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The variability of the inverse solution provided by electrocardiographic imaging (ECGI) is largely unknown when comparing different leadsets or (similar) beats. In four patients, we compared activation times (ATs), recovery times (RTs), and correlation coefficients during QRS complex and STT segment between: 1) consecutive sinus beats within one leadset, and 2) multiple beats for two leadsets. Furthermore, reasons behind differences in RT were investigated. Zero-th order Tikhonov regularization was used to reconstruct ventricular epicardial potentials. A spatiotemporal estimation method was then used to determine the ATs and RTs from the reconstructed epicardial electrograms. Inter-leadset differences were generally low for ATs, but exceeded intra-leadset beat-to-beat variations. RTs, however, showed larger variation independent of leadset. Differences in RTs between beats or leadsets could partially be explained by low T-wave amplitudes and high levels of noise, which suggests that RT determination may require more advanced methods in these cases. These findings increase our understanding of the consequences of electrode placement for the inverse solution, as well as our understanding of the complexities of recovery time estimation in ECGI.

Inverse electrocardiography (iECG) estimates epi- and endocardial electrical activity from body surface potentials maps (BSPM). In individuals at risk for cardiomyopathy, non-invasive estimation of normal ventricular activation may provide valuable information to aid risk stratification to prevent sudden cardiac death. However, multiple simultaneous activation wavefronts initiated by the His-Purkinje system, severely complicateiECG. To improve the estimation of normal ventricular activation, theiECG method should accurately mimic the effect of the His-Purkinje system, which is not taken into account in the previously published multi-focaliECG. Therefore, we introduce the novel multi-waveiECG method and report on its performance. Multi-waveiECG and multi-focaliECG were tested in four patients undergoing invasive electro-anatomical mapping during normal ventricular activation. In each subject, 67-electrode BSPM were recorded and used as input for bothiECG methods. TheiECG and invasive local activation timing (LAT) maps were compared. Median epicardial inter-map correlation coefficient (CC) between invasive LAT maps and estimated multi-waveiECG versus multi-focaliECG was 0.61 versus 0.31. Endocardial inter-map CC was 0.54 respectively 0.22. Modeling the His-Purkinje system resulted in a physiologically realistic and robust non-invasive estimation of normal ventricular activation, which might enable the early detection of cardiac disease during normal sinus rhythm.

Background: Familial cascade screening is well established in patients with heritable cardiac disease and in cases of sudden arrhythmic death syndrome. The clinical benefit of family screening in idiopathic ventricular fibrillation (IVF) is unknown. Methods: Patients with IVF were identified from national and institutional registries. All underwent systematic and comprehensive clinical evaluation to exclude identifiable causes of cardiac arrest with a minimum requirement of ECG, cardiac (echocardiogram or magnetic resonance imaging) and coronary imaging, exercise ECG, and sodium channel blocker provocation. Additional investigations including genetic testing were performed at the physician’s discretion. First-degree relatives who were assessed with at least a 12-lead ECG were included in the final cohort. Results of additional investigations, performed at the physician’s discretion, were also recorded. Results were coded as normal, abnormal, or minor findings. Results: We identified 201 first-degree relatives of 96 IVF patients. In addition to a 12-lead ECG, echocardiography was performed in 159 (79%) and ≥1 additional investigation in 162 (80%) relatives. An inherited arrhythmia syndrome was diagnosed in 5 (3%) individuals from 4 (4%) families. Two relatives hosted the DPP6 risk haplotype identified in a single proband, one of whom received a primary prevention implantable cardioverter defibrillator. In 3 separate families, an asymptomatic parent of the IVF proband developed a type 1 Brugada ECG pattern during sodium channel blocker provocation. All were managed with lifestyle measures only. The early repolarization (ER) ECG pattern was present in 16% probands and was more common in relatives in those families than those where the proband did not have early repolarization (25% versus 8%, P =0.04). Conclusions: The yield of family screening in relatives of IVF probands is low when the proband is comprehensively investigated. The significance of J wave syndromes in relatives and the role for systematic sodium channel blocker provocation are, however, uncertain and require further research.

