Previous Ablation Research Articles

Abstract 15646: The Need for Speed - Early Experience of Very High-Power Short Duration (QDOT TM ) Ablation

Introduction: Ablation is a cornerstone of therapy for atrial fibrillation (AF), as well as one of the most common procedures in electrophysiology. Use of intermediate-power ablation has given way to high-power short duration radiofrequency ablation. However, more recently the emergence of very high-power very short duration (vHPvSD) ablation at 90W may prove to be more efficient and effective in the management of AF. The radius of the resistive heating zone is increased, while the conductive heating zone tapers off more quickly, potentially reducing collateral tissue damage. Methods: This was a single centre prospective study using the QDOT TM (Biosense Webster, Irvine, California) ablation catheter. Our workflow involves double trans-septal puncture via TOE guidance, use of a deflectable sheath, LASSO 10-pole mapping for first time AF ablations or PENTARAY TM for redo procedures, ablation while paced in sinus rhythm were possible, general anaesthetic, low tidal volumes, and an I:E ratio of 1:4. All pulmonary vein isolations (PVI) and posterior wall isolations (PWI) were performed at 90W for 4s, while cavo-tricuspid isthmus (CTI) lines were completed using QMode at 40W for 20s. Results: 65 patients under went vHPvSD for treatment of atrial fibrillation. Of these 12 were re-do cases that had previously been treated with either radiofrequency or cryo-ablation. The average age was 58.9±9.7 (yrs) with 73% males. Paroxysmal atrial fibrillation was seen in 69%, 31% had persistent AF, and 7% had co-morbid atrial flutter. The average CHADSVASC score was 1.18±1.03. Pulmonary vein isolation was achieved in 100% of patients, 10% had posterior wall isolation, and 16% underwent cavo-tricuspid isthmus ablation. Average skin-to-skin and total ablation times were 58.2±13.1 (mins) and 23.4±6.5 (mins), respectively. Average RF time was 8.1±0.7 (mins). Mean follow up was 126±21 days, where 2 recurrences were seen. We saw no complications in our patient cohort. Conclusions: The method of vHPvSD is safe and durable in the treatment of atrial fibrillation. Total procedure time and RF time were significantly lower than previous RF ablation therapies. This relatively large study on the safety and early efficacy of vHPvSD adds to the emerging data on this promising technology.

Abstract 13843: Real World Outcomes of Concomitant Hybrid Convergent Ablation and Left Atrial Appendage Exclusion in Patients With Long Standing Persistent Atrial Fibrillation

Introduction: Management of patients with long standing persistent atrial fibrillation (LSPAF) presents a clinical challenge. Hybrid convergent ablation has been shown to have superior efficacy compared to endocardial ablation in patients with LSPAF. However, real world outcomes of concomitant hybrid convergent ablation and left atrial appendage (LAA) exclusion with an atrial clip are sparse. Hypothesis: To evaluate effectiveness of concomitant hybrid convergent ablation and LAA clipping in patients with long standing persistent AF (LSPAF). Methods: We conducted a retrospective analysis of all patients with LSPAF that underwent hybrid convergent ablation (surgical ablation plus endocardial catheter ablation) and LAA clipping at our institution. All patients had implantable cardiac devices (27.9% CIED and 81.4% ILR). ILRs were programmed to detect >6-minute episodes of AF. Primary end point was recurrence of AF at 12 months. Results: A total of 43 patients underwent hybrid convergent ablation and LAA exclusion from 2019-2020. Mean age of the cohort was 64.9 + 8.9 years and 62.8% were male. 61.9% patients had previous AF catheter ablation and majority (84%) were on anti-arrhythmic drugs (AAD). LAA clipping was performed in all patients with a median clip size of 45. Mean time between the surgical and endocardial catheter ablation procedure was 2.6 + 1.7 months. All patients were continued on AAD following the hybrid procedure. Overall AF free survival on continued anti-arrhythmic drugs at 12 month follow up was 68.3%. Conclusions: Concomitant hybrid convergent ablation and LAA exclusion with an atrial clip provides reasonable long term AF free survival in patients with LSPAF.

