Use of biomarkers in the emergency department and chest pain unit

Desempenho Diagnóstico da Angiotomografia Computadorizada e da Avaliação Seriada de Troponina Cardíaca Sensível em Pacientes com Dor Torácica e Risco Intermediário para Eventos Cardiovasculares

Fundamento

A angiotomografia coronária (ATC) tem sido usada para avaliação de dor torácica principalmente em pacientes de baixo risco, e poucos dados existem com pacientes em risco intermediário.

Objetivo

Avaliar o desempenho de medidas seriadas de troponinas sensíveis e de ATC em pacientes de risco intermediário.

Métodos

Um total de 100 pacientes com dor torácica, TIMI score 3 ou 4 e troponina negativa foram prospectivamente incluídos. Todos os pacientes foram submetidos à ATC, e aqueles com obstruções ≥ 50% foram encaminhados à cineangiocoronariografia. Pacientes com lesões < 50% recebiam alta hospitalar, receberam alta e foram contatados 30 dias depois por telefonema para avaliação dos desfechos clínicos. Os desfechos foram hospitalização, morte, e infarto agudo do miocárdio em 30 dias. A comparação entre os métodos foi realizada pelo teste de concordância kappa. O desempenho das medidas de troponina e da ATC na detecção de lesões coronárias significativas e desfechos clínicos foi calculado. Os resultados foram considerados estatisticamente significativos quando p <0,05.

Resultados

Estenose coronária ≥ 50% na ATC foi encontrada em 38% dos pacientes e lesões coronárias significativas na angiografia coronária foram encontradas em 31 pacientes. Dois eventos clínicos foram observados. A análise de concordância Kappa mostrou baixa concordância entre as medidas de troponina e ATC na detecção de lesões coronárias significativas (kappa = 0,022, p = 0,78). O desempenho da ATC para detectar lesões coronárias significativas na angiografia coronária ou para prever eventos clínicos em 30 dias foi melhor que as medidas de troponina sensível (acurácia de 91% versus 60%).

Conclusão

ATC teve melhor desempenho que as medidas seriadas de troponina na detecção de doença coronariana significativa em pacientes com dor torácica e risco intermediário para eventos cardiovasculares.

Use of Multifactorial Treatments to Address the Challenge of Translating Experimental Myocardial Infarct Reduction Strategies

Myocardial tissue damage that occurs during an ischemic event leads to a spiraling deterioration of cardiac muscle structural and functional integrity. Reperfusion is the only known efficacious strategy and is the most commonly used treatment to reduce injury and prevent remodeling. However, timing is critical, and the procedure is not always feasible for a variety of reasons. The complex molecular basis for cardioprotection has been studied for decades but formulation of a viable therapeutic that can significantly attenuate myocardial injury remains elusive. In this review, we address barriers to the development of a fruitful approach that will substantially improve the prognosis of those suffering from this widespread and largely unmitigated disease. Furthermore, we proffer that ephrinA1, a candidate molecule that satisfies many of the important criteria discussed, possesses robust potential to overcome these hurdles and thus offers protection that surpasses the limitations currently observed.

Intramyocardial administration of chimeric ephrinA1-Fc promotes tissue salvage following myocardial infarction in mice

The purpose of this study was to investigate the role of intramyocardial administration of chimeric ephrinA1-Fc in modulating the extent of injury and inflammation in non reperfused myocardial infarction (MI). Our results show that intramyocardial injection of 6 μg ephrinA1-Fc into the border zone immediately after permanent coronary artery ligation in B6129s mice resulted in 50% reduction of infarct size, 64% less necrosis, 35% less chamber dilatation and 32% less left ventricular free wall thinning at 4 days post-MI. In the infarct zone, Ly6G+ neutrophil density was 57% reduced and CD45+ leukocyte density was 21% reduced. Myocyte damage was also reduced in ephrinA1-Fc-treated hearts, as evidenced by 54% reduced serum cardiac troponin I. Further, we observed decreased cleaved PARP, increased BAG-1 protein expression, increased phosphorylated AKT/total AKT protein, and reduced NF-κB protein with ephrinA1-Fc administration, indicating improved cellular survival. Of the eight EphA receptors known to be expressed in mice (A1–A8), RT-PCR revealed that A1–A4, A6 and A7 were expressed in the uninjured adult myocardium. Expression of EphA1–A3 and EphA7 were significantly increased following MI while EphA6 expression decreased. Treatment with ephrinA1-Fc further increased EphA1 and EphA2 gene expression and resulted in a 2-fold increase in EphA4. Upregulation and combinatorial activation of these receptors may promote tissue survival. We have identified a novel, beneficial role for ephrinA1-Fc administration at the time of MI, and propose this as a promising new target for infarct salvage in non reperfused MI. More experiments are in progress to identify receptor-expressing cell types as well as the functional implications of receptor activation.

Proteomic characterization of protein phosphatase 1 complexes in ischemia-reperfusion and ischemic tolerance

Serine/threonine protein phosphatase 1 (PP1) regulates multiple cellular processes. Protein phosphorylation-dephosphorylation is largely altered during ischemia and subsequent reperfusion. The brain is particularly vulnerable to stress resulting from ischemia-reperfusion (IR), however, the acquisition of ischemic tolerance (IT) protects against IR stress. We studied PP1 complexes in response to IR stress and IT in brain using proteomic characterization of PP1 complexes in animal models of IR and IT. PP1alpha and PP1gamma were immunoprecipitated and resolved by 2-D. DIGE analysis detected 14 different PP1-interacting proteins that exhibited significant changes in their association with PP1alpha or PP1gamma. These proteins were identified by MALDI-TOF MS. Seven had the PP1-binding RVxF motif. IR altered the interaction of heat shock cognate 71 kDa-protein, creatine kinase B, and dopamine- and cAMP-regulated phosphoprotein 32 kDa (DARPP32) with both PP1alpha and PP1gamma, and the interaction of phosphodiesterase-6B, transitional ER ATPase, lamin-A, glucose-regulated 78 kDa-protein, dihydropyrimidinase-related protein-2, gamma-enolase, neurofilament-L, and ubiquitin ligase SIAH2 with PP1gamma. IT prevented most of the IR-induced effects. This study identifies novel PP1alpha- and PP1gamma-interacting proteins and reveals an in vivo modularity of PP1 holoenzymes in response to physiological ischemic stress. It supports a potential role of PP1 in IR stress and as a target of the endogenous protective mechanisms induced by IT.