Effect of seasonal influenza and COVID-19 vaccination on severity and long-term outcomes of patients with heart failure decompensations.

AIMS: To investigate whether seasonal influenza and COVID-19 vaccinations influence the severity of decompensations and long-term outcomes of patients with acute heart failure (AHF). METHODS AND RESULTS: We included consecutive AHF patients attended at 40 Spanish emergency departments during November and December 2022. They were grouped according to whether they had received seasonal influenza and COVID-19 vaccination. The severity of heart failure (HF) decompensation was assessed with the MEESSI scale, need for hospitalization, intensive care unit (ICU) admission, and in-hospital mortality. Long-term outcomes were 90-day and 1-year all-cause mortality. Associations between vaccination, HF decompensation severity, and long-term outcomes were investigated. Subgroup analyses were executed for 16 patient characteristics and their relationship with vaccination and 1-year mortality. We analysed 4243 patients (median age 85 years; interquartile range 77-90; 57% female): 1841 (43%) had received influenza vaccination, 3139 (74%) COVID-19 vaccination, 1773 (41.8%) received both vaccines (full vaccination) and 1036 (24.4%) none. Previous episodes of AHF, chronic obstructive pulmonary disease and chronic treatment with diuretics were associated with vaccination (either influenza, COVID-19 and full vaccination). High or very-high risk decompensation occurred in 18.6%; hospitalization in 72.3%, ICU admission in 1.1%, and in-hospital mortality in 8.4%. Influenza vaccination was associated with lower hospitalization rates (adjusted odds ratio [OR] 0.746, 95% confidence interval [CI] 0.636-0.876) and in-hospital mortality (OR 0.761, 95% CI 0.583-0.992), while COVID-19 vaccination was associated with increased hospitalizations (OR 1.215, 95% CI 1.016-1.454). Overall, 90-day and 1-year mortality were 20.3% and 34.4%. Both were decreased in influenza-vaccinated patients (adjusted hazard ratio [HR] 0.831, 95% CI 0.709-0.973; and HR 0.885, 95% CI 0.785-0.999, respectively) but only at 90 days in COVID-19 vaccinated patients (HR 0.829, 95% CI 0.702-0.980). Full vaccination achieved even greater reductions in in-hospital, 90-day, and 1-year mortality (HR 0.638, 95% CI 0.479-0.851; HR 0.702, 95% CI 0.592-0.833; and HR 0.815, 95% CI 0.713-0.931, respectively). Subgroup analysis based on patient-related characteristics demonstrated the consistence of vaccination with long-term survival. CONCLUSION: In HF patients, seasonal influenza vaccination appears to be associated with less severe decompensation and lower 1-year mortality, while no firm conclusions can be drawn from the results of the present study regarding the benefits of COVID-19 vaccination. Full vaccination is associated with the greatest reduction in short- and long-term mortality.

Effect of early initiation of noninvasive ventilation in patients transported by emergency medical service for acute heart failure.

