Coherent Resonant Tunneling through Double Metallic Quantum Well States.

Study of resonant tunneling through multimetallic quantum well (QW) structure is not only important for the fundamental understanding of quantum transport but also for the great potential to generate advanced functionalities of spintronic devices. However, it remains challenging to engineer such a structure due to the short electron phase coherence length in metallic QW system. Here, we demonstrate the successful fabrication of double-QW structure in a single fully epitaxial magnetic tunnel junction (MTJ) heterostructure, where two Fe QW layers are sandwiched between three MgAlO x tunnel barriers. We show clear evidence of the coherent resonant tunneling through the discrete QW states in the two QWs. The coherent resonant tunneling condition is fulfilled only when the middle barrier between the two QWs is thin enough and available QW states are present simultaneously in both QWs under a certain bias. Compared to the single QW structure, the resonant tunneling in double-QW MTJ produces strong conductivity oscillations with much narrower peak width (about half) owing to the enhanced energy filtering effect. This study presents a comprehensive understanding of the resonant tunneling mechanism in MTJ with multiple QWs, which is essential for future development of new spintronic devices operating in the quantum tunneling regime.

Twenty-year trends in profile, management and outcomes of patients with ST-segment elevation myocardial infarction according to use of reperfusion therapy: Data from the FAST-MI program 1995-2015.

The increased use of reperfusion therapy in ST-segment-elevation myocardial infarction (STEMI) patients in the past decades is generally considered the main determinant of improved outcomes. The aim was to assess 20-year trends in profile, management, and one-year outcomes in STEMI patients in relation with use or non-use of reperfusion therapy (primary percutaneous coronary intervention (pPCI) or fibrinolysis). METHODS: We used data from 5 one-month French nationwide registries, conducted 5 years apart from 2005 to 2015, including 8579 STEMI patients (67% with and 33% without reperfusion therapy) admitted to cardiac intensive care units in France. RESULTS: Use of reperfusion therapy increased from 49% in 1995 to 82% in 2015, with a shift from fibrinolysis (37.5% to 6%) to pPCI (12% to 76%). Early use of evidence-based medications gradually increased over the period in both patients with and without reperfusion therapy, although it remained lower at all times in those without reperfusion therapy. One-year mortality decreased in patients with reperfusion therapy (from 11.9% in 1995 to 5.9% in 2010 and 2015, hazard ratio [HR] adjusted on baseline profile 0.40; 95% CI: 0.29-0.54, P < .001) and in those without reperfusion therapy (from 25.0% to 18.2% in 2010 and 8.1% in 2015, HR: 0.33; 95% CI: 0.24-0.47, P < .001). CONCLUSIONS: In STEMI patients, one-year mortality continues to decline, both related to increased use of reperfusion therapy and progress in overall patient management. In patients with reperfusion therapy, mortality has remained stable since 2010, while it has continued to decline in patients without reperfusion therapy.

Chaos in Magnetic Nanocontact Vortex Oscillators.

We present an experimental study of spin-torque driven vortex self-oscillations in magnetic nanocontacts. We find that, above a certain threshold in applied currents, the vortex gyration around the nanocontact is modulated by relaxation oscillations, which involve periodic reversals of the vortex core. This modulation leads to the appearance of commensurate but also, more interestingly here, incommensurate states, which are characterized by devil's staircases in the modulation frequency. We use frequency- and time-domain measurements together with advanced time-series analyses to provide experimental evidence of chaos in incommensurate states of vortex oscillations, in agreement with theoretical predictions.

[Outpatient coronary angiography and angioplastie/ why, how and for wich patients?] / Coronarographie et angioplastie coronaire ambulatoire ; pourquoi, comment, pour quels patients ?

There is great heterogeneity in lengths of stay in interventional cardiology but the number of outpatient procedures is increasing. The expected benefits of an outpatient procedure are numerous and non-inferiority of this strategy has been demonstrated. Proper selection of patients eligible for this treatment is essential to minimize the risks of unplanned hospitalization and early complications. It is based on clinical, medico-social and organizational criteria. Perfect management of the care pathway based on an organizational unit and a geographical unit is essential.

