3D delayed-enhanced magnetic resonance sequences improve conducting channel delineation prior to ventricular tachycardia ablation.

AIMS: Non-invasive depiction of conducting channels (CCs) is gaining interest for its usefulness in ventricular tachycardia (VT) ablation. The best imaging approach has not been determined. We compared characterization of myocardial scar with late-gadolinium enhancement cardiac magnetic resonance using a navigator-gated 3D sequence (3D-GRE) and conventional 2D imaging using either a single shot inversion recovery steady-state-free-precession (2D-SSFP) or inversion-recovery gradient echo (2D-GRE) sequence. METHODS AND RESULTS: We included 30 consecutive patients with structural heart disease referred for VT ablation. Preprocedural myocardial characterization was conducted in a 3 T-scanner using 2D-GRE, 2D-SSFP and 3D-GRE sequences, yielding a spatial resolution of 1.4 × 1.4 × 5 mm, 2 × 2 × 5 mm, and 1.4 × 1.4 × 1.4 mm, respectively. The core and border zone (BZ) scar components were quantified using the 60% and 40% threshold of maximum pixel intensity, respectively. A 3D scar reconstruction was obtained for each sequence. An electrophysiologist identified potential CC and compared them with results obtained with the electroanatomic map (EAM). We found no significant differences in the scar core mass between the 2D-GRE, 2D-SSFP, and 3D-GRE sequences (mean 7.48 ± 6.68 vs. 8.26 ± 5.69 and 6.26 ± 4.37 g, respectively, P = 0.084). However, the BZ mass was smaller in the 2D-GRE and 2D-SSFP than in the 3D-GRE sequence (9.22 ± 5.97 and 9.39 ± 6.33 vs. 10.92 ± 5.98 g, respectively; P = 0.042). The matching between the CC observed in the EAM and in 3D-GRE was 79.2%; when comparing the EAM and the 2D-GRE and the 2D-SSFP sequence, the matching decreased to 61.8% and 37.7%, respectively. CONCLUSION: 3D scar reconstruction using images from 3D-GRE sequence improves the overall delineation of CC prior to VT ablation.

Benefit of left atrial roof linear ablation in paroxysmal atrial fibrillation: a prospective, randomized study.

BACKGROUND: Isolation of the pulmonary veins (PVs) for the treatment of atrial fibrillation (AF) is often supplemented with linear lesions within the left atrium (LA). However, there are conflicting data on the effects of creating a roof line (RL) joining the superior PVs in paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: A cohort of 120 patients with drug-refractory PAF referred for ablation were prospectively randomized into 2 strategies: (1) PV isolation in combination with RL ablation (LA roof ablation [LARA]-1: 59 patients) or (2) PV isolation (LARA-2: 61 patients). Follow-up was performed at 1, 3, and 6 months after the procedure and every 6 months thereafter. After a 3-month blanking period, recurrence was defined as the ocurrence of any atrial tachyarrhythmia lasting ≥30 seconds. PV isolation was achieved in 89% and complete RL block in 81%. RF duration, fluoroscopy, and procedural times were slightly, but not significantly, longer in the LARA-1 group. After 15±10 months, there was no difference in the arrhythmia-free survival after a single AF ablation procedure (LARA-1: 59% vs. LARA-2: 56% at 12 months; log rank P=0.77). The achievement of complete RL block did not influence the results. The incidence of LA macroreentrant tachycardias was 5.1% in the LARA-1 group (n=3) versus 8.2% in the LARA-2 (n=5) (P=ns). Univariate analysis only identified AF duration as a covariate associated with arrhythmia recurrence (hazard ratio, 1.01 [95% confidence interval, 1.002 to 1.012]; P<0.01). CONCLUSION: The linear block at the LA roof is not associated with an improved clinical outcome compared with PV isolation alone. CLINICAL TRIAL REGISTRATION URL: ClinicalTrials.gov. Unique identifier: NCT01203241.

A wavelet-based electrogram onset delineator for automatic ventricular activation mapping.

