Atrial substrate characterization in patients with atrial fibrillation and hypertrophic cardiomyopathy: Evidence for an extensive fibrotic disease.

INTRODUCTION: Data regarding the left atrial (LA) electroanatomical substrate in patients with hypertrophic cardiomyopathy (HCM) and atrial fibrillation (AF) are missing. In this electroanatomical mapping (EAM) study, we evaluated the extent of LA fibrosis and its impact on catheter ablation outcomes in patients with HCM and AF. MATERIALS AND METHODS: High-density LA EAM was performed during AF in 28 consecutive patients with obstructive HCM and AF (42.9% displayed paroxysmal AF and 57.1% persistent AF). Propensity score (PS) matching analysis was performed to reduce the impact of potential confounding factors. PS were derived to match patients at a 1:1 ratio. Patients were matched according to age, sex and LA diameter. After PS, 28 non-HCM patients with AF were selected, and served as controls. Two different cut-off values of bipolar signal amplitude were investigated for fibrosis characterization (≤0.25 mV and ≤ 0.4 mV). HCM patients underwent pulmonary vein antral isolation (PVAI) and roof line, while non-HCM patients PVAI only. RESULTS: After the 3-month blanking period, 10 HCM patients (35.7%) displayed atrial arrhythmia recurrence. HCM patients with arrhythmia recurrence showed significantly greater low voltage areas defined as either bipolar voltage ≤0.25 mV (22.5 ± 10% vs. 5.5 ± 6.4%, p = 0.001) or ≤ 0.4 mV (32 ± 13.9% vs. 5.9 ± 5.1%, p < 0.001). The presence of low voltage areas ≤0.4 mV greater than 14.1% of the total LA area also predicted arrhythmia recurrence with excellent sensitivity (100%) and specificity (100%). Univariate analysis revealed that the extent of LA fibrosis was the only predictor of AF recurrence. After PS matching with non-HCM patients, patients with HCM exhibited wider fibrotic regions ≤0.25 mV compared to non-HCM patients (p = 0.016). CONCLUSIONS: High-density EAM reveals extensive LA fibrotic disease in patients with HCM, an event with certain implications in catheter ablation outcomes.

The aortic cusps are the predominant successful ablation site of idiopathic outflow-tract ventricular arrhythmias.

BACKGROUND: Data regarding the successful ablation site of idiopathic outflow tract (OT) ventricular arrhythmias (VAs) in the modern era of mapping and ablation are limited. METHODS AND RESULTS: Over a 4-year period, a total of 309 patients underwent detailed activation mapping of OT VAs including the right ventricular outflow tract (RVOT), the left ventricular outflow tract (LVOT) and the aortic cusps (AC), and the coronary venous system. 244 cases were successfully ablated at the index procedure (78.9%). The successful ablation site was more frequently located at the LVOT/ACs (51.6%) followed by RVOT (36.2%). In particular, the ACs was the predominant successful ablation site of idiopathic OT VAs (46.7%). An epicardial site of origin was predictor of ablation failure (p < 0.05). CONCLUSIONS: The ACs is the predominant successful ablation site of idiopathic OT VAs. TAKE-HOME MESSAGE: The aortic cusps are the predominant successful ablation site of idiopathic idiopathic outflow tract ventricular arrhythmias.

Right ventricular outflow tract low-voltage areas identify the site of origin of idiopathic ventricular arrhythmias: A high-density mapping study.

INTRODUCTION: Electronatomical mapping allows direct and accurate visualization of myocardial abnormalities. This study investigated whether high-density endocardial bipolar voltage mapping of the right ventricular outflow tract (RVOT) during sinus rhythm may guide catheter ablation of idiopathic ventricular arrhythmias (VAs). METHODS AND RESULTS: Forty-four patients (18 males, mean age: 38.1 ± 13.8 years) with idiopathic RVOT VAs and negative cardiac magnetic resonance imaging underwent a stepwise mapping approach for the identification of the site of origin (SOO). High-density electronatomical mapping (1096.6 ± 322.3 points) was performed during sinus rhythm and identified at least two low bipolar voltage areas less than 1 mV (mean amplitude of 0.20 ± 0.10 mV) in 39 of 44 patients. The mean low-voltage surface area was 1.4 ± 0.8 cm2 . Group 1 consisted of 28 patients exhibiting low-voltage areas and high-arrhythmia burden during the procedure. Pace match to the clinical VAs was produced in one of these low-voltage areas. Activation mapping established the SOO at these sites in 27 of 28 cases. Group 2 comprised 11 patients exhibiting abnormal electroanatomical mapping, but very low-arrhythmia burden during the procedure. Pace mapping produced a near-perfect or perfect match to the clinical VAs in one of these areas in 9 of 11 patients which was marked as potential SOO and targeted for ablation. During the follow-up period, 25 of 28 patients from group 1 (89%) and 7 of 9 patients from group 2 (78%) were free from VAs. CONCLUSIONS: Small but detectable very low-voltage areas during mapping in sinus rhythm characterize the arrhythmogenic substrate of idiopathic RVOT VAs and may guide successful catheter ablation.

