Effect of Cangrelor on Infarct Size in ST-Segment Elevation Myocardial Infarction Treated By Primary Percutaneous Coronary Intervention: A Randomized Controlled Trial (The PITRI Trial).

Background: The administration of intravenous cangrelor at reperfusion achieves faster onset of platelet P2Y12 inhibition than oral ticagrelor and has been shown to reduce myocardial infarct (MI) size in the pre-clinical setting. We hypothesized that the administration of cangrelor at reperfusion will reduce MI size and prevent microvascular obstruction (MVO) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Methods: This was a Phase 2, multi-center, randomized, double-blind, placebo controlled clinical trial conducted between November 2017 to November 2021 in six cardiac centers in Singapore (NCT03102723). Patients were randomized to receive either cangrelor or placeboinitiated prior to the PPCI procedure on top of oral ticagrelor. The key exclusion criteria included: presenting <6 hours of symptom onset, prior MI and stroke or transient ischemic attack; on concomitant oral anticoagulants; and a contraindication for cardiovascular magnetic resonance (CMR). The primary efficacy endpoint was acute MI size by CMR within the first week expressed as percentage of the left ventricle mass ( %LVmass). MVO was identified as areas of dark core of hypoenhancement within areas of late gadolinium enhancement. The primary safety endpoint was Bleeding Academic Research Consortium (BARC)-defined major bleeding in the first 48 hours. Continuous variables were compared by Mann-Whitney U test [reported as median (1st quartile- 3rd quartile)] and categorical variables were compared by Fisher's exact test. A 2-sided P<0.05 was considered statistically significant. Results: Of 209 recruited patients, 164 patients (78% ) completed the acute CMR scan. There were no significant differences in acute MI size [placebo: 14.9 (7.3 - 22.6) %LVmass versus cangrelor: 16.3 (9.9 - 24.4)%LVmass, P=0.40] or the incidence [placebo: 48% versus cangrelor: 47%, P=0.99] and extent of MVO [placebo:1.63 (0.60 - 4.65)%LVmass versus cangrelor: 1.18 (0.53 - 3.37)%LVmass, P=0.46] between placebo and cangrelor despite a two-fold decrease in platelet reactivity with cangrelor. There were no BARC-defined major bleeding events in either group in the first 48 hours. Conclusions: Cangrelor administered at time of PPCI did not reduce acute MI size or prevent MVO in STEMI patients given oral ticagrelor despite a significant reduction of platelet reactivity during the PCI procedure.

Prediction of adverse cardiac events in emergency department patients with chest pain using machine learning for variable selection.

BACKGROUND: The key aim of triage in chest pain patients is to identify those with high risk of adverse cardiac events as they require intensive monitoring and early intervention. In this study, we aim to discover the most relevant variables for risk prediction of major adverse cardiac events (MACE) using clinical signs and heart rate variability. METHODS: A total of 702 chest pain patients at the Emergency Department (ED) of a tertiary hospital in Singapore were included in this study. The recruited patients were at least 30 years of age and who presented to the ED with a primary complaint of non-traumatic chest pain. The primary outcome was a composite of MACE such as death and cardiac arrest within 72 h of arrival at the ED. For each patient, eight clinical signs such as blood pressure and temperature were measured, and a 5-min ECG was recorded to derive heart rate variability parameters. A random forest-based novel method was developed to select the most relevant variables. A geometric distance-based machine learning scoring system was then implemented to derive a risk score from 0 to 100. RESULTS: Out of 702 patients, 29 (4.1%) met the primary outcome. We selected the 3 most relevant variables for predicting MACE, which were systolic blood pressure, the mean RR interval and the mean instantaneous heart rate. The scoring system with these 3 variables produced an area under the curve (AUC) of 0.812, and a cutoff score of 43 gave a sensitivity of 82.8% and specificity of 63.4%, while the scoring system with all the 23 variables had an AUC of 0.736, and a cutoff score of 49 gave a sensitivity of 72.4% and specificity of 63.0%. Conventional thrombolysis in myocardial infarction score and the modified early warning score achieved AUC values of 0.637 and 0.622, respectively. CONCLUSIONS: It is observed that a few predictors outperformed the whole set of variables in predicting MACE within 72 h. We conclude that more predictors do not necessarily guarantee better prediction results. Furthermore, machine learning-based variable selection seems promising in discovering a few relevant and significant measures as predictors.

Theoretical assessment of binding and mass-transport effects in electrochemical affinity biosensors that utilize nanoparticle labels for signal amplification.

This paper presents a theoretical study of electrochemical affinity biosensors for the detection of DNA/protein that utilize nanoparticle labels for signal amplification. This study analyzes the effects of binding and mass transport of the analytes on biosensor performance by using numerical simulations. Four cases were considered: 1) nanoparticles used to increase the loading of an electroactive species, or used as catalysts under pseudo-first-order conditions; 2) nanoparticles used as ultramicroelectrode arrays for the electrolysis of large concentrations of substrate; 3) nanoparticles used as seeds to deposit electrochemically detectable species; and 4) nanoparticles used to mediate the deposition of electrocatalysts. By using nanoparticle labels, high sensitivity is possible under all conditions considered. However, theoretical findings suggested that nonspecific adsorption could be more problematic in cases 2-4 due to the mismatch between the chemistry of surface binding and the principle of signal amplification that originates from the effect of mass transport. Under these conditions, any given signal would plateau at a much lower analyte concentration, well before the analyte binding had actually reached a plateau. Views on possible solutions to the above limitations are also presented.

Ultrasensitive electrochemical immunosensor employing glucose oxidase catalyzed deposition of gold nanoparticles for signal amplification.

