P1111Arrhythmogenic substrate detection in ischemic patients undergoing ventricular tachycardia ablation using multi-detector computed tomography: compared evaluation with cardiac magnetic resonance

Background

 Cardiac magnetic resonance (CMR) is capable of accurately identifying arrhythmogenic substrate (AS), leading to longer arrhythmia-free survival when used to guide ventricular tachycardia (VT) substrate ablation procedures. However, the use of CMR may be limited in certain centers or patient subsets. 

Purpose

 To evaluate the performance of multidetector cardiac computed tomography (MDCT) imaging in identifying heterogeneous tissue channels (HTCs) detected by CMR in ischemic patients undergoing VT substrate ablation.

Methods

 Thirty ischemic patients undergoing both CMR and MDCT before VT substrate ablation were included. Using a dedicated post-processing software, two blinded operators, assigned either to CMR or MDCT analysis, characterized the presence of CMR- and CT-channels, respectively. CMR-channels were classified as endocardial (layers <50%), epicardial (layers ≥50%) or transmural. CMR- vs. CT-channel concordance was considered when the orientation was the same and they were located in the same AHA segment.

Results

 Mean age was 69 ± 10 years; 90% were male. Mean left ventricular ejection fraction (LVEF) was 35 ± 10%. All patients had CMR-channels (n = 76), whereas only 26/30 (86.7%) had CT-channels (n = 91). Global sensitivity (Se) and positive predictive values (PPV) for detecting CMR-channels were 61.8% and 51.6%, respectively. MDCT performance improved in patients with epicardial CMR-channels (Se 80.5%), and transmural scars (Se 72.2%). In 4/11 (36%) patients with subendocardial MI, MDCT was unable to identify the AS.

Conclusion

 MDCT fails to detect the presence of AS in 36% of patients with subendocardial MI and shows a modest sensitivity identifying the presence of HTCs, although its performance improves in patients with transmural scar.

Abstract Figure. Multimodality imaging AS detection

P1106Fundamental differences and predictors of scar arrhythmogenicity in ischemic patients using cardiac magnetic resonance: a propensity score-matching study

Introduction

 Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) permits to identify the arrhythmogenic substrate (AS) in ischemic patients. However, it is unknown why the majority of them never develop ventricular tachycardias (VT), irrespectively of their left ventricular ejection fraction (LVEF). 

Purpose

 To characterize the fundamental differences and potential predictors of scar arrhythmogenicity in post-myocardial infarction (MI) patients with and without VT.

Methods

 36 consecutive ischemic patients with no arrhythmia evidence underwent a LGE-CMR study 4 years after the MI (controls). Scar data were compared with those obtained from 49 ischemic patients referred for VT substrate ablation (cases). Propensity score matching (PSM) was performed to adjust for age, LVEF, scar mass, and time from MI. The myocardium was segmented in 10 layers (endo- to epicardium), characterizing the core, border zone (BZ) and BZ channels (BZCs) using a dedicated post-processing software.

Results

 Compared to controls, cases were significantly older (67.3 ± 9.1 vs. 56.5 ± 11), had lower LVEF (33.1 ± 10.1 vs. 51 ± 9.4), greater scar mass (33.9 ± 17.2 vs. 14.2 ± 11.6 g), BZ mass (21.1 ± 9.9 vs. 9.6 ± 7.6 g), core mas (12.6 ± 8.8 vs. ± g), number of BZC (2.9 ± 1.4 vs. 1.1 ± 1.1) and BZC mass (10.5 ± 4.2 vs. 2.3 ± 2.4 g) (p < 0.001 in all cases). After PSM (2:1) adjustment[BJG1] , cases had more BZCs (2.9 ± 1.4 vs. 2.2 ± 0.6; p = 0.01) and a greater BZC mass (10.5 ± 4.2 vs. 4.6 ± 2.6 g; p < 0.001). In the multivariable logistic regression analysis, the BZC mass was the only independent predictor of being a case [OR 2.3 (1.5–3.4); p < 0.001]. Receiver operating characteristic curve analysis identified a cut-off point of BZC mass >4.28 g (AUC 0.98; p < 0.001), showing 100% sensitivity and 91% specificity for cases’ discrimination.

