Electrocardiographic imaging demonstrates electrical synchrony improvement by dynamic atrioventricular delays in patients with left bundle branch block and preserved atrioventricular conduction

Aims: Cardiac resynchronization therapy programmed to dynamically fuse pacing with intrinsic conduction using atrioventricular (AV) timing algorithms (e.g. SyncAV) has shown promise; however, mechanistic data are lacking. This study assessed the impact of SyncAV on electrical dyssynchrony across various pacing modalities using non-invasive epicardial electrocardiographic imaging (ECGi). Methods and results: Twenty-five patients with left bundle-branch block (median QRS duration (QRSd) 162.7 ms) and intact AV conduction (PR interval 174.0 ms) were prospectively enrolled. ECGi was performed acutely during biventricular pacing with fixed nominal AV delays (BiV) and using SyncAV (optimized for the narrowest QRSd) during: BiV + SyncAV, LV-only single-site (LVSS + SyncAV), MultiPoint pacing (MPP + SyncAV), and LV-only MPP (LVMPP + SyncAV). Dyssynchrony was quantified via ECGi (LV activation time, LVAT; RV activation time, RVAT; LV electrical dispersion index, LVEDi; ventricular electrical uncoupling index, VEU; and biventricular total activation time, VVtat). Intrinsic conduction LVAT (124 ms) was significantly reduced by BiV pacing (109 ms) (P = 0.001) and further reduced by LVSS + SyncAV (103 ms), BiV + SyncAV (103 ms), LVMPP + SyncAV (95 ms), and MPP + SyncAV (90 ms). Intrinsic RVAT (93 ms), VVtat (130 ms), LVEDi (36 ms), VEU (50 ms), and QRSd (163 ms) were reduced by SyncAV across all pacing modes. More patients exhibited minimal LVAT, VVtat, LVEDi, and QRSd with MPP + SyncAV than any other modality. Conclusion: Dynamic AV delay programming targeting fusion with intrinsic conduction significantly reduced dyssynchrony, as quantified by ECGi and QRSd for all evaluated pacing modes. MPP + SyncAV achieved the greatest synchrony overall but not for all patients, highlighting the value of pacing mode individualization during fusion optimization

Remote Clinics and Investigations in Arrhythmia Services: What Have We Learnt During Coronavirus Disease 2019?

The coronavirus disease 2019 (COVID-19) pandemic has had a dramatic impact on the way that medical care is delivered. To minimise hospital attendance by both patients and staff, remote clinics, meetings and investigations have been used. Technologies including hand-held ECG monitoring using smartphones, patch ECG monitoring and sending out conventional Holter monitors have aided remote investigations. Platforms such as Google Meet and Zoom have allowed remote multidisciplinary meetings to be delivered effectively. The use of phone consultations has allowed outpatient care to continue despite the pandemic. The COVID-19 pandemic has resulted in a radical, and probably permanent, change in the way that outpatient care is delivered. Previous experience in remote review and the available technologies for monitoring have allowed the majority of outpatient care to be conducted without obviously compromising quality or safety

Amplified sinus-P-wave analysis predicts outcomes of cryoballoon ablation in patients with persistent and long-standing persistent atrial fibrillation: A multicentre study

IntroductionOutcomes of catheter ablation for non-paroxysmal atrial fibrillation (AF) remain suboptimal. Non-invasive stratification of patients based on the presence of atrial cardiomyopathy (ACM) could allow to identify the best responders to pulmonary vein isolation (PVI).MethodsObservational multicentre retrospective study in patients undergoing cryoballoon-PVI for non-paroxysmal AF. The duration of amplified P-wave (APW) was measured from a digitally recorded 12-lead electrocardiogram during the procedure. If patients were in AF, direct-current cardioversion was performed to allow APW measurement in sinus rhythm. An APW cut-off of 150 ms was used to identify patients with significant ACM. We assessed freedom from arrhythmia recurrence at long-term follow-up in patients with APW ≥ 150 ms vs. APW < 150 ms.ResultsWe included 295 patients (mean age 62.3 ± 10.6), of whom 193 (65.4%) suffered from persistent AF and the remaining 102 (34.6%) from long-standing persistent AF. One-hundred-forty-two patients (50.2%) experienced arrhythmia recurrence during a mean follow-up of 793 ± 604 days. Patients with APW ≥ 150 ms had a significantly higher recurrence rate post ablation compared to those with APW < 150 ms (57.0% vs. 41.6%; log-rank p < 0.001). On a multivariable Cox-regression analysis, APW≥150 ms was the only independent predictor of arrhythmia recurrence post ablation (HR 2.03 CI95% 1.28–3.21; p = 0.002).ConclusionAPW duration predicts arrhythmia recurrence post cryoballoon-PVI in persistent and long-standing persistent AF. An APW cut-off of 150 ms allows to identify patients with significant ACM who have worse outcomes post PVI. Analysis of APW represents an easy, non-invasive and highly reproducible diagnostic tool which allows to identify patients who are the most likely to benefit from PVI-only approach

QT dispersions : Moving from risk stratification towards underlying mechanisms

Experimental studies have shown that when pathological processes disrupt the normal orderly sequence of electrical recovery following activation, the conditions favouring the development of reentrant arrhythmias are created. Comparatively little is known about the role of so-called increased dispersion of repolarisation in human arrhythmias, due in part to the difficulty in measuring this process. QT dispersion, defined as the difference between the longest and shortest QT intervals measured from the surface electrocardiogram, has been proposed as just such a measure. A fundamental assumption in the use of QT dispersion is that interlead variations in QT dispersion do indeed reflect regional variations in ventricular repolarisation time. Comparatively few data exist to support this hypothesis and the relationship is explored in this thesis. The last decade has seen a proliferation of studies testing the association between increased QT dispersion and the development of life threatening arrhythmias or sudden death in a variety of cardiac and noncardiac disease states. In the largest group of patients at risk of such events - those with ischaemic heart disease - these studies have so far failed to demonstrate the predictive value of QT dispersion. This may in part be explained by the way in which the methodology has been applied. Dispersion of repolarisation is a dynamic process that may change on a beat to beat basis. A single measure of QT dispersion from a resting electrocardiogram may therefore fail to reflect an individual's capacity to develop the substrate for life threatening arrhythmias. This thesis concerns an exploration of the factors contributing to increased QT dispersion in individuals with heart disease. In particular the influence of acute ischaemia and premature beats, separately and in combination, have been studied as conditions predisposing to arrhythmia development and associated in experimental studies with increased dispersion of repolarisation