Allogeneic CD20-targeted γδ T cells exhibit innate and adaptive antitumor activities in preclinical B-cell lymphoma models.

OBJECTIVES: Autologous chimeric antigen receptor (CAR) αß T-cell therapies have demonstrated remarkable antitumor efficacy in patients with haematological malignancies; however, not all eligible cancer patients receive clinical benefit. Emerging strategies to improve patient access and clinical responses include using premanufactured products from healthy donors and alternative cytotoxic effectors possessing intrinsic tumoricidal activity as sources of CAR cell therapies. γδ T cells, which combine innate and adaptive mechanisms to recognise and kill malignant cells, are an attractive candidate platform for allogeneic CAR T-cell therapy. Here, we evaluated the manufacturability and functionality of allogeneic peripheral blood-derived CAR+ Vδ1 γδ T cells expressing a second-generation CAR targeting the B-cell-restricted CD20 antigen. METHODS: Donor-derived Vδ1 γδ T cells from peripheral blood were ex vivo-activated, expanded and engineered to express a novel anti-CD20 CAR. In vitro and in vivo assays were used to evaluate CAR-dependent and CAR-independent antitumor activities of CD20 CAR+ Vδ1 γδ T cells against B-cell tumors. RESULTS: Anti-CD20 CAR+ Vδ1 γδ T cells exhibited innate and adaptive antitumor activities, such as in vitro tumor cell killing and proinflammatory cytokine production, in addition to in vivo tumor growth inhibition of B-cell lymphoma xenografts in immunodeficient mice. Furthermore, CD20 CAR+ Vδ1 γδ T cells did not induce xenogeneic graft-versus-host disease in immunodeficient mice. CONCLUSION: These preclinical data support the clinical evaluation of ADI-001, an allogeneic CD20 CAR+ Vδ1 γδ T cell, and a phase 1 study has been initiated in patients with B-cell malignancies (NCT04735471).

Replication study: Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET.

As part of the Reproducibility Project: Cancer Biology we published a Registered Report (Lesnik et al., 2016) that described how we intended to replicate selected experiments from the paper 'Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET' (Peinado et al., 2012). Here we report the results. We regenerated tumor cells stably expressing a short hairpin to reduce Met expression (shMet) using the same highly metastatic mouse melanoma cell line (B16-F10) as the original study, which efficiently downregulated Met in B16F10 cells similar to the original study (Supplementary Figure 5A; Peinado et al., 2012). Exosomes from control cells expressed Met, which was reduced in exosomes from shMet cells; however, we were unable to reliably detect phosphorylated Met in exosomes. We tested the effect of exosome-dependent Met signaling on primary tumor growth and metastasis. Similar to the results in the original study, we did not find a statistically significant change in primary tumor growth. Measuring lung and femur metastases, we found a small increase in metastatic burden with exosomes from control cells that was diminished when Met expression was reduced; however, while the effects were in the same direction as the original study (Figure 4E; Peinado et al., 2012), they were not statistically significant. Differences between the original study and this replication attempt, such as level of knockdown efficiency, cell line genetic drift, sample sizes, study endpoints, and variability of observed metastatic burden, are factors that might have influenced the outcomes. Finally, we report meta-analyses for each result.

Viral Cre-LoxP tools aid genome engineering in mammalian cells.

BACKGROUND: Targeted nucleases have transformed genome editing technology, providing more efficient methods to make targeted changes in mammalian genome. In parallel, there is an increasing demand of Cre-LoxP technology for complex genome manipulation such as large deletion, addition, gene fusion and conditional removal of gene sequences at the target site. However, an efficient and easy-to-use Cre-recombinase delivery system remains lacking. RESULTS: We designed and constructed two sets of expression vectors for Cre-recombinase using two highly efficient viral systems, the integrative lentivirus and non-integrative adeno associated virus. We demonstrate the effectiveness of those methods in Cre-delivery into stably-engineered HEK293 cells harboring LoxP-floxed red fluorescent protein (RFP) and puromycin (Puro) resistant reporters. The delivered Cre recombinase effectively excised the floxed RFP-Puro either directly or conditionally, therefore validating the function of these molecular tools. Given the convenient options of two selections markers, these viral-based systems offer a robust and easy-to-use tool for advanced genome editing, expanding complicated genome engineering to a variety of cell types and conditions. CONCLUSIONS: We have developed and functionally validated two viral-based Cre-recombinase delivery systems for efficient genome manipulation in various mammalian cells. The ease of gene delivery with the built-in reporters and inducible element enables live cell monitoring, drug selection and temporal knockout, broadening applications of genome editing.