Stereotactic Arrhythmia Radioablation for Ventricular Tachycardia (StAR-VT): A Single Institution, Dose De-Escalation, Phase II Trial

<h3>Purpose/Objective(s)</h3> Ventricular tachycardia (VT) is characterized by electrical re-entry within patches of heterogeneous myocardial fibrosis leading to sustained consecutive ventricular beats at a rate > 100 per minute. Implantable cardioverter-defibrillators (ICD) are the main intervention for reducing mortality, however, they are exclusively a symptom-control therapy. Catheter ablation is the standard of care adjunctive therapy for patients who are refractory to medical therapy. Recently, a treatment approach with a stereotactic body radiation therapy (SBRT) to arrhythmogenic scar regions has been described. Initial results, using a single 25 Gy fraction, suggest this technique may improve morbidity for patient's refractory to standard of care therapy. The optimal dose for this therapy remains unclear and major adverse events with 25 Gy have been reported. This clinical trial hypothesizes that refractory VT treated with SBRT in a single fraction of 20 Gy is non-inferior to 25 Gy. <h3>Materials/Methods</h3> Inclusion criteria are age > 18 years, cardiomyopathy, recurrent episodes of monomorphic VT failing standard treatment with at least 1 antiarrhythmic drug and previous electrophysiologic ablation. Exclusion criteria are participants with previous thoracic radiation, connective tissue disease, interstitial pulmonary fibrosis, and pregnancy. Participants with contraindications to electrophysiology studies may be eligible for the study, provided the arrhythmic substrate can be defined through other non-invasive methods. We anticipate an incidence rate of approximately 5 VT events per person-year in participants treated with 25 Gy as a historical comparator based on a previous phase I/II trial. Based on a Poisson distribution, and using a non-inferiority margin of 8.5 events per-year (incident rate ratio of 1.70), recruiting 9 participants will provide 80% power when using a one-sided type I error, set at 0.05. Non-inferiority of 20 Gy relative to 25 Gy will be determined if the upper bound of the one-sided 95% confidence interval for the incidence rate ratio is below the pre-specified non-inferiority margin (incidence rate ratio=1.70). The primary efficacy endpoint is the reduction in arrhythmia burden measured by the total number of VT events and ICD treatments for VT comparing the 6 and 12-month periods after a single fraction of 20 Gy SBRT with a single fraction of 25 Gy in the published literature. Our primary safety endpoint is defined as the rate of severe treatment-related adverse events at ≤ 90 days as defined by the CTCAE v5.0. Secondary endpoints include overall survival, late adverse events, antiarrhythmic drug use, and quality of life. <h3>Results</h3> The Research Ethics Board at the institution has approved this research study and will provide ongoing ethical oversight. <h3>Conclusion</h3> This study is currently recruiting participants. This trial is registered at ClinicalTrials.gov, NCT05258422.

Successful Ablation of Decrementally Conducting Atrioventricular Fiber (Mahaim) at The Distal Ventricular Insertion Site by Using 3D-High Density Mapping after Previous Multiple Failed Conventional Ablation Attemps

Successful Ablation of Decrementally Conducting Atrioventricular Fiber (Mahaim) at The Distal Ventricular Insertion Site by Using 3D-High Density Mapping after Previous Multiple Failed Conventional Ablation Attemps

Real-time electrophysiological characterization of acute and chronic radiofrequency ablation lesions

Abstract Background Assessment of lesion formation remains one of the most important goals to guide radiofrequency (RF) procedures in the cardiac electrophysiology laboratory. Cardiac navigation systems use specific algorithms to predict the effective lesion size, but these metrics are based only on ablation parameters and ignore local electric tissue characteristics. [1] Recent studies show that local multiparametric impedance is influenced by the intrinsic structural characteristics of the tissue. [2] Purpose This study aimed to assess the ability of local multiparametric impedance to characterize acute and chronic RF ablation lesions in the right atrium of pigs. Methods Four anesthetized closed-chest pigs were submitted to two interventions. The first intervention aimed at creating RF ablation lesions (30W, 60s, 55°) in the right atrium using an electrocatheter connected to a conventional cardiac navigation system, while mapping the local multiparametric impedance (LMI), the generator impedance (GI) and the bipolar voltage (BiV). All RF ablation lesions were performed with a stable contact force. Four weeks later, the second intervention aimed at mapping again the previous ablation sites. After the second intervention animals were euthanized and the hearts were removed and processed to identify the presence of fibrosis in the previously ablated lesions (Figure). Results We performed 19 ablations (5±2 per animal) with an average contact force of 14.2±4.6g. Four weeks later, 14/19 (74%) ablation lesions were identified as fibrotic points in the explanted heart (Figure 1). These showed decreased acute LMI and BiV values that persisted low after 4 weeks (Table 1). The remaining 5/19 ablations that did not present fibrosis had lower baseline LMI and bipolar values that resulted in lower LMI and BiV drops (Table 1). The absolute drop in LMI between effective and non-effective lesions was around 50%, while GI drop was only 21% (LMI drop @51KHz: From −3.0±1.4° to −1.5±0.3°, T-TEST p&amp;lt;0.05; GI drop: From 12.7±27.6Ω to 10.5±21.3Ω, T-TEST p=0.89). Conclusion The local baseline electrical properties of atrial myocardium are directly related to the effectiveness of RF ablation lesions. RF ablation sites that resulted into persistent fibrosis points had larger LMI and BiV values, with higher absolute drops than non-effective lesions. The use of LMI in clinical practice could improve the outcome of the procedures of arrhythmia ablation in the electrophysiology lab. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by grants from ISCI-MINECO (FIS PI21/00392), FEDER, CIBERCV (CB16/11/00276)

