564 Controversial role of intracardiac eletrophysiology study in Brugada syndrome: analysis of a single-centre retrospective cohort study

Aims According to European guidelines, aborted sudden cardiac death (SCD) in Brugada syndrome (BrS) is regarded as a I class recommendation for secondary prevention implantable cardioverter defibrillator (ICD). However, the risk stratification of BrS patients for primary prevention ICD still represents a clinical conundrum. Although intracardiac electrophysiology (EP) study proved useful for the selection of high-risk patients in this setting. Therefore, aim of this study was to assess all clinical and EP variables associated with the induction of VA at EP study and the rate of appropriate/inappropriate ICD interventions and/or clinical SCD events in these patients occurring at follow-up. Methods and results From 2001 to 2021, all EP studies performed in symptomatic/asymptomatic patients (46 ± 14 years, M 88%) with/without family history of SCD spontaneous/drug-induced type I pattern (TIP) on ECG and no spontaneous ventricular arrhythmias were retrospectively considered at our study centre. Clinical variables, BrS pattern, EP study data (including right ventricular site and type of stimulation protocol), and ICD interventions (DC-shocks or Anti-Tachycardia Pacing events, ATP) and/or SCD events occurring at follow-up were all evaluated. EP study was deemed positive for any polymorphic VA induced during programmed ventricular stimulation; non-sustained episodes included. ICD was routinely implanted in all patients with a positive EP study. Follow-up data were detected by the collection of medical and home-monitoring recordings at study-site level. Follow-up data were available in 50 patients (9 ± 6 years on average). Patients were generally young with few cardiovascular comorbidities. SCD history was known in 21 (42%) with a significant number of asymptomatic patients (48%). Br patterns were equally distributed in the investigated population (spontaneous and drug-induced TIP in 52% and 48%, respectively) and AF history was fairly common (16%). In the study population, EP study tested positive in 30 patients (60%): spontaneous TIP (P = 0.0518), few extrastimuli during programmed ventricular stimulation (P = 0.0015), and right ventricular stimulation at the apical site (P ≤ 0.0001) were the only variables to be clearly associated with a positive EP study in the appraised patients. At follow-up, appropriate ICD shocks were documented in 4 out of 30 implanted patients (13%) at generally 5 ± 7 years from EP study evaluation. Although three ICD interventions (75%) occurred in patients with spontaneous TIP, one patient with drug-induced TIP pattern and positive EP study referred to Emergency Department for unrelenting VT storm after roughly 13 years from ICD implantation. Inappropriate ICD interventions for fast rate AF were detected in 10% of cases. Finally, no SCD events were documented at follow up in patients with a negative EP study. Conclusions In a retrospective analysis, EP study proved useful in the risk stratification of SCD in BrS patients. A few ventricular extrastimuli delivered at the right ventricular apex seem sufficient to prompt the induction of life-threatening VA in high-risk BrS patients during EP study. Moreover, in this setting, a negative EP study seems protective against the development of VA/SCD events at follow-up. However, not only is spontaneous TIP associated with an increased risk of arrhythmic death, but a drug-induced TIP, generally regarded as a low-risk condition, might also be associated with a long-term hazard of SCD in these patients.

Noninvasive programmed ventricular stimulation for prediction of future events in patients with cardioverter-defibrillator implanted for primary prevention of sudden cardiac death

