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Resumo Fundamento Os limiares de corte para a “relação do ciclo completo de repouso” (RFR) oscilam em diferentes séries, sugerindo que as características da população podem influenciá-los. Da mesma forma, foram documentados preditores de discordância entre a RFR e a reserva de fluxo fracionado (FFR). O Estudo RECOPA, mostrou que a capacidade diagnóstica está reduzida na “zona cinzenta” da RFR, tornando necessária a realização de FFR para descartar ou confirmar isquemia. Objetivos Determinar os preditores de discordância, integrar as informações que eles fornecem em um índice clínico-fisiológico: a “RFR Ajustada”, e comparar sua concordância com o FFR. Métodos Usando dados do Estudo RECOPA, os preditores de discordância em relação à FFR foram determinados na “zona cinzenta” da RFR (0,86 a 0,92) para construir um índice (“RFR Ajustada”) que pesaria a RFR juntamente com os preditores de discordância e avaliar sua concordância com a FFR. Resultados Foram avaliadas 156 lesões em 141 pacientes. Os preditores de discordância foram: doença renal crônica, cardiopatia isquêmica prévia, lesões não envolvendo a artéria descendente anterior esquerda e síndrome coronariana aguda. Embora limitada, a “RFR Ajustada” melhorou a capacidade diagnóstica em comparação com a RFR na “zona cinzenta” (AUC-RFR = 0,651 versus AUC-“RFR Ajustada” = 0,749), mostrando também uma melhora em todos os índices diagnósticos quando foram estabelecidos limiares de corte otimizados (sensibilidade: 59% a 68%; especificidade: 62% a 75%; acurácia diagnóstica: 60% a 71%; razão de verossimilhança positiva: 1,51 a 2,34; razão de verossimilhança negativa: 0,64 a 0,37). Conclusões Ajustar a RFR integrando as informações fornecidas pelos preditores de discordância para obter a “RFR Ajustada” melhorou a capacidade diagnóstica em nossa população. Mais estudos são necessários para avaliar se os índices clínico-fisiológicos melhoram a capacidade diagnóstica da RFR ou de outros índices coronarianos. Abstract Background Cutoff thresholds for the “resting full-cycle ratio” (RFR) oscillate in different series, suggesting that population characteristics may influence them. Likewise, predictors of discordance between the RFR and fractional flow reserve (FFR) have been documented. The RECOPA Study showed that diagnostic capacity is reduced in the RFR “grey zone”, requiring the performance of FFR to rule out or confirm ischemia. Objectives To determine predictors of discordance, integrate the information they provide in a clinical-physiological index, the “Adjusted RFR”, and compare its agreement with the FFR. Methods Using data from the RECOPA Study, predictors of discordance with respect to FFR were determined in the RFR “grey zone” (0.86 to 0.92) to construct an index (“Adjusted RFR”) that would weigh RFR together with predictors of discordance and evaluate its agreement with FFR. Results A total of 156 lesions were evaluated in 141 patients. Predictors of discordance were: chronic kidney disease, previous ischemic heart disease, lesions not involving the anterior descending artery, and acute coronary syndrome. Though limited, the “Adjusted RFR” improved the diagnostic capacity compared to the RFR in the “grey zone” (AUC-RFR = 0.651 versus AUC-“Adjusted RFR” = 0.749), also showing an improvement in all diagnostic indices when optimal cutoff thresholds were established (sensitivity: 59% to 68%; specificity: 62% to 75%; diagnostic accuracy: 60% to 71%; positive likelihood ratio: 1.51 to 2.34; negative likelihood ratio: 0.64 to 0.37). Conclusions Adjusting the RFR by integrating the information provided by predictors of discordance to obtain the “Adjusted RFR” improved the diagnostic capacity in our population. Further studies are required to evaluate whether clinical-physiological indices improve the diagnostic capacity of RFR or other coronary indices.

