Activation mapping using noninvasive electrocardiographic imaging (ECGi) has recently been used to describe the physiology of different cardiac abnormalities. These descriptions differ from prior ...invasive studies, and both methods have not been thoroughly confronted in a clinical setting.
The goal of the present study was to provide validation of noninvasive activation mapping in a clinical setting through direct confrontation with invasive epicardial contact measures.
Fifty-nine maps were obtained in 55 patients and aligned on a common geometry. Nearest-neighbor interpolation was used to avoid map smoothing. Quantitative comparison was performed by computing between-map correlation coefficients and absolute activation time errors.
The mean activation time error was 20.4 ± 8.6 ms, and the between-map correlation was poor (0.03 ± 0.43). The results suggested high interpatient variability (correlation −0.68 to 0.82), wide QRS patterns, and paced rhythms demonstrating significantly better mean correlation (0.68 ± 0.17). Errors were greater in scarred regions (21.9 ± 10.8 ms vs 17.5 ± 6.7 ms; P < .01). Fewer epicardial breakthroughs were imaged using noninvasive mapping (1.3 ± 0.5 vs 2.3 ± 0.7; P < .01). Primary breakthrough locations were imaged 75.7 ± 38.1 mm apart. Lines of conduction block (jumps of ≥50 ms between contiguous points) due to structural anomalies were recorded in 27 of 59 contact maps and were not visualized at these same sites noninvasively. Instead, artificial lines appeared in 33 of 59 noninvasive maps in regions of reduced bipolar voltage amplitudes (P = .03). An in silico model confirms these artificial constructs.
Overall, agreement of ECGi activation mapping and contact mapping is poor and heterogeneous. The between-map correlation is good for wide QRS patterns. Lines of block and epicardial breakthrough sites imaged using ECGi are inaccurate. Further work is required to improve the accuracy of the technique.
Introduction
Radiofrequency (RF) lesion metrics are influenced by underlying parameters like RF power, duration, and contact force (CF), and utilization of lesion metric indices (ablation index AI) ...is a proposed strategy to predict lesion quality. The aim of this study was to analyze the influence of underlying parameters on lesion metrics of high‐power short‐duration (HPSD) and standard RF applications using an in silico and ex vivo model.
Methods and Results
An in silico simulation study was designed to simulate HPSD and standard ablations, in which ablation parameters could systematically be varied. For each simulated ablation process (n = 5732), the corresponding AI value was calculated. HPSD and standard RF settings were then applied in a porcine ex vivo model (
n = 120 lesions). The resulting lesion metrics were compared and analyzed regarding underlying parameters. RF applications of 50 W/13 seconds, 60 W/10 seconds, 70 W/7 seconds, and 80 W/6 seconds resulted in lesion volumes not significantly different from standard RF applications (30 W/30 seconds,
P > 0.05). HPSD lesion diameters were significantly larger and lesion depths were significantly smaller (
P < 0.01) when compared with standard settings. Prolonging RF duration from 5 to 10 seconds resulted in a +27.5% increase, whereas a prolongation of RF duration from 35 to 40 seconds resulted in a +4.8% increase of AI value only. An increase of CF from 1 to 10 g resulted in a +73.0%, an increase of CF from 20 to 30 g resulted in a +10.1% increase of AI value.
Conclusion
HPSD RF applications resulted in similar lesion volumes but significantly different lesion geometries when compared with standard setting RF applications.
Within the span of a few years, watches have functionally morphed from objects that tell time to wearable minicomputers that allow real-time recording of electrocardiograms (ECGs). Considerable ...information can be deduced from these single lead tracings, and it is now not uncommon to see patients in whom diagnostic tracings of clinically relevant but elusive arrhythmias are captured using a smartwatch. Empowering individuals to record their own ECG tracings in scenarios such as palpitations, syncope, and for risk stratification of sudden death intuitively has considerable potential, but its value remains to be robustly demonstrated. The main objective of this review is to describe the information that can be obtained from smartwatch-based single-lead ECG recordings beyond simply differentiating between sinus rhythm and atrial fibrillation. We also review the strengths and limitations of using these devices in clinical settings and offer potential solutions to address the latter.
Atrial Fibrosis on MRI in Patients
Introduction
We studied the extent and distribution of left atrial (LA) fibrosis on delayed‐enhanced (DE) MRI in a general cardiology population.
Methods and ...Results
One hundred ninety consecutive patients referred for cardiac MRI underwent DE imaging using a free breathing method. The population comprised 60 AF patients and 130 patients without AF, including 75 with structural heart disease (SHD). DE was quantified using histogram thresholding, expressed in % of the wall. Regression analysis was performed to identify predictors of DE. Additionally, DE was registered on a template to study its distribution in subpopulations. In the total population, age, AF, and SHD were independently associated with DE. DE was increasingly observed from 11.1 ± 4.7% in patients with no SHD nor AF, 18.8 ± 7.8% in SHD and no AF history, 22.9 ± 7.8% in paroxysmal AF, to 27.8 ± 7.7% in persistent AF. Among non‐AF patients, age and SHD were independently associated with DE. Among AF patients, female gender and AF persistence were independently associated with DE. DE was variably distributed but more frequently detected in the posterior wall.
Conclusion
Age, history of AF, and SHD are the most powerful predictors of atrial fibrosis, as detected by MRI, in a general cardiology population. Atrial fibrosis predominates in the posterior LA wall.
Brugada syndrome (BrS) is a highly arrhythmogenic cardiac disorder, associated with an increased incidence of sudden death. Its arrhythmogenic substrate in the intact human heart remains ill-defined.
