Assessment of optimal thresholds for ventricular scar substrate characterization using the high density grid multipolar mapping catheter

Funding Acknowledgements

Type of funding sources: None.

Background

Voltage thresholds for ventricular scar definition are based on historic data collected using catheters with widely spaced bipoles in the absence of contact force. Modern multipolar mapping catheters employ smaller electrodes and interelectrode spacing that theoretically allows for mapping with increased resolution and reduced far-field electrogram (EGM) component. Despite the advancement in technology, historic cut-offs of <0.5mV for dense scar and 0.5-1.5mV for scar borderzone continue to be used in contemporary electrophysiology.

Purpose

We aimed to assess the optimal voltage cut-offs for ventricular scar substrate characterization using the HD Grid multipolar mapping catheter. Voltage cut-offs were assessed against cardiac MRI derived scar. We compared optimal voltage cut-offs using conventional bipolar sampling, the Best Duplicate Algorithm and with the HD wave solution plus best duplicate algorithm on.

Methods

A multicentre study of twenty patients undergoing VT ablation was conducted. Substrate mapping was performed using the high-density HD-grid multipolar mapping catheter. Bipolar voltage maps were co-registered with cardiac MRI obtained prior to the procedure to assess the voltage characteristics of scar defined by cardiac MRI (CMR) (Figure 1). Pre-procedure contrast enhanced CMR data were analysed using ADAS software (Galgo medical). Data points were collected in regions of scar during (1) HD wave mapping with best duplicate algorithm on(Waveon), (2) Mapping with HD wave off and best duplicate on (Waveoff) and (3) with conventional bipolar mapping (Alloff).

Results

The median bipolar voltage for regions of dense CMR scar using (Waveon) HD wave solution and best duplicate algorithm was 0.27mV (IQR 0.14 – 0.46). The median voltage with (Waveoff) HD wave off was 0.29mV (0.15 – 0.45). The median voltage with (Alloff) HD wave off and best duplicate off was 0.32mV (0.19 – 0.5). ROC analysis using AUC suggested the optimal cut-off for endocardial dense scar using (Waveon) HD wave mapping and best duplicate algorithm was 0.30mV (sensitivity: 69.6%, specificity: 60.74%), (Waveoff) cut-off with the best duplicate and without the HD wave mapping was 0.34mV (sensitivity: 69.78%, specificity: 64.46%) and (Alloff) without wave mapping or best duplication was 0.36mV (sensitivity: 84%, specificity: 52%) Figure 2.

Conclusion

Ventricular substrate characterization with newer mapping technology using narrow electrode spacing and smaller electrode size suggests that traditional voltage cut-offs may need revision for delineation of scar characteristics. Additionally, the ability to repeat sample in a region to obtain the best signal (Best Duplicate), and the ability to obviate the effect of wavefront direction using the HD wave solution omnipolar technology, may further increase the fidelity of scar characterization. This has important implications for mapping VT and characterizing channels in order to identify VT circuits.

Integration of structural and functional data in VT ablation -- SENSE2 protocol mapping

Funding Acknowledgements

Type of funding sources: None.

Background

We have previously developed the sense protocol functional substrate mapping technique for VT ablation(1). However, functional substrate characterizaiton can involve protracted mapping time.

Purpose

We incorporated the integration of MRI data using ADAS-3D software into the mapping workflow, to integrate structural mapping information into the functional mapping substrate characterization, in order to improve procedural efficiency.

Methods

CMRs were performed in 20 patients with ischemic related VT and VT therapy in the previous 6 months. These were processed with the ADAS-3D software to characterize the extent of ventricular scars and also ADAS corridors which may correlate with VT channels. Focused substrate maps were then performed in patients, guided by the extent of ADAS scar and corridors, looking at the scar substrate in intrinsic rhythm and then functional channels using single extra pacing from the RV at 20ms above ERP (SENSE2 Protocol). Specifically healthy areas 2cm beyond the scar borderzone based on ADAS were not mapped, in order to reduce substrate mapping time and complete geometries were not created. Following delineation of functional channels pacemapping and entrainment mapping were used to confirm targets for ablation.

The ADAS 3D MRI was integrated into the into the VT substrate map on Ensite-Precision with alignment to the aorta, RV and PA (Figure 1). We compared our data with previous functional mapping data without the integration of MRI.

Results

20 patients (age 70 years; 19 male subjects) underwent ablation. Mean EF 28%. Median procedure time was 161 minutes compared with 246 minutes (in our previous study)(p=<0.001) Mean substrate mapping time was 32 mins vs 63 mins (p=<0.001). Mean ablation time was 22 mins vs 32 mins (p=0.11). 85% (17 of 20) patients were free from symptomatic VT/ anti-tachycardia pacing or implantable cardioverter defibrillator shocks at a median follow-up of 171 days. The mean VT burden was reduced from 22 events per patient in the 6 months’ pre-ablation to 1 event per patient in the median follow up period of 171 days post ablation (p=0.02). Mean shocks per-patient burden decreased from 3.5 to 0.08 in the same time period(p=0.03).