Can lesion parameters predict effective pulmonary vein isolation in very-high-power short-duration radiofrequency ablation?

Abstract Background Pulmonary vein isolation (PVI) is the cornerstone treatment for patients with atrial fibrillation (AF) refractory to medical therapy. Recent advancements have led to the development of contact-force (CF) sensing very-high-power short-duration (vHPSD) radiofrequency (RF) ablation (90W/4 seconds). Previous RF ablation utilized Ablation Index (AI) as a marker of lesion quality to guide the operator which is not utilized in QMODE+ (vHPSD) and thus, there is limited information on effective lesion formation. In this study, we evaluated the correlation between various lesion parameters to identify relationships and potential surrogate markers for effective lesion formation. Moreover, we studied the relationship between different anatomical locations on these parameters to gain further insight. Methods 50 consecutive AF patients (33 males, age 62.0±1.31 years, 66% paroxysmal AF) underwent first time PVI using QMODE+. All wide antral circumferential ablation (WACA) QMODE+ lesions (n=5022) were analyzed for force-time integral (FTI), impedance drop, average CF, maximum temperature attained and anatomical location. The anatomical regions assessed across both left and right WACA were posterior-superior (region 1–2), posterior-inferior (region 3–4), anterior-inferior (region 5–6), anterior-superior (region 7–8) and pulmonary vein carina (region 9). All pulmonary veins (PVs) were checked with pacing maneuvers to examine for gaps in ablation lesions and adenosine for acute pulmonary vein reconnection post-ablation. Results PVI was successful in all patients while a first pass isolation was observed in 26 patients (52%). A total of 5022 lesions were performed with 2461 and 2561 lesions in the left and right WACA respectively. The average CF exhibited positive correlation with maximum temperature attained and impedance drop (p&amp;lt;0.0001) while displaying negative correlation with FTI (p&amp;lt;0.0001) (Figure 1). The PV carina (region 9) of the right WACA had the smallest impedance drop (p&amp;lt;0.0001) while the PV carina of the left WACA exhibited the lowest average CF and temperature attained (p&amp;lt;0.0001) (Figure 2). The highest number of gaps or acute reconnection (12 out of 24 patients) were seen in the region of the left pulmonary vein carina (p&amp;lt;0.0001). Conclusion This is the first study that has investigated the characteristics of vHPSD ablation lesions at different regions in the left atrium. CF was positively correlated with maximum temperature and impedance drop but negatively correlated with FTI. Furthermore, ablation at both right and left PV carina demonstrates lower impedance drop and average CF which may potentially explain the greater prevalence of gaps or reconnections. This study provides detailed insight into the relationship between the anatomical region, contact force, temperature and impedance drop, and will facilitate the optimization for effective vHPSD lesion formation. Funding Acknowledgement Type of funding sources: None.

Catheter ablation of atrial arrhythmias by using a multipolar grid-patterned high density mapping catheter in patients with congenital heart disease: a single-center experience