BACKGROUND: While the indication for noninvasive ventilation (NIV) in severely hypoxemic patients with acute heart failure (AHF) is often indicated and may improve clinical course, the benefit of early initiation before patient arrival to the emergency department (ED) remains unknown. OBJECTIVE: This study aimed to assess the impact of early initiation of NIV during emergency medical service (EMS) transportation on outcomes in patients with AHF. DESIGN: A secondary retrospective analysis of the EAHFE (Epidemiology of AHF in EDs) registry. SETTING: Fifty-three Spanish EDs. PARTICIPANTS: Patients with AHF transported by EMS physician-staffed ambulances who were treated with NIV at any time during of their emergency care were included and categorized into two groups based on the place of NIV initiation: prehospital (EMS group) or ED (ED group). OUTCOME MEASURES: Primary outcome was the composite of in-hospital mortality and 30-day postdischarge death, readmission to hospital or return visit to the ED due to AHF. Secondary outcomes included 30-day all-cause mortality after the index event (ED admission) and the different component of the composite primary endpoint considered individually. Multivariate logistic regressions were employed for analysis. RESULTS: Out of 2406 patients transported by EMS, 487 received NIV (EMS group: 31%; EMS group: 69%). Mean age was 79 years, 48% were women. The EMS group, characterized by younger age, more coronary artery disease, and less atrial fibrillation, received more prehospital treatments. The adjusted odds ratio (aOR) for composite endpoint was 0.66 (95% CI: 0.42-1.05). The aOR for secondary endpoints were 0.74 (95% CI: 0.38-1.45) for in-hospital mortality, 0.74 (95% CI: 0.40-1.37) for 30-day mortality, 0.70 (95% CI: 0.41-1.21) for 30-day postdischarge ED reconsultation, 0.80 (95% CI: 0.44-1.44) for 30-day postdischarge rehospitalization, and 0.72 (95% CI: 0.25-2.04) for 30-day postdischarge death. CONCLUSION: In this ancillary analysis, prehospital initiation of NIV in patients with AHF was not associated with a significant reduction in short-term outcomes. The large confidence intervals, however, may preclude significant conclusion, and all point estimates consistently pointed toward a potential benefit from early NIV initiation.

Magnetic Bead Handling Using a Paper-Based Device for Quantitative Point-of-Care Testing.

Microfluidic paper-based analytical devices (µPADs) have been extensively proposed as ideal tools for point-of-care (POC) testing with minimal user training and technical requirements. However, most µPADs use dried bioreagents, which complicate production, reduce device reproducibility and stability, and require transport and storage under temperature and humidity-controlled conditions. In this work, we propose a µPAD produced using an affordable craft-cutter and stored at room temperature, which is used to partially automate a single-step colorimetric magneto-immunoassay. As a proof-of-concept, the µPAD has been applied to the quantitative detection of Plasmodium falciparum lactate dehydrogenase (Pf-LDH), a biomarker of malaria infection. In this system, detection is based on a single-step magneto-immunoassay that consists of a single 5-min incubation of the lysed blood sample with immuno-modified magnetic beads (MB), detection antibody, and an enzymatic signal amplifier (Poly-HRP). This mixture is then transferred to a single-piece paper device where, after on-chip MB magnetic concentration and washing, signal generation is achieved by adding a chromogenic enzyme substrate. The colorimetric readout is achieved by the naked eye or using a smartphone camera and free software for image analysis. This µPAD afforded quantitative Pf-LDH detection in <15 min, with a detection limit of 6.25 ng mL−1 when the result was interpreted by the naked eye and 1.4 ng mL−1 when analysed using the smartphone imaging system. Moreover, the study of a battery of clinical samples revealed concentrations of Pf-LDH that correlated with those provided by the reference ELISA and with better sensitivity than a commercial rapid diagnostic test (RDT). These results demonstrate that magneto-immunoassays can be partly automated by employing a µPAD, achieving a level of handling that approaches the requirements of POC testing.

Radiography-based triage for COVID-19 in the Emergency Department in a Spanish cohort of patients.

Background: Strategies to determine who could be safely discharged home from the Emergency Department (ED) in COVID-19 are needed to decongestion healthcare systems. Objectives: To describe the outcomes of an ED triage system for non-severe patients with suspected COVID-19 and possible pneumonia based on chest X-ray (CXR) upon admission. Material and methods: Retrospective, single-center study performed in Barcelona (Spain) during the COVID-19 peak in March-April 2020. Patients with COVID-19 symptoms and potential pneumonia, without respiratory insufficiency, with priority class IV-V (Andorran triage model) had a CXR upon admission. This approach tried to optimize resource use and to facilitate discharges. The results after adopting this organizational approach are reported. Results: We included 834 patients, 53% were female. Most patients were white (66%) or Hispanic (27%). CXR showed pneumonia in 523 (62.7%). Compared to those without pneumonia, patients with pneumonia were older (55 vs 46.6 years old) and had a higher Charlson comorbidity index (1.9 vs 1.3). Patients with pneumonia were at a higher risk for a combined outcome of admission and/or death (91 vs 12%). Death rates tended to be numerically higher in the pneumonia group (10 vs 1). Among patients without pneumonia in the initial CXR, 10% reconsulted (40% of them with new pneumonia). Conclusion: CXR identified pneumonia in a significant number of patients. Those without pneumonia were mostly discharged. Mortality among patients with an initially negative CXR was low. CXR triage for pneumonia in non-severe COVID-19 patients in the ED can be an effective strategy to optimize resource use.