In-hospital prognostic value of TAPSE/sPAP in patients hospitalized for acute heart failure.

AIMS: Tricuspid annular plane systolic excursion over systolic pulmonary artery pressure (TAPSE/sPAP) assessed by echocardiography appears to be a good non-invasive approach for right ventricular to pulmonary artery coupling assessment. We aimed to assess the in-hospital prognostic value of TAPSE/sPAP among patients hospitalized for acute heart failure (AHF). METHODS AND RESULTS: In total, 333 consecutive patients (mean age 68 ± 14 years, 70% of male, mean left ventricular ejection fraction 44 ± 16%) were hospitalized for AHF across 39 French cardiology departments, with TAPSE/sPAP measured by echocardiography within the first 24 h of hospitalization were included in this prospective study. The primary outcome was in-hospital major adverse cardiovascular events (MACEs) defined as all-cause death, resuscitated cardiac arrest or cardiogenic shock and occurred in 50 (15%) patients. Using receiver operating characteristic curve analysis, the best TAPSE/sPAP threshold for in-hospital MACEs was 0.40 mm/mmHg. TAPSE/sPAP < 0.40 mm/mmHg was independently associated with in-hospital MACEs, even after adjustment with comorbidities [odds ratio (OR): 3.75, 95% CI (1.87-7.93), P < 0.001], clinical severity [OR: 2.80, 95% CI (1.36-5.95), P = 0.006]. Using a 1:1 propensity-matched population, TAPSE/sPAP ratio < 0.40 was associated with a higher rate of in-hospital MACEs [OR: 2.98, 95% CI (1.53-6.12), P = 0.002]. After adjustment, TAPSE/sPAP < 0.40 showed the best improvement in model discrimination and reclassification above traditional prognostic factors (C-statistic improvement: 0.05; χ2 improvement: 14.4; likelihood-ratio test P < 0.001). These results were consistent in an external validation cohort of 133 patients. CONCLUSION: TAPSE/sPAP < 0.40 mm/mmHg assessed by an early echocardiography during an AHF episode is independently associated with in-hospital MACEs suggesting enhanced close monitoring and strengthened heart failure-specific care in these patients. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05063097.

Carbon monoxide and prognosis in smokers hospitalised with acute cardiac events: a multicentre, prospective cohort study.

Background: Smoking cigarettes produces carbon monoxide (CO), which can reduce the oxygen-carrying capacity of the blood. We aimed to determine whether elevated expiratory CO levels would be associated with a worse prognosis in smokers presenting with acute cardiac events. Methods: From 7 to 22 April 2021, expiratory CO levels were measured in a prospective registry including all consecutive patients admitted for acute cardiac event in 39 centres throughout France. The primary outcome was 1-year all-cause death. Initial in-hospital major adverse cardiac events (MAE; death, resuscitated cardiac arrest and cardiogenic shock) were also analysed. The study was registered at ClinicalTrials.gov (NCT05063097). Findings: Among 1379 patients (63 ± 15 years, 70% men), 368 (27%) were active smokers. Expiratory CO levels were significantly raised in active smokers compared to non-smokers. A CO level >11 parts per million (ppm) found in 94 (25.5%) smokers was associated with a significant increase in death (14.9% for CO > 11 ppm vs. 2.9% for CO ≤ 11 ppm; p < 0.001). Similar results were found after adjustment for comorbidities (hazard ratio [HR] [95% confidence interval (CI)]): 5.92 [2.43-14.38]) or parameters of in-hospital severity (HR 6.09, 95% CI [2.51-14.80]) and propensity score matching (HR 7.46, 95% CI [1.70-32.8]). CO > 11 ppm was associated with a significant increase in MAE in smokers during initial hospitalisation after adjustment for comorbidities (odds ratio [OR] 15.75, 95% CI [5.56-44.60]) or parameters of in-hospital severity (OR 10.67, 95% CI [4.06-28.04]). In the overall population, CO > 11 ppm but not smoking was associated with an increased rate of all-cause death (HR 4.03, 95% CI [2.33-6.98] and 1.66 [0.96-2.85] respectively). Interpretation: Elevated CO level is independently associated with a 6-fold increase in 1-year death and 10-fold in-hospital MAE in smokers hospitalized for acute cardiac events. Funding: Grant from Fondation Coeur & Recherche.