Targeted ablation of specific electrogram patterns in low-voltage areas after pulmonary vein antral isolation in persistent atrial fibrillation: Termination to an organized rhythm reduces atrial fibrillation recurrence.

BACKGROUND: Ablation strategies have been developed to improve outcomes in patients with persistent atrial fibrillation (PsAF). However, the impact of atrial fibrillation (AF) termination on late AF recurrence is not well known. The aim of our study was to evaluate the impact of AF termination to atrial tachycardia (AT) or sinus rhythm (SR) during catheter ablation on late AF recurrence after the 3-month blanking period. METHODS AND RESULTS: We prospectively recruited 140 patients (mean age: 58.5 ± 12.3 years old, 74.3% males) with uninterrupted PsAF of a mean duration of 3.7 months. Pulmonary vein antral isolation (PVAI) was the first ablation step, and if AF did not terminate (to SR or AT), we ablated low-voltage areas less than 0.4 mV with specific electrogram characteristics. We successfully converted AF to AT or SR in 56 patients (40%) during PVAI (n = 24) or low-voltage ablation ( n = 32). The remaining 84 patients (60%) were electrically cardioverted to SR at the end of the procedure. One hundred patients (71.4%) maintained SR after a single procedure during a mean follow-up of 21.1 ± 0.8 months. Of the 56 patients with AF termination, 46 (82.1%) had no recurrence, while in the group of 84 patients without AF termination, 54 patients (64.3%) remained in SR ( P < 0.02). CONCLUSION: Ablation of PVAI and specific electrograms in low-voltage areas less than 0.4 mV can lead to encouraging outcomes with a low recurrence rate as well as a lower need for redo procedures.

Right ventricular outflow tract high-density endocardial unipolar voltage mapping in patients with Brugada syndrome: evidence for electroanatomical abnormalities.

Aims: Epicardial structural abnormalities at the right ventricular outflow tract (RVOT) may provide the arrhythmia substrate in Brugada syndrome (BrS). Electroanatomical endocardial unipolar voltage mapping is an emerging tool that accurately identifies epicardial abnormalities in different clinical settings. This study investigated whether endocardial unipolar voltage mapping of the RVOT detects electroanatomical abnormalities in patients with BrS. Methods and results: Ten asymptomatic patients (8 males, 34.5 ± 11.2 years) with spontaneous type 1 ECG pattern of BrS and negative late gadolinium enhancement-cardiac magnetic resonance imaging (LGE-c-MRI) underwent high-density endocardial electroanatomical mapping (>800 points). Using a cut-off of 1 mV and 4 mV for normal bipolar and unipolar voltage, respectively, derived from 20 control patients without structural heart disease established by LGE-c-MRI, the extend of low-voltage areas within the RVOT was estimated using a specific calculation software. The mean RVOT area presenting low-voltage bipolar signals in BrS patients was 3.4 ± 1.7 cm2 (range 1.5-7 cm2). A significantly greater area of abnormal unipolar signals was identified (12.6 ± 4.6 cm2 [range 7-22 cm2], P: 0.001). Both bipolar and unipolar electroanatomical abnormalities were mainly located at the free wall of the RVOT. The mean RVOT activation time was significantly prolonged in BrS patients compared to control population (86.4 ± 16.5 vs. 63.4 ± 9.7 ms, P < 0.001). Isochronal mapping demonstrated lines of conduction slowing within the RVOT in 8/10 BrS patients. Conclusion: Wide areas of endocardial unipolar voltage abnormalities that possibly reflect epicardial structural abnormalities are identified at the RVOT of BrS patients.

Left atrial voltage mapping using a new impedance-based algorithm in patients with paroxysmal atrial fibrillation.

