Atrial fibrillation begets ventricular fibrillation when the AV node fails

Deterioration of atrial fibrillation into ventricular fibrillation has frequently been described in patients with pre-excitation of the ventricles. We report two cases of atrial fibrillation without pre-excitation leading to rapid ventricular tachycardias and recurrent implantable cardioverter defibrillator therapy in young idiopathic ventricular fibrillation patients

Upper Extremity Deep Vein Thrombosis and Asymptomatic Vein Occlusion in Patients With Transvenous Leads: A Systematic Review and Meta-Analysis

Aims: The presence of transvenous leads for cardiac device therapy may increase the risk of venous thromboembolisms. The epidemiology of these complications has not yet been determined systematically. Therefore, this study aims to determine (I) the incidence of symptomatic upper extremity deep vein thrombosis (UEDVT) and (II) the prevalence of asymptomatic upper extremity vein occlusion in patients with transvenous leads, both after the initial 2 months following lead implantation. Methods: PubMed, EMBASE, and Cochrane Library were searched until March 31, 2020 to identify studies reporting incidence of UEDVT and prevalence of asymptomatic vein occlusion after the initial 2 months after implantation in adult patients with transvenous leads. Incidence per 100 patient years of follow-up (PY) and proportions (%) were calculated to derive pooled estimates of incidence and prevalence. Results: Search and selection yielded 20 and 24 studies reporting on UEDVT and asymptomatic vein occlusion, respectively. The overall pooled incidence of UEDVT was 0.9 (95% CI 0.5–1.4) per 100PY after 2 months after lead implantation. High statistical heterogeneity was present among studies (I2 = 82.4%; P = < 0.001) and only three studies considered to be at low risk of bias. The overall pooled prevalence of asymptomatic upper extremity vein occlusion was 8.6% (95% CI 6.0–11.5) with high heterogeneity (I2 = 81.4%; P = <0.001). Meta-regression analysis showed more leads to be associated with a higher risk of UEDVT. Conclusion: Transvenous leads are an important risk factor for symptomatic UEDVT, which may occur up to multiple years after initial lead implantation. Existing data on UEDVT after lead implantation is mostly of poor quality, which emphasizes the need for high quality prospective research. Asymptomatic vein occlusion is present in a substantial proportion of patients and may complicate any future lead addition. Clinical Trial Registration: (URL: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020178136, Identifier: PROSPERO 2020 CRD42020178136)

On-Screen Image-Guided Lead Placement in Cardiac Resynchronization Therapy: Feasibility and Outcome in a Multicenter Setting

Background: Image guidance to assist left ventricular (LV) lead placement may improve outcome after cardiac resynchronization therapy (CRT), but previous approaches and results varied greatly, and multicenter feasibility is lacking altogether. Objective: We sought to investigate the multicenter feasibility of image guidance for periprocedural assistance of LV lead placement for CRT. Methods: In 30 patients from 3 hospitals, cardiac magnetic resonance imaging was performed within 3 months prior to CRT to identify myocardial scar and late mechanical activation (LMA). LMA was determined using radial strain, plotted over time. Segments without scar but clear LMA were classified as optimal for LV lead placement, according to an accurate 36-segment model of the whole heart. LV leads were navigated using image overlay with periprocedural fluoroscopy. After 6 months, volumetric response and super-response were defined as ≥15% or ≥30% reduction in LV end-systolic volume, respectively. Results: Periprocedural image guidance was successfully performed in all CRT patients (age 66 ± 10 years; 59% men, 62% with nonischemic cardiomyopathy, 69% with left bundle branch block). LV leads were placed as follows: within (14%), adjacent (62%), or remote (24%) from the predefined target. According to the conventional 18-segment model, a remote position occurred only once (3%). On average, 86% of patients demonstrated a volumetric response (mean LV end-systolic volume reduction 36 ± 29%), and 66% of all patients were super-responders. Conclusion: On-screen image guidance for LV lead placement in CRT was feasible in a multicenter setting. Efficacy will be further investigated in the randomized controlled ADVISE (Advanced Image Supported Lead Placement in Cardiac Resynchronization Therapy) trial (NCT05053568)

Dutch Outcome in Implantable Cardioverter-Defibrillator Therapy:Implantable Cardioverter-Defibrillator-Related Complications in a Contemporary Primary Prevention Cohort

Background One third of primary prevention implantable cardioverter-defibrillator patients receive appropriate therapy, but all remain at risk of defibrillator complications. Information on these complications in contemporary cohorts is limited. This study assessed complications and their risk factors after defibrillator implantation in a Dutch nationwide prospective registry cohort and forecasts the potential reduction in complications under distinct scenarios of updated indication criteria. Methods and Results Complications in a prospective multicenter registry cohort of 1442 primary implantable cardioverter-defibrillator implant patients were classified as major or minor. The potential for reducing complications was derived from a newly developed prediction model of appropriate therapy to identify patients with a low probability of benefitting from the implantable cardioverter-defibrillator. During a follow-up of 2.2 years (interquartile range, 2.0-2.6 years), 228 complications occurred in 195 patients (13.6%), with 113 patients (7.8%) experiencing at least one major complication. Most common ones were lead related (n=93) and infection (n=18). Minor complications occurred in 6.8% of patients, with lead-related (n=47) and pocket-related (n=40) complications as the most prevailing ones. A surgical reintervention or additional hospitalization was required in 53% or 61% of complications, respectively. Complications were strongly associated with device type. Application of stricter implant indication results in a comparable proportional reduction of (major) complications. Conclusions One in 13 patients experiences at least one major implantable cardioverter-defibrillator-related complication, and many patients undergo a surgical reintervention. Complications are related to defibrillator implantations, and these should be discussed with the patient. Stricter implant indication criteria and careful selection of device type implanted may have significant clinical and financial benefits

