New insights into risk stratification of Brugada syndrome from high density epicardial electroanatomic mapping

Background/Introduction

Brugada syndrome (BrS) has been initially described as a channelopathy with no structural heart disease but a growing body of evidence points towards structural anomalies in the epicardium of right ventricle outflow tract (RVOT-EPI). Since its first description the electrical substrate of BrS has been thought to be a fractionation of the electrograms (EGMs) in the RVOT-EPI. Also there is recent evidence that SCN5A mutation BrS patients might be at increased risk of sudden cardiac death (SCD). No studies correlated high-density mapping substrate with clinical outcomes.

Purpose

The aim of the current study was to compare clinical characteristics of BRS patients with EGMs characteristics from high-density epicardial mapping with Advisor HD-Grid mapping catheter.

Methods

All consecutive patients with BrS who underwent hybrid RVOT-EPI substrate ablation at our University Hospital between April 2018 and March 2021 were retrospectively included in the study. Genetic analysis was performed in all patients and clinical data were collected. BrS was diagnosed following current recommendations. Inclusion criteria were: 1) use of Advisor HD-Grid mapping catheter and 3D-electroanatomical (EAM) mapping system EnSite Precision; 2) acquisition of EAM before and after ajmaline infusion at standard protocol (1 mg/kg in 5 minutes). Bipolar EGMs were considered abnormal (aEGMs) if they met at least 1 of the following: prolonged duration (>80 ms), fragmented components (at least 2 distinct peaks), and/or late potentials extending beyond the end of the QRS complex. aEGMs duration (Ed) was defined as the time from surface QRS onset in D2 to bipolar EGM offset.

Results

Fifteen patients were included in the study. Six patients (40%) had history of SCD or inducible ventricular arrhythmias (VAs) at electrophysiological study and 5 patients (33.3%) had a mutation of SCN5A. The mean number of points of EAMs was 1020±500. Patients with history of SCD or VAs compared with patients without history had similar Ed before ajmaline [117.5 ms (100.6–132.5) vs 110.5 ms (106.8–114.8), p=0.72] but longer Ed after ajmaline [247.5 ms (231.6–273.9) vs 188.0 ms (178.0, 211.5), p=0.034]. The best cutoff of Ed after ajmaline to predict VAs history was 233 msec (AUC of the model 0.83, sensitivity: 0.98, specificity: 0.66). Patients with SCN5A mutation compared with patients without had similar Ed before ajmaline [125.2 ms (117.9–132.6) vs 105.0 ms (103.0–119.0), p=0.24] but longer Ed after ajmaline [270.0 ms (259.0–280.5) vs 200.8 ms (181.2–224.2), p=0.037], figure 1. The best cutoff of Ed after ajmaline to predict SCN5A mutation was 256.5 ms (AUC of the model 0.84, sensitivity: 0.80, specificity: 0.98), figure 2.

Conclusions

High density RVOT epicardial mapping provides data of clinical meaning in risk stratification of BrS patients. These data should be interpreted in the context of a population undergone RVOT-EPI substrate ablation.

Funding Acknowledgement

Type of funding sources: None. aEGM duration and SCD/VA or SCN5AROC curves for EGM derived prediction

The potential impact of acute coronary syndromes on automatic sensing system in Subcutaneous-ICDs

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75 patients with ACS or CCS underwent S-ICD screening upon arrival and after PCI.

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Before PCI, STEMI patients had lower screening pass rates than NSTE-ACS ones

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STEMI was the only predictor of screening failure at multivariate regression analysis.

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Patient selection and dynamic device programming are fundamental in ischemic subjects

Background

The Subcutaneous-ICD (S-ICD) is emerging as a suitable option for most ICD candidates, however some open issues regarding the sensing algorithm still remain.

Objectives

We aimed to examine the performance of the S-ICD sensing algorithm in patients hospitalized for ST elevation myocardial infarction (STEMI), non ST elevation acute coronary syndrome (NSTE-ACS) or chronic coronary syndrome (CCS), before and after revascularization.

Methods

We performed a S-ICD automated screening on 75 patients, 21 hospitalized for STEMI, 23 for NSTE-ACS and 31 for CCS, before and after percutaneous revascularization, regardless their eligibility to ICD implantation.

Results

Patients did not differ in clinical, electrocardiographic and echocardiographic parameters. Rates of screening pass were significantly lower in STEMI patients compared to NSTE-ACS and CCS (5% vs 56.7% vs 81% respectively, p < .0001). The viability of the primary vector was lower in STEMI patients compared to NSTE-ACS and CCS (33% vs 56% vs 71%, p .027 respectively). After revascularization, there were no more significant differences between groups. Pairing subjects at baseline and after revascularization, STEMI subjects percentages of screening success were respectively 5% and 81% (p < .001) and the rates of primary vector viability were 33% and 81% (p .002). STEMI was the only independent predictor of screening failure at multivariate logistic regression analysis (odds ratio 10.68 confidence interval 2.77–41.38, p = .001)

Conclusion

The performance of the S-ICD and possible malfunction detections in the context of an acute ischemic event deserve further evaluation. Adequate patient selection and the development of dynamic device programming are warranted.

Long term stability of the subcutaneous cardioverter defibrillator implanted by means of the intermuscular two incision technique

Funding Acknowledgements

Type of funding sources: None.

Background To ensure effective defibrillation with the subcutaneous implantable cardioverter defibrillator (S-ICD), both the lead and the generator must be adequately positioned extrathoracically. We assessed the long-term adequacy of the S-ICD system position and its stability in a group of patients who received the S-ICD by means of the two-incision intermuscular technique.