AIMS: Atrial fibrosis is associated with the pathogenesis and progression of atrial fibrillation (AF). We sought to evaluate the extent of left atrial (LA) scarring in patients with paroxysmal AF (PAF) undergoing catheter ablation using a new impedance-based algorithm. METHODS: We prospectively enrolled 73 consecutive patients (43 males, 58 years) with PAF who underwent pulmonary vein antral isolation. We first performed high-density bipolar voltage mapping during sinus rhythm using Tissue Proximity Indicator (TPI), one of the features of the ConfiDense mapping module integrated in the electroanatomic mapping system. A dense LA shell was created initially without TPI (mean points 2,411) and subsequently activating TPI (mean points 1,167). Each point was classified according to the peak-to-peak bipolar voltage electrogram based on two criteria (criterion A: healthy >0.8 mV, border zone: 0.4-0.8 mV, scarred: <0.4 mV; criterion B: healthy: >0.5 mV, border zone: 0.25-0.5 mV, scarred: <0.25 mV). RESULTS: LA voltage analysis represented significantly smaller scarred areas when mapping was performed with TPI-ON compared with TPI-OFF in both voltage criteria (average LA voltage area: 3.02 ± 5.28 cm2 vs 9.15 ± 13.11 cm2 vs in criterion A and 1.19 ± 2.54 cm2 vs 5.61 ± 9.56 cm2 in criterion B). A statistically significant voltage difference was observed in all segments of the left atrium between the two mapping protocols, particularly on the inferior wall. CONCLUSION: A more specific delineation of LA fibrosis may be produced using the TPI feature of the ConfiDense mapping module, through elimination of false-positive annotated mapping points due to low contact.

Low-voltage areas detected by high-density electroanatomical mapping predict recurrence after ablation for paroxysmal atrial fibrillation.

INTRODUCTION: We aimed to evaluate the extent of atrial fibrosis in paroxysmal atrial fibrillation (AF) and the correlation with ablation outcomes after pulmonary vein antral isolation (PVΑI) using a mapping system with high-resolution and high-spatial sampling. METHODS AND RESULTS: We prospectively enrolled 80 consecutive patients (45 males, median age 60.26 years) with symptomatic paroxysmal AF who were scheduled for PVAI. Prior to PVAI, high-density bipolar voltage mapping (median number of 2,485 points) was carried out during sinus rhythm in all patients. Criteria for an adequate left atrium (LA) shell were > 2,000 points. Each acquired point was classified according to the peak-to-peak bipolar voltage electrogram based on two criteria (criterion A: healthy > 0.8 mV, border zone: 0.4-0.8 mV and scarred: < 0.4 mV, criterion Β: healthy: > 0.5 mV, border zone: 0.25-0.5 mV and scarred: < 0.25 mV). The extent of low-voltage area < 0.4 mV significantly predicted atrial tachyarrhythmia recurrence after the blanking period (P = 0.002). In univariate analysis, the presence of LA voltage areas < 0.4 mV more than 10% of the total surface area was the only significant predictor of arrhythmia recurrence. The analysis based on window B cutoff values failed to demonstrate any predictors of arrhythmia recurrence. CONCLUSION: These data demonstrate that the existence of LA voltage areas < 0.4 mV more than 10% of the total LA surface area predicts arrhythmia recurrence following PVAI for paroxysmal AF.

Catheter Ablation of Ventricular Arrhythmias Arising from the Distal Great Cardiac Vein.

Catheter ablation of idiopathic ventricular arrhythmias arising from the distal great cardiac vein represents a great challenge. We report data regarding the electrocardiographic and electrophysiologic characteristics in two patients with ventricular arrhythmias arising from the distal great cardiac vein. The technical difficulties to advance and navigate the ablation catheter within the coronary venous system as well as the close proximity to the major coronary vessels are discussed.

The impact of catheter ablation in the interpulmonary isthmus on atrial fibrillation ablation outcomes: a randomized study.

INTRODUCTION: Previous studies have underscored the importance of the interpulmonary isthmus in the initiation and maintenance of atrial fibrillation (AF). The efficacy of additional radiofrequency energy delivery in the interpulmonary isthmus following pulmonary vein antral isolation (PVAI) was investigated. METHODS AND RESULTS: A total of 76 patients (49 males, mean age 56.8 ± 10.3) with drug-resistant paroxysmal (n = 64) and short-lasting persistent AF (n = 12) underwent PVAI. Patients were then randomly assigned to receive either "no further ablation" (group I, n = 38) or additional lesions in the interpulmonary isthmus of both ipsilateral pulmonary veins (group II, n = 38). There were no significant differences between study groups regarding the clinical and echocardiographic data. A trend towards a longer fluoroscopy time was observed in group II (P = 0.076). After a mean follow-up period of 11.1 ± 2.6 months, 22 patients in group I (57.9%) and 25 patients in group II (65.8%) were free from arrhythmia recurrence without any antiarrhythmic drug treatment after a single ablation procedure. The Kaplan-Meier arrhythmia-free survival curves showed no significant differences between study groups (P = 0.460). CONCLUSIONS: Additional lesions in the interpulmonary isthmus following PVAI do not have incremental value in preventing AF recurrence.

The RV1-V3 transition ratio: A novel electrocardiographic criterion for the differentiation of right versus left outflow tract premature ventricular complexes.