...Using noninvasive ECG imaging, we studied 25 BrS patients to characterize the electrophysiological substrate and 6 patients with right bundle-branch block for comparison. Seven healthy subjects provided control data. Abnormal substrate was observed exclusively in the right ventricular outflow tract with the following properties (in comparison with healthy controls; P<0.005): (1) ST-segment elevation and inverted T wave of unipolar electrograms (2.21±0.67 versus 0 mV); (2) delayed right ventricular outflow tract activation (82±18 versus 37±11 ms); (3) low-amplitude (0.47±0.16 versus 3.74±1.60 mV) and fractionated electrograms, suggesting slow discontinuous conduction; (4) prolonged recovery time (381±30 versus 311±34 ms) and activation-recovery intervals (318±32 versus 241±27 ms), indicating delayed repolarization; (5) steep repolarization gradients (Δrecovery time/Δx=96±28 versus 7±6 ms/cm, Δactivation-recovery interval/Δx=105±24 versus 7±5 ms/cm) at right ventricular outflow tract borders. With increased heart rate in 6 BrS patients, reduced ST-segment elevation and increased fractionation were observed. Unlike BrS, right bundle-branch block had delayed activation in the entire right ventricle, without ST-segment elevation, fractionation, or repolarization abnormalities on electrograms.
The results indicate that both slow discontinuous conduction and steep dispersion of repolarization are present in the right ventricular outflow tract of BrS patients. ECG imaging could differentiate between BrS and right bundle-branch block.
The mainstay of treatment for atrial fibrillation (AF) remains pharmacological; however, catheter ablation has increasingly been used over the last decade. The relative merits of each strategy have ...not been extensively studied.
We conducted a randomized multicenter comparison of these 2 treatment strategies in patients with paroxysmal AF resistant to at least 1 antiarrhythmic drug. The primary end point was absence of recurrent AF between months 3 and 12, absence of recurrent AF after up to 3 ablation procedures, or changes in antiarrhythmic drugs during the first 3 months. Ablation consisted of pulmonary vein isolation in all cases, whereas additional extrapulmonary vein lesions were at the discretion of the physician. Crossover was permitted at 3 months in case of failure. Echocardiographic data, symptom score, exercise capacity, quality of life, and AF burden were evaluated at 3, 6, and 12 months by the supervising committee. Of 149 eligible patients, 112 (18 women 16%; age, 51.1+/-11.1 years) were enrolled and randomized to ablation (n=53) or "new" antiarrhythmic drugs alone or in combination (n=59). Crossover from the antiarrhythmic drugs and ablation groups occurred in 37 (63%) and 5 patients (9%), respectively (P=0.0001). At the 1-year follow-up, 13 of 55 patients (23%) and 46 of 52 patients (89%) had no recurrence of AF in the antiarrhythmic drug and ablation groups, respectively (P<0.0001). Symptom score, exercise capacity, and quality of life were significantly higher in the ablation group.
This randomized multicenter study demonstrates the superiority of catheter ablation over antiarrhythmic drugs in patients with AF with regard to maintenance of sinus rhythm and improvement in symptoms, exercise capacity, and quality of life.
The Early Repolarization Pattern: A Consensus Paper Macfarlane, Peter W; Antzelevitch, Charles; Haissaguerre, Michel ...
Journal of the American College of Cardiology,
07/2015, Letnik:
66, Številka:
4
Journal Article
Recenzirano
The term early repolarization has been in use for more than 50 years. This electrocardiographic pattern was considered benign until 2008, when it was linked to sudden cardiac arrest due to idiopathic ...ventricular fibrillation. Much confusion over the definition of early repolarization followed. Thus, the objective of this paper was to prepare an agreed definition to facilitate future research in this area. The different definitions of the early repolarization pattern were reviewed to delineate the electrocardiographic measures to be used when defining this pattern. An agreed definition has been established, which requires the peak of an end-QRS notch and/or the onset of an end-QRS slur as a measure, denoted Jp, to be determined when an interpretation of early repolarization is being considered. One condition for early repolarization to be present is Jp ≥0.1 mV, while ST-segment elevation is not a required criterion.
Biventricular pacing (BVP) may not achieve complete electrical resynchronization.
The purpose of this study was to assess whether the resynchronizing effect of BVP varies among patients depending on ...the underlying electrical substrate.
High-resolution electrocardiographic mapping with invasive measurement of the maximal rate of systolic left ventricular (LV) pressure rise (LVdP/dtmax) was performed during baseline activation and during BVP in 61 patients with heart failure with various conduction delays: 13 with narrow QRS duration (<120 ms), 22 with nonspecific intraventricular conduction disturbance, and 26 with left bundle branch block. Electrical dyssynchrony, both during baseline activation and BVP, was quantified by total and LV activation times (TAT and LVTAT) and by ventricular electrical uncoupling (VEU = mean LVTAT - mean right ventricular activation time). Response to BVP was defined as a ≥10% increase in LVdP/dtmax.
The electrical activation pattern during BVP was similar for all patient groups and, hence, not dependent on baseline conduction disturbance. During BVP, TAT, LVTAT, and VEU were similar for all groups and were either not correlated or weakly correlated with the change in LVdP/dtmax. In contrast, changes in electrical dyssynchrony correlated significantly with the change in LVdP/dtmax: r=0.71, 0.69, and 0.69 for ∆TAT, ∆LVTAT, and ∆VEU, respectively (all P < .001). Responders showed higher baseline dyssynchrony levels and BVP-induced dyssynchrony reduction than did nonresponders (all P < .001); in nonresponders, BVP worsened activation times than did baseline activation.
BVP does not eliminate electrical dyssynchrony, but rather brings it to a common level independent of the patient's underlying electrical substrate. Therefore, BVP is of benefit to patients with dyssynchrony but not to patients with insufficient electrical dyssynchrony in whom it induces an iatrogenic electropathy.
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