Abstract Objective Catheter ablation of arrhythmias in patients with congenital heart disease (CHD) remains challenging and time-consuming. A novel diagnostic catheter with a multipolar grid-patterned electrode configuration for high density mapping may reduce mapping time and enhance ablation success. Here we describe our experience of catheter ablation by using a multipolar grid-patterned mapping catheter in patients with CHD suffered from atrial tachycardia. Methods All patients with CHD underwent catheter ablation for atrial tachycardia by using multipolar grid-patterned high density mapping catheter between 04/2018 and 12/2021 were enrolled. Primary success was defined as non-inducibility of atrial tachycardia. Only the first catheter ablation was included in the study. Results A total of 37 consecutive patients (median age 34.2±33.0 years (range 7–65), female n=20) underwent 37 ablation procedures with initial high density mapping. The underlying heart defects were s/p ASD-closure (n=2), ASD-closure and corrected partial anomalous pulmonary venous return (n=2), corrected unroofed coronary sinus (n=1), pulmonary valve commissurotomy (n=2), repaired Tetralogy of Fallot (n=2), tricuspid and pulmonary valve replacement in PA/IVS (n=1), mitral valve replacement (n=1), Hypoplastic right heart syndrome (n=1), atrial switch procedure for dTGA (n=7), TA with Glenn shunt (n=1), Ross operation (n=1), Fontan palliation (tricuspid atresia n=6, DILV n=5, HLHS n=1, DORV n=1, dTGA n=1, criss-cross heart n=1, single ventricle n=1). A history of previous ablation was positive in 8 patients. During mapping of the cardiac chambers, the mean value of total collected points and used points were 32657.8±46171 and 3851.6±3295.5 respectively. Mean mapping and fluoroscopy time were 62.1±40.7 minute (range 3–178) and 11.4±8.5 minutes (range 0–32.2), respectively. There were 69 atrial tachycardia substrates in the 37 patients (median 2, range 1–4 per patient). All tachycardia substrates were completely ablated in 33/37 (89.2%) patients and partially in 4/37 (11.8%) patients. Acute success was achieved with successful ablation of 65 of 69 (94.2%) atrial substrates. During a median follow-up time of 20 months (range 5–49), recurrence rate was 5/65 (7.7%) atrial substrates in 5/37 (13.5%) patients. Comparison of 16 patients with Fontan palliation to the 23 patients without Fontan operation showed higher partially success rate in the patients with Fontan palliation (4/16 vs. 0/21, p=0.028). Conclusion In this series, high density mapping allowed elucidation of the tachycardia mechanism in all patients with a high primary ablation success, a limited radiation exposure and a low rate of arrhythmia recurrence. Funding Acknowledgement Type of funding sources: None.

The first Brazilian cardiovascular registry of atrial fibrillation: the primary results of the RECALL study

Abstract Background There is limited prospective real-world evidence of patients with atrial fibrillation (AF) in Latin America. Methods The rationale and design of the study were previously published (1). Briefly, RECALL was the first nationwide prospective study of patients in Brazil with known atrial fibrillation. A total of 4,585 patients were included among 89 sites from April 2012 to August 2019. All patients were followed for one year by the protocol. Patient characteristics, medications under use and clinical outcomes during the follow-up were collected. Results From the total of patients enrolled, 41 were excluded from the analysis since they did not have a confirmed diagnosis of atrial fibrillation. The median age was 70 (61–78) years, 46% were women and the majority of the cases were permanent AF (53,8%). The mean CHA2DS2VASc was 3.2±1.6 and the median HASBLED was 2 [2–3]. The most common risk factor was arterial hypertension (77.9%). The median heart rate was 74 [65–85] and the mean ejection fraction was 52.2±2.6 (%). Only 4.4% of patients had history of previous ablation and 30.4% were using anti-arrhythmic. At baseline, 22.0% did not use anticoagulants (Figure 1) and 9.1% did not use any antithrombotic therapy. The most common anticoagulant was vitamin K antagonist – VKA (62.6%) while the remaining 37.4% were direct oral anticoagulants. The main reasons for not using an oral anticoagulant were physician judgment's (low risk of stroke – 24.6%) and difficult to control (14.7%) or perform INR (9.9%) while patient preference and adverse event represented respectively 5.3% and 4.1%, respectively. Only 42.5% of the INRs at baseline were between 2 and 3. During follow-up, the use of anticoagulants and INR in the therapeutic range increased to 87.1% and 59.1%, respectively. In one year, 17.8% of patients were hospitalized due to atrial fibrillation. At 1 year, the rates of death, stroke, systemic embolism and major bleeding were 5.76 [5.12–6.47], 2.77 [2.32–3.32] 1.01 [0.75–1.36], 2.21 [1.81–2.70], respectively. Among VKA users, the rate of mortality and bleeding was higher in the group with time in therapeutic range below 60% (Figure 2). Conclusion RECALL represents the largest prospective registry of patients with atrial fibrillation in Latin America. Our findings highlight important gaps in the treatment of patients which can inform clinical practice and help to guide future interventions to improve the care of these patients. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Brazilian Society of Cardiology

Cuantificación de la fibrosis auricular derecha mediante resonancia magnética cardiaca: verificación del método para la estandarización de umbrales

