Atrial Cardiomyopathy: a Role in the Pathogenesis of Atrial Fibrillation and Influence on the Results of Its Treatment

The work is dedicated to the issue of atrial cardiomyopathies (ACs). They have a significant effect on the heart function, provoke rhythm disturbances and increase the risk of thromboembolic complications. The aim. To analyze the latest publications on the topic. The material for the analysis were the papers published by the leading arrhythmological clinics. Discussion. This paper describes the origin of the term “atrial cardiomyopathy”, highlights the conditional classification of changes in the atrial myocardium according to the EHRAS classification. The causes of this nosological form may be some types of gene mutations, as well as hypertension, congestive circulatory failure, diabetes mellitus, myocarditis, etc. ACs play an important role in the occurrence of atrial fibrillation (AF) and also affect its natural course and treatment outcomes. Electroanatomical mapping and magnetic resonance data show significant fibrotic changes in the atria in individuals with this form of arrhythmia. The DECAAF study (Delayed enhancement MRI and atrial fibrillation catheter ablation) showed that fibrotic changes in the atrial myocardium are directly related to the frequency of recurrent arrhythmias after catheter ablation. The DECAAFII study confirmed the effectiveness of the influence on the fibrous substrate in the catheter treatment of AF at stages 1 and 2 of fibrosis. The results of catheter treatment depend on the severity of fibrosis, which shows the importance of taking this factor into account when determining the indications for ablation. Conclusions. Thus, AC is an important component of the pathogenesis of AF. Improvement of techniques for influencing the fibrous substrate will improve the results of catheter treatment of AF.

35 Electrophysiology and electrostimulation: experience

In the last 50 years, cardiac electrophysiology has undergone rapid technological development which has led to a numerical increase in both patients who have been able to benefit from the therapies of rediscovery and rhythm control, and of the devices. The activity of an electrophysiology and electrostimulation room is based on the intensive use of ionizing radiation even if electrophysiology studies, ablation, and cryoablation techniques have benefited from the support of computerized electroanatomical mapping systems with consequent dose reduction. Over the years, the instruments to be managed inside the room have increased both in complexity and numerically. Starting from the biventricular PM, we go through the implantation of subcutaneous defibrillators up to the transseptal ablations. Patient management requires additional skills that each member of the team must possess. Continuous training and updates are of fundamental importance. The purpose of this work is our experience based on the activity now more 10 years.

Telerobotic interventions from a distance: an initial experience in 3D phantom mapping

Introduction The current COVID-19 pandemic has fostered several accelerations in “remote” patient care such as video and telephone clinics, as well as multidisciplinary collaborations using online platforms with experts consulting the local teams from a distance. The next logical step would be to also offer remote-controlled interventions which the expert operator not on site, but in support of the local team. This is especially valuable for complex interventions when either patient or expert operator can not be present at the same place. Purpose We aimed to demonstrate that an expert operator located at far distance (Austria) could directly interact with the remote magnetic navigation system in London (UK) whilst mapping a 3D phantom using an electroanatomical mapping system. Method Two experienced operators of the magnetic navigation system were tasked with creating fast anatomic maps (FAM) of the atrial and ventricular chambers of a 3D phantom using remote magnetic navigation in combination with 3D electroanatomical mapping. One was located in the control room of the magnetic catheter lab (UK) and the second one was in Tirol, Austria and connected through a secure remote desktop connection (via high speed fibre optic cable). Using a solid tip magnetic catheter connected to a mechanical drive, all interactions with the system were carried out via the Odyssey platform. Acquisitions for right and left atrium, as well as right and left ventricles plus aorta was compared with regards to mapping duration, map completeness (as judged by the average distance of surface points from 3D CT scan reconstruction), total 3D map volume and need for additional radiation exposure during the mapping process. Results Mapping time and map completeness when performed by the distant operator was not inferior to the local operator and both did not require any additional radiation exposure during the mapping process. Table 1 demonstrates the mean parameters for each chamber, respectively. Figure 1 depicts the matched data for chamber completeness as compared for the LA (green= local operator, pink= distant operator) using a contrast CT scan as the gold standard. Conclusion Telerobotic 3D mapping of a 3D phantom from a distance was equally fast delivered from the control room as compared to an operator located 1200 km away without compromising on map completeness. This demonstrates the feasibility of telerobotic interventions and stress the need for remote collaboration which is especially valuable when travel of patients and/or physician experts is restricted. Funding Acknowledgement Type of funding sources: None. Matched data for aorta

493 Prognostic value of myocardial scar and chamber enlargement at electroanatomical mapping during catheter ablation in adult congenital heart disease

