How do cardiologists select patients for dual antiplatelet therapy continuation beyond 1 year after a myocardial infarction? Insights from the EYESHOT Post-MI Study

Background: Current guidelines suggest to consider dual antiplatelet therapy (DAPT) continuation for longer than 12 months in selected patients with myocardial infarction (MI). Hypothesis: We sought to assess the criteria used by cardiologists in daily practice to select patients with a history of MI eligible for DAPT continuation beyond 1 year. Methods: We analyzed data from the EYESHOT Post-MI, a prospective, observational, nationwide study aimed to evaluate the management of patients presenting to cardiologists 1 to 3 years from the last MI event. Results: Out of the 1633 post-MI patients enrolled in the study between March and December 2017, 557 (34.1%) were on DAPT at the time of enrolment, and 450 (27.6%) were prescribed DAPT after cardiologist assessment. At multivariate analyses, a percutaneous coronary intervention (PCI) with multiple stents and the presence of peripheral artery disease (PAD) resulted as independent predictors of DAPT continuation, while atrial fibrillation was the only independent predictor of DAPT interruption for patients both at the second and the third year from MI at enrolment and the time of discharge/end of the visit. Conclusions: Risk scores recommended by current guidelines for guiding decisions on DAPT duration are underused and misused in clinical practice. A PCI with multiple stents and a history of PAD resulted as the clinical variables more frequently associated with DAPT continuation beyond 1 year from the index MI

The dilatometric technique for studying sigma phase precipitation kinetics in F55 steel grade

Sigma phase precipitation occurring during the exposure of duplex stainless steels in the temperature range from 800 to 900 °C deeply affects the material toughness and corrosion resistance. σ-Phase precipitation process is strongly influenced by many physical parameters, such as the specific chemical composition, the ferrite amount and its average grain size, and the entity of plastic deformation due to the previous technological process. The strong dependencies of σ-phase precipitation on all these factors justify the continuous study of the process kinetics. This paper focuses on the σ-phase precipitation kinetics in F55 steel grade. The investigation has been performed by an innovative experimental method, such as the anisothermal dilatometric technique. The application of the Kissinger’s method has been used for deriving the process activation energy and kinetics. The results have been compared with the ones obtained by metallographic analysis and hardness tests performed on isothermally aged samples, heat-treated in a laboratory furnace at 850 °C

Heat treatment and impact toughness of the f55-grade steel

Low-temperature impact tests are commonly performed to test the quality of industrial forgings in Duplex Stainless Steels (DSS). The F55 grade is a highly alloyed Super DSS characterized by excellent low-temperature toughness in the solution annealed condition. Because of the rich chemical composition, it is very prone to precipitation phenomena during quenching. This research investigates the effect of the material cooling rate on the impact toughness of a water-quenched F55 steel, characterized by the absence of s-phase. Furthermore, by elaborating the impact test data, the T45J [°C] and the KV-46°C [J] parameters have been identified. They are two indicators based on the austenite/ferrite ratio and the material cooling rate, useful for predicting the material impact behavior prior to testing

High-temperature mechanical properties of P91 weld metal

Increasing temperature is one of the key factors for improving the efficiency of steam power plants. Important metallurgical phenomena are activated at such high temperatures and creep resistance becomes a driving criterion for the material selection. Ferritic steels, including 2Cr, 9Cr, and 12Cr steels, are among the best candidates; their continuous development and optimization with the addition of Mo, V, Nb, and W have resulted in a significant improvement in creep strength together with a good weldability. This study investigates the high-temperature mechanical properties of two Grade 91 welded plates and focuses on the creep behavior, proposing a modified expression of the Larson-Miller parameter for the estimation of critical combinations of temperature, stress, and time, which could lead to rupture. The suggested parameter, which is highly sensitive to temperature, is able to outline the criticality of the welding and it is useful for predicting the duration of a creep test with the specimen rupture

Crack initiation and propagation in Chromium pre-alloyed PM-steel under cyclic loading

Powder metallurgy processing of steels typically results in materials characterized by residual porosity, whose sizes and morphology, together with the microstructure, strongly affect the fatigue crack growth behaviour of the materials. Prismatic specimens were pressed at 7.0 g/cm3 density from Astaloy CrM powder and sintered under different conditions, varying the sintering temperature and the cooling rate after sintering. Optical observations allowed us to evaluate the sizes and the morphology of the porosity and the microstructural characteristics for all the investigated conditions. Fatigue tests were performed at R-ratio equal to 0.1 to investigate the threshold zone and to calculate the coefficients of the Paris law. All the tests were carried out according to the compliance method, and the crack length was evaluated during the tests. Moreover, KIC tests were performed in order to complete the investigation. On both fatigue and KIC samples, a fractographic analysis was carried out to investigate the crack path and the fracture surface features. The results show that the exponent of the Paris law is about 6.0 for 1120°C sintered and about 4.7 for 1250°C sintered materials. Interesting data have been also found for the threshold values

Influence of prior microstructure on the mechanical and microstructural properties of C–Mn–B steel after spheroidizing annealing

During spheroidizing annealing of steels, the carbide shape is modified from lamellar to spheroidal for increasing cold deformability. The aim of this work is to study the kinetics and the mechanical properties of a C–Mn–B steel grade after spheroidizing annealing, varying the prior microstructure produced by industrial conventional and thermo-mechanical hot rolling with different Stelmor cooling rates. Moreover, different prior microstructures were also produced by laboratory heat treatments. Microstructural analysis, hardness tests, and tensile tests were carried out at different soaking times. The results show that a better distribution of the carbon in the metal matrix obtained in bainitic and martensitic microstructures results in a more uniform dispersion of the carbides with higher mechanical resistance and deformability. The ferritic and pearlitic microstructures obtained by thermo-mechanical hot rolling are able to produce more homogeneous carbides when compared with the traditional hot rolling