Cutoff thresholds for the "resting full-cycle ratio" (RFR) oscillate in different series, suggesting that population characteristics may influence them. Likewise, predictors of discordance between the RFR and fractional flow reserve (FFR) have been documented. The RECOPA Study showed that diagnostic capacity is reduced in the RFR "grey zone", requiring the performance of FFR to rule out or confirm ischemia.To determine predictors of discordance, integrate the information they provide in a clinical-physiological index, the "Adjusted RFR", and compare its agreement with the FFR.Using data from the RECOPA Study, predictors of discordance with respect to FFR were determined in the RFR "grey zone" (0.86 to 0.92) to construct an index ("Adjusted RFR") that would weigh RFR together with predictors of discordance and evaluate its agreement with FFR.A total of 156 lesions were evaluated in 141 patients. Predictors of discordance were: chronic kidney disease, previous ischemic heart disease, lesions not involving the anterior descending artery, and acute coronary syndrome. Though limited, the "Adjusted RFR" improved the diagnostic capacity compared to the RFR in the "grey zone" (AUC-RFR = 0.651 versus AUC-"Adjusted RFR" = 0.749), also showing an improvement in all diagnostic indices when optimal cutoff thresholds were established (sensitivity: 59% to 68%; specificity: 62% to 75%; diagnostic accuracy: 60% to 71%; positive likelihood ratio: 1.51 to 2.34; negative likelihood ratio: 0.64 to 0.37).Adjusting the RFR by integrating the information provided by predictors of discordance to obtain the "Adjusted RFR" improved the diagnostic capacity in our population. Further studies are required to evaluate whether clinical-physiological indices improve the diagnostic capacity of RFR or other coronary indices.Os limiares de corte para a “relação do ciclo completo de repouso” (RFR) oscilam em diferentes séries, sugerindo que as características da população podem influenciá-los. Da mesma forma, foram documentados preditores de discordância entre a RFR e a reserva de fluxo fracionado (FFR). O Estudo RECOPA, mostrou que a capacidade diagnóstica está reduzida na “zona cinzenta” da RFR, tornando necessária a realização de FFR para descartar ou confirmar isquemia.Determinar os preditores de discordância, integrar as informações que eles fornecem em um índice clínico-fisiológico: a “RFR Ajustada”, e comparar sua concordância com o FFR.Usando dados do Estudo RECOPA, os preditores de discordância em relação à FFR foram determinados na “zona cinzenta” da RFR (0,86 a 0,92) para construir um índice (“RFR Ajustada”) que pesaria a RFR juntamente com os preditores de discordância e avaliar sua concordância com a FFR.Foram avaliadas 156 lesões em 141 pacientes. Os preditores de discordância foram: doença renal crônica, cardiopatia isquêmica prévia, lesões não envolvendo a artéria descendente anterior esquerda e síndrome coronariana aguda. Embora limitada, a “RFR Ajustada” melhorou a capacidade diagnóstica em comparação com a RFR na “zona cinzenta” (AUC-RFR = 0,651 versus AUC-“RFR Ajustada” = 0,749), mostrando também uma melhora em todos os índices diagnósticos quando foram estabelecidos limiares de corte otimizados (sensibilidade: 59% a 68%; especificidade: 62% a 75%; acurácia diagnóstica: 60% a 71%; razão de verossimilhança positiva: 1,51 a 2,34; razão de verossimilhança negativa: 0,64 a 0,37).Ajustar a RFR integrando as informações fornecidas pelos preditores de discordância para obter a “RFR Ajustada” melhorou a capacidade diagnóstica em nossa população. Mais estudos são necessários para avaliar se os índices clínico-fisiológicos melhoram a capacidade diagnóstica da RFR ou de outros índices coronarianos.

Background. The resting full‐cycle ratio (RFR) is a novel resting index which in contrast to the gold standard (fractional flow reserve (FFR)) does not require maximum hyperemia induction. The objectives of this study were to evaluate the agreement between RFR and FFR with the currently recommended thresholds and to design a hybrid RFR-FFR ischemia detection strategy, allowing a reduction of coronary vasodilator use. Materials and Methods. Patients subjected to invasive physiological study in 9 Spanish centers were prospectively recruited between April 2019 and March 2020. Sensitivity and specificity studies were made to assess diagnostic accuracy between the recommended levels of RFR ≤0.89 and FFR ≤0.80 (primary objective) and to determine the RFR “grey zone” in order to define a hybrid strategy with FFR affording 95% global agreement compared with FFR alone (secondary objective). Results. A total of 380 lesions were evaluated in 311 patients. Significant correlation was observed (R2 = 0.81; P < 0.001 ) between the two techniques, with 79% agreement between RFR ≤ 0.89 and FFR ≤ 0.80 (positive predictive value, 68%, and negative predictive value, 80%). The hybrid RFR-FFR strategy, administering only adenosine in the “grey zone” (RFR: 0.86 to 0.92), exhibited an agreement of over 95% with FFR, with high predictive values (positive predictive value, 91%, and negative predictive value, 92%), reducing the need for vasodilators by 58%. Conclusions. Dichotomous agreement between RFR and FFR with the recommended thresholds is significant but limited. The adoption of a hybrid RFR-FFR strategy affords very high agreement, with minimization of vasodilator use.