Aims Atrial and ventricular tachyarrhythmias are common among patients with adult congenital heart disease (ACHD) and can impair quality of life and prognosis. Catheter ablation is often the main treatment option in this population, despite anatomical hurdles. Substrate mapping findings have not been thoroughly investigated as predictors of arrhythmia recurrence success and cardiovascular clinical outcome after ablation. We sought to determine the prognostic value of myocardial scar and chamber enlargement detected at electroanatomical mapping in ACHD patients undergoing catheter ablation of tachyarrhythmias. Methods and results Consecutive ACHD patients undergoing catheter ablation of atrial and ventricular tachycardias using different electroanatomical mapping systems were retrospectively identified from a hospital-based database. Scar extent detected at the electroanatomical mapping, as well as the total mapped area, was calculated. Arrhythmia recurrence, hospitalization for cardiovascular (CV) reasons, and a combined endpoint (arrhythmia recurrence and/or CV hospitalization) were evaluated during the follow-up. The relationship between the aforementioned electroanatomical findings and the patients’ outcome was assessed. Twenty patients (12 male, 60%; mean age 40 ± 11 years) undergoing atrial (n = 14; 70%) or ventricular (n = 6; 30%) tachyarrhythmia were included. Acute procedural success (arrhythmia termination and/or no reinduction) was achieved in all the patients. At a mean follow-up of 171 ± 135 weeks, eight patients (40%) had arrhythmia recurrence (4/6 in the ventricular tachycardia group, 67%, 4/14 in the atrial tachycardia group, 28%). Patients with arrhythmia recurrence had a more extensive bipolar scar (P = 0.029) and a larger total mapped area (P = 0.03) than patients without recurrence, and so did the patients with the composite endpoint (P = 0.029 and P = 0.03, respectively). Patients with subsequent CV hospitalization had a larger total mapped area than patients without CV hospitalization (P = 0.017). The presence of a bipolar scar ≥22.95 cm2 predicted arrhythmia relapse (0.039) at the multivariate analysis. Conclusions Patients with ACHD show a high recurrence rate after catheter ablation, especially for ventricular tachycardias. A large bipolar scar at the electroanatomical mapping and total mapped area predict arrhythmia recurrence, likely due to the presence of more extensive reentry circuits. A large total mapped area, which may reflect a greater disease severity, predicts both arrhythmia recurrence and CV hospitalizations. Early referral of ACHD patients for catheter ablation may be a sound strategy in order to perform the procedure in the setting of less advanced heart disease.

Autoimmune Myocarditis and Arrhythmogenic Mitral Valve Prolapse: An Unexpected Overlap Syndrome

Background: both myocarditis and mitral valve prolapse (MVP) are known uncommon causes of ventricular arrhythmias in young patients. Aim: to report the first clinical case of endomyocardial biopsy (EMB)-proven autoimmune myocarditis and associated arrhythmogenic MVP in a patient with recurrent ventricular fibrillation (VF) episodes. Methods: myocarditis was diagnosed both by cardiac magnetic resonance (CMR) and EMB. Arrhythmogenic MVP was documented by transthoracic echocardiogram, CMR, and electroanatomical mapping of the trigger premature ventricular contractions (PVCs). Results: a 22-year-old woman underwent immunosuppressive therapy after EMB-proven diagnosis of autoimmune myocarditis with VF onset and early implantable cardioverter defibrillator (ICD) placement. Three years later, she experienced two VF recurrences and persistent PVCs, despite no signs of myocarditis recurrence. An echocardiogram revealed bileaflet MVP with high arrhythmic risk features. Finally, electroanatomical mapping and ablation of the trigger PVC were successfully performed. Conclusion: in patients with recurrent VF episodes despite evidence-based medical treatment for myocarditis, MVP should be considered as an alternative arrhythmogenic substrate, and warrants early ICD implant and PVC-targeted therapy.

Detection of left atrial fibrosis in LGE-MRI and high-density electroanatomical mapping: finding a threshold for the best match

