Abstract Background The underlying mechanisms sustaining human persistent atrial fibrillation (PsAF) is poorly understood. Objectives This study sought to investigate the complexity and distribution ...of AF drivers in PsAF of varying durations. Methods Of 135 consecutive patients with PsAF, 105 patients referred for de novo ablation of PsAF were prospectively recruited. Patients were divided into 3 groups according to AF duration: PsAF presenting in sinus rhythm (AF induced), PsAF <12 months, and PsAF >12 months. Patients wore a 252-electrode vest for body surface mapping. Localized drivers (re-entrant or focal) were identified using phase-mapping algorithms. Results In this patient cohort, the most prominent re-entrant driver regions included the pulmonary vein (PV) regions and inferoposterior left atrial wall. Focal drivers were observed in 1 or both PV regions in 75% of patients. Comparing between the 3 groups, with longer AF duration AF complexity increased, reflected by increased number of re-entrant rotations (p < 0.05), number of re-entrant rotations and focal events (p < 0.05), and number of regions harboring re-entrant (p < 0.01) and focal (p < 0.05) drivers. With increased AF duration, a higher proportion of patients had multiple extra-PV driver regions, specifically in the inferoposterior left atrium (p < 0.01), superior right atrium (p < 0.05), and inferior right atrium (p < 0.05). Procedural AF termination was achieved in 70% of patients, but decreased with longer AF duration. Conclusions The complexity of AF drivers increases with prolonged AF duration. Re-entrant and focal drivers are predominantly located in the PV antral and adjacent regions. However, with longer AF duration, multiple drivers are distributed at extra-PV sites. AF termination rate declines as patients progress to longstanding PsAF, underscoring the importance of early intervention.
Specific noninvasive signal processing was applied to identify drivers in distinct categories of persistent atrial fibrillation (AF).
In 103 consecutive patients with persistent AF, accurate biatrial ...geometry relative to an array of 252 body surface electrodes was obtained from a noncontrast computed tomography scan. The reconstructed unipolar AF electrograms acquired at bedside from multiple windows (duration, 9±1 s) were signal processed to identify the drivers (focal or reentrant activity) and their cumulative density map. The driver domains were catheter ablated by using AF termination as the procedural end point in comparison with the stepwise-ablation control group. The maps showed incessantly changing beat-to-beat wave fronts and varying spatiotemporal behavior of driver activities. Reentries were not sustained (median, 2.6 rotations lasting 449±89 ms), meandered substantially but recurred repetitively in the same region. In total, 4720 drivers were identified in 103 patients: 3802 (80.5%) reentries and 918 (19.5%) focal breakthroughs; most of them colocalized. Of these, 69% reentries and 71% foci were in the left atrium. Driver ablation alone terminated 75% and 15% of persistent and long-lasting AF, respectively. The number of targeted driver regions increased with the duration of continuous AF: 2 in patients presenting in sinus rhythm, 3 in AF lasting 1 to 3 months, 4 in AF lasting 4 to 6 months, and 6 in AF lasting longer. The termination rate sharply declined after 6 months. The mean radiofrequency delivery to AF termination was 28±17 minutes versus 65±33 minutes in the control group (P<0.0001). At 12 months, 85% patients with AF termination were free from AF, similar to the control population (87%,); P=not significant.
Persistent AF in early months is maintained predominantly by drivers clustered in a few regions, most of them being unstable reentries.
Antral pulmonary vein isolation (PVI) for treatment of atrial fibrillation may induce left atrial tachycardias (ATs).
To determine the prevalence, time course of occurrence, mechanisms, and ...correlation with the electrocardiogram as well as the outcome of ablation of these tachycardias.
Out of the 839 patients who underwent circumferential antral radiofrequency PVI guided by a circumferential pulmonary vein catheter at our institution between February 2005 and April 2011, 35 patients (4%) developed AT during follow-up. Six patients with left AT and a previous PVI at other institutions were also included. Of these 41 patients (26 men, 63%; age 59 ± 10 years), 26 (63%) had underlying paroxysmal atrial fibrillation and 15 (37%) had persistent atrial fibrillation. AT ablation was performed 47 ± 60 weeks after initial PVI, within the first 3 months in 16 patients (39%). The tachycardia mechanism was focal in 15 patients (37%), macroreentry in 25 patients (61%), and undetermined in 1 (2%). Focal tachycardias had an isoelectric line between distinct P waves in 13 of the 15 patients (87%), while only 4 (16%) with a macroreentrant mechanism had an isoelectric line (P <.001). Although difficult to measure, a P-wave width of >140 ms had the highest sensitivity and specificity to identify macroreentrant mechanism. Ablation was acutely successful in 32 patients (78%) and not successful in 4 (10%). In 5 patients, success could not be determined as the tachycardia terminated or degenerated during mapping. During a mean follow-up of 31 ± 17 months, 11 patients (27%; n = 9 82% with macroreentry) underwent repeat ablation procedure for AT. Eight patients had true recurrence, for example, the same AT, and 3 patients had a second mechanism of AT.