Conclusion

The SENSE2 protocol involves the integration of structural and functional data into the VT workflow for substrate characterization. It enables focused substrate maps to be performed without the need for complete geometry to be created in large ventricles. Outcomes compare favourably with our previous data but with significantly shorter procedure times. This streamlined workflow has the potential to improve care in VT ablation by shortening procedure times with similar outcomes which may reduce risks for the patient.

Figure 1: Comparison of Voltage Map with MRI scar & corridors using ADAS

Mood and suicidality amongst cyberbullied adolescents- a cross-sectional study from youth risk behavior survey

Introduction

There is a limited literature available showing mental health burden among adolescents following cyberbullying.

Objectives

Aim is to evaluate the association of low mood and suicidality amongst cyberbullied adolescents.

Methods

A study on CDC National Youth Risk Behavior Surveillance (YRBS) (1991-2017). Responses from adolescence related to cyberbullying and suicidality were evaluated. Chi-square and mix-effect multivariable logistic regression analysis was performed to find out the association of cyberbullying with sadness/hopelessness, suicide consideration, plan, and attempts.

Results

A total of 10,463 adolescents, 14.8% of adolescents faced cyberbullying a past year. There was a higher prevalence of cyberbullying in youths aged 15-17 years (25 vs 26 vs 23%), which included more females to males (68 vs 32%).(p<0.0001) Caucasians (53%) had the highest number of responses to being cyberbullied compared to Hispanics (24%), African Americans (11%).(p<0.0001) There was an increased prevalence of cyberbullied youths with feelings of sadness/hopelessness (59.6 vs 25.8%), higher numbers considering suicide (40.4 vs 13.2%), suicide plan (33.2 vs 10.8%), and multiple suicidal attempts in comparison to non-cyberbullied.(p<0.0001) On regression analysis, cyberbullied adolescence had a 155% higher chance of feeling sad and hopeless [aOR=2.55; 95%CI=2.39-2.72], considered suicide [1.52 (1.39-1.66)], and suicide plan [1.24 (1.13-1.36)].

Conclusions

In our study, cyberbullying was associated with negative mental health outcomes. Further research is warranted to examine the impact and outcomes of cyberbullying amongst adolescents and guiding the policies to mitigate the consequences.

Disclosure

No significant relationships.

Mitral regurgitation in acute heart failure: prevalence and response to treatment

 

Heart failure (HF) affects an estimated 90 000 people within the UK. As a consequence of ventricular remodelling, mitral regurgitation (MR) is common in patients with HF, further contributing to poor prognosis, frequent hospitalisation, and higher rates of mortality. Conventional treatment options include medical therapy, cardiac resynchronisation and conventional mitral valve surgery, with transcatheter mitral valve repair (TMVR) reserved for symptomatic patients with left ventricular dysfunction and multiple comorbidities, considered high surgical risk.

Aim

Our objectives were to determine: (1) the proportion of patients with an acute HF admission, ejection fraction (EF) of &lt;50% and moderate or more MR; (2) the effectiveness of optimal medical therapy (OMT) in reducing the severity of MR and symptoms; (3) the number of patients with moderate or more MR, EF &lt;50% and symptoms despite OMT.

Method

We performed a retrospective analysis of patients who presented with acute HF to two large tertiary centres over a five-year period. Based on a combination of electronic care records, and national registry and mortality data, we determined baseline symptoms, symptom progression, and co-morbidities. Echocardiography data was used to assess the degree of MR and EF. Where patients underwent a subsequent echocardiogram on OMT, the change in the degree of MR, EF and symptoms (NYHA class) was examined.

Results

Over a five-year period (Jan 2012–Dec 2017), 1884 patients presented with acute HF. Of this cohort, 302 (16%) had moderate or more MR and EF of &lt;50%. Mortality amongst patients with moderate or more MR was 29.9% at one year (compared to 26.9% for those with less than moderate MR, p=0.058). Of this cohort, 45% had sufficient clinical and echocardiographic paired follow up data to enable assessment of the effects of OMT (Age 78±20.78; Male n=76 (56.3%). This analysis showed, despite OMT, all 135 patients still had moderate or more MR. When compared with previous echocardiography data, 11 (8%) patients showed a reduction in the severity of MR which meant 92% (124) of patient with MR either saw no improvement or worsening of their MR severity. Of those with severe MR, 23% (7) demonstrated an improvement in the degree of MR following OMT. Clinically 70 (51.4%) patients had an improvement in symptoms. There was significant improvement in the NYHA class pre and post optimisation of medical therapy (p&lt;0.001) across all grades of MR. Despite OMT, 124 (92%) patients with moderate or more MR and EF &lt;50% remained symptomatic.

Conclusions

A large portion of patients who present with acute HF have moderate or more MR. Although medical therapy is effective in providing some relief from symptoms, the large majority of patients continue to have moderate or more MR. We propose a portion of these patients are potential candidates for TMVR, and should be considered for further intervention.

Funding Acknowledgement

Type of funding source: None