Introduction The benefit of implantable cardioverter‐defibrillator (ICD) implantation in patients with hemodynamically not tolerated ventricular tachycardia (VT) and midrange reduced to normal ejection fraction (LVEF >35%) is currently unclear. The purpose of this study was to investigate follow‐up after hemodynamically not tolerated VT in patients with LVEF >35%. In addition, we aimed to find possible predictive factors to identify who will benefit from ICD implantation. Methods In a retrospective single‐centre case series, all patients with hemodynamically not tolerated VT and LVEF >35% that underwent electrophysiological study (EPS) and/or radiofrequency VT ablation were included. Results Forty‐two patients (5 women, median age 68 years) with hemodynamically not tolerated VT and LVEF >35% underwent EPS. VT ablation was performed in thirty‐one patients, which was considered successful in twenty‐three patients. Nineteen patients had an ICD at discharge while 23 patients were discharged without an ICD. The severity of hemodynamic compromise, LVEF and ablation success played an important role in the decision‐making for ICD implantation. Six patients (14.3%) had recurrence of VT, all hemodynamically tolerated. Conclusions In this small case series, patients with hemodynamically not tolerated VT and LVEF >35% had a relatively low recurrence rate and all recurrences were nonfatal. Based on our results, we hypothesize that the severity of hemodynamic compromise, LVEF and ablation success might modify the risk for VA recurrence. A prospective study to determine the prognostic value of these factors in patients with hemodynamically not tolerated VT and LVEF >35% is necessary.

When a young person suddenly dies, there is a real chance that this was caused by genetic heart disease. Autopsy plays an important role in determining the cause of death, but the autopsy rate in the Netherlands is relatively low. Practical problems and a lack of information on autopsy play a role. It is important to inform the family on the importance of autopsy and DNA testing. If the family refuses autopsy, consent can be given for removal of material for DNA testing. If no autopsy and no DNA test were done, cardiological screening of family members remains highly recommended. New guidelines and procedures for diagnostics after sudden death are very important. For that reason, we developed a step-by-step plan to support healthcare providers. Early detection of genetic heart disease may prevent sudden death of family members, for example, by using preventive medication or internal defibrillators (ICD).

BACKGROUND The correct interpretation of the ECG is pivotal for the accurate diagnosis of many cardiac abnormalities, and conventional computerized interpretation has not been able to reach physician‐level accuracy in detecting (acute) cardiac abnormalities. This study aims to develop and validate a deep neural network for comprehensive automated ECG triage in daily practice. METHODS AND RESULTS We developed a 37‐layer convolutional residual deep neural network on a data set of free‐text physician‐annotated 12‐lead ECG s. The deep neural network was trained on a data set with 336.835 recordings from 142.040 patients and validated on an independent validation data set (n=984), annotated by a panel of 5 cardiologists electrophysiologists. The 12‐lead ECG s were acquired in all noncardiology departments of the University Medical Center Utrecht. The algorithm learned to classify these ECG s into the following 4 triage categories: normal, abnormal not acute, subacute, and acute. Discriminative performance is presented with overall and category‐specific concordance statistics, polytomous discrimination indexes, sensitivities, specificities, and positive and negative predictive values. The patients in the validation data set had a mean age of 60.4 years and 54.3% were men. The deep neural network showed excellent overall discrimination with an overall concordance statistic of 0.93 (95% CI , 0.92–0.95) and a polytomous discriminatory index of 0.83 (95% CI , 0.79–0.87). CONCLUSIONS This study demonstrates that an end‐to‐end deep neural network can be accurately trained on unstructured free‐text physician annotations and used to consistently triage 12‐lead ECG s. When further fine‐tuned with other clinical outcomes and externally validated in clinical practice, the demonstrated deep learning–based ECG interpretation can potentially improve time to treatment and decrease healthcare burden.