An Optimized Protocol for Packaging Pseudotyped Integrase Defective Lentivirus.

BACKGROUND: A number of integrase defective lentiviral (IDLV) packaging systems have been developed to produce integration deficient lentiviruses for gene delivery and epichromosomal expression. However, despite their growing demand, a comparative study to systemically evaluate the performance efficiency of different mutants on virus packaging and gene expression has not been done. RESULTS: Site-directed mutagenesis was used to generate five integrasedeficient mutants for non-integrative lentiviral packaging (NILVP). The five mutants were then individually incorporated to make different integrase defective lentivirus plasmid packaging mix, keeping other packaging factors constant. CD511B-1, a lentivectorexpressing GFP from an EF1 promoter, was packaged with each of the five different lentivirus packaging mix to make pseudotypedviral particles. The performance and packaging efficiency of each of the integrase deficient mutants was evaluated based on GFP expression in HT1080 cells, while the wild type lentivirus packaging mix was used as a control. Of the five integrase mutant candidates, one with the highestGFP transgene expression level was chosen for further characterization. The non-integrative nature of this candidate was confirmed by quantitative polymerase chain reaction and characterized using both dividing and non-dividing cells. Finally, a detailed standard protocol for NILVP using this integrase defective mutant was developed. CONCLUSIONS: An efficient lentiviral packaging system for producing on-integrative lentivirus was established. This system is compatible with most existing lentivectors and can be used to transduce both dividing and non-dividing cells.

Lactobacillus fermentum AGR1487 cell surface structures and supernatant increase paracellular permeability through different pathways.

Lactobacillus fermentum is commonly found in food products, and some strains are known to have beneficial effects on human health. However, our previous research indicated that L. fermentum AGR1487 decreases in vitro intestinal barrier integrity. The hypothesis was that cell surface structures of AGR1487 are responsible for the observed in vitro effect. AGR1487 was compared to another human oral L. fermentum strain, AGR1485, which does not cause the same effect. The examination of phenotypic traits associated with the composition of cell surface structures showed that compared to AGR1485, AGR1487 had a smaller genome, utilized different sugars, and had greater tolerance to acid and bile. The effect of the two strains on intestinal barrier integrity was determined using two independent measures of paracellular permeability of the intestinal epithelial Caco-2 cell line. The transepithelial electrical resistance (TEER) assay specifically measures ion permeability, whereas the mannitol flux assay measures the passage of uncharged molecules. Both live and UV-inactivated AGR1487 decreased TEER across Caco-2 cells implicating the cell surfaces structures in the effect. However, only live AGR1487, and not UV-inactivated AGR1487, increased the rate of passage of mannitol, implying that a secreted component(s) is responsible for this effect. These differences in barrier integrity results are likely due to the TEER and mannitol flux assays measuring different characteristics of the epithelial barrier, and therefore imply that there are multiple mechanisms involved in the effect of AGR1487 on barrier integrity.

The role of cell surface architecture of lactobacilli in host-microbe interactions in the gastrointestinal tract.

Lactobacillus species can exert health promoting effects in the gastrointestinal tract (GIT) through many mechanisms, which include pathogen inhibition, maintenance of microbial balance, immunomodulation, and enhancement of the epithelial barrier function. Different species of the genus Lactobacillus can evoke different responses in the host, and not all strains of the same species can be considered beneficial. Strain variations may be related to diversity of the cell surface architecture of lactobacilli and the bacteria's ability to express certain surface components or secrete specific compounds in response to the host environment. Lactobacilli are known to modify their surface structures in response to stress factors such as bile and low pH, and these adaptations may help their survival in the face of harsh environmental conditions encountered in the GIT. In recent years, multiple cell surface-associated molecules have been implicated in the adherence of lactobacilli to the GIT lining, immunomodulation, and protective effects on intestinal epithelial barrier function. Identification of the relevant bacterial ligands and their host receptors is imperative for a better understanding of the mechanisms through which lactobacilli exert their beneficial effects on human health.

Packaging HIV- or FIV-based lentivector expression constructs and transduction of VSV-G pseudotyped viral particles.