Funding Acknowledgements Type of funding sources: None. OnBehalf The NIPS-ICD Investigators Background Implantable cardioverter-defibrillator (ICD) offers an opportunity to examine vulnerability to ventricular tachycardia (VT) or ventricular fibrillation (VF) by performing non-invasive programmed ventricular stimulation (NIPS). Whether NIPS can predict mortality in patients with primary prevention ICD, has not yet been examined. Purpose To examine a long-term predictive value of NIPS for identification of patients at increased risk of death during follow up. Methods The study group consisted of consecutive 41 patients with ICD implanted for primary prevention of sudden cardiac death, included in the prospective NIPS-ICD study (ClinicalTrials ID: NCT02373306) (34 males, age 64 ± 11 years). The patients underwent NIPS using the protocol up to three premature extrastimuli at 600, 500 and 400ms drive cycle lengths. The end-point of NIPS was induction of sustained VT or VF or completion of the protocol. Results At baseline NIPS, VT/VF was induced in 8 (20%) patients. After 5 year follow up mortality rate was significantly higher in patients who had VT/VF induced at NIPS vs no VT/VF at NIPS (38% vs 12%, p = 0.04). The difference in mortality was most remarkable at 3 (38% vs 3%, p = 0.001) and 4 years (38% vs 6%, p = 0.007). The NIPS-induced VT/VF had a sensitivity of 37.5%, specificity of 88%, positive predictive value of 43% and negative predictive value of 85% for occurrence of death during follow up. An occurrence of secondary composite endpoint consisting of VT/VF recurrence or death was also most frequent in NIPS-inducible group (75% vs 24%, p = 0.037). In a multivariate Cox-Proportional Hazard model induction of VT/VF at NIPS along with age≥65, and treatment with amiodarone was an independent predictor of the composite endpoint during follow-up Conclusions Inducibility of VF/VF during NIPS in patients with primary prevention ICD is associated with higher mortality and higher incidence of composite endpoint consisting of death or VT/VF during a long term observation. Abstract Figure. Kaplan-Meier survival curves

Noninvasive risk factors for the prediction of inducibility on programmed ventricular stimulation in post-MI patients with ejection fraction over 40% at SCD risk, insights from the PRESERVE EF study

Funding Acknowledgements Type of funding sources: None. Background Sudden cardiac arrest (SCA) in post myocardial infarction (post-MI) patients with a relatively preserved left ventricular systolic function (LVEF≥40%) has an annual incidence of 1%, in the absence of adequate risk stratification methods and guideline recommendations for primary prevention. In the PRESERVE-EF study we used a two-step SCA risk stratification approach to detect patients at risk for major arrhythmic events. Seven noninvasive risk factors (NIRFs) were extracted from ambulatory electrocardiography (AECG). Patients with at least one NIRF present were referred for invasive programmed ventricular stimulation (PVS). Inducible patients received an ICD. Purpose To assess the performance of NIRFs extracted from 24hr AECG, based on the PRESERVE EF criteria, in predicting inducibility. Methods The PRESERVE EF study enrolled 575 patients. Two hundred and four of them had at least one NIRF and an indication for PVS, but 52 of them declined. Finally, 41 out of 152 patients who underwent PVS were inducible. For the present analysis data from these 152 patients (mean age 60 ± 10years, LVEF 49 ± 6%, 89% males) were analyzed. Chi-square test, univariate logistic regression and areas under ROC curves were calculated for the PVS inducibility endpoint. Results Age, male gender and LVEF for the PVS inducible patients group (n = 41) and the noninducible patients group (n = 111) were, respectively: 61 ± 9years vs 59 ± 10years (p = 0.310), 98% vs 86% (p = 0.048), 45 ± 4% vs 51 ± 7% (p < 0.001). Among NIRFs examined, LVEF ≤ 50%, nsVT≥1/24hour and presence of LPs on SAECG presented high and significant Odds Ratios (ORs) for a positive PVS study end point. A simple risk score based on cutoff points of LVEF ≤ 50%, NSVTepisode≥1/24hour and presence of LPs missed only 1 out of the 41 inducible patients and yielded: OR 14.146 (p = 0.01) with a high sensitivity 98% but low specificity 26% for a positive PVS (AUC = 0.65). Conclusion Cut off points of LVEF ≤ 50%, nsVTepisode≥1/24hour and presence of LPs were important predictors of inducibility. A simple risk score based on these predictors achieves high sensitivity but low specificity. The final decision for an ICD implantation should be based on a positive PVS, which is irreplaceable in risk stratification.

Advances in Physiological Cardiac Stimulation

Advances in cardiac stimulation demonstrate that bradyarrhythmia treatments go beyond heart rate control. The concern with the ventricular stimulation site and, consequently, with the maintenance of intraventricular synchrony has become routine in most services. Techniques of physiological cardiac stimulation, such as stimulation of the bundle of His and the left branch, have been improved. Despite the indisputable benefits of these therapeutic modalities, there are technical difficulties that limit systematic use. In this sense, to make physiological cardiac stimulation more practical and reproducible, the concept of parahissian stimulation was expanded and studied. The technique, simpler and reproducible, contemplates a conventional approach of the right ventricle. The big difference is the use of QRS spatial variance analysis technology (Synchromax®, Exo S.A., Argentina) to confirm the maintenance of ventricular synchrony according to the implanted site.