Late ventricular potential for risk prediction of sudden cardiac death risk: a valuable tool or an unnecessary step?

Background/Introduction

Signal-averaged electrocardiography (SA-ECG) is a high-resolution electrocardiography that can detect late ventricular potential, which known to be a noninvasive tool for risk stratification of sudden cardiac death (SCD) by predicting reentrant ventricular tachyarrhythmia. There is a paucity of data with SA-ECG on SCD survivors without structural heart disease, whereas majority of previous studies had been focused on post myocardial infarction survivors.

Purpose

This study assessed the clinical utility of SA-ECG as a risk stratification modality for lethal arrhythmic event in patients at risk of SCD without definite structural heart disease.

Methods

Total 629 patients who experienced or had potential risk of SCD were studied with SA-ECG. Among them, 48 patients who were found to have significant structural heart disease were excluded, except arrhythmogenic right ventricular cardiomyopathy. Major arrhythmic event (MAE) was defined as composite of all-cause death, aborted SCD, and sustained VT during any time either before visit of clinic or during follow up period. Syncope and non-sustained VT was defined as non-major arrhythmic event. SA-ECG was defined positive when fulfilling three or more criterion: (1) unfiltered QRS duration ≥114ms, (2) filtered QRS duration ≥114ms, (3) duration of terminal QRS <40uV exceeding 40ms, and (4) root mean square voltage in the terminal 40ms of ≤20ms.

Results

Among total 581 patients, 145 patients with positive SA-ECG showed higher incidence of MAE compared to patients with negative SA-ECG (21.4% vs. 6.7%, OR 3.816 [95% CI 2.208–6.597], p<0.001, Table). As the number of positive SA-ECG criteria increases, incidence of MAE tended to increase sequentially, which was markedly noted from 2 positive to 3 positive criteria (10.7% to 20.8%, p<0.001, Figure). In particular, patient with inherited arrhythmia showed higher rate of positive late potential compared to those with non-inherited arrhythmia (51.0% vs. 19.3%, p<0.001).

Conclusion

This study showed that at least 3 out of 4 diagnostic criteria in SA-ECG can independently predict lethal arrhythmic events and the positive late potential was associated with lethal arrhythmic event that leads to SCD, suggesting risk prediction for SCD using SA-ECG in patients even without structural heart disease including inherited arrhythmias.

Funding Acknowledgement

Type of funding sources: None.

Clinical role of genetic testing for overlapping between Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy

Background/Introduction

Brugada syndrome (BrS) and arrhythmogenic right ventricular cardiomyopathy (ARVC) are inherited arrhythmias that may predispose to sudden cardiac arrest. Although its pathogenetic mechanisms differ, overlapping features between BrS and ARVC have been demonstrated previously. However, it remains to be determined whether genetic testing for ARVC-related gene is needed in patients with BrS.

Purpose

This study is aimed to analyze genetic profiles of BrS patients using next generation sequencing (NGS) based multigene panel including ARVC related genes.

Methods

Patients who were confirmed as BrS or clinically suspected as BrS with type 2 or 3 Brugada pattern electrocardiography were studied. Genetic testing using NGS panels (Illumina Inc., San Diego, CA, USA) included 30 genetic variants associated with inherited arrhythmia and genetic cardiomyopathy.

Results

Among the total 119 patients from BrS registry, 63 patients were confirmed as BrS and 56 patients were clinically suspected as BrS without fulfilling diagnostic criteria. One-hundred-fourteen patients (95.8%) were male, and mean age of onset was 43.6 year-old. Genetic variants were identified in 25 of 42 patients who received genetic testing. Six out of 25 patients (24.0%) showed ARVC-related genotypes (2 PKP2, 1 DSG2, 1 TMEM43, 1 JUP, and 1 DSP) (Figure 1 and Table 1). None of the patients showed structural or electrocardiographic features that fulfill diagnostic criteria of ARVC. It is notable that ARVC-related genotypes were mostly frequently accounted for BrS patients, following SCN5A and SCN10A.

Conclusion

In the clinic setting, ARVC-related genetic variants were identified in significant proportion of BrS patients, supporting that genetic testing of ARVC-overlapping is needed. This study suggests that follow-up including imaging study should be considered in BrS patients with ARVC-related genotypes to monitor disease progression as ARVC.

Funding Acknowledgement

Type of funding sources: None.