Conclusions

 Compared with the cases, an otherwise similar control group (PS-matched for age, LVEF, scar mass, and time from MI) showed fewer BZC and a reduced BZC mass. BZC mass was the only independent predictor of being a case. A BZC mass cut-off point of > 4.28 g showed a 100% sensitivity and 91% specificity for the identification of ischemic patients with documented VT.

Abstract Figure. Mean BZC mass and ROC curve analysis

125Manual vs. automatic local activation time annotation for guiding premature ventricular complex ablation procedures (MANIaC - PVC study)

Funding Acknowledgements

Financial support was provided in form of a research grant from Biosense Webster

Introduction

 The use of an algorithmic method (wavefront, WF) based on automatic annotation of the maximal negative slope of the unipolar electrogram (uni-EGM) within the window demarcated by the bipolar EGM (bi-EGM) may accurately identify the earliest activation site (EAS) during premature ventricular complex (PVC) ablation procedures.

Purpose

 To assess the potential benefits of a local activation time (LAT) automatic acquisition protocol using WF plus an automatic algorithm for ECG pattern matching recognition (AUT-arm) instead of a manual LAT annotation plus ECG visual inspection (MAN-arm) during premature ventricular complexes (PVCs) ablation procedures.

Methods

 Prospective, randomized, controlled and international multicenter study (NCT03340922). 69 consecutive patients with indication for PVC ablation were enrolled and randomized to AUT (n = 34) or MAN (n = 35) annotation protocols using the CARTO3 navigation system. The primary endpoint was mapping success, defined as complete PVC abolition after a maximum of 2 radiofrequency (RF) applications or up to 90 seconds at the identified EAS, considered the site of origin (SOO). Complete PVC abolition was considered as the procedure success, whereas clinical success was defined as the PVC-burden reduction of >80% in the 24-h Holter at least 1 month after the procedure. Concordance analysis of the maps obtained with both methods was performed.

Results

 Mean age was 69 ± 15, 58% men. The mean baseline PVC burden was 26 ± 13%, mean LVEF 55 ± 12%. Baseline characteristics were similar between groups. The most frequent PVC-SOO were RVOT (41%), LV (25%; being the summit the most frequent location), and LVOT (16%), with no MAN-AUT differences. Total mapping time, number of RF applications, RF time, and procedure time were similar for both groups. The AUT-arm had a higher number of mapping points acquired (164 vs. 61; p = 0.002). There was a delayed detection of LAT at the EAS in the AUT-arm (mean 23 ± 13 ms), being more significant in left-sided PVCs (30 ± 12 vs. 15 ± 9 ms, p < 0.001). The 10-ms isochronal area was significantly bigger in the MAN-arm (1.95 ± 2.7 vs. 1.0 ± 1.0; p = 0.05). The median (interquartile range) distance between AUT-EAS and MAN-EAS was 4 (0–6.8) mm. Mapping success was similar for AUT (65%) and MAN (63%) (p = 1.0). Procedure success was significantly better for the AUT-arm (100% AUT vs. 86% MAN; p = 0.04), but without differences in clinical success (87% AUT vs. 82% MAN; p = 0.7). There were no procedure-related complications.

Conclusions

 The use of a complete automatic protocol for LAT annotation (WF + ECG pattern matching) during PVC ablation procedures is feasible and safe, allowing to achieve equivalent procedural and clinical endpoints as compared to manual procedures carried out by expert operators.

P1427 Mechanical dispersion assessed with echocardiography versus scar characterization with cardiac magnetic resonance to predict malignant arrhythmia in cardiac resynchronization therapy patients

Background

Recent data have shown that scar characterization with late gadolinium enhancement magnetic resonance (LGE-CMR) is useful to predict malignant arrhythmic events in a cardiac resynchronization therapy (CRT) population. On the other hand, echocardiography 2D strain parameters (such as mechanical dispersion – MD) have been recently suggested as a predictor of ventricular arrhythmia (VA).

Purpose

To compare the usefulness of strain echocardiography and MR scar parameters to predict VA and sudden cardiac death (SCD) in CRT patients (pa).