As with standard plasmid vectors, it is possible to transfect lentivectors in plasmid form into cells with low-to-medium efficiency to obtain transient expression of effectors. Packaging lentiviral expression constructs into pseudoviral particles, however, enables up to 100% transduction, even with difficult-to-transfect cells, such as primary, stem, and differentiated cells. Moreover, the lentiviral delivery does not produce the specific cellular responses typically associated with chemical transfections, such as cell death resulting from toxicity of the transfection reagent. When transduced into target cells, the lentiviral construct integrates into genomic DNA and provides stable expression of the small hairpin RNA (shRNA), cDNA, microRNA or reporter gene. Target cells stably expressing the effector molecule can be isolated using a selectable marker contained in the expression vector construct such as puromycin or GFP. After pseudoviral particles infect target cells, they cannot replicate within target cells because the viral structural genes are absent and the long terminal repeats (LTRs) are designed to be self-inactivating upon transduction. There are three main components necessary for efficient lentiviral packaging. 1. The lentiviral expression vector that contains some of the genetic elements required for packaging, stable integration of the viral expression construct into genomic DNA, and expression of the effector or reporter. 2. The lentiviral packaging plasmids that provide the proteins essential for transcription and packaging of an RNA copy of the expression construct into recombinant pseudoviral particles. This protocol uses the pPACK plasmids (SBI) that encode for gag, pol, and rev from the HIV or FIV genome and Vesicular Stomatitis Virus g protein (VSV-G) for the viral coat protein. 3. 293TN producer cells (derived from HEK293 cells) that express the SV40 large T antigen, which is required for high-titer lentiviral production and a neomycin resistance gene, useful for reselecting the cells for maintenance. An overview of the viral production protocol can be seen in Figure 1. Viral production starts by co-transfecting 293TN producer cells with the lentiviral expression vector and the packaging plasmids. Viral particles are secreted into the media. After 48-72 hours the cell culture media is harvested. Cellular debris is removed from the cell culture media, and the viral particles are precipitated by centrifugation with PEG-it for concentration. Produced lentiviral particles are then titered and can be used to transduce target cells. Details of viral titering are not included in this protocol, but can be found at: http://www.systembio.com/downloads/global_titer_kit_web_090710.pdf. This protocol has been optimized using the specific products indicated. Other reagents may be substituted, but the same results cannot be guaranteed.

New, simple echocardiographic indexes for the estimation of filling pressure in patients with cardiac disease and preserved left ventricular ejection fraction.

BACKGROUND: There are few data on echocardiographic indexes incorporating peak mitral inflow velocity (E), left atrial volume index (LAVi), and pulmonary artery pressure (PAP) for estimation of left ventricular (LV) filling pressure in patients with preserved LV ejection fraction (EF ≥ 50%). METHODS: Patients underwent echocardiography ≤20 minutes of cardiac catheterization. Echocardiographic variables were compared to invasively measured LV end-diastolic pressure (LVEDP). RESULTS: Of the 122 patients, 67 (55%) were women, the mean age was 55 ± 9 years, the mean left ventricular ejection fraction (LVEF) was 61 ± 6%, 107 (88%) were hypertensive, and 79 (65%) had significant coronary artery disease at catheterization. E/Ea correlated with LVEDP (R = 0.68, P < 0.0001), compared to PAP (R = 0.53, P < 0.001), peak E velocity (R = 0.48, P < 0.001), and LAVi (R = 0.48, P < 0.001). E/Ea > 12 had 75% sensitivity and 78% specificity for LVEDP ≥ 20 mmHg (area under curve (AUC) = 0.79, P < 0.0001), compared with (PAP + LAVi)/2 > 30 (sensitivity = 72%, specificity = 80%, AUC = 0.84, P < 0.001) and (E + LAVi)/2 > 57 (sensitivity = 73% and specificity = 81%, AUC = 0.82, P < 0.001) (P = NS). E <60 cm/sec had 94% negative, and E>90 cm/sec had 96% positive, predictive value for LVEDP ≥ 20 mmHg. (E + LAVi)/2 added incrementally to E/Ea when E/Ea was in the gray zone. CONCLUSIONS: New, simple echocardiographic equations, (E + LAVi)/2 and (PAP + LAVi)/2, have comparable accuracy to E/Ea for LVEDP estimation in patients with cardiac disease and preserved LVEF, and (E + LAVi)/2 added incrementally to E/Ea alone when E/Ea was in the gray zone. Peak E velocity alone had high negative and positive predictive value for elevated LVEDP in this population. These simple echocardiographic variables could be used-in isolation or with E/Ea-in patients with cardiac disease and preserved LVEF for the diagnosis of diastolic heart failure.