Electroanatomical mapping (EAM) systems are commonly used in clinical practice for guiding catheter ablation treatments of common arrhythmias. In focal tachycardias, the ablation target is defined by locating the earliest activation area determined by the joint analysis of electrogram (EGM) signals at different sites. However, this is currently a manual time-consuming and experience-dependent task performed during the intervention and thus prone to stress-related errors. In this paper, we present an automatic delineation strategy that combines electrocardiogram (ECG) information with the wavelet decomposition of the EGM signal envelope to identify the onset of each EGM signal for activation mapping. Fourteen electroanatomical maps corresponding to ten patients suffering from non-tolerated premature ventricular contraction (PVC) beats and admitted for ablation procedure were used for evaluation. We compared the results obtained automatically with two types of manual annotations: one during the intervention by an expert technician (on-procedure) and other after the intervention (off-procedure), free from time and procedural constraints, by two other technicians. The automatic annotations show a significant correlation (0.95, p 0.01) with the evaluation reference (off-procedure annotation sets combination) and has an error of 2.1 ± 10.9 ms, around the order of magnitude of the on-procedure annotations error ( - 2.6 ± 6.8 ms). The results suggest that the proposed methodology could be incorporated into EAM systems to considerably reduce processing time during ablation interventions.

CMR-guided approach to localize and ablate gaps in repeat AF ablation procedure.

OBJECTIVES: The aim of this study was to test the feasibility and usefulness of a new delayed-enhancement cardiac magnetic resonance (DE-CMR)-guided approach to ablate gaps in redo procedures. BACKGROUND: Recurrences of atrial fibrillation (AF) after pulmonary vein isolation (PVI) may be related to gaps at the ablation lines. DE-CMR allows identification of radiofrequency lesions and gaps (CMR gaps). METHODS: Fifteen patients undergoing repeated AF ablations were included (prior procedure was PVI in all patients and roof-line ablation in 8 patients). Pre-procedure 3-dimensional (3D) DE-CMR was performed with a respiratory-navigated (free-breathing) and electrocardiographically gated inversion-recovery gradient-echo sequence (voxel size 1.25 × 1.25 × 2.5 mm). Endocardium and epicardium were manually segmented to create a 3D reconstruction (DE-CMR model). A pixel signal intensity map was projected on the DE-CMR model and color-coded (thresholds 40 ± 5% and 60 ± 5% of maximum intensity). The DE-CMR model was imported into the navigation system to guide the ablation of CMR gaps, with the operator blinded to electrical data. Fifteen conventional procedures were used as controls to compare procedural duration, radiofrequency, and fluoroscopy times. RESULTS: Fifteen patients (56 pulmonary veins [PVs]; 57 ± 8 years of age; 9 with paroxysmal AF) were analyzed. In total, 67 CMR gaps were identified around PVs (mean 4.47 gaps/patient; median length 13.33 mm/gap) and 9 at roof line. All of the electrically reconnected PVs (87.5%) had CMR gaps. The site of electrical PV reconnection (assessed by circular mapping catheter) matched with a CMR gap in 79% of PVs. CMR-guided ablation led to reisolation of 95.6% of reconnected PVs (median radiofrequency time of 13.3 [interquartile range: 7.5 to 21.7] min/patient) and conduction block through the roof line in all patients (1.4 [interquartile range: 0.7 to 3.1] min/patient). Compared with controls, the CMR-guided approach shortened radiofrequency time (1,441 ± 915 s vs. 930 ± 662 s; p = 0.026) but not the procedural duration or fluoroscopy time. CONCLUSIONS: DE-CMR can successfully guide repeated PVI procedures by accurately identifying and localizing gaps and may reduce procedural duration and radiofrequency application time.

Reversal of spherical remodelling of the left atrium after pulmonary vein isolation: incidence and predictors.