Methods

110 pa undergoing CRT implant were included. A 2D strain echo and a 3D LGE-CMR were performed before the implant. In the echocardiographic exam, left ventricle ejection fraction (LVEF), global longitudinal strain (GLS), mechanical dispersion (MD) and delta contraction time were quantified. Regarding LGE-CMR, scar mass, border zone (BZ) mass and the presence of BZ channels were assessed with specific software. The primary endpoint was the presence of SCD or appropriate implantable cardioverter-defibrillator therapy at long-term follow-up (FU).

Results

The primary outcome occurred in 23 pa (20.9%) during a mean FU of 53.5 ± 10.4 months. In these pa, MD was significantly increased (130.3 ± 55.5ms vs. 102.0 ± 45.1ms, p < 0.05) whereas LVEF, GLS and delta contraction time were not significantly different. All LGE-CMR parameters were significantly increased in PA with events. At multivariate analysis, both MD and LGE-CMR parameters were independent predictors of malignant arrhythmia (table). The MD cut-off value for prediction of VA was 80.88 ms, with 91.3% sensitivity and 36.8% specificity. The figure shows the Kaplan-Meier curves. Regarding LGE-CMR parameters, the cut-off value, sensitivity, and specificity were 13.8g/82.6%/81.6% for scar mass, 5.54g/85.7%/81.8% for BZ mass, and 90.9%/82.1% for presence of BZ channels.

Conclusions

MD and LGE-CMR scar parameters are independent predictors of VA and SCD in CRT. Due to its high sensitivity, MD could be used to identify pa at high arrhythmic risk that could benefit from a more complex and specific LGE-CMR study.

Multivariate analysis Model 1 Model 2 Model 3 HR (95% CI) p HR (95% CI) p HR (95% CI) p Basal LVEF 1.01 (0.94-1.09) 0.731 1 (0.93-1.07) 0.974 1.04 (0.97-1.11) 0.273 MD (ms) 1.01 (1.00-1.02) 0.043 1.01 (1.00-1.02) 0.017 1.01 (1.00-1.02) 0.003 BZ mass (g) 1.08 (1.05-1.11) <0.001 Presence of BZ channels 18.39 (4.26-79.51) <0.001 Scar mass (g) 1.06 (1.04-1.08) <0.001 LVEF: left ventricle ejection fraction; MD:mechanical dispersion; BZ:border zone

Abstract P1427 Figure. Kaplan-Meier curves

Evaluación del almidón de papa (Solanum tuberosum) en la obtención de bioplástico

Los bioplásticos a partir de almidón, son productos innovadores con un gran potencial de desarrollo y altamente amigables con el medio ambiente; en tal sentido, se evaluó el almidón extraído de cinco variedades de papa categoría richi (Superior (S), ICA Capiro (IC), Betina (B), Parda Pastusa (PP) y Criolla (C)) para la obtención de bioplásticos. Para lo anterior, se extrajo el almidón por el método de decantación natural, se determinó sus propiedades fisicoquímicas como temperatura de gelatinización (Tg), índice de absorbancia (IA), índice de solubilidad (IS), poder de hinchamiento (PDH), proteína, amilosa y amilopectina teniendo en cuenta la norma ISO 6647. Los resultados de cada variedad se evaluaron con una matriz de priorización, posteriormente, se elaboró el bioplástico siguiendo la metodología realizada por (Meza, 2016) y validado con un diseño unifactorial, donde se evalúa la incidencia del porcentaje de almidón (3, 6, 8%) en la mezcla, como variables de respuesta resistencia y calibre con 2 réplicas. Los resultados indican que la variedad (B) tiene las mejores características con 64,125 °C para Tg, para IA 3.130 g gel/g, IS 18,75 g/ml, PDH 4.03, proteína 0.341 %, amilosa 20,751 mg/L y amilopectina 79,249 mg/L. El bioplástico obtenido de esta variedad presentó características de resistencia de 25.35 MPa y calibre 0.17 mm obteniendo las mejores características mecánicas del bioplástico. Se concluye que el almidón de papa de categoría richi tiene alta potencialidad para la generación de bioplástico.