[Acute myocarditis in a patient with dengue infection]. / Myocardite aiguë induite par la dengue.

Dengue is a febrile viral illness transmitted by Aedes Aegypti mosquito with growing incidence, it could be associated with cardiovascular complication mediated by inflammation and notably acute myocarditis. We report the case of a 36-year old woman admitted in cardiology department with initial diagnosis of acute coronary syndrome and ultimately diagnosed to have an acute myocarditis induced by dengue infection; we describe diagnostic modalities and clinical evolution.

Prevalence and impact of recreational drug use in patients with acute cardiovascular events.

OBJECTIVE: While recreational drug use is a risk factor for cardiovascular events, its exact prevalence and prognostic impact in patients admitted for these events are not established. We aimed to assess the prevalence of recreational drug use and its association with in-hospital major adverse events (MAEs) in patients admitted to intensive cardiac care units (ICCU). METHODS: In the Addiction in Intensive Cardiac Care Units (ADDICT-ICCU) study, systematic screening for recreational drugs was performed by prospective urinary testing all patients admitted to ICCU in 39 French centres from 7 to 22 April 2021. The primary outcome was prevalence of recreational drug detection. In-hospital MAEs were defined by death, resuscitated cardiac arrest, or haemodynamic shock. RESULTS: Of 1499 consecutive patients (63±15 years, 70% male), 161 (11%) had a positive test for recreational drugs (cannabis 9.1%, opioids 2.1%, cocaine 1.7%, amphetamines 0.7%, 3,4-methylenedioxymethamphetamine (MDMA) 0.6%). Only 57% of these patients declared recreational drug use. Patients who used recreational drugs exhibited a higher MAE rate than others (13% vs 3%, respectively, p<0.001). Recreational drugs were associated with a higher rate of in-hospital MAEs after adjustment for comorbidities (OR 8.84, 95% CI 4.68 to 16.7, p<0.001). After adjustment, cannabis, cocaine, and MDMA, assessed separately, were independently associated with in-hospital MAEs. Multiple drug detection was frequent (28% of positive patients) and associated with an even higher incidence of MAEs (OR 12.7, 95% CI 4.80 to 35.6, p<0.001). CONCLUSION: The prevalence of recreational drug use in patients hospitalised in ICCU was 11%. Recreational drug detection was independently associated with worse in-hospital outcomes. CLINICAL TRIAL REGISTRATION: NCT05063097.

ST elevation myocardial infarction with no structural lesions after a wasp sting.

BACKGROUND: Acute coronary syndromes after hymenoptera stings and other environmental exposures are referred to as the Kounis syndrome or allergic myocardial ischemia and infarction. CASE REPORT: We report the case of a 58-year-old man with transient inferior ST-segment elevation consistent with myocardial ischemia after a single wasp sting. Urgent cardiac catheterization revealed normal coronary arteries with a normal left ventriculogram. The evaluation and treatment of cardiac ischemia associated with an allergic reaction is discussed. CONCLUSION: ST elevation myocardial infarction after wasp envenomation is an exceptional and interesting pathology with a partially elucidated pathogenesis. The management of cardiac ischemia in this setting is uncertain.

Engineering Co2 MnAlx Si1- x Heusler Compounds as a Model System to Correlate Spin Polarization, Intrinsic Gilbert Damping, and Ultrafast Demagnetization.

Engineering of magnetic materials for developing better spintronic applications relies on the control of two key parameters: the spin polarization and the Gilbert damping, responsible for the spin angular momentum dissipation. Both of them are expected to affect the ultrafast magnetization dynamics occurring on the femtosecond timescale. Here, engineered Co2 MnAlx Si1- x Heusler compounds are used to adjust the degree of spin polarization at the Fermi energy, P, from 60% to 100% and to investigate how they correlate with the damping. It is experimentally demonstrated that the damping decreases when increasing the spin polarization from 1.1 × 10-3 for Co2 MnAl with 63% spin polarization to an ultralow value of 4.6 × 10-4 for the half-metallic ferromagnet Co2 MnSi. This allows the investigation of the relation between these two parameters and the ultrafast demagnetization time characterizing the loss of magnetization occurring after femtosecond laser pulse excitation. The demagnetization time is observed to be inversely proportional to 1 - P and, as a consequence, to the magnetic damping, which can be attributed to the similarity of the spin angular momentum dissipation processes responsible for these two effects. Altogether, the high-quality Heusler compounds allow control over the band structure and therefore the channel for spin angular momentum dissipation.