Introducción: La pandemia de COVID-19 conlleva una alta ocupación de los servicios de urgencias (SU). Se requieren nuevas estrategias para optimizar la gestión de estos recursos. Objetivos: Describir los resultados de un sistema de triaje en urgencias para pacientes no graves con sospecha de COVID-19 y posible neumonía, basado en la radiografía de tórax (RT). Material y métodos: Estudio retrospectivo, unicéntrico realizado en Barcelona (España) entre marzo y abril de 2020. Se realizó una RT al ingreso en SU de pacientes con síntomas de COVID-19 y sospecha de neumonía, sin insuficiencia respiratoria, con una prioridad clase IV-V (sistema andorrano de triaje). Esta medida pretende optimizar los recursos y facilitar las altas. Se reportan los resultados tras adoptar esta estrategia. Resultados: Se incluyeron 834 pacientes (53% mujeres, 66% caucásicos, 27% hispánicos). La RT mostró neumonía en 523 (62,7%). Comparados con los pacientes sin neumonía, los que sí la padecían eran mayores (55 vs. 46,6 años), con un índice de comorbilidad de Charlson más elevado (1,9 vs. 1,3) y con mayor riesgo de ingreso y/o muerte (91 vs. 12%). La mortalidad fue numéricamente mayor en el grupo con neumonía (10 vs. 1). El 10% de los pacientes sin neumonía en RT consultaron de nuevo al SU (40% con neumonía). Conclusión: La RT identificó neumonía en múltiples pacientes. Los que no tenían neumonía fueron mayoritariamente dados de alta. La mortalidad entre pacientes con RT negativa fue baja. La RT como triaje para neumonía en pacientes con COVID-19 no grave puede ahorrar recursos.

Radiography-based triage for COVID-19 in the Emergency Department in a Spanish cohort of patients.

BACKGROUND: Strategies to determine who could be safely discharged home from the Emergency Department (ED) in COVID-19 are needed to decongestion healthcare systems. OBJECTIVES: To describe the outcomes of an ED triage system for non-severe patients with suspected COVID-19 and possible pneumonia based on chest X-ray (CXR) upon admission. MATERIAL AND METHODS: Retrospective, single-center study performed in Barcelona (Spain) during the COVID-19 peak in March-April 2020. Patients with COVID-19 symptoms and potential pneumonia, without respiratory insufficiency, with priority class IV-V (Andorran triage model) had a CXR upon admission. This approach tried to optimize resource use and to facilitate discharges. The results after adopting this organizational approach are reported. RESULTS: We included 834 patients, 53% were female. Most patients were white (66%) or Hispanic (27%). CXR showed pneumonia in 523 (62.7%). Compared to those without pneumonia, patients with pneumonia were older (55 vs 46.6 years old) and had a higher Charlson comorbidity index (1.9 vs 1.3). Patients with pneumonia were at a higher risk for a combined outcome of admission and/or death (91 vs 12%). Death rates tended to be numerically higher in the pneumonia group (10 vs 1). Among patients without pneumonia in the initial CXR, 10% reconsulted (40% of them with new pneumonia). CONCLUSION: CXR identified pneumonia in a significant number of patients. Those without pneumonia were mostly discharged. Mortality among patients with an initially negative CXR was low. CXR triage for pneumonia in non-severe COVID-19 patients in the ED can be an effective strategy to optimize resource use.