Sudden cardiac death in the young is a rare and devastating event. A dedicated and focused post-mortem investigation is essential in detecting potential inherited cardiac diseases in sudden death victims, which facilitates appropriate management of the victim’s family members. Many specialized clinical disciplines are involved, and a multidisciplinary approach is required to provide the best outcome in these cases.

The diagnosis and management of idiopathic ventricular fibrillation is challenging, as it requires extensive diagnostic testing and offers few curative options due to unknown underlying disease. The resulting population is a heterogeneous group of patients with a largely unknown natural history. Structural patient characterisation, follow-up and innovations in diagnostic testing can improve our understanding of the disease mechanisms of idiopathic ventricular fibrillation, detect underlying disease during follow-up and aid in therapeutic management. Recently, initiatives have been launched in the Netherlands to investigate the role of high-resolution non-invasive electrocardiographic imaging and genetic and familial screening in idiopathic ventricular fibrillation.

BACKGROUND: Measuring repolarization characteristics is challenging and has been reserved for experienced physicians. In electrocardiographic imaging (ECGI), activation-recovery interval (ARI) is used as a measure of local cardiac repolarization duration. We hypothesized that repolarization characteristics, such as local electrogram morphology and local and global dispersion of repolarization timing and duration could be of significance in ECGI.OBJECTIVE: To further explore their potential in arrhythmic risk stratification we investigated the use of novel repolarization parameters in ECGI.MATERIALS AND METHODS: We developed and compared methods for T-peak and T-end detection in reconstructed potentials. All methods were validated on annotated reconstructed electrograms (EGMs). Characteristics of the reconstructed EGMs and epicardial substrate maps in IVF patients were analyzed by using data recorded during sinus rhythm. The ECGI data were analyzed for EGM morphology, conduction, and repolarization.RESULTS: We acquired ECGI data from 8 subjects for this study. In all patients we evaluated four repolarization parameters: Repolarization time, T-wave area, Tpeak-Tend interval, and T-wave alternans. Most prominent findings were steep repolarization time gradients in regions with flat EGMs. These regions were also characterized by low T-wave area and large differences in Tpeak-Tend interval.CONCLUSIONS: Measuring novel repolarization parameters in reconstructed electrograms acquired with ECGI is feasible, can be done in a fully automated manner and may provide additional information on underlying arrhythmogenic substrate for risk stratification. Further studies are needed to investigate their potential use and clinical application.

AimsIdiopathic ventricular fibrillation (IVF) is a rare cause of sudden cardiac arrest. Implantable cardioverter-defibrillator (ICD) implantation is currently the only treatment option. Limited data are available on the prevalence and complications of ICD therapy in these patients. We sought to investigate ICD therapy and its complications in patients with IVF.Methods and resultsPatients were selected from a national registry of IVF patients. Patients in whom no underlying diagnosis was found during follow-up were eligible for inclusion. Recurrence of ventricular arrhythmia (VA) was derived from medical and ICD records, electrogram records of ICD therapies were used to differentiate between appropriate or inappropriate interventions. Independent predictors for appropriate ICD shock were calculated using cox regression. In 217 IVF patients, recurrence of sustained VAs occurred in 66 patients (30%) during a median follow-up period of 6.1 years. Ten patients died (4.6%). Thirty-eight patients (17.5%) experienced inappropriate ICD therapy, and 32 patients (14.7%) had device-related complications. Symptoms before cardiac arrest [hazard ratio (HR): 2.51, 95% confidence interval (CI): 1.48–4.24], signs of conduction disease (HR: 2.27, 95% CI: 1.15–4.47), and carrier of the DPP6 risk haplotype (HR: 3.24, 1.70–6.17) were identified as independent predictors of appropriate shock occurrence.ConclusionImplantable cardioverter-defibrillator therapy is an effective treatment in IVF, treating recurrences of potentially lethal VAs in approximately one-third of patients during long-term follow-up. However, device-related complications and inappropriate shocks were also frequent. We found significant predictors for appropriate ICD therapy. This may imply that these patients require additional management to prevent recurrent events.