With the use of an identical ablation protocol, it was found that approximately 4% of the patients developed AT after mere circumferential antral PVI. The majority of ATs developed within a few months after ablation but occurred as late as several years after the initial PVI. Macroreentry was more frequent than a focal mechanism. Broad P waves and isoelectric lines between P waves help to distinguish a focal mechanism from a macroreentrant mechanism. Ablation has a high acute success rate, and AT recurrence occurs predominantly in macroreentrant AT.
Recent evidence suggests that cardiac sarcoidosis (CS) and arrhythmogenic right ventricular cardiomyopathy (ARVC) can manifest very similarly.
To investigate whether there are significant demographic ...and electrophysiological differences between patients with CS and ARVC.
We prospectively compared patients with proven CS or ARVC who underwent radiofrequency catheter ablation of ventricular tachycardias by using 3-dimensional electroanatomical mapping. Furthermore, we evaluated whether the diagnostic criteria for ARVC would have excluded ARVC in patients with CS.
Eighteen patients (13 men; mean age 44.9 years) were included. All 18 patients had mild to moderately reduced right ventricular ejection fraction. Patients with cardiac sarcoidosis (n = 8) had a significantly lower mean left ventricular ejection fraction (35.6±19.3 vs 60.6±9.4; P = .002). Patients with CS had a significantly wider QRS (0.146 vs 0.110s; P = .004). Five of 8 (63%) patients with CS fulfilled the diagnostic ARVC criteria. Ventricular tachycardias (VTs) with a left bundle branch block pattern were documented in all but one patient (with CS). Programmed ventricular stimulation induced an average of 3.7 different monomorphic VTs in patients with CS vs 1.8 in patients with ARVC (P = .01). VT significantly more often originated in the apical region of the right ventricle in CS vs ARVC (P = .001), with no other predilection sites. Ablation success and other electrophysiological parameters were not different.
The current diagnostic ARVC guidelines do not reliably exclude patients with CS. Clinical and electrophysiological parameters that were characteristic of CS in our patients include reduced left ventricular ejection fraction, a significantly wider QRS, right-sided apical VT, and more inducible forms of monomorphic VT.
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes sudden death and right ventricular heart failure in the young. Clinical data suggest that competitive ...sports may provoke ARVC in susceptible persons. Genetically, loss-of-function mutations in desmosomal proteins (plakophilin, desmoplakin, or plakoglobin) have been associated with ARVC. To test the hypothesis that reduced desmosomal protein expression causes ARVC, we studied the cardiac effects of heterozygous plakoglobin deficiency in mice.
Ten-month-old heterozygous plakoglobin-deficient mice (plakoglobin+/-) had increased right ventricular volume, reduced right ventricular function, and spontaneous ventricular ectopy (all P<0.05). Left ventricular size and function were not altered. Isolated, perfused plakoglobin+/- hearts had spontaneous ventricular tachycardia of right ventricular origin and prolonged right ventricular conduction times compared with wild-type hearts. Endurance training accelerated the development of right ventricular dysfunction and arrhythmias in plakoglobin+/- mice. Histology and electron microscopy did not identify right ventricular abnormalities in affected animals.
Heterozygous plakoglobin deficiency provokes ARVC. Manifestation of the phenotype is accelerated by endurance training. This suggests a functional role for plakoglobin and training in the development of ARVC.