One-catheter strategy, based in multipurpose catheters, allows exploring both coronary arteries with a single catheter. This strategy could simplify coronary catheterization and reduce the volume of contrast administration, by reducing radial spasm. To date, observational studies showed greater benefits regarding contrast consumption and catheterization performance than controlled trials. The aim of this work is to perform the first systematic review and meta-analysis of randomized clinical trials (RCT) to adequately quantify the benefits of one-catheter strategy, with multipurpose catheters, over conventional two-catheter strategy on contrast consumption, and catheterization performance.A search in PubMed, CINALH, and CENTRAL databases was conducted to identify randomized trials comparing one-catheter and two-catheter strategies. The primary outcome was volume of iodinated contrast administrated. Secondary endpoints, evaluating coronary catheterization performance included: arterial spasm, fluoroscopy time, and procedural time.Five RCT were included for the final analysis, with a total of 1599 patients (802 patients with one-catheter strategy and 797 patients with two-catheter strategy). One-catheter strategy required less administration of radiological contrast (difference in means [DiM] [95% confidence interval (CI)]; -3.831 mL [-6.165 mL to -1.496 mL], p = 0.001) as compared to two-catheter strategy. Furthermore, less radial spasm (odds ratio [95% CI], 0.484 [0.363 to 0.644], p0.001) and less procedural time (DiM [95% CI], -72.471 s [-99.694 s to -45.249 s], p0.001) were observed in one-catheter strategy. No differences on fluoroscopy time were observed.One-catheter strategy induces a minimal reduction on radiological contrast administration but improves coronary catheterization performance by reducing arterial spasm and procedural time as compared to conventional two-catheter strategy.La estrategia de catéter único permite explorar ambas coronarias con un solo catéter. Nuestro objetivo es realizar la primera revisión sistemática y meta-análisis de ensayos clínicos aleatorizados para cuantificar adecuadamente los beneficios de la estrategia de catéter único, con catéteres multipropósito, sobre la estrategia convencional de dos catéteres.Se realizó una búsqueda en PubMed, CINALH y CENTRAL, identificando ensayos aleatorizados que compararan estrategias de un catéter y dos catéteres. El resultado primario fue volumen de contraste administrado. Los secundarios, que evaluaron el rendimiento del cateterismo, incluyeron: espasmo radial, tiempo de fluoroscopia y de procedimiento.Se incluyeron cinco ensayos, totalizando 1,599 pacientes (802 con estrategia de un catéter y 797 con estrategia de dos catéteres). La estrategia de catéter único requirió menos contraste (diferencia-de-medias; −3.831 mL [−6.165 mL a −1.496 mL], p = 0.001), presentando menos espasmo radial (odds ratio, 0.484 [0.363 a 0.644], p0.001) y menos tiempo de procedimiento (diferencia-de-medias; −72.471 s [−99.694 s a −45.249 s], p0.001). No hubo diferencias en el tiempo de fluoroscopia.La estrategia de catéter único induce una reducción mínima en la administración de contraste, pero mejora el rendimiento del cateterismo al reducir el espasmo radial y el tiempo de procedimiento en comparación con la estrategia convencional.

