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Background/Introduction Over the last decade, epidemiology and pathology studies have suggested that gamma-glutamyl transferase (GGT) has an independent role in the pathogenesis and clinical evolution of cardiovascular diseases associated with atherosclerosis. Recently, machine learning (ML) algorithms have identified pre-procedural GGT as a significant predictor of long-term mortality after coronary revascularization in the SYNTAX trial. Purpose The aim of this study is to investigate the impact of pre-procedural GGT on 10-year all-cause mortality in patients with three-vessel disease (3VD) and/or left main coronary artery disease (LMCAD) following revascularization. Methods The SYNTAX trial was a randomized trial comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in 1,800 patients with complex CAD. The present report is a post-hoc sub-analysis of the SYNTAXES study, an investigator-driven extended 10-year follow-up of the SYNTAX trial. Before revascularization, blood samples were taken for GGT as well as other biological markers and analyzed by an independent central chemistry laboratory. The primary endpoint was all-cause mortality at 10-years. The changes in hazard for all-cause mortality in GGT over time were modelled using restricted cubic spline functions in a Cox regression model adjusted by age and sex. Subsequently, we compared survival in four groups defined by gender specific GGT thresholds of <32 IU and ≥32 IU for females and <64 IU and ≥64 IU for males, in accordance with prior studies. Results Out of 1,800 patients enrolled in the SYNTAX study, 167 (9.3%) did not have a GGT available at baseline and 1,633 (90.7%) patients were included in the present study. The mean values of GGT for males and females were 43.5±48.5 and 36.4±46.1 U/L, respectively. In the overall population a 10 U/L increase in GGT was significantly associated with 10-year all-cause death (adjusted hazard ratio [HR] 95% confidence interval [CI]: 1.03 [1.02–1.04], p <0.001, Figure A). For Kaplan–Meier analysis, patients were stratified into four groups according to previously reported sex related GGT thresholds. Ten-year mortality was numerically higher in males (adjusted HR 1.31, 95% CI: 0.90–1.91), and significantly higher in females (adjusted HR 1.88, 95% CI: 1.16–3.05) among patients with higher versus lower GGT (Figure B). Furthermore, GGT was significantly associated with CRP, a surrogate-marker of inflammation, as well as established cardiovascular risk biomarkers such as TG, total cholesterol, and glucose. Conclusions Preprocedural GGT is an independent predictor of 10-year mortality following coronary revascularization in patients with 3VD and/or LMCAD. This long-term association has been identified using ML algorithms and should be corroborated using data from large biobanks.Figure AFigure B
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Background — Earlier reports have shown that the outcome of balloon angioplasty or bypass surgery in unstable angina is less favorable than in stable angina. Recent improvements in percutaneous treatment (stent implantation) and bypass surgery (arterial grafts) warrant reevaluation of the relative merits of either technique in treatment of unstable angina. Methods and Results — Seven hundred fifty-five patients with stable angina were randomly assigned to coronary stenting (374) or bypass surgery (381), and 450 patients with unstable angina were randomly assigned to coronary stenting (226) or bypass surgery (224). All patients had multivessel disease considered to be equally treatable by either technique. Freedom from major adverse events, including death, myocardial infarction, and cerebrovascular events, at 1 year was not different in unstable patients (91.2% versus 88.9%) and stable patients (90.4% versus 92.6%) treated, respectively, with coronary stenting or bypass surgery. Freedom from repeat revascularization at 1 year was similar in unstable and stable angina treated with stenting (79.2% versus 78.9%) or bypass surgery (96.3% versus 96%) but was significantly higher in both unstable and stable patients treated with stenting (16.8% versus 16.9%) compared with bypass surgery (3.6% versus 3.5%). Neither the difference in costs between stented or bypassed stable or unstable angina ($2594 versus $3627) nor the cost-effectiveness was significantly different at 1 year. Conclusions — There was no difference in rates of death, myocardial infarction, and cerebrovascular event at 1 year in patients with unstable angina and multivessel disease treated with either stented angioplasty or bypass surgery compared with patients with stable angina. The rate of repeat revascularization of both unstable and stable angina was significantly higher in patients with stents.
Structural engineering is a discipline with a distinguished history in its own right with its landmark monuments and famous personalities from centuries past to the present [1, 2]. Moreover, it is also a discipline that relies on rich nonlinear mathematics as its basis. The aim of this article to show some of the interesting features and practical relevance of nonlinear mathematics in the behaviour of real structures. It is an area of research where the UK has led the way for many years. In the response of structures under loading there are many different sources of nonlinearities. However, for the purpose herein the various cases can be grouped into two distinct categories: (1) material and (2) geometric nonlinearities. The sources of nonlinear material behaviour can arise from the response where the constitutive law (relating stress to strain) in the elastic range is not linear—termed nonlinear elasticity. Materials such as mild structural steel have a linear elastic constitutive law, but other important structural materials such as concrete, aluminium, and alloys of iron such as stainless steel are all examples where the elastic constitutive law is nonlinear. Another route to nonlinearity in the material response can occur even in linear elastic materials when the stress exceeds the so-called yield stress; permanent deformation (plasticity) ensues and the constitutive law departs from the initial linear relationship (Fig. 1). For brittle materials, such as cast iron, fracture, rather than plasticity, follows the elastic response; a further example of material nonlinearities governing the mechanical response during failure. The main focus herein is, however, on geometric nonlinearities that govern structural behaviour when large and possibly sudden deflections are seen, often as a loss of stability when the phenomenon known as buckling is triggered. In structural engineering this is most likely elements in whole or in part compression such as columns and beams. Most rudimentary structural mechanics principles are based on the linear assumptions in that although structures deform, they do so slowly with small deflections. Linearization in this context can be typified by the familiar assumption when dealing with small angles: