Automated isochronal late activation mapping for substrate characterization in patients with repaired tetralogy of Fallot.

AIMS: Slow conduction (SC) anatomical isthmuses (AIs) are the dominant substrate for monomorphic ventricular tachycardia (VT) in patients with repaired tetralogy of Fallot (rTF). This study aimed to evaluate the utility of automated propagational analysis for the identification of SC-AI in patients with rTF. METHODS AND RESULTS: Consecutive rTF patients undergoing VT substrate characterization were included. Automated isochronal late activation maps (ILAM) were obtained with multielectrode HD Grid Catheter. Identified deceleration zones (DZs) were compared with both SC-AI defined by conduction velocity (CV) (<0.5 m/s) and isthmuses of induced VT for mechanistic correlation. Fourteen patients were included (age 48; p25-75 35-52 years; 57% male), 2 with spontaneous VT and 12 for risk stratification. Nine VTs were inducible in seven patients. Procedure time was 140 (p25-75 133-180) min and mapping time 29.5 (p25-75 20-37.7) min, using a median of 2167 points. All the patients had at least one AI by substrate mapping, identifying a total of 27 (11 SC-AIs). Isochronal late activation maps detected 10 DZs mostly in the AI between ventricular septal defect and pulmonary valve (80%). Five patients had no DZs. A significant negative correlation between number of isochrones/cm and CV was observed (rho -0.87; P < 0.001). Deceleration zones correctly identified SC-AI (90% sensitivity; 100% specificity; 0.94 accuracy) and was related to VT inducibility (P = 0.006). Deceleration zones co-localized to the critical isthmus of induced VTs in 88% of cases. No complications were observed. CONCLUSION: Deceleration zones displayed by ILAM during sinus rhythm accurately identify SC-AIs in rTF patients allowing a safe and short-time VT substrate characterization procedure.

Brugada syndrome masked by complete left bundle branch block: A clinical and functional study of its association with the p.1449Y>H SCN5A variant.

SCN5A gene variants are associated with both Brugada syndrome and conduction disturbances, sometimes expressing an overlapping phenotype. Functional consequences of SCN5A variants assessed by patch-clamp electrophysiology are particularly beneficial for correct pathogenic classification and are related to disease penetrance and severity. Here, we identify a novel SCN5A loss of function variant, p.1449Y>H, which presented with high penetrance and complete left bundle branch block, totally masking the typical findings on the electrocardiogram. We highlight the possibility of this overlap combination that makes impossible an electrocardiographic diagnosis and, through a functional analysis, associate the p.1449Y>H variant to SCN5A pathogenicity.

Analysis of late reconnections after pulmonary vein isolation: Impact of interlesion contiguity and ablation index.

BACKGROUND: Interlesion distance and ablation index (AI) have been proposed as parameters of radiofrequency (RF) lesion durability. This study analyzes the relationship between RF parameters of automatically acquired lesion tags and late reconnections in repeat pulmonary vein isolation (PVI) procedures. METHODS: One hundred fifty-seven patients underwent contact force (CF)-guided PVI with automatic acquisition of RF lesions. During follow-up, 21 patients underwent a repeat PVI procedure. The relationship between RF parameters (power, CF, impedance drop, and AI) of the initial PVI procedure and reconnections observed at repeat PVI was analyzed. Visual gap was defined as the existence of a discontinuity between two RF lesions automatically acquired in the initial PVI procedure. Regional values of AI associated with lesion durability were identified. RESULTS: Twenty-one patients were included. Three hundred thirty-six segments and 2507 RF lesions were analyzed. The median interval between the initial and repeat PVI procedures was 17 (11-24) months. All patients showed ≥1 reconnected segment. Sixty-three segments (18.7%) were reconnected. Reconnected segments showed visual gaps more frequently than non-reconnected segments (66.6% vs 17.6%; P < .001; negative predictive value 91.4%). The mean distance of visual gaps was 8 ± 2.8 mm. No differences were observed in power (31.4 ± 4.7 W vs 31 ± 4.1 W; P = .573), CF (14.4 ± 5.3 g vs 15.4 ± 5.4 g; P = .315), and impedance drop (6.9 ± 5.2 ohms vs 6.5 ± 3.8 ohms; P = .576) between reconnected and non-reconnected segments. Among segments without visual gap, the minimum AI value was significantly higher in the non-reconnected segments (325 ± 96.1 vs 204.7 ± 78.5; P < .001). No reconnections were observed in segments without visual gap and minimum AI ≥ 330/220 in anterior/posterior wall, respectively. CONCLUSIONS: Contiguity between automatically acquired RF lesions and minimum AI value are the main determinants of long-term PVI durability.

