelines have recommended that SGLT2 inhibitors should be avoided in cases of serious illness and suggest they are not recommended for routine in-hospital use. However, recent data suggest potential beneficial effects of SGLT2 inhibitors in the setting of acute illness with COVID-19 with no increase in adverse events and low rates of DKA, which were non-severe. Given the low rates of DKA in cardiovascular outcome trials and in hospitalized patients with type 2 diabetes, the potential for SGLT2 inhibitors not being re-initiated following discharge and their cardiovascular and kidney benefits, we believe the practice of routine ‘sick day’ guidance should be re-examined based on current evidence with a call for further research in this area. Furthermore, high-quality trials of initiation of SGLT2 inhibitors in people admitted to hospital with cardiovascular disease or kidney disease, and trials of continuation of SGLT2 inhibitors in people, with careful monitoring of DKA should be conducted. These should be further supplemented with large observational studies
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