Introduction and objectivesLate gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) allows noninvasive detection of left atrial fibrosis in patients with atrial fibrillation (AF). However, whether the same methodology can be used in the right atrium (RA) remains unknown. Our aim was to define a standardized threshold to characterize RA fibrosis in LGE-CMR. MethodsA 3 Tesla LGE-CMR was performed in 53 individuals; the RA was segmented, and the image intensity ratio (IIR) calculated for the RA wall using 1 557 767 IIR pixels (40 994±10 693 per patient). The upper limit of normality of the IIR (mean IIR+2 standard deviations) was estimated in healthy volunteers (n=9), and patients who had undergone previous typical atrial flutter ablation (n=9) were used to establish the dense scar threshold. Paroxysmal and persistent AF patients (n=10 each) were used for validation. IIR values were correlated with a high-density bipolar voltage map in 15 patients undergoing AF ablation. ResultsThe upper normality limit (total fibrosis threshold) in healthy volunteers was set at an IIR = 1.21. In the postablation group, 60% of the maximum IIR pixel (dense fibrosis threshold) was calculated as IIR = 1.29. Endocardial bipolar voltage showed a weak but significant correlation with IIR. The overall accuracy between the electroanatomical map and LGE-CMR to characterize fibrosis was 56%. ConclusionsAn IIR > 1.21 was determined to be the threshold for the detection of right atrial fibrosis, while an IIR > 1.29 differentiates interstitial fibrosis from dense scar. Despite differences between the left and right atria, fibrosis could be assessed with LGE-CMR using similar thresholds in both chambers.

Magnetic resonance imaging and histopathology of catheter ablation lesions after ventricular tachycardia ablation in patients with nonischemic cardiomyopathy.

Late gadolinium enhanced cardiac magnetic resonance (LGE-CMR) imaging may help identify radiofrequency ablation lesions, which have been poorly described in patients with nonischemic cardiomyopathy (NICM). The purpose of this study was to describe LGE-CMR characteristics of ablation lesions in patients with NICM and correlate them with histopathology. Twenty-six patients (24 men; ejection fraction 38% ± 14%; age 61 ± 9 years) who had undergone CMR imaging after ventricular tachycardia (VT) ablation were included. Areas of both dark and bright core lesions correlating with previous radiofrequency ablation lesions were identified. Histology was performed on an explanted heart. Mean time between the ablation procedure and the LGE-CMR study was 8 [2-20] months. Twenty-three of 26 patients demonstrated dark core lesions (volume 2.16 ± 1.8 cm3; thickness 3.6 ± 1.3 mm) with transmurality of 42% ± 16% overlaying areas of intramural or transmural LGE. Fourteen of 26 patients demonstrated bright core lesions (volume 0.8 ± 0.6 cm3; depth 4.15 ± 1.76 mm) with transmurality of 34% ± 14%, which was located in areas without underlying LGE in 11 of 13 patients. Both dark and bright core lesions were visualized on standard clinical LGE-CMR imaging obtained in the acute setting and chronic settings (within 3 days and up to 2090 days postablation). Histopathologic analysis demonstrated coagulation necrosis in the area that corresponded to dark core lesions in the postablation CMR. Ablation lesions can be detected by LGE-CMR after VT ablation in NICM patients and have a different appearance than scar tissue. These lesions can be observed in the acute and chronic settings after ablations.

Multidetector computed tomography identification of previous ablation lines: Insights for left atrial flutter ablation.

Creating complete lines of block in the left atrium (LA) can be challenging.1 Multidetector computed tomography (MDCT)–derived LA wall thickness (LAWT) information during atrial fibrillation redo procedures already showed that conduction gaps in previously attempted ablation lines frequently occur at points in the LA where the wall is thicker.2

Dynamic electrophysiological mechanism in patients with long-standing persistent atrial fibrillation.