Clinical validation of automatic local activation time annotation during focal premature ventricular complex ablation procedures.

Aims: Current navigation systems incorporate algorithms for automatic identification of local activation time (LAT). However, data about their utility and accuracy in premature ventricular complex (PVC) ablation procedures are scarce. This study analyses the accuracy of an algorithmic method based on automatic annotation of the maximal negative slope of the unipolar electrogram within the window demarcated by the bipolar electrogram compared with conventional manual annotation during PVC ablation procedures. Methods and results: Forty patients with successful ablation of focal PVC in three centres were included. Electroanatomical activation maps obtained with the automatic system (WF-map) were compared with manual annotation maps (M-map). Correlation and concordance of LAT obtained with both methods were assessed at 3536 points. The distance between the earliest activation site (EAS) and the effective radiofrequency application point (e-RFp) were determined in M-map and WF-map. The distance between WF-EAS and M-EAS was assessed. Successful ablation sites included left ventricular outflow tract (LVOT; 55%), right ventricular outflow tract (40%), and tricuspid annulus (5%). Good correlation was observed between the two annotation approaches (r = 0.655; P < 0.0001). Bland-Altman analysis revealed a systematic delayed detection of LAT by WF-map (bias 33.8 ± 30.9 ms), being higher in LVOT than in the right ventricle (42.6 ± 29.2 vs. 27.2 ± 30.5 ms, respectively; P < 0.0001). No difference in EAS-eRFp distance was observed between M-map and WF-map (1.8 ± 2.8 vs. 1.8 ± 3.4 mm, respectively; P = 0.986). The median (interquartile range) distance between WF-EAS and M-EAS was 2.2(0-6) mm. Conclusion: Good correlation was found between M-map and WF-map. Local activation time detection was systematically delayed in WF-map, especially in LVOT. Accurate identification of e-RFp was achieved with both annotation approaches.

Impact of Contact Force Monitoring in Acute Pulmonary Vein Isolation Using an Anatomic Approach. A Randomized Study.

BACKGROUND: The impact of contact force (CF) monitoring in pulmonary vein (PV) isolation after a circumferential anatomic ablation (CAA) is unknown. We analyze the usefulness of CF monitoring in acute PV isolation and procedure parameters using a CAA. METHODS: Fifty patients with paroxysmal atrial fibrillation were randomized into CF-on (CF >10 grams; n = 25) or CF-off (CF blinded; n = 25) groups. We performed a first round of CAA with a ThermoCool(®) SmartTouch(®) catheter blinded to the LASSO(®) catheter (Biosense Webster, Diamond Bar, CA, USA), with radiofrequency (RF) lesions tagged with the VisiTag(™) Module. After the CAA, each PV was reviewed with the LASSO(®) catheter recording the segments with gaps. RESULTS: All the PVs were isolated with a CAA in 20 patients of the CF-on versus eight of the CF-off (P = 0.001). Of the 45 segments with gaps in the left PVs, 38 were from the CF-off (P = 0.0001). Of the eight segments with gaps in the right PVs, seven were from the CF-off (P = 0.06). The CF in the left PVs was higher in the CF-on (16.3 ± 3.2 grams vs 10.5 ± 4.3 grams; P = 0.0001) and similar in the right PVs (17.6 ± 3.6 grams vs 15.2 ± 5.3 grams; P = 0.08). All of the gaps were closed with additional RF LASSO(®) -guided touch-up. Procedure and fluoroscopy times were shorter in the CF-on (139 ± 24 minutes vs 157 ± 32 minutes and 20 ± 6 minutes vs 24 ± 7 minutes; both P = 0.039). At 12 months the patients free of AF recurrence was 84% CF-on versus 75% CF-off (log-rank P = 0.4) [corrected]. CONCLUSIONS: In paroxysmal atrial fibrillation, a CAA guided by CF reduces PV gaps and shortens the procedure parameters at the expense of the left PVs.

Reverse atrial remodeling following pulmonary vein isolation: the importance of the body mass index.