Background One-catheter strategy, based in multipurpose catheters, allows exploring both coronary arteries with a single catheter. This strategy could simplify coronary catheterization and reduce the volume of contrast administration, by reducing radial spasm. To date, observational studies showed greater benefits regarding contrast consumption and catheterization performance than controlled trials. The aim of this work is to perform the first systematic review and meta-analysis of randomized clinical trials (RCT) to adequately quantify the benefits of one-catheter strategy, with multipurpose catheters, over conventional two-catheter strategy on contrast consumption, and catheterization performance. Methods A search in PubMed, CINALH, and CENTRAL databases was conducted to identify randomized trials comparing one-catheter and two-catheter strategies. The primary outcome was volume of iodinated contrast administrated. Secondary endpoints, evaluating coronary catheterization performance included: arterial spasm, fluoroscopy time, and procedural time. Results Five RCT were included for the final analysis, with a total of 1599 patients (802 patients with one-catheter strategy and 797 patients with two-catheter strategy). One-catheter strategy required less administration of radiological contrast (difference in means [DiM] [95% confidence interval (CI)]; -3.831 mL [-6.165 mL to -1.496 mL], p = 0.001) as compared to two-catheter strategy. Furthermore, less radial spasm (odds ratio [95% CI], 0.484 [0.363 to 0.644], p < 0.001) and less procedural time (DiM [95% CI], -72.471 s [-99.694 s to -45.249 s], p < 0.001) were observed in one-catheter strategy. No differences on fluoroscopy time were observed. Conclusions One-catheter strategy induces a minimal reduction on radiological contrast administration but improves coronary catheterization performance by reducing arterial spasm and procedural time as compared to conventional two-catheter strategy.

Class II major histocompatibility complex molecules (MHCII) are transmembrane glycoproteins that display peptides generated and selected by intracellular antigen processing and presentation mechanisms to CD4+T cells, initiating an adaptive immune response. MHCII is expressed on the cell surface and in endosomal compartments, each of which have their own signature membrane characteristics. The traditional strategy to investigate peptide binding to MHCII has relied on the use of soluble MHCII, in which the transmembrane portion has been removed. This work studied MHCII in its native, membrane-embedded form. To this end, we used nanodisc, a synthetic model membrane device, to evaluate the effect of membrane lipid composition on MHCII assembly. The full-length human MHCII allele HLA-DR1 (DR1) was isolated from B-lymphoblastoid cell lines via immunoaffinity chromatography. Three types of nanodisc were generated: simple, fluid disordered and rigid ordered, each of them characterized by a unique lipid composition. Nanodiscs were separated using fast protein liquid chromatography (FPLC), the readings from which showed clear differences between nanodisc types. We observed that the fluid disordered nanodisc showed DR1 assembly as a cluster, with one major FPLC-generated peak. In contrast, simple and rigid nanodiscs were distinguished by multiple peaks. As DR1 tends to form aggregates, we inferred that in simple and rigid nanodiscs DR1 tetramers and dimers form in separate nanodisc assemblies. Taken together, our results indicate that membrane lipid composition has a strong impact on native MHCII assembly. As such, we predict that MHCII conformation and activity are function of the cell compartment they reside at any point in time.

The combination of percutaneous coronary intervention (PCI) and therapeutic hypothermia in comatose patients after cardiac arrest due to an acute coronary syndrome has been reported to be safe and effective. However, recent investigations suggest that hypothermia may be associated with impaired response to clopidogrel and greater risk of thrombotic complications after PCI. This investigation aimed to evaluate the effect of hypothermia on the pharmacodynamic response of aspirin and clopidogrel in patients (n = 20) with ST elevation myocardial infarction undergoing primary PCI. Higher platelet reactivity (ADP stimulus) was observed in samples incubated at 33 °C compared with those at 37 °C (multiple electrode aggregometry, 235.2 ± 31.4 AU×min vs. 181.9 ± 30.2 AU×min, p 0.001; VerifyNow P2Y12, 172.9 ± 20.3 PRU vs. 151.0 ± 19.3 PRU, p = 0.004). Numerically greater rates of clopidogrel poor responsiveness were also observed at 33 °C. No differences were seen in aspirin responsiveness. In conclusion, mild hypothermia was associated with reduced clopidogrel-mediated platelet inhibition with no impact on aspirin effects.Mild therapeutic hypothermia is associated with impaired response to clopidogrel therapy, which might contribute to increase the risk of thrombotic events in ACS comatose patients undergoing PCI.

BACKGROUND: False-positive results for hepatitis C virus antibody (anti-HCV) occur with unacceptable frequency in low-prevalence populations. The purpose of the study was to determine whether signal-to-cutoff (S/CO) ratios of anti-HCV assay–reactive samples could be used to discriminate false-positive from true-positive anti-HCV results and avoid the need for supplemental testing. STUDY DESIGN AND METHODS: Using receiver-operating characteristic curve, the cutoff point that identifies the major proportion (≥95%) of false-positive results, with a minor proportion (