Do additional echocardiographic variables increase the accuracy of E/e' for predicting left ventricular filling pressure in normal ejection fraction? An echocardiographic and invasive hemodynamic study.

BACKGROUND: There are few data on adding left atrial volume index (LAVi) or pulmonary artery systolic pressure (PAP) to the ratio of early mitral inflow to mitral annular velocity (E/e') for the estimation of left ventricular (LV) filling pressure in patients with preserved LV ejection fractions (LVEFs) (>50%). METHODS: Patients underwent echocardiography within 20 minutes of cardiac catheterization. Echocardiographic variables were compared with invasively measured LV preatrial contraction pressure (pre-A). RESULTS: Of the 122 patients studied (mean age, 55 +/- 9 years; mean LVEF, 61 +/- 6%), 67 (55%) were women, 108 (88%) had hypertension, and 79 (65%) had significant coronary artery disease at catheterization. E/e' was significantly correlated with pre-A (R = 0.63, P < .0001) compared with LAVi (R = 0.49, P < .001) and PAP (R = 0.48, P < .001). E/e' > 13 had sensitivity of 70% and specificity of 93% (area under the curve [AUC], 0.82; P < .0001), LAVi > 31 mL/m2 had sensitivity of 78% and specificity of 76% (AUC, 0.80, P < .001), and PAP > 28 mm Hg had sensitivity of 80% and specificity of 64% for pre-A > 15 mm Hg (AUC, 0.77, P < .001). Adding LAVi >31 mL/m2 for E/e' = 8 to 13 significantly increased the accuracy of E/e' > 13 alone (sensitivity, 87%; specificity, 88%; AUC, 0.89; P = .01 for comparison). However, adding PAP > 28 mm Hg for E/e' = 8 to 13 did not significantly increase the accuracy of E/e' > 13 alone (AUC, 0.82; sensitivity, 82%; specificity, 72%; P = NS for comparison). CONCLUSIONS: In patients with preserved LVEFs, adding LAVi > 31 mL/m2 to E/e' (when E/e' was in the gray zone, but not when E/e' was >13) significantly increased the accuracy of E/e' alone for the estimation of LV filling pressure. These data support the notion of using several, rather than any single, Doppler echocardiographic parameter for the accurate assessment of LV diastolic function.

Correlation of tissue Doppler and two-dimensional speckle myocardial velocities and comparison of derived ratios with invasively measured left ventricular filling pressures.

BACKGROUND: There are a paucity of data comparing spectral and color tissue Doppler (TD) with non-Doppler, speckle-based myocardial velocities, and it is unknown how early transmitral diastolic velocity/mitral annular velocity (E/Ea) calculated using speckle velocities compares with TD-derived E/Ea. METHODS: We measured systolic (Sa), Ea, and late diastolic (Aa) myocardial velocities using these 3 methods and compared calculated E/Ea with invasively measured left ventricular (LV) hemodynamics. Consecutive patients referred for cardiac catheterization were imaged, and LV pre-A contraction pressure was measured by retrograde aortic cardiac catheterization. RESULTS: Fifty patients (22 women, 44%) were studied with a mean age of 54 +/- 10 years and a mean LV ejection fraction of 48% +/- 19%. Speckle and color TD Sa, Ea, and Aa were significantly lower than spectral TD velocities, resulting in higher E/Ea values compared with spectral TD E/Ea. Spectral TD E/Ea (R = 0.65, P < .001), color TD E/Ea (R = 0.69, P < .001), and speckle E/Ea (R = 0.76, P < .001) all correlated with LV pre-A pressure. Different cutoff values were needed for spectral TD, color TD, and speckle E/Ea to predict LV pre-A pressure >or= 15 mm Hg; spectral E/Ea > 14 (area under the curve [AUC] = 0.87, P < .001, sensitivity = 83%, specificity = 77%), color E/Ea > 16 (AUC = 0.89, P < .0001, sensitivity = 79%, specificity = 81%), and speckle E/Ea > 18 (AUC = 0.87, P < .0001, sensitivity = 88%, specificity = 74%; P = not significant for comparisons between the groups). CONCLUSION: Spectral TD, color TD, and speckle imaging measure different velocities, and consequently different cutoff values are needed for E/Ea to predict invasively measured LV filling pressure.