Short-Term Variability of the QT Interval Can be Used for the Prediction of Imminent Ventricular Arrhythmias in Patients With Primary Prophylactic Implantable Cardioverter Defibrillators

Background Short-term variability of the QT interval (STVQT) has been proposed as a novel electrophysiological marker for the prediction of imminent ventricular arrhythmias in animal models. Our aim is to study whether STVQT can predict imminent ventricular arrhythmias in patients. Methods and Results In 2331 patients with primary prophylactic implantable cardioverter defibrillators, 24-hour ECG Holter recordings were obtained as part of the EU-CERT-ICD (European Comparative Effectiveness Research to Assess the Use of Primary Prophylactic Implantable Cardioverter Defibrillators) study. ECG Holter recordings showing ventricular arrhythmias of >4 consecutive complexes were selected for the arrhythmic groups (n=170), whereas a control group was randomly selected from the remaining Holter recordings (n=37). STVQT was determined from 31 beats with fiducial segment averaging and calculated as [Formula: see text], where Dn represents the QT interval. STVQT was determined before the ventricular arrhythmia or 8:00 am in the control group and between 1:30 and 4:30 am as baseline. STVQT at baseline was 0.84±0.47 ms and increased to 1.18±0.74 ms (P<0.05) before the ventricular arrhythmia, whereas the STVQT in the control group remained unchanged. The arrhythmic patients were divided into three groups based on the severity of the arrhythmia: (1) nonsustained ventricular arrhythmia (n=32), (2) nonsustained ventricular tachycardia (n=134), (3) sustained ventricular tachycardia (n=4). STVQT increased before nonsustained ve

The concept of triple wavefront fusion during biventricular pacing : Using the EGM to produce the best acute hemodynamic improvement in CRT

Background: Previous reports suggest that biventricular pacing (BiVp) fused with intrinsic conduction (BiVp-fusion, triple wavefront fusion) is associated with improved resynchronization compared to pure-BiVp in cardiac resynchronization therapy (CRT). This study aimed to assess the association between acute hemodynamic benefit of CRT and signs of BiVp-fusion by using a novel electrogram (EGM)-based method. Methods: In 17 patients undergoing CRT implantation, 28 combinations of atrioventricular (AV) and interventricular (VV) delays were applied while invasively measuring acute hemodynamic response based on maximum rate of left ventricular (LV) pressure rise (LV dP/dtmax) to assess optimal BiVp settings. BiVp-fusion was noted if farfield signal (caused by first intrinsic ventricular depolarization) was seen prior to right ventricular (RV) pacing (RVp) artifact on integrated bipolar RV EGM, or QRS morphology changed compared to pure-BiVp (short AV-delay) as seen on electrocardiogram (ECG). Results: Mean optimal RVp timing was at 98 ± 17% of intrinsic right atrial (RA)-RVfarfield (interval from right atrial pace or sense to RV farfield signal) interval, while preactivating the LV at 50 ± 11% of RA-RVsense (interval from right atrial pace or sense to RV sense interval) interval. BiVp-fusion was noted in 16 of 17 (94%) patients on ECG during optimal BiVp. Eight of these patients showed intrinsic farfield signal prior to RVp artifact on RV EGM. In the remaining eight, the RVp was paced just within the RA-RVfarfield interval with a mean of 25 ± 14 ms prior to the onset; therefore, the intrinsic farfield was masked. Conclusion: Optimal hemodynamic BiVp facilitates triple wavefront fusion, by pacing the RV around the onset of intrinsic farfield signal on RV EGM, while preactivating the LV. Aiming at BiVp-fusion could be a target for noninvasive EGM-based CRT device setting optimization

Circadian pattern of RR- and QT-interval.

<p><b>(</b>A) mean ± SEM at beginning of every hour of total cohort (n = 30). Significant higher values are seen at night compared to during the day. * = p< 0.05 compared to 0:00. (B) Mean ± SEM at beginning of every hour of low AS-group (blue line, n = 15) and high AS group (red line, n = 15). No significant differences are found in the circadian pattern of RR-interval or QT-interval between low and high AS group.</p

Circadian pattern of STV-QT in AS subgroups.

<p>Mean ± SEM at beginning of every hour in low AS (blue line, n = 15) and patients with high AS (red line, n = 15). * p < 0.05 compared to 0:00; § p <0.05 compared to low AS. STV-QT peaks at 08:00 and 18:00 in high AS patients, but is stable during the day in low AS patients.</p

Arrhythmia score (AS).

<p>Arrhythmia score (AS).</p

Circadian pattern of STV-QT.

<p>Mean ± SEM at beginning of every hour of total cohort (n = 30). No clear circadian pattern is found, however, two non-significant peaks at 08:00 and 18:00 can be discerned.</p