Effect of simulated mechanical recycling processes on the structure and properties of poly(lactic acid)

The aim of this work is to study the effects of different simulated mechanical recycling processes on the structure and properties of PLA. A commercial grade of PLA was melt compounded and compression molded, then subjected to two different recycling processes. The first recycling process consisted of an accelerated ageing and a second melt processing step, while the other recycling process included an accelerated ageing, a demanding washing process and a second melt processing step. The intrinsic viscosity measurements indicate that both recycling processes produce a degradation in PLA, which is more pronounced in the sample subjected to the washing process. DSC results suggest an increase in the mobility of the polymer chains in the recycled materials; however the degree of crystallinity of PLA seems unchanged. The optical, mechanical and gas barrier properties of PLA do not seem to be largely affected by the degradation suffered during the different recycling processes. These results suggest that, despite the degradation of PLA, the impact of the different simulated mechanical recycling processes on the final properties is limited. Thus, the potential use of recycled PLA in packaging applications is not jeopardized.

First identification and characterization of Streptococcus iniae obtained from tilapia (Oreochromis aureus) farmed in Mexico

This is the first study to isolate, identify and characterize Streptococcus iniae as the causative disease agent in two tilapia (Oreochromis aureus) populations. The populations were geographically isolated, of distinct origins, and did not share water sources. Affected fish showed various external (e.g., exophthalmia and cachexia, among others) and internal (e.g., granulomatous septicaemia and interstitial nephritis, among others) signs. All internal organ samples produced pure cultures, two of which (one from each farm, termed S-1 and S-2) were subjected to biochemical, PCR and 16S rRNA sequencing (99.5% similarity) analyses, confirming S. iniae identification. The two isolates presented genetic homogeneity regardless of technique (i.e., RAPD, REP-PCR and ERIC-PCR analyses). Pathogenic potentials were assessed through intraperitoneal injection challenges in rainbow trout (Oncorhynchus mykiss) and zebrafish (Danio rerio). Rainbow trout mortalities were respectively 40% and 70% at 10⁴ and 10⁶  CFU per fish with the S-1 isolate, while 100% mortality rates were recorded in zebrafish at 10² and 10⁴  CFU per fish with the S-2 isolate. The obtained data clearly indicate a relationship between intensified aquaculture activities in Mexico and new disease appearances. Future studies should establish clinical significances for the tilapia industry.

Biomarkers of resistance to radiation therapy: a prospective study in cervical carcinoma

Background

Clinical parameters and proteins have recently been suggested as possible causes of radiotherapy (RT) resistance in cervical carcinoma (CC). The objective of the present study was to validate prognostic biomarkers of radiation resistance.

Methods

The present prospective study included patients undergoing RT with curative intent for histologically proven locally advanced squamous cell CC. Tissues and blood samples were systematically collected before RT initiation. Immuno-histochemistry was performed (IGF-IR α and β, GAPDH, HIF-1 alpha, Survivin, GLUT1, CAIX, hTERT and HKII). Response to radiation was assessed through tumour response 3 months after RT completion, through overall survival (OS) and through progression-free survival (PFS).

Results

One hundred forty nine patients with a mean age of 46 years were included, with FIGO IIB (n = 53) and FIGO IIIB (n = 96) CCs. 61 patients were treated with exclusive RT + brachytherapy and 88 underwent chemo-radiotherapy + brachytherapy. Our findings suggest an association between hemoglobin level (Hb) (>11 g/dL) and 3 months complete response (p = 0.02). Hb level < 11 g/dL was associated with decreased PFS (p = 0.05) and OS (p = 0.08). Overexpression of IGF-1R β was correlated with a decreased OS (p = 0.007). Overexpression of GLUT1 was marginally correlated with reduced OS (p = 0.05). PFS and OS were significantly improved in patients undergoing chemoradiation versus exclusive radiotherapy (PFS: p = 0.04; OS: p = 0.01).

Conclusions

IGF-1R β overexpression and Hb level (≤11 g/dl) were associated with poor prognosis, and thus appear to be possible interesting biomarkers of radiation resistance. Our results corroborate previous pre-clinical studies suggesting IGF-1R and hypoxia to be part of the biological pathways leading to radio-resistance.