BACKGROUND: Pulmonary vein isolation (PVI) causes a reduction in left atrium size that is attributable to reverse atrial remodeling (RAR). The objective of this study was to identify predictors of RAR and determine its association with other parameters of improvement in cardiac function. METHODS: It is a prospective study with 74 patients (52 ± 9 years old, 81% male), and 51% of patients had paroxysmal atrial fibrillation. Patients were serially assessed with transthoracic echocardiography; plasma N-terminal B-type natriuretic peptide (NT-proBNP); and high-sensitivity C-reactive protein levels at baseline and 3, 6, and 12 months following the PVI. RAR was defined as a reduction in the left atrial volume index (LAV-index) >10% from baseline at the end of follow-up. A multivariate analysis was conducted to identify predictors of RAR. RESULTS: The LAV-index decreased significantly during follow-up in the entire population (P = 0.0005). RAR (experienced by 63.5% of the patients) was more frequent (76% vs. 42%; P = 0.004) and pronounced (reduction 16.65 ± 14% vs. 8 ± 14%; P = 0.015) in patients with a successful ablation (46 of 74 patients, 62.2%). Only patients with RAR showed significant improvement in NT-proBNP levels (P = 0.0001), systolic function (P = 0.035), and diastolic function (P = 0.005). Multivariable analysis revealed that a successful ablation (odds ratio [OR] = 4.6; 95% confidence interval [CI] 1.46-14.68; P = 0.009), LAV-index (OR = 1.15; 95% CI 1.03-1.2; P = 0.021), and patient's body mass index (OR = 0.84; 95% CI 0.74-0.96; P = 0.012) were independent predictors of RAR. CONCLUSIONS: Successful PVI ablation is the main predictor of RAR that is associated with other parameters of improvement in cardiac function. The patient's body mass index may have a negative effect on RAR.

Delineation of intracavitary electrograms for the automatic quantification of decrement-evoked potentials in the coronary sinus with deep-learning techniques.

Cardiac arrhythmias cause depolarization waves to conduct unevenly on the myocardial surface, potentially delaying local components with respect to a previous beat when stimulated at faster frequencies. Despite the diagnostic value of localizing the distinct local electrocardiogram (EGM) components for identifying regions with decrement-evoked potentials (DEEPs), current software solutions do not perform automatic signal quantification. Electrophysiologists must manually measure distances on the EGM signals to assess the existence of DEEPs during pacing or extra-stimuli protocols. In this work, we present a deep learning (DL)-based algorithm to identify decrement in atrial components (measured in the coronary sinus) with respect to their ventricular counterparts from EGM signals, for disambiguating between accessory pathways (APs) and atrioventricular re-entrant tachycardias (AVRTs). Several U-Net and W-Net neural networks with different configurations were trained on a private dataset of signals from the coronary sinus (312 EGM recordings from 77 patients who underwent AP or AVRT ablation). A second, separate dataset was annotated for clinical validation, with clinical labels associated to EGM fragments in which decremental conduction was elucidated. To alleviate data scarcity, a synthetic data augmentation method was developed for generating EGM recordings. Moreover, two novel loss functions were developed to minimize false negatives and delineation errors. Finally, the addition of self-attention mechanisms and their effect on model performance was explored. The best performing model was a W-Net model with 6 levels, optimized solely with the Dice loss. The model obtained precisions of 91.28%, 77.78% and of 100.0%, and recalls of 94.86%, 95.25% and 100.0% for localizing local field, far field activations, and extra-stimuli, respectively. The clinical validation model demonstrated good overall agreement with respect to the evaluation of decremental properties. When compared to the criteria of electrophysiologists, the automatic exclusion step reached a sensitivity of 87.06% and a specificity of 97.03%. Out of the non-excluded signals, a sensitivity of 96.77% and a specificity of 95.24% was obtained for classifying them into decremental and non-decremental potentials. Current results show great promise while being, to the best of our knowledge, the first tool in the literature allowing the delineation of all local components present in an EGM recording. This is of capital importance at advancing processing for cardiac electrophysiological procedures and reducing intervention times, as many diagnosis procedures are performed by comparing segments or late potentials in subsequent cardiac cycles.

Paroxysmal atrial fibrillation burden before and after pulmonary veins isolation: an observational study through a subcutaneous leadless cardiac monitor.