BackgroundImproved understanding of the mechanisms that sustain persistent and long-standing persistent atrial fibrillation (LSpAF) is essential for providing better ablation solutions. The findings of traditional catheter-based electrophysiological studies can be impacted by the sedation required for these procedures. This is not required in non-invasive body-surface mapping (ECGI). ECGI allows for multiple mappings in the same patient at different times. This would expose potential electrophysiological changes over time, such as the location and stability of extra-pulmonary vein drivers and activation patterns in sustained AF.Materials and methodsIn this electrophysiological study, 10 open-heart surgery candidates with LSpAF, without previous ablation procedures (6 male, median age 73 years), were mapped on two occasions with a median interval of 11 days (IQR: 8–19) between mappings. Bi-atrial epicardial activation sequences were acquired using ECGI (CardioInsight™, Minneapolis, MN, United States).ResultsBi-atrial electrophysiological abnormalities were documented in all 20 mappings. Interestingly, the anatomic location of focal and rotor activities changed between the mappings in all patients [100% showed changes, 95%CI (69.2–100%), p < 0.001]. Neither AF driver type nor their number varied significantly between the mappings in any patient (median total number of focal activities 8 (IQR: 1–16) versus 6 (IQR: 2–12), p = 0.68; median total number of rotor activities 48 (IQR: 44–67) versus 55 (IQR: 44–61), p = 0.30). However, individual zones showed a high number of quantitative changes (increase/decrease) of driver activity. Most changes of focal activity were found in the left atrial appendage, the region of the left lower pulmonary vein and the right atrial appendage. Most changes in rotor activity were found also at the left lower pulmonary vein region, the upper half of the right atrium and the right atrial appendage.ConclusionThis clinical study documented that driver location and activation patterns in patients with LSpAF changes constantly. Furthermore, bi-atrial pathophysiology was demonstrated, which underscores the importance of treating both atria in LSpAF and the significant role that arrhythmogenic drivers outside the pulmonary veins seem to have in maintaining this complex arrhythmia.

Atypisches Vorhofflattern

Im Gegensatz zum typischen Vorhofflattern handelt es sich beim atypischen Vorhofflattern um eine heterogene Gruppe von rechts- und linksatrialen Makro- bzw. Localized-Reentry-Tachykardien, deren kritischer Bestandteil zur Aufrechterhaltung der Tachykardie nicht der cavotrikuspidale Isthmus ist. Atypisches Vorhofflattern tritt gehäuft nach vorangegangener Katheterablation sowie nach herzchirurgischen Eingriffen auf. Die intraprozedurale Erfolgsrate während der Ablation ist hoch, wobei die Rezidivrate von strukturellen Veränderungen der Vorhöfe sowie des zugrundeliegenden Mechanismus abhängig ist. Dieser Artikel bietet einen Überblick über die Mechanismen sowie über Mapping- und Ablationsstrategien der häufigsten Formen von rechts- und linksatrialem atypischem Vorhofflattern. Dieser Beitrag ist Teil der Serie „EP-Basics“ zur gezielten Fortbildung im Bereich Invasive Elektrophysiologie. Grundlagen, Klinik und Therapie des atypischen Vorhofflatterns werden mit Fokus auf klinisch relevante Aspekte dargelegt. Vorgehensweise und Befunde der invasiven elektrophysiologischen Diagnostik und die Ablationsbehandlung bilden den Schwerpunkt dieses Artikels.

Hybrid-Approach Ablation in Drug-Refractory Arrhythmogenic Right Ventricular Cardiomyopathy

Management of ventricular arrhythmias (VAs) beyond implantable cardioverter-defibrillator positioning in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) is challenging. Catheter ablation of the ventricular substrate often requires a combination of endocardial and epicardial approaches, with disappointing outcomes due to the progressive nature of the disease. We report the Universitair Ziekenhuis Brussel experience through a case series of 16 patients with drug-refractory ARVC, who have undergone endocardial and/or epicardial catheter ablation of VAs with a thoracoscopic hybrid-approach. After a mean follow-up time of 5.16 years (SD 2.9 years) from the first hybrid-approach ablation, VA recurrence was observed in 5 patients (31.25%): among these, patients 4 patients (80%) received a previous ablation and 1 of 11 patients (9.09%) who had a hybrid ablation as first approach had a VA recurrence (80% vs 9.09%; log-rank p=0.04). Despite the recurrence rate of arrhythmic events, all patients had a significant reduction in the arrhythmic burden after ablation, with a mean of 4.65 years (SD 2.9 years) of freedom from clinically significant arrhythmias, defined as symptomatic VAs or implantable cardioverter-defibrillator-delivered therapies. In conclusion, our case series confirms that management of VAs in patients with ARVC is difficult because patients do not always respond to antiarrhythmic medications and can require multiple invasive procedures. A multidisciplinary approach involving cardiologists, cardiac surgeons, and cardiac electrophysiologists, together with recent cardiac mapping techniques and ablation tools, might mitigate these difficulties and improve outcomes.

Patient motivation and adherence to an on-demand app-based heart rate and rhythm monitoring for atrial fibrillation management: data from the TeleCheck-AF project.