Coronary artery spasm and dobutamine stress echocardiography.

AIMS: The aim of this article was to assess whether abnormal dobutamine stress echocardiography (DSE) can be due to a dobutamine-induced coronary spasm in patients with angiographically documented vasospastic coronary arteries. METHODS AND RESULTS: Between January 2004 and April 2008, we prospectively evaluated all patients with known or suspected coronary artery disease (CAD) referred to the echocardiography laboratory for dobutamine stress tests (6061 examinations). Those with abnormal DSE underwent coronary angiogram with a systematic methylergometrine intracoronary injection in the case of absence of significant coronary stenosis or spontaneous occlusive coronary spasm. Patients who had spontaneous occlusive coronary spasm or positive methylergometrine test, but no significant stenoses, were ultimately included in this study. About 581 patients had abnormal DSE, among them only 20 (3.4%) fulfilled the inclusion criteria. There were 15 males and 5 females, and mean age was 64.35 years (range 52-85); 8 patients had a known history of CAD and all of them had at least two established cardiovascular risk factors. The culprit vessel was the left anterior descending artery in 10 cases (50%), right coronary artery in 8 cases (40%), and left circumflex in 2 cases (10%). There was a systematic correspondence between the culprit arteries and dobutamine-induced wall motion abnormality territories. No complications occurred during examination or during the provocation test. All the patients were discharged with a calcium channel blocker and were doing well after 13 months of mean follow-up. CONCLUSION: Coronary artery spasm can be induced at DSE, but is a rare finding; it could, though, be clinically relevant as it may partly explain some erroneously labelled 'false-positive' examinations. Methylergometrine provocation test is a safe and advisable approach in such situations.

Impressive ST-segment elevation during dobutamine stress echocardiography in a patient with normal coronary arteries: dobutamine-induced vasospasm?

ST-segment elevation during dobutamine stress echocardiography is a serious complication usually related to severe coronary artery disease. However, it can occur in absence of significant coronary artery disease supposedly as a consequence of an occlusive dobutamine-induced coronary artery spasm. We report the case of a 56-year-old man without cardiovascular history who presented during a dobutamine stress echocardiography an intense precordial pain along with an impressive 10-mm ST elevation and in whom urgent catheterization documented the absence of significant coronary artery stenoses.

In-hospital outcomes and 5-year mortality following an acute myocardial infarction in patients with a history of cancer: Results from the French registry on Acute ST-elevation or non-ST-elevation myocardial infarction (FAST-MI) 2005 cohort.

BACKGROUND: Cancer and acute myocardial infarction (AMI) have important prognostic consequences. Treatment of some cancers may affect coronary artery disease, myocardial function and/or AMI management. Whether the early and long-term mortality of patients with AMI differ according to their history of cancer remains questionable. AIMS: To determine in-hospital outcomes and 5-year mortality following AMI according to patient history of cancer. METHODS: The FAST-MI registry is a nationwide French survey collecting data on characteristics, management and outcomes of 3670 consecutive patients admitted for AMI during October 2005. RESULTS: Overall, 246/3664 patients (6.7%) admitted for an AMI (47.6% with ST-segment elevation myocardial infarction [STEMI]; 52.4% with non-STEMI [NSTEMI]) had a history of cancer. In-hospital mortality was not significantly different for patients with versus without a history of cancer, overall (adjusted odds ratio [OR]: 1.15, 95% confidence interval [CI]: 0.68-1.94; P=0.61) and in patients with STEMI (adjusted OR: 1.37, 95% CI: 0.69-2.71; P=0.37) or NSTEMI (adjusted OR: 0.97, 95% CI: 0.41-2.28; P=0.95). All-cause mortality at 5 years was higher among patients with a history of cancer (adjusted hazard ratio [HR]: 1.36, 95% CI: 1.08-1.69; P=0.008), whereas 5-year cardiovascular mortality did not differ (adjusted HR: 1.17, 95% CI: 0.89-1.53; P=0.25), regardless of whether the patients had STEMI or NSTEMI. Similar results were found in populations matched on a propensity score including baseline characteristics and early management. CONCLUSION: A history of cancer, per se, does not appear to be a risk factor for increased in-hospital mortality or long-term cardiovascular mortality in patients admitted for AMI.

