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Aims: Idiopathic 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 Results: Patients 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., Conclusion: Implantable 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., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Background and Purpose: Left ventricular ejection fraction lacks specificity to predict sudden cardiac death in heart failure. T-wave alternans (TWA; beat-to-beat T-wave instability, often measured during exercise) is deemed a promising noninvasive predictor of major cardiac arrhythmic event. Recently, it was demonstrated that TWA during recovery from exercise has additional predictive value. Another mechanism that potentially contributes to arrhythmogeneity is exercise-recovery hysteresis in action potential morphology distribution, which becomes apparent in the spatial ventricular gradient (SVG). In the current study, we investigated the performance of TWA amplitude (TWAA) during a complete exercise test and of exercise-recovery SVG hysteresis (SVGH) as predictors for lethal arrhythmias in a population of heart failure patients with cardioverter-defibrillators (ICDs) implanted for primary prevention., Methods: We performed a case-control study with 34 primary prevention ICD patients, wherein 17 patients (cases) and 17 patients (controls) had no ventricular arrhythmia during follow-up. We computed, in electrocardiograms recorded during exercise tests, TWAA (maximum over the complete test) and the exercise-recovery hysteresis in the SVG. Statistical analyses were done by using the Student t test, Spearman rank correlation analysis, receiver operating characteristics analysis, and Kaplan-Meier analysis. Significant level was set at 5%., Results: Both SVGH and TWAA differed significantly (P < .05) between cases (mean ± SD, SVGH: -18% ± 26%, TWAA: 80 ± 46 μV) and controls (SVGH: 5% ± 26%, TWAA: 49 ± 20 μV). Values of TWAA and SVGH showed no significant correlation in cases (r = -0.16, P = .56) and in controls (r = -0.28, P = .27). Receiver operating characteristics of SVGH (area under the curve = 0.734, P = .020) revealed that SVGH less than 14.8% discriminated cases and controls with 94.1% sensitivity and 41.2% specificity; hazard ratio was 3.34 (1.17-9.55). Receiver operating characteristics of TWA (area under the curve = 0.699, P = .048) revealed that TWAA greater than 32.5 μV discriminated cases and controls with 93.8% sensitivity and 23.5% specificity; hazard ratio was 2.07 (0.54-7.91)., Discussion and Conclusion: Spatial ventricular gradient hysteresis bears predictive potential for arrhythmias in heart failure patients with an ICD for primary prevention, whereas TWA analysis seems to have lesser predictive value in our pilot group. Spatial ventricular gradient hysteresis is relatively robust for noise, and, as it rests on different electrophysiologic properties than TWA, it may convey additional information. Hence, joint analysis of TWA and SVGH may, possibly, improve the noninvasive identification of high-risk patients. Further research, in a large group of patients, is required and currently carried out by our group., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Introduction: Patients with established arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) based on task force (TF) criteria and ventricular tachycardia (VT) are at risk of VT recurrence and sudden death. Data on patients with VT due to right ventricular (RV) scar not fulfilling TF criteria are lacking. The purpose of this study was to assess the long-term arrhythmia recurrence rate and outcome in patients with scar-related right VT with and without a diagnosis of ARVC/D., Methods: Sixty-four patients (age 43.5 +/- 15 years, 49 males) presenting with nonischemic scar-related VT of RV origin were studied. Scar was identified by electroanatomical mapping, contrast echocardiography, and/or magnetic resonance imaging (MRI). Patients were evaluated and treated according to a standard institute protocol., Results: Twenty-nine (45%) patients were diagnosed with ARVC/D according to TF criteria (TF+) and 35 (55%) with RV scar of undetermined origin (TF-) at the end of follow-up (64 +/- 42 months). Patients were treated with antiarrhythmic drugs, radiofrequency catheter ablation, and/or implantable cardioverter-defibrillator (ICD) implantation. VT recurrence-free survival for TF+ and TF- was 76% versus 74% at 1 year and 45% versus 50% at 4 years (P = ns). Patients with fast index VT (cycle length [CL]< or = 250 ms, n = 31) were more likely to experience a fast VT during follow-up than patients with a slow index VT (CL > 250 ms, n = 33) (61% vs 3%, P < 0.001)., Conclusions: Scar-related RV VTs have a high recurrence rate in TF+ and TF- patients. Patients presenting with a fast index VT are at high risk for fast VT recurrence and may benefit most from ICD therapy.