Hydrolyzed casein influences intestinal mucin gene expression in the rat.

The effect of hydrolyzed casein (HC) on the expression of three mucin genes (Muc2, Muc3, and Muc4) in the rat intestine was investigated using quantitative real-time polymerase chain reaction. After a 10 day acclimatization period, rats received for 8 days the test diets containing either HC or a synthetic amino acid (SAA) mixture as the sole source of nitrogen or a protein-free (PF) diet (n = 12 per treatment). The addition of HC or the SAA mixture to the diet significantly improved average daily gain, average daily food intake, and gain:feed ratio as compared with the PF diet. Terminal ileal endogenous N flow was significantly higher for the HC-fed rats in comparison with either the SAA or the PF rats (p < or = 0.001). HC supported a significant increase of Muc3 mRNA (277 and 229% of that for diets PF and SAA, respectively; p < or = 0.05) in the small intestinal tissue and Muc4 mRNA (325 and 265% of that for diets PF and SAA, respectively; p < or = 0.05) in the colon. In conclusion, HC enhances ileal endogenous N flow and up-regulates in vivo the expression of some individual mucin genes.

Assessment of left ventricular systolic function using echocardiography in patients with preserved ejection fraction and elevated diastolic pressures.

There is controversy regarding the nature of systolic function in patients with elevated filling pressure and preserved left ventricular (LV) ejection fraction. In this study, tissue Doppler variables and 2-dimensional echocardiographic systolic strain (SS) and systolic strain rate (SSr) were measured in patients who underwent cardiac catheterization to determine correlations with invasively measured LV end-diastolic pressure (LVEDP), dP/dt, and LV mass. Forty patients were studied. Their mean age was 55.9+/-9.9 years, and their mean LV ejection fraction was 59.8+/-5.2%. Tissue Doppler systolic annular velocity (5.4+/-1.1 vs 6.4+/-1.0 cm/s, p=0.04), SS (13.4+/-3.7% vs 18.8+/-2.3%, p <0.001), and SSr (0.73+/-0.17 vs 0.98+/-0.14 s(-1), p <0.001) were significantly lower in patients with LVEDP >20 mm Hg compared with those with LVEDP <20 mm Hg. Tissue Doppler systolic velocity, SSr, and SS were correlated with LV mass (R=0.58, R=0.57, and R=0.52, respectively, all p values <0.001) and with LVEDP (R=0.49, p=0.002; R=0.79, p<0.001; and R=0.70, p<0.001, respectively). However, dP/dt was not significantly different between patients with LVEDP >20 mm Hg and those with LVEDP <20 mm Hg (1,387+/-520 vs 1,495+/-594 mm Hg/s, respectively, p=0.55) and was not correlated with LV mass (R=0.18, p=0.25). The optimum cut-off values for LVEDP >20 mm Hg were SSr <0.85 s(-1) (area under the curve 0.88, p<0.001, positive predictive value 89%, negative predictive value 86%) and SS<16% (area under the curve 0.84, p=0.002, positive predictive value 88%, negative predictive value 79%). In conclusion, as opposed to invasively measured dP/dt, tissue Doppler systolic velocity and 2-dimensional echocardiographic SS and SSr are significantly depressed in patients with preserved LV ejection fraction and LVEDP >20 mm Hg, suggesting that systolic abnormalities are present in at least some of these patients. These differences are likely because invasively measured dP/dt and these echocardiographic variables measure different systolic properties in patients with preserved LV ejection fraction.

Usefulness of new diastolic strain and strain rate indexes for the estimation of left ventricular filling pressure.

Tissue Doppler indexes of left ventricular (LV) filling pressure are prone to angulation errors and tethering and are less reliable in patients with preserved LV ejection fraction and indeterminate early peak transmitral diastolic flow (E)/mitral early diastolic velocity (Ea) (8 or =8 had higher sensitivity and specificity (95% and 94%, respectively; area under the curve = 0.96, p <0.0001) than E/Ea > or =15 (sensitivity 81%, specificity 75%; area under the curve = 0.85, p <0.0001) for the prediction of LV pre-A pressure > or =15 mm Hg (p = 0.01 for comparison). In patients with LV ejection fraction > or =50% and 8 or =50% or indeterminate E/Ea, both E/Ds and E/10DSr (a ratio based on global DSR) were better predictors of LV filling pressure than E/Ea.

Usefulness of B-type natriuretic peptide levels to predict left ventricular filling pressures in patients with body mass index >35, 31 to 35, and < or =30 kg/m2.