AIMS: Pulmonary vein isolation (PVI) induces left atrial (LA) volume reduction, known as reverse remodelling (RR). The related changes in LA shape have not yet been evaluated. Left atrial sphericity (LASP) is a new shape-based marker of remodelling that compares LA geometry and a perfect sphere and is a powerful predictor of PVI success. We aimed to evaluate the effect of PVI on LASP and describe the concept of spherical and volumetric RR. METHODS AND RESULTS: Left atrial sphericity and volume were automatically obtained with self-customized software using a magnetic resonance imaging-based three-dimensional reconstruction of LA. Reverse remodelling was defined as improvement in LASP (spherical RR) or volume reduction (volumetric RR). In a series of 102 patients, spherical and volumetric RR was observed in 42.2 and 69%, respectively. Patients with paroxysmal atrial fibrillation (AF) had higher probability to present spherical RR as compared with patients with persistent AF (50.8 vs. 29.3%, P = 0.03). Patients with persistent AF showed significant post-procedural worsening of LASP (81.9 vs. 82.9%, P = 0.04). Patients with no recurrence showed a trend towards a higher proportion of spherical RR compared with those with recurrences (46.2 vs. 32.4%, respectively); no differences were observed in volumetric RR (62.1 vs. 62.9%, respectively). Paroxysmal AF was the only independent predictor of spherical RR. CONCLUSION: Pulmonary vein isolation leads to spherical RR in a substantial proportion of patients, and in higher proportion of patients with paroxysmal AF. Reverse remodelling may be caused by a combination of scarring and myocardial structural recovery. Changes in LASP might be more specific than volume reduction to detect favourable remodelling.

Impact of atrial fibrillation-induced tachycardiomyopathy in patients undergoing pulmonary vein isolation.

INTRODUCTION: Atrial fibrillation (AF) is a recognized treatable cause of tachycardiomyopathy (TMP), with class IIb indication for catheter ablation (CA). The aim of this study is to analyze the prevalence, clinical characteristics and effect of CA in patients with TMP and to evaluate TMP as a prognostic factor for AF recurrence in these patients (TMP group), compared to controls with normal left ventricular ejection fraction (LVEF) and patients with heart failure due to structural cardiomyopathy (HF group). METHODS AND RESULTS: The study groups included 659 consecutive patients undergoing CA between 2003 and 2011: TMP group (n = 61), HF group (n = 36) and control group (n = 562). Compared to controls, patients with TMP were younger, had a shorter AF course and more often had persistent AF. Regarding echocardiographic parameters, the TMP group had lower LVEF (40% vs. 62%, P < 0.05), larger left atrial diameter (LAD: 46 vs. 41 mm, P < 0.05) and LV end-diastolic diameter (LVEDD: 55 vs. 51 mm, P < 0.05) compared to controls, with significant improvement at six-month follow-up, including those patients with AF recurrence. The probability of being arrhythmia-free did not differ between the TMP group and the other groups after a first or last procedure. The only independent predictor of AF recurrence was LAD. CONCLUSIONS: Patients with tachycardiomyopathy secondary to AF benefit from CA, with a significant improvement in LVEF, LVEDD and LAD. The outcome after CA of this group did not differ from patients with no structural cardiomyopathy.

Left atrial sphericity: a new method to assess atrial remodeling. Impact on the outcome of atrial fibrillation ablation.

BACKGROUND: Atrial fibrillation (AF) ablation outcome is mainly determined by atrial remodeling that, nowadays, is only estimated through clinical presentation (persistent vs. paroxysmal) and left atrial (LA) dimension. The aim of the study was to stage the atrial remodeling process using the Left Atrial Sphericity (LASP) and determine whether this technique may help to predict AF ablation outcome. METHODS: Consecutive patients who underwent contrast-enhanced cardiac magnetic resonance angiography before AF ablation were included in the study. Three-dimensional reconstruction of LA excluding pulmonary veins and the LA appendage was used to define the LA cavity. The LASP was automatically obtained with self-customized software. RESULTS: 106 patients were included and categorized in 3 groups (Gs): discoid-LA (G1), intermediate-LA (G2), and spherical-LA (G3). The G3 patients had larger LA anteroposterior diameter than G1 and G2 patients (47 ± 7 vs 43 ± 6 and 39 ± 5 mm; P < 0.001), greater LA volume (90 ± 39 vs 86 ± 24 and 73 ± 20 mm; P = 0.012), and higher prevalence of persistent AF (75% vs 48% and 29%; P = 0.034) structural heart disease (75% vs 19% and 19%; P < 0.001), and AF recurrence at 12 months follow-up (58% vs 29% and 5%, P < 0.001). The LASP had linear correlation to predicted probability of recurrence. Multivariate analysis identified LASP (OR 1.320 [1.096-1.591], P = 0.004) and hypertension (OR 3.694 [1.282-10.645]; P = 0.016) as independent risk factors for arrhythmia recurrence. CONCLUSION: Left Atrial Sphericity is a new independent predictor of recurrence after AF ablation and may be useful in selecting the best candidates for AF ablation.