The aim of this TeleCheck-AF sub-analysis was to evaluate motivation and adherence to on-demand heart rate/rhythm monitoring app in patients with atrial fibrillation (AF). Patients were instructed to perform 60 s app-based heart rate/rhythm recordings 3 times daily and in case of symptoms for 7 consecutive days prior to teleconsultation. Motivation was defined as number of days in which the expected number of measurements (≥3/day) were performed per number of days over the entire prescription period. Adherence was defined as number of performed measurements per number of expected measurements over the entire prescription period.Data from 990 consecutive patients with diagnosed AF [median age 64 (57-71) years, 39% female] from 10 centres were analyzed. Patients with both optimal motivation (100%) and adherence (≥100%) constituted 28% of the study population and had a lower percentage of recordings in sinus rhythm [90 (53-100%) vs. 100 (64-100%), P < 0.001] compared with others. Older age and absence of diabetes were predictors of both optimal motivation and adherence [odds ratio (OR) 1.02, 95% coincidence interval (95% CI): 1.01-1.04, P < 0.001 and OR: 0.49, 95% CI: 0.28-0.86, P = 0.013, respectively]. Patients with 100% motivation also had ≥100% adherence. Independent predictors for optimal adherence alone were older age (OR: 1.02, 95% CI: 1.00-1.04, P = 0.014), female sex (OR: 1.70, 95% CI: 1.29-2.23, P < 0.001), previous AF ablation (OR: 1.35, 95% CI: 1.03-1.07, P = 0.028). In the TeleCheck-AF project, more than one-fourth of patients had optimal motivation and adherence to app-based heart rate/rhythm monitoring. Older age and absence of diabetes were predictors of optimal motivation/adherence.

Advanced Techniques for Ethanol Ablation of Left Ventricular Summit Region Arrhythmias.

Coronary venous ethanol ablation (VEA) can be used as a strategy to treat ventricular arrhythmias arising from the left ventricular summit, but collateral flow and technical challenges cannulating intramural veins in complex venous anatomies can limit its use. Advanced techniques for VEA can capitalize on collateral vessels between target and nontarget sites to improve success. Of 55 patients with left ventricular summit ventricular arrhythmia, advanced techniques were used in 15 after initial left ventricular summit intramural vein mapping failed to show suitable targets for single vein, single-balloon VEA. All patients had previous radiofrequency ablation attempts. Techniques included: double-balloon for distal protection to block distal flow and target the proximal portion of a large intramural vein where best signal was proximal (n=6); balloons in 2 different left ventricular summit veins for a cross-fire multivein VEA (n=4); intramural collateral vein-to-vein cannulation to reach of targeted vein via collateral with antegrade ethanol and proximal balloon block (n=2); prolonged ethanol dwell time for vein sclerosis of large intramural vein and subsequent VEA (n=3); and intramural collateral VEA (n=1). Fifteen (8 females) patients (age 60.6±17.6 years) required advanced techniques. Procedure time was 210±49.9 minutes, fluoroscopy time was 25.3±14.1 minutes, and 113±17.9 cc of contrast was utilized. A median of 7 cc of ethanol was delivered (range, 4-15 cc). Intraprocedural radiofrequency ablation was delivered before ethanol in 9 out of 15 patients but failed. Ethanol achieved acute success in all 15 patients. Ethanol was used as the sole treatment in two patients. At a median follow-up of 194 days, one patient experienced recurrence. Advanced techniques capitalizing on venous anatomy can enable successful VEA and selective targeting of arrhythmogenic sites, by blocking distal flow, utilization of collaterals between nontarget and target veins and multivein VEA. Understanding individual anatomy is critical for VEA success.

Quantification of right atrial fibrosis by cardiac magnetic resonance: verification of the method to standardize thresholds

Introduction and objectivesLate gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) allows noninvasive detection of left atrial fibrosis in patients with atrial fibrillation (AF). However, whether the same methodology can be used in the right atrium (RA) remains unknown. Our aim was to define a standardized threshold to characterize RA fibrosis in LGE-CMR. MethodsA 3 Tesla LGE-CMR was performed in 53 individuals; the RA was segmented, and the image intensity ratio (IIR) calculated for the RA wall using 1 557 767 IIR pixels (40 994±10 693 per patient). The upper limit of normality of the IIR (mean IIR+2 standard deviations) was estimated in healthy volunteers (n=9), and patients who had undergone previous typical atrial flutter ablation (n=9) were used to establish the dense scar threshold. Paroxysmal and persistent AF patients (n=10 each) were used for validation. IIR values were correlated with a high-density bipolar voltage map in 15 patients undergoing AF ablation. ResultsThe upper normality limit (total fibrosis threshold) in healthy volunteers was set at an IIR = 1.21. In the postablation group, 60% of the maximum IIR pixel (dense fibrosis threshold) was calculated as IIR = 1.29. Endocardial bipolar voltage showed a weak but significant correlation with IIR. The overall accuracy between the electroanatomical map and LGE-CMR to characterize fibrosis was 56%. ConclusionsAn IIR > 1.21 was determined to be the threshold for the detection of right atrial fibrosis, while an IIR > 1.29 differentiates interstitial fibrosis from dense scar. Despite differences between the left and right atria, fibrosis could be assessed with LGE-CMR using similar thresholds in both chambers.

