Global longitudinal strain to identify low-risk patients with suspected ACS

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Albert Einstein Society

Background

Determining which chest pain presentations should be treated and considered an acute coronary syndrome/myocardial infarction (ACS/MI) versus those with non-cardiac chest pain (NCCP) can be difficult. Initial evaluation of suspected ACS requires assessment of presenting symptoms, risk factors, ECG, and cardiac biomarkers. Bedside echocardiography can assist in rapid assessment of suspected ACS through measurement of echocardiographic wall motion score index and left ventricular ejection fraction, though the sensitivity of these measurements has been called into question. Global longitudinal strain (GLS) has been associated with significant CAD and has been found to be more reproducible than LVEF. However, its utility in rapid ED evaluation of chest pain remains under-explored.

Purpose

Assess the utility of speckle-tracking strain in addition to clinical and demographic factors in identification of low-risk patients among those presenting to the ED with suspected ACS.

Methods

This was a retrospective single center study of 434 hospitalized patients aged 18 years or older in whom ACS (excluding STEMI) was suspected by ED assessment, from 9/1/2015 – 12/31/2019. Echocardiography within 24 hours of admission was analyzed, with left ventricular global longitudinal strain (LVGLS) obtained via AutoSTRAIN software (TOMTEC Imaging Systems GmbH). Patients were identified as having NCCP (n = 158, 36%), myocardial injury (n = 110, 25%), or MI (n = 166, 38%; subdivided into NSTEMI [n = 74, 44.6%] and type II MI [n = 92, 55.4%]) according to the 4th universal definition of MI. Mean strain values were compared between study groups using Independent T tests. Logistic regression and ROC analysis was done to determine the value of LVGLS in the prediction of ACS.

Results

Non-white subjects were over-represented in the NCCP group (92% vs 8%), versus the myocardial injury and MI groups (65% vs 35%, p < 0.001), and on average the NCCP group was younger (56.5 ± 14.5 vs 64.8 ± 15, p < 0.001). LVGLS was significantly higher for NCCP versus the MI group (17.7 ± 2.8 vs 14.9 ± 3.9, p < 0.001). ROC analysis (c-statistic = 0.72) identified an optimal cutoff at ≤15.6, with sensitivity of 56% and specificity of 82%. Logistic regression analysis, including demographic and clinical variables, identified age, LVGLS, LV end-diastolic volume and serum creatinine as significant independent predictors for NCCP vs ACS. The addition of these factors in the predictive analysis resulted in slightly improved model performance (c-statistic = 0.78).

Conclusions

LVGLS among patients with suspected ACS is significantly different between NCCP and MI; however, low sensitivity for MI makes it inadequate as a single test to discriminate between the two. Combining LVGLS with other clinical/laboratory factors may have potential utility and will be explored in future work. Abstract Figure. Distribution Plot for LVGLS  Abstract Figure. ROC Curve for LVGLS

A feasibility study using time-driven activity-based costing as a management tool for provider cost estimation: lessons from the national TB control program in Zimbabwe in 2018

Background

Insufficient cost data and limited capacity constrains the understanding of the actual resources required for effective TB control. This study used process maps and time-driven activity-based costing to document TB service delivery processes. The analysis identified the resources required to sustain TB services in Zimbabwe, as well as several opportunities for more effective and efficient use of available resources.

Methods

A multi-disciplinary team applied time-driven activity-based costing (TDABC) to develop process maps and measure the cost of clinical pathways used for Drug Susceptible TB (DS-TB) at urban polyclinics, rural district and provincial hospitals, and community based targeted screening for TB (Tas4TB). The team performed interviews and observations to collect data on the time taken by health care worker-patient pairs at every stage of the treatment pathway. The personnel’s practical capacity and capacity cost rates were calculated on five cost domains. An MS Excel model calculated diagnostic and treatment costs.

Findings

Twenty-five stages were identified in the TB care pathway across all health facilities except for community targeted screening for TB. Considerable variations were observed among the facilities in how health care professionals performed client registration, taking of vital signs, treatment follow-up, dispensing medicines and processing samples.

The average cost per patient for the entire DS-TB care was USD324 with diagnosis costing USD69 and treatment costing USD255. The average cost for diagnosis and treatment was higher in clinics than in hospitals (USD392 versus USD256). Nurses in clinics were 1.6 time more expensive than in hospitals. The main cost components were personnel (USD130) and laboratory (USD119). Diagnostic cost in Tas4TB was twice that of health facility setting (USD153 vs USD69), with major cost drivers being demand creation (USD89) and sputum specimen transportation (USD5 vs USD3).

Conclusion

TDABC is a feasible and effective costing and management tool in low-resource settings. The TDABC process maps and treatment costs revealed several opportunities for innovative improvements in the NTP under public health programme settings. Re-engineering laboratory testing processes and synchronising TB treatment follow-up with antiretroviral treatments could produce better and more uniform TB treatments at significantly lower cost in Zimbabwe.

Role of the SH3-ligand domain of simian immunodeficiency virus Nef in interaction with Nef-associated kinase and simian AIDS in rhesus macaques

The nef gene of the human and simian immunodeficiency viruses (HIV and SIV) is dispensable for viral replication in T-cell lines; however, it is essential for high virus loads and progression to simian AIDS (SAIDS) in SIV-infected adult rhesus macaques. Nef proteins from HIV type 1 (HIV-1), HIV-2, and SIV contain a proline-Xaa-Xaa-proline (PxxP) motif. The region of Nef with this motif is similar to the Src homology region 3 (SH3) ligand domain found in many cell signaling proteins. In virus-infected lymphoid cells, Nef interacts with a cellular serine/threonine kinase, designated Nef-associated kinase (NAK). In this study, analysis of viral clones containing point mutations in the nef gene of the pathogenic clone SIVmac239 revealed that several strictly conserved residues in the PxxP region were essential for Nef-NAK interaction. The results of this analysis of Nef mutations in in vitro kinase assays indicated that the PxxP region in SIV Nef was strikingly similar to the consensus sequence for SH3 ligand domains possessing the minus orientation. To test the significance of the PxxP motif of Nef for viral pathogenesis, each proline was mutated to an alanine to produce the viral clone SIVmac239-P104A/P107A. This clone, expressing Nef that does not associate with NAK, was inoculated into seven juvenile rhesus macaques. In vitro kinase assays were performed on virus recovered from each animal; the ability of Nef to associate with NAK was restored in five of these animals as early as 8 weeks after infection. Analysis of nef genes from these viruses revealed patterns of genotypic reversion in the mutated PxxP motif. These revertant genotypes, which included a second-site suppressor mutation, restored the ability of Nef to interact with NAK. Additionally, the proportion of revertant viruses increased progressively during the course of infection in these animals, and two of these animals developed fatal SAIDS. Taken together, these results demonstrated that in vivo selection for the ability of SIV Nef to associate with NAK was correlated with the induction of SAIDS. Accordingly, these studies implicate a role for the conserved SH3 ligand domain for Nef function in virally induced immunodeficiency.