AIMS: Data on the success rate of ablation in atrial fibrillation (AF) are controversial. Our hypothesis is that the efficacy must be evaluated considering the AF burden (AFB) before the procedure. Moreover, the clinical significance of early recurrence (ERAT) of AF or atrial tachyarrhythmias (AT) is debatable. The aim is to describe the outcome of pulmonary vein isolation in paroxysmal AF through a subcutaneous cardiac monitor (ICM) implanted before the procedure. METHODS: Using CARTO 3, circumferential lesions around the pulmonary veins were placed. The study endpoint was the first documented recurrence of AF/AT by ICM after the blanking period (3 months). AFB (percentage of time in AF/AT) was collected every month before and after the procedure during the 12-month follow-up. RESULTS: The ICM was implanted 94 ± 23 days before the procedure in 35 patients with paroxysmal AF (54 ± 11 years, refractory to 1.8 ± 0.6 antiarrhythmic drugs). Cumulative AFB before the procedure and after the blanking period was 2.5% (1-5%) versus 0% (0-0.25%), P < 0.001. Twenty patients (57.1%) were free of documented AF/AT recurrence, 5 patients (14.2%) reduced the AFB 90%, 6 patients (17.1%) continued the same, and 4 patients (11.4%) increased the AFB 90% for AT. The success rate with second procedure was 71.4%. All 13 patients with ERAT had recurrence after the blanking period. CONCLUSIONS: The outcome of pulmonary vein isolation in patients with paroxysmal AF is well documented by an ICM. The success rate is dependent of the previous AFB that can be randomly variable and lower than expected. ERATs predict late recurrence.

Ablation of atrioventricular nodal reentrant tachycardia in a patient with tricuspid atresia guided by electroanatomic mapping.

We describe a case of ablation of atrioventricular nodal reentrant tachycardia in a patient with tricuspid atresia and L-malposition of great vessels using an electroanatomical mapping system integrated with cardiac magnetic resonance imaging. Atrial activation mapping during tachycardia identified the retrograde fast pathway proximal to the His bundle, observed in the left interatrial septum. Ablation was successfully completed below this area. Map integration with the patient's anatomy allowed a safe, individualized procedure.

Long-Term Survival After Implantable Cardiac Defibrillator Therapy According to Sex: A Propensity Matched Study.

Background: Whether the sex factor influences the benefit of the implantable cardioverter-defibrillator (ICD) for the prevention of sudden death remains a subject of debate. Using a prospective registry, we sought to analyze the survival and time to first ICD therapy according to sex. Materials and Methods: Retrospective analysis of a prospective cohort of patients undergoing an ICD implant from 2008 to 2019. Data about time to first appropriate therapy, type of therapy administered, and incidence and causes of mortality were collected. Results: Among 756 ICD patients, 150 (19.8%) were women. Women were younger (51 ± 15 years vs. 61 ± 14 years; p < 0.001) and showed a lower rate of ischemic cardiomyopathy (23% vs. 54%; p < 0.001) and atrial fibrillation (12% vs. 19%; p = 0.05). Women had higher left ventricular ejection fraction (39% ± 17% vs. 35% ± 13%) and showed more frequently left bundle branch block (39% vs. 28%, p = 0.027). The rate of primary prevention (68% vs. 59.6%; p = 0.058) and cardiac resynchronization therapy (27% vs. 19%, p = 0.02) were higher in women. After a median follow-up of 46 months (3382 patient-years), the incidence of both the primary combined endpoint of mortality/transplant (20% vs. 29%; logrank = 0.031) and ICD therapies (27% vs. 34%; p = 0.138) were lower in women. According to the propensity score-matching analysis, no differences were observed between both sexes with respect to the incidence of mortality/transplant (24.8% vs. 28.6%; logrank = 0.88), ICD therapies (28% vs. 27%; logrank = 0.17), and main cause of death (heart failure [HF]). Conclusions: The clinical characteristics at the moment of ICD implant are different between sexes. After adjusting them, both sexes equally benefit from the ICD. HF is the main cause of mortality both in men and women.

Dramatic reduction of ventricular tachycardia burden after dronedarone plus mexiletine treatment in a patient refractory to hybrid ablation.

Antiarrhythmic drugs are often the last resort for recurrent ventricular tachycardia refractory to catheter ablation in implantable cardioverter-defibrillator carriers. Amiodarone, alone or combined with mexiletine, is usually but not always highly effective, and its use is usually limited by systemic adverse effects. We present the case of a 62 years old man with recurrent ICD shocks due to a VT refractory to an endo-epicardial hybrid ablation. Starting of dronedarone plus mexiletine combination showed an excellent result.

Long-term outcomes of ventricular tachycardia substrate ablation incorporating hidden slow conduction analysis.