Noninvasive left ventricular (LV) pressure estimation in obese patients has not been well described. Simultaneous B-type natriuretic peptide (BNP) and echocardiographic Doppler examinations were performed in patients with dyspnea undergoing cardiac catheterization. Patients were divided into body mass index (BMI) >35 (markedly obese), 31 to 35 (obese), and < or =30 kg/m2 (nonobese). BNP levels and mitral early diastolic/tissue Doppler annular velocity (E/Ea) were compared with invasively measured LV end-diastolic and pre-atrial (pre-A) pressures. Seventy-two patients were studied. Except for BMI, LV mass index, and LV diastolic dimension, there were no significant differences in baseline, echocardiographic Doppler, or hemodynamic characteristics among the groups. However, BNP was significantly lower in markedly obese compared with obese and nonobese patients (116 +/- 187 vs 241 +/- 674 and 277 +/- 352 pg/ml, respectively; p = 0.03). BNP did not correlate with LV pre-A pressure in markedly obese patients (R = 0.13, p = 0.47), whereas BNP significantly correlated with this variable in the obese (R = 0.64) and nonobese (R = 0.58) groups. Mitral E/Ea significantly correlated with LV pre-A and LV end-diastolic pressures in all BMI groups. In markedly obese patients with dyspnea, BNP did not correlate with invasively measured LV filling pressure, whereas this correlated in obese and nonobese patients. However, mitral E/Ea significantly correlated with LV filling pressures in all BMI groups. In conclusion, BNP is not recommended for LV filling pressure estimation in ambulatory patients with dyspnea with BMI >35 kg/m2.

Usefulness of right ventricular tissue Doppler imaging to predict outcome in left ventricular heart failure independent of left ventricular diastolic function.

It is unknown whether right ventricular (RV) tissue Doppler (TD) predicts outcome in patients with left ventricular (LV) heart failure (HF) independently of contemporary echocardiographic Doppler variables of LV diastolic function. Comprehensive echocardiographic Doppler examination was performed before discharge in 107 patients hospitalized with LV HF. The primary end point was cardiac death or rehospitalization for HF. Follow-up was complete for 100 of 107 patients a mean of 527 days after hospital discharge. There were no significant differences in baseline clinical variables (mean age 58+/-12 years, 46% women, 77% hypertensive, 48% diabetic, 41% current smokers, and 23% known coronary artery disease) in prediction of the primary end point. Compared with patients without an event, patients with an event had a larger left atrial volume index (42+/-16 vs 33+/-13 ml/m2, p=0.001), lower LV ejection fraction (35+/-19% vs 46+/-22%, p=0.01), higher mitral peak early diastolic flow velocity/TD early diastolic velocity (19+/-7 vs 14+/-7, p=0.001), lower RV fractional area change (39+/-11% vs 43+/-10%, p=0.04), and lower RV TD systolic velocity (8+/-2 vs 10+/-3 cm/s, p=0.005). On Cox proportional hazards multivariate analysis, left atrial volume index (p=0.01), mitral peak early diastolic flow velocity/TD early diastolic velocity (p=0.03), and RV TD systolic velocity (p=0.04) were independent predictors of outcome. Even when contemporary echocardiographic Doppler measures of LV diastolic function are considered, RV TD systolic velocity is an independent predictor of cardiac death or rehospitalization for HF in patients hospitalized with HF and appears to be superior to conventional 2-dimensional parameters of RV function.

Atrial pacing stress echocardiography: an alternative diagnostic test for chest pain in the elderly.

The authors utilized rapid right atrial pacing and handgrip exercise to provoke myocardial ischemia in 20 participants (age >65 years) who, for reasons of disability, were not candidates for exercise and pharmacologic stress testing. Echocardiographic left ventricular ejection fraction and left ventricular wall motions were obtained during pacing at baseline and at maximal pacing rates and were compared with coronary angiography. Using the failure of left ventricular ejection fraction to increase with pacing as an indicator of myocardial ischemia, the test yielded a sensitivity of 75%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 71%. When a pacing-induced decrease of wall-motion index was taken as an ischemia indicator, the sensitivity was 63%, specificity 100%, positive predictive value 100%, and negative predictive value 80%. Rapid atrial pacing echocardiography is a safe test. It may be considered in a select group of elderly patients as an alternative to exercise or pharmacologic tests before resorting to coronary angiography.