Electrochemical Capillary-Flow Immunoassay for Detecting Anti-SARS-CoV-2 Nucleocapsid Protein Antibodies at the Point of Care.

Rapid and inexpensive serological tests for SARS-CoV-2 antibodies are needed to conduct population-level seroprevalence surveillance studies and can improve diagnostic reliability when used in combination with viral tests. Here, we report a novel low-cost electrochemical capillary-flow device to quantify IgG antibodies targeting SARS-CoV-2 nucleocapsid proteins (anti-N antibody) down to 5 ng/mL in low-volume (10 µL) human whole blood samples in under 20 min. No sample preparation is needed as the device integrates a blood-filtration membrane for on-board plasma extraction. The device is made of stacked layers of a hydrophilic polyester and double-sided adhesive films, which create a passive microfluidic circuit that automates the steps of an enzyme-linked immunosorbent assay (ELISA). The sample and reagents are sequentially delivered to a nitrocellulose membrane that is modified with a recombinant SARS-CoV-2 nucleocapsid protein. When present in the sample, anti-N antibodies are captured on the nitrocellulose membrane and detected via chronoamperometry performed on a screen-printed carbon electrode. As a result of this quantitative electrochemical readout, no result interpretation is required, making the device ideal for point-of-care (POC) use by non-trained users. Moreover, we show that the device can be coupled to a near-field communication potentiostat operated from a smartphone, confirming its true POC potential. The novelty of this work resides in the integration of sensitive electrochemical detection with capillary-flow immunoassay, providing accuracy at the point of care. This novel electrochemical capillary-flow device has the potential to aid the diagnosis of infectious diseases at the point of care.

Development of a Fast Chemiluminescent Magneto-Immunoassay for Sensitive Plasmodium falciparum Detection in Whole Blood.

The World Health Organization (WHO) estimates that over three billion people are at risk of acquiring malaria, a parasitic infection that produces more than 200 million new infections and nearly half a million deaths each year. Expanding the access to early diagnosis and treatment is one of the most effective ways to prevent disease complications, reduce patient mortality, and curb the community transmission. However, none of the diagnostic methods used currently for malaria detection, including light microscopy, polymerase chain reaction (PCR), and rapid diagnostic tests (RDTs), can provide simultaneously fast results, high sensitivity, and parasitaemia quantitation with minimal user intervention. Here, we present a magneto-immunoassay that, based on the unique combination of magnetic beads (MB), an enzymatic signal amplifier (Poly-HRP), and chemiluminescence detection, provides fast, sensitive, and quantitative malaria diagnosis with easy user manipulation. This assay quantifies Plasmodium falciparum lactate dehydrogenase (PfLDH) in lysed whole blood samples in <15 min, exhibiting a limit of detection (LOD) of 0.02 ng mL-1 and providing patient stratification consistent with the reference methods. These figures of merit surpass the performance of the magneto-immunoassays reported previously for Plasmodium detection and demonstrate for the first time that the proposed combination of MB, Poly-HRP, and chemiluminescence detection produces extremely fast, simple, and efficient assays that approach the requirements of point-of-care (POC) malaria surveillance.

Smartphone-Enabled Personalized Diagnostics: Current Status and Future Prospects.

Smartphones are becoming increasingly versatile thanks to the wide variety of sensor and actuator systems packed in them. Mobile devices today go well beyond their original purpose as communication devices, and this enables important new applications, ranging from augmented reality to the Internet of Things. Personalized diagnostics is one of the areas where mobile devices can have the greatest impact. Hitherto, the camera and communication abilities of these devices have been barely exploited for point of care (POC) purposes. This short review covers the recent evolution of mobile devices in the area of POC diagnostics and puts forward some ideas that may facilitate the development of more advanced applications and devices in the area of personalized diagnostics. With this purpose, the potential exploitation of wireless power and actuation of sensors and biosensors using near field communication (NFC), the use of the screen as a light source for actuation and spectroscopic analysis, using the haptic module to enhance mass transport in micro volumes, and the use of magnetic sensors are discussed.