This paper describes a novel enzymatic amplification strategy for ultrasensitive electrochemical immunosensing. This approach utilizes glucose oxidase for the enzymatic deposition of gold nanoparticles onto an indium tin oxide (ITO) electrode surface using a novel gold developer solution consisting of 20 mM of glucose, 20 mM of NaSCN, 0.5 M of p-benzoquinone (PBQ) and 1 mM of AuCl(4)(-) dissolved in 0.1 M of pH 7.5 phosphate buffer solution. The amount of gold deposited was quantified electrochemically by monitoring the reduction of gold oxide in an aqueous solution of 0.5 M of H(2)SO(4), which was correlated to the amount of antigens in the solution. The effectiveness of this strategy was demonstrated experimentally through the construction of an immunosensor for the detection of mouse IgG using a sandwich immunoassay in a linear dynamic range of 5 pg/ml to 50 ng/ml. A good mean apparent recovery in the range of 88-102% was obtained over the entire linear dynamic range of the sensor response in the serum samples. This suggested that the immunosensor would be useful for the testing of proteins in real clinical samples.

Pt nanoparticle label-mediated deposition of Pt catalyst for ultrasensitive electrochemical immunosensors.

Herein we describe a novel signal amplification strategy for the development of ultrasensitive electrochemical immunosensors. The amplification strategy is based on platinum catalyzing a hydrogen evolution reaction. To demonstrate its practicality, the electrochemical signal enhancement strategy has been applied for the development of a novel prostate-specific antigen (PSA) immunosensor. The immunosensing protocol utilized a gold electrode with PSA capture antibodies bound to its surface via covalent bonding. After PSA was bound to the electrode surface, a secondary platinum nanoparticle-labeled detection antibody was used to complete the sandwich immunosensor. The resulting electrode was then dipped in a platinum developer solution containing 1 mM of PtCl4(2-), 0.1M of formate (reductant) and 0.5% Tween 80 (pH 6.5) to generate bare platinum catalysts in close proximity to the Au electrode surface through a seed-mediated nucleation and growth mechanism. The signal readout was obtained electrochemically via a Pt-catalyzed hydrogen evolution reaction in an acidic aqueous medium containing 10 mM of HCl and 1 M of KCl. A detection limit of 1 fg/ml was achieved.

The solid-state Ag/AgCl process as a highly sensitive detection mechanism for an electrochemical immunosensor.

The highly characteristic solid-state Ag/AgCl process was used as an ultrasensitive detection mechanism for electrochemical sensors, such as a prostate-specific antigen immunosensor.

A DNA biosensor based on the detection of doxorubicin-conjugated Ag nanoparticle labels using solid-state voltammetry.

This report describes an electrochemical biosensor for the detection of short DNA oligonucleotide of the avian flu virus H5N1 with sequence 5'-CCA AGC AAC AGA CTC AAA-3'. To fabricate this DNA biosensor, a gold (Au) electrode surface was modified with thiolated DNA probes with a sequence complementary to the target DNA. This modified Au electrode was incubated in a buffer solution containing the target DNA to form double-stranded DNA (ds-DNA) through hybridization. The ds-DNA on the electrode surface was then labeled with silver nanoparticles conjugated with a well-known DNA intercalator, doxorubicin. By performing cyclic voltammetry in an aqueous KCl solution (0.3M), the silver nanoparticle labels were detected as a result of the highly characteristic solid-state Ag/AgCl redox process. The signal obtained was subsequently used to quantify the amount of DNA. A detection limit of 1 pM has been achieved with this new DNA biosensor.

A DNA biosensor based on a morpholino oligomer coated indium-tin oxide electrode and a cationic redox polymer.

A simple and ultrasensitive electrochemical biosensor employing a morpholino oligomer as capture probe and a cationic redox polymer as signal generator for direct detection of DNA is presented in this report. It is based on the immobilization of the morpholino oligomer on an indium-tin oxide (ITO) electrode and amperometric detection of target DNA by forming a DNA/cationic redox polymer bilayer on the ITO electrode. After hybridizing the morpholino capture probe (MCP) to the target DNA, the cationic redox polymer was introduced to the ITO electrode via electrostatic interaction with the hybridized DNA. The deposited redox polymer exhibited excellent electrocatalytic activity towards the oxidation of ascorbic acid (AA), allowing for direct voltammetric and amperometric detection of DNA. Under optimized experimental conditions, a detection limit of 1.0 pM and linear current-concentration relationship up to 500 pM were obtained in amperometry. The resulting biosensors offered much better mismatch discrimination against mismatch sequences than their DNA counterparts.

A doubly amplified electrochemical immunoassay for carcinoembryonic antigen.

An ultrasensitive electrochemical immunoassay (EIA) for the detection of carcinoembryonic antigen (CEA) is described in this report. The assay involves utilizing enzyme-catalyzed deposition of a redox polymer and electrocatalytic oxidation of ascorbic acid (AA) by the deposited redox polymer, a dual-amplification scheme to enhance analytical signals. Briefly, CEA capturing antibody and redox polymer anchoring agent were covalently immobilized on a gold electrode. After incubating with CEA, the electrode was treated in detection antibody-glucose oxidase conjugate solution. Thereafter, it was dipped into the redox polymer solution. Upon the addition of glucose, the redox polymer was enzymatically reduced and deposited on the electrode surface. The deposited redox polymer exhibits excellent electrocatalytic activity towards the oxidation of AA. Consequently, CEA could be quantified amperometrically. This electrochemical immunoassay combines the specificity of the immunological reaction with the sensitivity of the doubly amplified electrochemical detection.