Methods The PRAETORIAN score uses chest radiography to provide feedback on S-ICD positioning, and identifies patients with high defibrillation thresholds. We compared radiographs taken immediately after implantation and on 12-month follow-up examination.

Results We analyzed data from 38 patients with the S-ICD generator positioned in an intermuscular pocket. The median PRAETORIAN score was 38 [25th to 75th percentile: 30 to 60]. Two (5%) patients had a score of 90 (intermediate risk of conversion failure). The thickness of the adipose tissue between the coil and the sternum was ≤1 coil width in 72% of patients, the generator was on, or posterior to, the midline in 94% of patients, and the amount of fat tissue between the generator and the thoracic wall was less than the generator width in 78% of patients. No generator or electrode dislodgments were detected on analyzing radiographs collected at the 12-month visit. In all patients, assessment of the PRAETORIAN score confirmed the values calculated on post-implantation analysis. During follow-up, no ineffective therapies, sudden cardiac or device-related deaths occurred.

Conclusions The position of the S-ICD system implanted using the two-incision intermuscular technique was adequate at the time of implantation and remained stable after 12 months.

P529Efficacy and safety of S-ICD implantation without use of defibrillation threshold testing: a retrospective multicentric observational study

Introduction

The subcutaneous ICD (S-ICD) is a valid alternative to transvenous systems (TV-ICD) for the treatment of life-threatening arrhythmias, and the extravascular position of the lead allows a significant reduction of the risk of infection. Current guidelines recommend defibrillation threshold testing (DFT) at the time of S-ICD implantation (class I). Although randomised trials have proven the safety of TV-ICD implantation with no DFT, it is unclear whether such an approach could be adopted for S-ICD as well. The PRAETORIAN score, based on post-implantation chest X-ray, can accurately predict a high defibrillation threshold after S-ICD implantation. The aim of this retrospective multicentre study was to evaluate the efficacy and safety of S-ICD implantation with no DFT.

Methods

We enrolled 203 consecutive patients undergoing S-ICD implantation in six different centres between October 2012 and January 2019. It was left at discretion of the operator whether performing or not DFT at the time of the procedure. Baseline device settings were collected, and the PRAETORIAN score was retrospectively calculated whenever chest X-ray was available. Both remote or in-clinic device interrogation reports were systemically analysed, and all the shocks and arrhythmia episodes identified. All the patients provided consent form and ethical approval was obtained.

Results

The population (mean age 57.6 ± 14.2) was divided in two groups, based on whether DFT was performed at the time of the S-ICD implantation: 72 patients (35.4%) underwent DFT (DFT+ group), while 131 patients (64.5%) did not (DFT- group). In the DFT- group, mean LVEF was lower (32 ± 8% vs 42 ± 17%, p &lt; 0.0001) and prevalence of diabetes mellitus and atrial fibrillation higher compared to the DFT+ group (27.5% vs 13.9%, p = 0.04 and 38.9% vs 19.44%, p = 0.007; respectively). In addition, the indication for S-ICD was more frequently primary prevention in the DFT- vs DFT+ group (70.8% vs 90.8%, p = 0.0004; respectively). No differences in terms of device programming were identified between the two cohorts. The PRAETORIAN score was significantly higher in the DFT- vs DFT+ patients (50 ± 26 vs 36 ± 18, p = 0.032; respectively). After a median follow-up of … months, we observed 5 appropriate shocks in 3 patients from the DFT+ group vs. 15 shocks in 8 patients from the DFT- group (p = 0.81). All the life-threatening arrhythmias were successfully recognised and treated by the device. DFT was complicated by pulseless electrical activity in one patient. One patient in the DFT- group suffered from an episode of ventricular tachycardia requiring a total of 4 shocks for being terminated. Six patients in the DFT- group died for non-arrhythmic causes. On the Kaplan-Meier analysis, cumulative survival was comparable between the two groups (log rank p value = 0.13).

Conclusions

This study suggests that implantation of S-ICD with no DFT might be reasonable. These results should be confirmed in prospective randomised trials.

Diagnostic role of echocardiography in patients admitted to the emergency room with suspect no-ST-segment elevation acute myocardial infarction

OBJECTIVE

We investigated whether echocardiography may help identify, among patients admitted with a suspect of non-ST-segment elevation acute myocardial infarction (NSTEMI), those with athero-thrombotic coronary artery disease (CAD).

PATIENTS AND METHODS

We studied consecutive patients admitted with a clinical suspect of first NSTEMI. Echocardiography was assessed within 24 hours from admission. Patients were divided into two groups, according to the results of coronary angiography: 1) patients with obstructive stenosis (≥ 50%) and/or images of thrombosis in one or more coronary arteries (CAD group); 2) patients with no evidence of obstructive coronary arteries (NOCAD group).

RESULTS

Of 101 patients enrolled in the study, 53 (52.5%) showed obstructive CAD and 48 (47.5%) NOCAD. At echocardiographic examination, regional wall motion abnormalities were found in 52.8% of patients in the CAD group and 43.7% in the NOCAD group (p=0.43). Left ventricle ejection fraction was 56.4±6.8 vs. 54.7±9.8% (p=0.30) and wall motion score index was 1.16±0.26 vs. 1.21±0.32 (p=0.39) in the two groups, respectively. A multivariable logistic regression independent predictors of obstructive CAD included age, male gender, typical angina, diabetes and hypertension.

CONCLUSIONS

Our data showed that, in patients with acute chest pain and increased serum troponin T concentration, routine standard echocardiography does not significantly improve the diagnostic accuracy for the presence of obstructive CAD.