Detection of Plasmodium falciparum malaria in 1 h using a simplified enzyme-linked immunosorbent assay.

Malaria is a parasitic disease caused by protists of the genus Plasmodium, which are transmitted to humans through the bite of infected female Anopheles mosquitoes. Analytical methodologies and efficient drugs exist for the early detection and treatment of malaria, and yet this disease continues infecting millions of people and claiming several hundred thousand lives each year. One of the reasons behind this failure to control the disease is that the standard method for malaria diagnosis, microscopy, is time-consuming and requires trained personnel. Alternatively, rapid diagnostic tests, which have become common for point-of-care testing thanks to their simplicity of use, tend to be insufficiently sensitive and reliable, and PCR, which is sensitive, is too complex and expensive for massive population screening. In this work, we report a sensitive simplified ELISA for the quantitation of Plasmodium falciparum lactate dehydrogenase (Pf-LDH), which is capable of detecting malaria in 45-60 min. Assay development was founded in the selection of high-performance antibodies, implementation of a poly-horseradish peroxidase (polyHRP) signal amplifier, and optimization of whole-blood sample pre-treatment. The simplified ELISA achieved limits of detection (LOD) and quantification (LOQ) of 0.11 ng mL-1 and 0.37 ng mL-1, respectively, in lysed whole blood, and an LOD comparable to that of PCR in Plasmodium in vitro cultures (0.67 and 1.33 parasites µL-1 for ELISA and PCR, respectively). Accordingly, the developed immunoassay represents a simple and effective diagnostic tool for P. falciparum malaria, with a time-to-result of <60 min and sensitivity similar to the reference PCR, but easier to implement in low-resource settings.

Detection of Viruses and Virus-Neutralizing Antibodies Using Synthetic Erythrocytes: Toward a Tuneable Tool for Virus Surveillance.

The hemagglutination inhibition assay (HAI) is a classical method used worldwide in many analytical applications, including pathogen identification, vaccine production monitoring, and detection and characterization of pathogen-neutralizing antibodies (n-Ab). This is also a World Health Organization (WHO) reference method for the global surveillance of influenza viruses, which provides the information needed for the annual reformulation of the flu vaccine. HAI is a simple and inexpensive method that is performed without sophisticated equipment. However, it has to be carried out with fresh red blood cells (RBCs), a highly variable, unstable, and hard to mass-produce reagent, which impairs assay reproducibility. Here, we used the tests employed for influenza surveillance as a model to develop synthrocytes©, a synthetic reagent that could substitute animal erythrocytes in HAI. Contrary to previous examples exploiting sophisticated production paths to generate therapeutic synthetic RBCs, we founded production on the identification of microparticles able to generate different sedimentation patterns when agglutinated or not, which is the main requirement for HAI testing. Upon incorporation of influenza-binding receptors and optimization of production and assay conditions, synthrocytes succeeded in binding influenza A(H1N1) and B viruses as erythrocytes do, but were faster and more stable. Synthrocytes were finally employed in an HAI-like assay to detect the WHO reference reagents for influenza surveillance. Our results show that it is possible to substitute erythrocytes in classical HAI by a highly tuneable and potentially mass-produced synthetic reagent, which should facilitate worldwide HAI standardization with minimal equipment or training requirements.

Electrochemical POC device for fast malaria quantitative diagnosis in whole blood by using magnetic beads, Poly-HRP and microfluidic paper electrodes.