Introduction: Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is based on a set of criteria proposed by the International Task Force (TF) for Cardiomyopathies in 1994. To fulfill these criteria, presence of both electrocardiographic and anatomical abnormalities must be assessed with ECG and imaging techniques, respectively. This may be difficult in patients with early/mild forms of the disease as detectable structural abnormalities may still be absent. We evaluated in which patients presenting with right ventricular tachycardia (VT) serial reevaluation for ARVD/C is indicated., Methods and Results: Sixty consecutive patients (41 men, mean age 40+/-15 years) were evaluated by the TF criteria for possible ARVD/C because of presentation with a left bundle branch block (LBBB) VT, representing 1 minor criterion. The presence on the ECG of a T-wave inversion beyond lead V2 (1 minor), right precordial QRS prolongation (1 major), or an epsilon wave (1 major) was assessed together with the visualization of severe regional/global right ventricle dysfunction (1 major) or mild segmental dilatation/regional hypokinesia (1 minor) by standard imaging techniques. Initially, 22 (37%) patients were diagnosed as having ARVD/C. After 47+/-39 (range 6-146) months, 23 initially TF-negative patients were reevaluated because of recurrent symptoms, with 12 (52%) additional patients now meeting the TF criteria. Eleven of these 12 (92%) patients presented initially with ECG abnormalities only, but developed structural abnormalities on imaging at follow-up., Conclusion: ECG abnormalities may precede structural abnormalities warranting serial reevaluation for ARVD/C in initially TF-negative patients presenting with LBBB VT with only ECG abnormalities.

Objective: Evaluation of the relation between clinical characteristics and incidence of recurrent ventricular arrhythmias (VAs) or death during long-term follow-up in a cohort of 300 consecutive ischemic heart disease (IHD) patients who had survived an episode of sudden cardiac arrest (SCA)., Background: Survivors of life-threatening VA are at high risk for recurrent events., Methods: A total of 300 consecutive survivors of SCA with IHD were included in a standardized screening and evaluation protocol. Multivariable Cox regression analysis was performed to determine the relation between clinical variables at baseline and the incidence of recurrent VA, all-cause mortality and the composite of both (composite endpoint)., Results: The presenting arrhythmia was VT in 156 (52%) patients and VF in 144 (48%) patients. Revascularization was performed in 78 (26%) patients and an ICD was implanted in 216 (72%) patients. During follow-up (mean 30 +/- 21 months) 37 (12%) patients died and 88 (29%) patients experienced a recurrence. Advanced age (adjusted hazard ratio (HR) 2.0; 1.2-3.3), history of heart failure (HR 1.8; 1.2-2.6), and amiodarone use (HR 3.1; 2.1-4.6) were independent predictors for the composite endpoint. VT as presenting arrhythmia was an independent predictor for all-cause mortality only (HR 2.4; 1.2-4.8). A decreased risk of recurrences was determined by beta-blocker use (HR 0.5; 0.4-0.8) and coronary revascularization (HR 0.3; 0.2-0.6)., Conclusion: In a cohort of 300 consecutive survivors of SCA the incidence of recurrent VA and death is dependent on patient age, history of heart failure, and use of amiodarone. In contrast, use of beta-blockers and aggressive coronary revascularization improve the outcome.