Development and validation of a predictive model for foodborne pathogens in ready-to-eat pork as a function of temperature and a mixture of potassium lactate and sodium diacetate

We developed and validated secondary models that can predict growth parameters of Salmonella Typhimurium and Staphylococcus aureus in cooked-pressed ready-to-eat (RTE) pork as a function of concentrations (0 to 3%) of a commercial potassium lactate and sodium diacetate mixture (PL+SDA) and temperature (10 to 30°C). The primary growth data were fitted to a Gompertz equation to determine the lag time (LT) and growth rate (GR). At 10°C, the growth of Salmonella Typhimurium and S. aureus in cooked-pressed RTE pork containing 2% and 3% PL+SDA was completely inhibited. The effects of temperature and concentration of PL+SDA on the growth kinetics of Salmonella Typhimurium and S. aureus in cooked-pressed RTE pork were modeled by response surface analysis using polynomial models of the natural logarithm transformation of both LT and GR. Model performance was also evaluated by use of the prediction bias (B(f)) and accuracy (A(f)) factors, median relative error, and mean absolute relative error, as well as the acceptable prediction zone method. The results showed that LT and GR models of Salmonella Typhimurium and S. aureus in cooked-pressed RTE pork are acceptable models. Thus, both the LT and GR growth models developed herein can be used for the development of tertiary models for Salmonella Typhimurium and S. aureus in cooked-pressed RTE pork in the matrix of conditions described in the present study.

A model of the effect of temperature on the growth of pathogenic and nonpathogenic Vibrio parahaemolyticus isolated from oysters in Korea

Vibrio parahaemolyticus is recognized as the leading cause of human gastroenteritis associated with the consumption of seafood. The objective of this study was to model the growth kinetics of pathogenic and nonpathogenic V. parahaemolyticus in broth and oyster slurry. Primary growth models of V. parahaemolyticus in broth and oyster slurry fit well to a modified Gomperz equation (broth R(2)=0.99; oyster slurry R(2)=0.96). The lag time (LT), specific growth rate (SGR), and maximum population density (MPD) of each primary model were compared. The growth of nonpathogenic V. parahaemolyticus was found to be more rapid than that of pathogenic V. parahaemolyticus, regardless of the model medium. In addition, significant (P<0.05) differences in the growth kinetics between pathogenic and nonpathogenic V. parahaemolyticus in broth were observed at 10 degrees C. When compared to growth in broth, the growth of V. parahaemolyticus was delayed in oyster slurry, and growth was not observed at 10 or 15 degrees C. The Davey and square root models were identified as appropriate secondary models for predicting the LT and SGR, respectively. For the broth model, the average B(f) and A(f) values for LT were found to be 0.97 and 1.3, respectively, whereas the average B(f) and A(f) values for SGR were 1.05 and 1.11, respectively. The model generated in this study predicted an LT that was shorter and an SGR that was similar to those that were actually observed, which indicates that these models provide a reliable and safe prediction of V. parahaemolyticus growth.

Apolipoprotein E genotype in Korean schizophrenic patients

The apolipoprotein E (APOE) epsilon4 allele is a known risk factor for the development of Alzheimer's disease, however, an association of the APOE genotype with schizophrenia is controversial. We investigated the association in 60 Korean schizophrenic patients and 60 healthy controls. APOE genotypes were identified by reverse hybridization-based line probe assay. There were significant differences in the distribution of APOE genotypes between schizophrenic patients and controls. APOE epsilon2 and epsilon3 allele frequencies in schizophrenic patients were significantly different from those in controls. Our results suggest that APOE alleles seem to be operative in the pathogenesis of schizophrenic disorders.

Analysis of the immunologic mechanism of intravesical bacillus Calmette-Guerin therapy for superficial bladder tumors: distribution and function of immune cells

Intravesical bacillus Calmette-Guerin (BCG) administration has been used as an adjuvant therapy after transurethral resection for superficial bladder cancer, but the exact mechanisms of its antitumor activity are not yet known. The aim of this study was to characterize the immunologic aspects of antitumor activity of BCG using an animal model. C3H/He inbred mice and murine bladder tumor cell line, MBT-2 were used. The changes in immune cells such as helper T cells, suppressor T cells, macrophages and natural killer cells in the bladder and spleen were analysed by immunohistochemical method in intravesical BCG instilled in normal bladder, MBT-2 implanted after electrocauterization of the bladder mucosa and MBT-2 implanted and intravesical BCG treated group. The changes in natural killer cell activity of the splenocytes and peritoneal lymphocytes were evaluated using 51chromium release assay at regular time intervals following intraperitoneal BCG instillation. The prophylactic anticancer effect was evaluated by observing the tumor growth in the intravesically BCG treated group after intravesical MBT-2 implantation. In immunohistochemical examination, a remarkable infiltration of macrophage and helper T cell was observed in the lamina propria of the bladder, and the helper and suppressor T cells ratio (Th/Ts ratio) was increased after intravesical BCG therapy. In 51chromium release assay, enhanced natural killer cell activity of the splenocytes and peritoneal lymphocytes was observed after intraperitoneal BCG inoculation. The growth of implanted tumor was suppressed following intravesical instillation of BCG. These results suggest that the antitumor activity of BCG is not related to the simple inflammatory reaction but to the local and systemic immune response in which helper T lymphocytes and mononuclear cells play an important role.