BACKGROUND: Several electrocardiographic (ECG) indices have been proposed to predict the origin of premature ventricular complexes (PVCs) with precordial transition in lead V3. However, the accuracy of these algorithms is limited. OBJECTIVES: We sought to evaluate a new ECG criterion differentiating the origin of outflow tract with precordial transition in lead V3. METHODS: We included in our study patients exhibiting outflow tract PVCs with precordial transition in lead V3 referred for ablation. We analyzed a novel new ECG criterion, RV1-V3 transition ratio, for distinguishing right from left idiopathic outflow tract PVCs with precordial transition in lead V3. The RV1-V3 transition ratio was defined as (RV1+RV2+RV3) PVC / (RV1+RV2+RV3) SR (sinus rhythm). RESULTS: We included 58 patients in our study. The ratio was lower for right ventricular outflow tract origins than left ventricular outflow tract (LVOT) origins (median [interquartile range], 0.6953 [0.4818-1.0724] vs 1.5219 [1.1582-2.4313], P < .001). Receiver operating characteristic analysis revealed an area under the curve of 0.856 for the ratio, and a cut-off value of ≥0.9 predicting LVOT origin with 94% sensitivity and 73% specificity. This ratio was superior to any previously proposed ECG criterion for differentiating right from left outflow tract PVCs. CONCLUSION: The RV1-V3 transition ratio is a simple and accurate novel ECG criterion for distinguishing right from left idiopathic outflow tract PVCs with precordial transition in lead V3.

High-density mapping of de novo focal atrial tachycardias using a new software: Protected low-voltage areas by zones of conduction delay.

BACKGROUND: The pathophysiological mechanism of focal atrial tachycardias (AT) remains obscure. METHODS: Fifteen patients (6 males, age 45 ± 18) with focal AT underwent high-density activation mapping using a new software called extended early-meets-late (EEML). RESULTS: Irrespective of the arrhythmia mechanism, low bipolar voltage fractionated signals (0.14 ± 0.10 mV) were seen at the earliest activation site. The mean low-voltage area (LVA) at the earliest activation site was 3.2 ± 1.0 cm2. EEML mapping revealed zones of conduction delay at the borders of LVAs. CONCLUSIONS: LVAs protected by zones of slow conduction appears to play an important role in the initiation and maintenance of focal ATs.

Safety, long-term outcomes and predictors of recurrence following a single catheter ablation procedure for atrial fibrillation.

Background: Data regarding long-term outcomes of atrial fibrillation (AF) catheter ablation are limited. This study evaluated the safety, long-term efficacy and predictors of recurrence after a single left atrial ablation procedure in patients with paroxysmal (PAF) and non-paroxysmal AF (NPAF). Methods: Data from 520 patients (354 males, mean age 57.08 ± 11.33 years) with PAF (n = 356, 68.5%) or NPAF (n = 164, 31.5%) who underwent a single radiofrequency ablation procedure were analysed. Across the NPAF group, there were 143 (27.5%) patients with persistent AF and 21 (4%) with long-standing persistent AF. The mean follow-up period was 39.05 ± 20.83 months (range 19-60 months). Results: Arrhythmia recurrence was observed in 102/356 (28.7%) of PAF patients and in 63/164 (38.4%) of NPAF patients. In patient with PAF, sinus rhythm maintenance was observed in 76.9%, 73% and 71.3% of patients at 1, 2 and 5 years of follow-up, respectively. In patients with NPAF, sinus rhythm was maintained in 68.7%, 63.4% and 61.6% of patients at 1, 2 and 5 years of follow-up, respectively. Independent predictors of AF recurrence were left atrial diameter (OR 1.15, 95% CI 1.10-1.21, p < 0.01) as well as early arrhythmia recurrence during the blanking period of 3 months after the procedure (OR 8.13, 95% CI 5.10-12.82, p < 0.01). Major complications were observed in 11 patients (2.1%). Conclusions: Long-term arrhythmia-free survival rates remain high among PAF and NPAF patients after a single catheter ablation procedure. Left atrial diameter and early arrhythmia recurrence were independent predictors of late arrhythmia recurrence in both PAF and NPAF patients.

Catheter ablation of anteroseptal accessory pathways from the aortic cusps: A case series and a review of the literature.

Data regarding catheter ablation of anteroseptal accessory pathways through the aortic cusps are limited. We describe two cases of true para-Hisian accessory pathways successfully ablated from the aortic cusps (right coronary cusp and non-coronary cusp, respectively) along with a review of the current literature. Due to the close proximity to the atrioventricular node and the high risk of complication, mapping of the aortic cusps should always be considered in the case of anteroseptal accessory pathways. Anteroseptal accessory pathways can be safely and effectively ablated from the aortic cusps with good long-term outcomes.