Multi-centre evaluation of recent troponin assays for the diagnosis of NSTEMI.

OBJECTIVES: We aimed to compare the use of nine different cardiac troponin (cTn) assays (2 cTnT and 7 cTnI) for the diagnosis of NSTEMI in a single multi-centre population. DESIGN AND METHODS: One hundred and fifty-eight patients were included (mean age 60 years, SD 17 years), including 23 patients (14%) with NSTEMI. RESULTS: The analytical comparison highlighted a large heterogeneity of cTn assays, as reflected by percentages of patients with detectable cTn, correlation coefficients, Passing-Bablok comparisons and concordance coefficients. Correlations within cTnI assays were good and correlation within cTnT assays was excellent. Diagnostic performances demonstrated that each cTn assay has specific threshold values. Furthermore, some assays (HS-cTnI and T, cTnI-Pathfast and cTnI-Centaur) indicated high sensitivity and negative predictive value using the limit of detection (LoD) diagnostic strategy. For the latter assays, a significant increase in specificity was found when using the 99th percentile or the H0-H3 strategies, in comparison to the LoD strategy. When applying the European Society of Cardiology H0-H3 algorithm, comparable diagnostic performances were obtained. CONCLUSION: All 9 cTn assays indicated overall good diagnostic performances for the diagnosis of NSTEMI in emergency departments when the recommended algorithm based on the variation of cTn value between two measurements at admission and 3 h later was used.

Bias dependence of tunneling magnetoresistance in magnetic tunnel junctions with asymmetric barriers.

The transport properties of magnetic tunnel junctions (MTJs) are very sensitive to interface modifications. In this work we investigate both experimentally and theoretically the effect of asymmetric barrier modifications on the bias dependence of tunneling magnetoresistance (TMR) in single crystal Fe/MgO-based MTJs with (i) one crystalline and one rough interface, and (ii) with a monolayer of O deposited at the crystalline interface. In both cases we observe an asymmetric bias dependence of TMR and a reversal of its sign at large bias. We propose a general model to explain the bias dependence in these and similar systems reported earlier. The model predicts the existence of two distinct TMR regimes: (i) a tunneling regime when the interface is modified with layers of a different insulator, and (ii) a resonant regime when thin metallic layers are inserted at the interface. We demonstrate that in the tunneling regime, negative TMR is due to the high voltage which overcomes the exchange splitting in the electrodes, while the asymmetric bias dependence of TMR is due to the interface transmission probabilities. In the resonant regime, inversion of TMR could happen at zero voltage depending on the alignment of the resonance levels with the Fermi surfaces of the electrodes. Moreover, the model predicts a regime in which TMR has different signs at positive and negative bias, suggesting possibilities of combining memory with logic functions.

Giant spin-dependent thermoelectric effect in magnetic tunnel junctions.

Thermoelectric effects in magnetic nanostructures and the so-called spin caloritronics are attracting much interest. Indeed it provides a new way to control and manipulate spin currents, which are key elements of spin-based electronics. Here we report on a giant magnetothermoelectric effect in a magnetic tunnel junction. The thermovoltage in this geometry can reach 1 mV. Moreover a magnetothermovoltage effect could be measured with ratio similar to the tunnel magnetoresistance ratio. The Seebeck coefficient can then be tuned by changing the relative magnetization orientation of the two magnetic layers in the tunnel junction. Therefore, our experiments extend the range of spintronic devices application to thermoelectricity and provide a crucial piece of information for understanding the physics of thermal spin transport.