Objectives We evaluated the feasibility and safety of epicardial substrate elimination with endocardial radiofrequency (RF) delivery in patients with scar-related ventricular tachycardia (VT). ...Background Epicardial RF delivery is limited by fat or associated with bleeding, extra-cardiac damages, coronary vessels and phrenic nerve injury. Alternative ablation approaches might be desirable. Methods Forty-six patients (18 ischemic cardiomyopathy ICM, 13 nonischemic dilated cardiomyopathy NICM, 15 arrhythmogenic right ventricular cardiomyopathy ARVC) with sustained VT underwent combined endo- and epicardial mapping. All patients received endocardial ablation targeting local abnormal ventricular activities in the endocardium (Endo-LAVA) and epicardium (Epi-LAVA), followed by epicardial ablation if needed. Results From a total of 173 endocardial ablations targeting Epi-LAVA at the facing site, 48 (28%) applications (ICM: 20 of 71 28%, NICM: 3 of 39 8%, ARVC: 25 of 63 40%) successfully eliminated the Epi-LAVA. Presence of Endo-LAVA, the most delayed and low bipolar amplitude of Epi-LAVA, low unipolar amplitude in the facing endocardium, and Epi-LAVA within a wall thinning area at computed tomography scan were associated with successful ablation. Endocardial ablation could abolish all Epi-LAVA in 4 ICM and 2 ARVC patients, whereas all patients with NICM required epicardial ablation. Endocardial ablation was able to eliminate Epi-LAVA at least partially in 15 (83%) ICM, 2 (13%) NICM, and 11 (73%) ARVC patients, contributing to a potential reduction in epicardial RF applications. Pericardial bleeding occurred in 4 patients with epicardial ablation. Conclusions Elimination of Epi-LAVA with endocardial RF delivery is feasible and might be used first to reduce the risk of epicardial ablation.
Atrial Function After Persistent AF Ablation
Introduction
The atrial outcome after extensive ablation is unknown. We sought to quantify atrial structure and function years after successful ablation ...for persistent atrial fibrillation (PsAF).
Methods and Results
We studied after 80 ± 15 months 26 patients (54 ± 8 years, 1 woman) with PsAF successfully treated by ablation (2.2 ± 0.7 stepwise approach procedures, cumulative RF duration 126 ± 37 minutes). At follow‐up atrial scar burden and atrial outflows were quantified using delayed–enhanced and velocity‐encoded MRI, respectively. Cine imaging was used to quantify atrial conduit function (CF), active emptying fraction (AEF), expansion index (EI), and the inter‐appendage mechanical activation delay. Patients underwent exercise testing at baseline and follow‐up. LA and RA scar extent were 29 ± 6 and 4.3 ± 2.8%, respectively. LA and RA AEF were 10.0 ± 5.3 and 30 ± 8%. Mean inter‐appendage delay was 83 ± 47 ms 42–217. Complete LAA isolation was found in 3 patients. A wave was absent in 9/26 patients. LA scar extent related to the number of procedures (R = 0.58, P = 0.002) and total RF duration (R = 0.56, P = 0.003). Among follow‐up characteristics, LA scar extent related to LAAEF (R = −0.73, P < 0.0001), LAEI (R = −0.64, P = 0.0003), A‐wave peak (R = −0.72, P < 0.0001), and inter‐appendage mechanical delay (R = 0.47, P = 0.02). At multivariable analysis, LA scar extent was independently related to LAAEF and LAEI. LAAEF and LA scar extent correlated with exercise capacity at follow‐up (R = 0.44, P = 0.02, and R = −0.40; P = 0.04).
Conclusion
LA contractility and compliance are markedly impaired years after successful PsAF ablation. LA dysfunction is closely related to scar burden.
Pulmonary vein (PV) electrical isolation is a therapeutic option in atrial fibrillation (AF). New technologies may reduce the complexity of the procedure.
The aim of the present study was to compare ...immediate results and short-term efficacy of a new circular ablation catheter (PVAC) with a conventional point-by-point ablation.
The prospective study enrolled 80 consecutive patients with paroxysmal AF or persistent AF, refractory to antiarrhythmic drugs, who were randomized to radiofrequency ablation using duty-cycled bipolar and unipolar radiofrequency by a decapolar circular catheter (PVAC group) or to point-by-point ablation supported by a 3-dimensional mapping system (3D group).
Forty patients per group were included. Mean age was 58 ± 10 years, 64% were male; 55% had paroxysmal AF, 45% had persistent AF. There were no significant differences between groups. Complete electrical isolation was reached in all but 1 PV, which was not isolated in the PVAC group because of phrenic nerve capture. Procedure and fluoroscopy times were lower in the PVAC group: 171 ± 40 minutes vs. 224 ± 27 minutes, P < .001; 26 ± 8 minutes vs. 35 ± 9 minutes, P < .001; respectively. There were no major complications. During a mean follow-up of 254 ± 99 days, 72% in the PVAC group and 68% in the 3D group were free of AF recurrences irrespective of the initial AF type (P = NS).
PVAC represents a safe alternative for PV isolation. It reduces both procedure and fluoroscopy time. The short- and middle-term efficacy is comparable to a conventional point-by-point antral ablation technique.
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