Termination of macroreentrant atrial arrhythmias by pacing stimuli without global propagation.

Electrical stimulation during ventricular tachycardia resulting in tachycardia termination without global propagation (TWGP) is a well-recognized phenomenon. However, there is a paucity of literature showing a similar phenomenon in atrial arrhythmias. The purpose of the study was to evaluate the significance of TWGP in atrial arrhythmias. Electrophysiological studies performed from 2000 to 2019 at Methodist Hospital, Indiana University were reviewed retrospectively. Thirty-four patients were identified in whom stimulation during atrial tachycardia/flutter resulted in TWGP. Of the 34 patients, 12 (29%) had cavotricuspid isthmus (CTI)-dependent atrial flutter and 22 (71%) had other atrial arrhythmias during which TWGP was seen. Mean age of the population was 53 ± 13 years; and 68% were male. Previous catheter ablation for atrial fibrillation, atrial flutter, or other atrial tachyarrhythmias had been performed in 70.5%, and 44% previously had undergone cardiac surgery involving the atria. Congenital heart disease was present in 20.5%; 3 patients were status post lung transplant. Mean cycle length of atrial arrhythmia in which TWGP was seen was 317 ± 76 ms. The sites at which TWGP was seen reproducibly were highly specific for successful termination of the arrhythmias with radiofrequency energy. The arrhythmia circuits were 12 CTI-dependent atrial flutter, 11 left atrial macroreentrant atrial tachycardia (MRAT), 1 involving both left and right atria, and 8 were other right atrial MRAT. Termination of macroreentrant atrial arrhythmias by pacing stimuli without global propagation identifies a narrow diastolic isthmus at which catheter ablation is highly effective.

Supraventicular tachycardia and atrial ectopic beats: electrophysiological findings in a patient after previous slow pathway ablation

In this case report we present electrophysiological features of supraventricular tachycardia in a 64-year-old patient after previous slow pathway catheter ablation; ECG features of the tachycardia and results of electrophysiological testing are discussed.

Redo Robotic Partial Nephrectomy for Recurrent Renal Tumors: A Multi-Institutional Analysis.

Introduction: As the experience with robot-assisted partial nephrectomy (RAPN) grows, the indications have expanded to incorporate previously operated ipsilateral kidneys with recurrent renal masses. We sought to analyze the outcomes of redo RAPN in patients with a recurrent renal mass. Methods: Using a multi-institutional series, the data of 72 patients who underwent RAPN for a recurrent renal mass between 2010 and 2020 were retrospectively analyzed. Patients with familial renal cell carcinoma and multiple renal tumors were excluded. Major complication was defined by Clavien grade ≥3. The median follow-up was 28.5 months. Baseline demographics, clinical and tumor characteristics, and perioperative and postoperative outcomes are reported. Results: Our cohort consisted of a combination of previous thermal ablation (19.6%), laparoscopic (19.6%), open (26.1%), and robotic (34.8%) partial nephrectomy. The median R.E.N.A.L. score was 8. Twenty percent had hilar tumors and 9.7% had a solitary kidney. RAPN was completed in all cases. Two cases (2.8%) were converted to open surgery. None of the cases were converted to radical nephrectomy intraoperatively. One patient underwent radical nephrectomy postoperatively because of bleeding. Transfusion rate was 5.9% and major complication rate was 8.3%. Median length of stay was 3 days. Estimated glomerular filtration rate preservation was 78.7% at discharge and 90.8% at 1-year follow-up. Positive surgical margin rate was 8.3%. Overall, distant recurrence was seen in 11 patients (15.3%), however, only 1 patient had local progression (1.4%). Conclusion: In experienced hands, RAPN is an effective approach to treat select cases of locally recurrent renal masses with promising perioperative and functional outcomes. Patients should be carefully monitored for distant recurrence.