Background: Zones of slow conduction facilitate reentry, the major mechanism of ventricular tachycardia (VT) after myocardial infarction (MI). Identification of these zones during sinus rhythm (SR) is desirable for radiofrequency (RF) catheter ablation of VT. Local conduction velocity may correlate with electrogram duration., Objectives: The purpose of this study was to revise the definition of normal electrogram characteristics and to reevaluate the significance of low-amplitude, long-duration electrograms recorded during SR to select RF catheter ablation sites in patients with VT., Methods: Electroanatomic mapping was performed during SR in 10 control patients with normal left ventricles (LVs) and in 10 patients with stable VT after MI. From the controls, reference values for electrogram amplitude, duration (first peak to last peak distance), and fragmentation (positive deflection) were derived. In patients after MI, areas with signals exceeding these values were annotated and related to successful ablation sites., Results: Ninety-five percent of normal LV electrograms were > or =1.0 mV and < or =28 ms (range 5-39 ms) and all had < or =4 deflections. Based on these results, cutoff values were set at 1 mV, four deflections, and 40 ms. In infarcted hearts, 653 electrograms (44%) were <1.0 mV and of these, 303 were > or =40 ms with >4 deflections and restricted to circumscribed areas. Twenty-seven of 28 targeted VTs remained noninducible after RF catheter ablation within these areas, resulting in 86% sensitivity and 94% specificity for low-amplitude, long-duration electrograms predicting successful ablation sites., Conclusion: Identification of successful RF target areas during SR in patients with VT is feasible with high sensitivity and specificity using a mapping strategy based on voltage and duration criteria.

We evaluated whether long-term cardiac resynchronization therapy affects the inducibility of ventricular tachyarrhythmias in relation to reverse remodeling in cardiac arrest survivors with either ischemic or idiopathic dilated cardiomyopathy. Clinical, electrophysiologic, and echocardiographic data of 18 patients were obtained before and after 6 months of cardiac resynchronization.

We evaluated whether cardiac resynchronization therapy affects the prevalence of ventricular tachycardia in relation to reverse remodeling in patients with end-stage heart failure. Clinical, echocardiographic, and implantable cardioverter-defibrillator (ICD) data of 17 patients with ICDs were obtained before and after they had received an upgrade to an ICD-cardiac resynchronization therapy device.

Introduction: Radiofrequency ablation (RFCA) of ventricular tachycardia (VT) is a potential curative treatment modality. We evaluated the results of RFCA in patients with VT., Methods and Results: One hundred fifty-one consecutive patients (122 men and 29 women; age 57 +/- 16 years) with drug-refractory VT were treated. Underlying heart disease was ischemic heart disease in 89 (59%), arrhythmogenic right ventricular cardiomyopathy (ARVC) in 32 (21%), and idiopathic VT in 30 (20%; left ventricle in 9 [30%]; right ventricle in 21 [70%]). Ablation was performed using standard ablation techniques. Three hundred six different VTs were treated (cycle length 334 +/- 87 msec, 2.0 +/- 1.4 VTs per patient). Procedural success (noninducibility of VT after RFCA) was achieved in 126 (83%) patients (70 ischemic heart disease [79%]; 28 ARVC [88%]; 27 idiopathic VT [93%]). Procedure-related complications (< 48 hours) occurred in 11 (7%) patients: death 3 (2.0%), cerebrovascular accident 2 (1.3%), complete heart block 4 (2.6%), and pericardial effusion 3 (2.0%). Thirty-three (22%) patients received an implantable cardioverter defibrillator (because of hemodynamic unstable VT, failure of the procedure, or aborted sudden death). During follow-up (34 +/- 11 months), VT recurrences occurred in 38 (26%) patients (recurrence rate: 19% in successfully ablated patients and 64% in nonsuccessfully ablated patients; P < 0.001). During follow-up, 12 (8%) patients died (heart failure 8, unknown cause 1, noncardiac cause 3)., Conclusion: RFCA of VT can be performed with a high degree of success (83%). The long-term outcome of successfully ablated patients is promising, with a 75% relative risk reduction compared with nonsuccessfully ablated patients. During follow-up, only one patient died suddenly, supporting a selective ICD placement approach in patients with hemodynamically stable VT.