Background Fibrotic atrial cardiomyopathy plays an important role in determining the outcome of ablation in patients with atrial fibrillation (AF). Two main methods are being used for the evaluation of fibrosis: voltage based high-density (HD) electroanatomical mapping (EAM) and late gadolinium enhancement MRI (LGE-MRI). The comparability between both methods in detecting fibrosis has not been systematically investigated. Method LGE-MRIs of the left atrium (LA) were performed in 21 patients (pts). The extent and distribution of fibrosis were evaluated using a custom-designed software generating a 3D model of the LA. HD-electroanatomical maps were recorded in each patient using a 3D mapping software (CARTO3, Biosense Webster). The MRI-3D-model of the LA was then integrated in the 3D mapping system. After processing the HD maps and the MRI models by excluding the mitral valve, pulmonary veins and the left atrial appendage, the atrium was then divided into three independent areas: anterior and posterior wall, and intra-atrial-septum. The LGE areas were then measured using the 3D surface measurement tool. These were then compared to the low voltage areas (LVA) measured in the HD maps using three different cut-off values of 0.5 mV, 0.7 mV, and 1.0 mV. Results In MRI 5 pts had no significant fibrosis (fibrotic area ≤1 cm2). 16 pts showed fibrosis on the anterior wall (7.3 cm2±6.2 cm2). 15 pts showed fibrosis at the septum (5 cm2±2.9 cm2) and 9 pts showed fibrosis on the posterior wall (3.9 cm2±2.5 cm2). Using EAM with a cut-off voltage value of 0.7 mV, 3 pts had no fibrosis. 15 pts showed fibrosis on the anterior wall (7.7 cm2±6.8 cm2). 16 pts showed fibrosis at the septum (5.3 cm2±4.1 cm2) and 8 patient showed fibrosis on the posterior wall (3.5 cm2±1.8 cm2). Using a lower voltage cut-off value of 0.5 mV, fibrosis was evident in less patients with smaller fibrotic areas in LA. Whereas when using a cut-off value of 1.0 mV more patients showed a greater extent of the LA fibrosis. We found significant differences between the two methods (MRI vs. 3D-mapping) when using a cut-off value of 0.5 mV (Wilcoxon, p<0.001 for the anterior and posterior wall and the septum). A cut-off value of 1.0 mV also showed significant differences on the anterior and posterior walls (Wilcoxon, p<0.001). When using a cut-off value of 0.7 mV we did not find a significant difference between the two groups (Wilcoxon, p=0.365) with a correlation coefficient of 0.97 (Pearson; p<0.001) for the anterior wall, 0.69 (Pearson; p=0.007) for the posterior wall, and 0.81 (Pearson; p=0.002) for the septum. Conclusion A cut-off value of 0.7 mV in EAM correlated best with the findings in LGE-MRI. The currently used predefined cut-off value of 0.5 mV in EAM may lead to an underestimation of the actual extent of the fibrosis. Increasing the voltage cut-off value towards 0.7 mV may therefore lead to a better characterisation of fibrotic atrial cardiomyopathy. FUNDunding Acknowledgement Type of funding sources: None.

Age and impaired left atrial performance are associated with increased atrial fibrosis in patients with paroxysmal and persistent atrial fibrillation

Background Atrial performance assessed by strain imaging is used as a surrogate for left atrial (LA) structural remodelling. Presence of low voltage zones (LVZs) detected by three-dimensional electroanatomical mapping in patients with atrial fibrillation (AF) denotes more expressed extrapulmonary substrate potentially leading to worse outcomes following pulmonary vein isolation (PVI) for the treatment of AF. Purpose The current study aims to investigate the association between strain imaging parameters from echocardiography and the presence and extent of LVZs derived from LA electroanatomical mapping in patients undergoing AF ablation. Methods Seventy-eight patients (58 males, 74%) aged 59±9.48 years undergoing PVI for paroxysmal (35 patients, 49%) or persistent AF were prospectively studied. Preprocedural echocardiography included LA strain imaging assessing global LA strain (LAS) and regional strain of the basolateral region (RSLB). During the procedure, LA electroanatomical mapping during paced atrial rhythm was performed in all patients obtaining a LA voltage map. All LA maps were analysed offline using a custom-made software calculating the zone of low bipolar voltage <0.5 mV (LVZ<0.5mV) and the total LA endocardial area excluding pulmonary veins antra. LVZ<0.5mv was expressed as an absolute value and as percentage of the whole LA area. Results Patients aged more than 65 years (N=21, 27%) demonstrated a larger area of LVZ<0.5mV: 25.5±17.8 cm2 vs. 9.4±10.6 cm2 in those younger than 65 years, P=0.001. This corresponded to a higher proportion of the LA area demonstrating LVZ<0.5mV in patients older than 65 years: 22.6±14.6% vs. 8.9±11.8% in those younger than 65 years, P<0.0001. Twenty-nine of 78 patients (37.1%) had preprocedural LAS<20% and 23 (29.5%) demonstrated RSLB of <21%. Patients with LAS <20% had a higher total LVZ<0.5mV: 20.3±16.6 cm2 vs. 9.8±12.1 cm2 in patients with LAS≥20% at baseline, P=0.004. This equaled to 17.7±15.6% vs. 9.5±11.9% of total LA area, respectively (P=0.011). Patients with RSLB<21% also demonstrated larger areas of LVZ<0.5mV in the LA: 21.6±17.9 cm2 vs. 10.39±11.83 cm2 in the patients with RSLB ≥21%, P=0.012. Expressed as a proportion of the whole LA area the difference remained significant: 18.8±17.1% vs. 9.9±11.6%, respectively P=0.01. Conclusion Older age and impaired LA performance assessed by LA strain imaging are associated with larger areas of LVZ<0.5mV possibly reflecting more expressed LA fibrotic changes in patients with paroxysmal and persistent AF. These findings might serve in the preprocedural selection of the patients undergoing catheter ablation of AF. FUNDunding Acknowledgement Type of funding sources: Other. Main funding source(s): Bulgarian Society of Cardiology