Malaria, a parasitic infection caused by Plasmodium parasites and transmitted through the bite of infected female Anopheles mosquitos, is one of the main causes of mortality in many developing countries. Over 200 million new infections and nearly half a million deaths are reported each year, and more than three billion people are at risk of acquiring malaria worldwide. Nevertheless, most malaria cases could be cured if detected early. Malaria eradication is a top priority of the World Health Organisation. However, achieving this goal will require mass population screening and treatment, which will be hard to accomplish with current diagnostic tools. We report an electrochemical point-of-care device for the fast, simple and quantitative detection of Plasmodiumfalciparum lactate dehydrogenase (PfLDH) in whole blood samples. Sample analysis includes 5-min lysis to release intracellular parasites, and stirring for 5 more min with immuno-modified magnetic beads (MB) along with an immuno-modified signal amplifier. The rest of the magneto-immunoassay, including sample filtration, MB washing and electrochemical detection, is performed at a disposable paper electrode microfluidic device. The sensor provides PfLDH quantitation down to 2.47 ng mL-1 in spiked samples and for 0.006-1.5% parasitemias in Plasmodium-infected cultured red blood cells, and discrimination between healthy individuals and malaria patients presenting parasitemias >0.3%. Quantitative malaria diagnosis is attained with little user intervention, which is not achieved by other diagnostic methods.

Competitive USB-Powered Hand-Held Potentiostat for POC Applications: An HRP Detection Case.

Considerable efforts are made to develop Point-of-Care (POC) diagnostic tests. POC devices have the potential to match or surpass conventional systems regarding time, accuracy, and cost, and they are significantly easier to operate by or close to the patient. This strongly depends on the availability of miniaturized measurement equipment able to provide a fast and sensitive response. This paper presents a low-cost, portable, miniaturized USB-powered potentiostat for electrochemical analysis, which has been designed, fabricated, characterized, and tested against three forms of high-cost commercial equipment. The portable platform has a final size of 10.5 × 5.8 × 2.5 cm, a weight of 41 g, and an approximate manufacturing cost of $85 USD. It includes three main components: the power module which generates a stable voltage and a negative supply, the front-end module that comprises a dual-supply potentiostat, and the back-end module, composed of a microcontroller unit and a LabVIEW-based graphic user interface, granting plug-and-play and easy-to-use operation on any computer. The performance of this prototype was evaluated by detecting chronoamperometrically horseradish peroxidase (HRP), the enzymatic label most widely used in electrochemical biosensors. As will be shown, the miniaturized platform detected HRP at concentrations ranging from 0.01 ng·mL-1 to 1 µg·mL-1, with results comparable to those obtained with the three commercial electrochemical systems.

Detection of plasma MMP-9 within minutes. Unveiling some of the clues to develop fast and simple electrochemical magneto-immunosensors.

Magnetic beads (MB) have been extensively used to produce sensitive and efficient electrochemical magneto-immunosensors. However, MB effective handling requires training, and MB washing after each incubation step is time consuming and contributes to raise result variability. Consequently, most of the electrochemical magneto-immunosensors reported to date, which entailed relatively long and complex multi-step procedures, would be difficult to carry out at point-of-care (POC) settings or by laypersons. For this reason, here we targeted the development of a simplified detection path, which is fast and simple enough to be operated at a POC setting, sufficiently efficient to provide analyte quantitation comparable to classical diagnostic methods, and dependent on minimal technical requirements to facilitate method global exploitation. As a proof-of-concept, we optimized an extremely simple, fast and efficient electrochemical magneto-immunosensor for detection of matrix metalloproteinase 9 (MMP-9). To accomplish this, we optimized MB immunomodification, produced an immunomodified Poly-HRP signal amplifier, developed a single-step magneto-immunoassay, and optimized electrochemical detection using a multiplexed magnetic holder and a ready-to-use commercial substrate solution. The sensor was finally calibrated by detecting MMP-9 in clinical samples. This electrochemical magneto-immunosensor detected MMP-9 in just 12-15 min, displaying linear response between 0.03 and 2 ng mL-1 of MMP-9, limits of detection (LOD) and quantification (LOQ) of 13 pg mL-1 and 70 pg mL-1, respectively, %CV< 6%, and accurate quantification of MMP-9 in patient plasma samples. These results were comparable to those afforded by a 5-h reference ELISA that used the same antibodies, confirming the applicability of our simplified method.