BACKGROUND: Ventricular tachycardia substrate ablation (VTSA) incorporating hidden slow conduction (HSC) analysis allows further arrhythmic substrate identification. OBJECTIVE: The purpose of this study was to analyze whether the elimination of HSC electrograms (HSC-EGMs) during VTSA results in better short- and long-term outcomes. METHODS: Consecutive patients (N = 70; 63% ischemic; mean age 64 ± 14.6 years) undergoing VTSA were prospectively included. Bipolar EGMs with >3 deflections and duration <133 ms were considered as potential HSC-EGMs. Whenever a potential HSC-EGM was identified, double or triple ventricular extrastimuli were delivered. If a local potential showed up as a delayed component, it was annotated as HSC-EGM. Ablation was delivered at conducting channel entrances and HSC-EGMs. Radiofrequency time, ventricular tachycardia (VT) inducibility after VTSA, and VT/ventricular fibrillation recurrence at 24 months after the procedure were compared with data from a historical control group. RESULTS: A total of 5076 EGMs were analyzed; 1029 (20.2%) qualified as potential HSC-EGMs, and 475 of them were tagged as HSC-EGMs. Scars in patients with HSC-EGMs (n = 43 [61.4%]) were smaller (32.2 [17-58] cm2 vs 85 [41-92.4] cm2; P = .006) and more heterogeneous (core/scar area ratio 0.15 [0.05-0.44] vs 0.44 [0.33-0.57]; P = .017); 32.4% of HSC-EGMs were located in normal voltage tissue. Patients undergoing VTSA incorporating HSC analysis required less radiofrequency time (15.6 [8-23.1] vs 23.9 [14.9-30.8]; P < .001) and had a lower rate of VT inducibility after VTSA (28.6% vs 52.9%; P = .003) than did the historical controls. Patients undergoing VTSA incorporating HSC analysis showed a higher 2-year VT/ventricular fibrillation-free survival (75.7% vs 58.8%; log-rank, P = .046) after VTSA. CONCLUSION: VTSA incorporating HSC analysis allowed further arrhythmic substrate identification (especially in the border zone and normal voltage areas) and was associated with increased VTSA efficiency and better short- and long-term outcomes.

Unusual tachycardia association in a patient without structural heart disease.

We report an unusual association of persistent atrial flutter and bundle branch re-entrant ventricular tachycardia in a young patient without structural heart disease. Atrial flutter masked the infra-Hisian conduction disease, was fundamentally dependent on a long PR interval, and could be a possible trigger of ventricular tachycardia.

Paroxysmal atrial fibrillation ablation: Achieving permanent pulmonary vein isolation by point-by-point radiofrequency lesions.

Pulmonary vein isolation by point-by-point radiofrequency catheter ablation constitutes the cornerstone of catheter ablation strategies for the treatment of atrial fibrillation. However, despite advances in pulmonary vein isolation ablation strategies, long-term success rates after ablation remain suboptimal, which highlights the need to develop techniques to achieve more durable lesions. Strategies proposed to improve the durability of pulmonary vein isolation can be divided into two groups: Those addressed to improving the quality of the lesion and those that optimize the detection of acute PV reconnection during the ablation procedure. This manuscript reviews the role and potential benefits of these techniques according to current clinical evidence.

Repeated procedures at the generator pocket are a determinant of implantable cardioverter-defibrillator infection.

BACKGROUND: Rates of cardiac-device infections have increased in recent years, but the current incidence and risk factors for infection in patients with implantable cardioverter-defibrillators (ICDs) are not well known. HYPOTHESIS: The increasing number of ICD infections is related to accumulated pocket manipulations over time. METHODS: This single-center, prospective study included patients that underwent ICD implantation from 2008 to 2015. The endpoint was time to infection. Multivariate analysis was performed to identify independent risk factors related to infection. RESULTS: The study included a total of 570 patients, of whom 419 (73.5%) underwent a first implantation. Mean age was 59 ± 14 years, and 80% were male. During a median follow-up of 36 months (interquartile range, 18-61 months; 1887 patient-years), infection was identified in 26 patients (4.56%), an incidence of 14.9 × 1000 patient-years. Median time to infection was 9.7 months (interquartile range, 1.35-23.4 months), and 38.5% were late infections (beyond 12 months of follow-up). In patients with replacement implants, the incidence was 3-fold higher than in first implantations (27.7 vs 9.1 × 1000 patient-years; P = 0.002). Cox regression identified 2 independent predictors of ICD infection: cumulative number of interventions at the generator pocket (hazard ratio: 1.92, 95% confidence interval: 1.42-2.6, P < 0.001) and pocket hematoma (hazard ratio: 7.0, 95% confidence interval: 2.7-17.9, P < 0.0001). CONCLUSIONS: The incidence of infection in ICD patients is greater than previously reported, largely due to late infections. Each new cumulative intervention at the same generator pocket nearly doubles the risk of infection.