NaNO3/NaCl Oxidant and Polyethylene Glycol (PEG) Capped Gold Nanoparticles (AuNPs) as a Novel Green Route for AuNPs Detection in Electrochemical Biosensors.

Gold nanoparticles (AuNPs) have been exploited as signal-producing tags in electrochemical biosensors. However, the electrochemical detection of AuNPs is currently performed using corrosive acid solutions, which may raise health and environmental concerns. Here, oxidant salts, and specifically the environmentally friendly and occupational safe NaNO3/NaCl mixture, have been evaluated for the first time as potential alternatives to the acid solutions traditionally used for AuNPs electrooxidation. In addition, a new strategy to improve the sensitivity of the biosensor through PEG-based ligand exchange to produce less compact and easier to oxidize AuNPs immunoconjugates is presented too. As we show, the electrochemical immunosensor using NaNO3/NaCl measurement solution for AuNPs electrooxidation and detection, coupled to the employment of PEG-capped nanoimmunoconjugates, produced results comparable to classical HCl detection. The procedure developed was next tested for human matrix metallopeptidase-9 (hMMP9) analysis, exhibiting a 0.18-23 ng/mL linear range, a detection limit of 0.06 ng/mL, and recoveries between 95 and 105% in spiked human plasma. These results show that the procedure developed is applicable to the analysis of protein biomarkers in blood plasma and could contribute to the development of more environmentally friendly AuNP-based electrochemical biosensors.

A risk score to predict the absence of left ventricular reverse remodeling: Implications for the timing of ICD implantation in primary prevention.

BACKGROUND: A prophylactic implantable cardioverter defibrillator (ICD) in patients with heart failure and reduced left ventricular ejection fraction (HFrEF) is only indicated when left ventricular ejection fraction (LVEF) reassessment remains ≤35% after 3-6 months on optimal pharmacological therapy. However, LVEF may not improve during this period and the patient may be exposed to an unnecessary risk of sudden cardiac death. This study aimed to determine the incidence and predictors of the absence of left ventricular reverse remodeling (LVRR) after pharmacological treatment optimization in patients with HFrEF to design a risk score of absence of LVRR. METHODS: Consecutive outpatients with LVEF ≤35% were included in this observational prospective study. Up-titration of angiotensin-converting enzyme (ACE) inhibitors/angiotensin II receptor blockers (ARBs), beta-blockers, mineralocorticoid receptor antagonists (MRAs), and ivabradine was performed in our Heart Failure (HF) Unit. The absence of LVRR was defined as the persistence of an LVEF ≤35% at the 6-month follow-up. RESULTS: One hundred and twenty patients were included. At the 6-month follow-up, 64%, 76%, 72%, and 7% of patients were at 100% of the target dose of ACE inhibitors/ARBs, beta-blockers, MRAs, and ivabradine, respectively. LVRR was observed in 48% of the patients. Ischemic cardiomyopathy, prolonged HF duration, and larger left ventricular end-diastolic diameter index (LVEDDI) were independent predictors of the absence of LVRR. The risk score based on these predictors showed a c-statistic value of 0.81. CONCLUSIONS: Pharmacological treatment optimization is associated with LVRR in approximately half of cases, reducing potential ICD indications in parallel. However, ischemic cardiomyopathy, prolonged HF duration, and larger LVEDDI predict the absence of LVRR and favor ICD implantation without delay. The risk score based on the former predictors may help the clinician with the timing of ICD implantation.

Using magnetic beads and signal amplifiers to produce short and simple immunoassays: Application to MMP-9 detection in plasma samples.

Magnetic beads (MB) and signal amplifiers, such as horseradish peroxidase polymers (poly-HRP), have been used before for the production of highly sensitive immunoassays. However, most of the examples reported previously entailed long and tedious multi-step procedures, which were not necessarily shorter or simpler than classical paths such as Enzyme-Linked Immunosorbent Assay (ELISA). Here, instead of exploiting the combination of MB and poly-HRP to ameliorate sensitivity, we show that they conform a powerful tool that can be used to shorten the incubation times, which allows optimizing extremely simple, fast and efficient immunoassays with minimal technical requirements. In order to do so, here we used the highly sensitive and specific pair of antibodies of a commercial ELISA kit to optimize a magneto-ELISA for the detection of matrix metallopeptidase 9 (MMP-9). Three signal amplifiers were then tested and the best performing one was implemented in the magneto-assay to shorten the incubation times and improve assay performance. As we show, the shortened magneto-assay could be carried out in about 35 min, which included two 5-min incubations, washing, and incubation with enzyme substrate for 20 min before colorimetric detection. Moreover, the quantification of MMP-9 provided by the shortened assay in 12 plasma samples collected from patients was comparable to that generated by the 5-h ELISA, which was 8.5 times longer.

Miniaturized metal oxide pH sensors for bacteria detection.

It is well known that the metabolic activity of some microorganisms results in changes of pH of the culture medium, a phenomenon that can be used for detection and quantification of bacteria. However, conventional glass electrodes that are commonly used for pH measurements are bulky, fragile and expensive, which hinders their application in miniaturized systems and encouraged to the search for alternatives. In this work, two types of metal oxide pH sensors have been tested to detect the metabolic activity of the bacterium Escherichia coli (E. coli). These pH sensors were produced on silicon chips with platinum metal contacts, onto which thin layers of IrOx or Ta2O5 were incorporated by two different methods (electrodeposition and e-beam sputtering, respectively). In order to facilitate measurement in small sample volumes, an Ag/AgCl pseudo-reference was also screen-printed in the chip and was assayed in parallel to an external Ag/AgCl reference electrode. As it is shown, the developed sensors generated results indistinguishable from those provided by a conventional glass pH-electrode but could be operated in significantly smaller sample volumes. After optimization of the detection conditions, the metal oxide sensors are successfully applied for detection of increasing concentrations of viable E. coli, with detection of less than 10(3)cfu mL(-1) in undiluted culture medium in just 5h.

Reversible nanostructuration of microfluidic electrode devices by CNT magnetic co-entrapment.

Carbon nanotubes (CNTs) have been extensively used to produce electrodes of enhanced performance but have only been very recently exploited in microfluidic devices. In these cases, CNT electrodes had to be produced prior to device assembly, which might damage the CNT layer. Here, we show a fast and simple method for the reversible nanostructuration of microfluidic electrode devices in situ. The procedure is based on the attachment of single-walled CNTs (SWCNTs) onto the surface of magnetic particles (MPs) and magnetic confinement of the MP/SWCNT composite onto the sensor in a two-step process that provided homogeneous coating. As it is shown, subsequent magnet removal allows MP/SWCNT release and electrode reutilization. Compared to most previously described methods, ours is faster, simpler and also reversible.

Dual chronoamperometric detection of enzymatic biomarkers using magnetic beads and a low-cost flow cell.

In this work we report on the production of a low cost microfluidic device for the multiplexed electrochemical detection of magneto bioassays. As a proof of concept, the device has been used to detect myeloperoxidase (MPO), a cardiovascular biomarker. With this purpose, two bioassays have been optimized in parallel onto magnetic beads (MBs) for the simultaneous detection of MPO endogenous peroxidase activity and quantification of total MPO. Since the two bioassays produced signals of different magnitude for each concentration of MPO tested, two detection strategies have been compared, which entailed registering steady state currents (Iss) under substrate flow, and measuring the peak currents (Ip) produced in a stopped flow approach. As it will be shown, appropriate tuning of the detection and flow conditions can provide extremely sensitive detection, but also allow simultaneous detection of assays or parameters that would produce signals of different orders of magnitude when measured by a single detection strategy. In order to demonstrate the feasibility of the detection strategy reported, a dual MPO mass and activity assay has been finally applied to the study of 10 real plasma samples, allowing patient classification according to the risk of suffering a cardiovascular event.