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Introduction Feasibility of concomitant leadless-pacemaker (LP) implantation plus atrioventricular node ablation (AVNA) is unknown. Moreover, safety issues in the long run are also undetermined. It seems theoretically attractive since it could avoid one additional procedure and catheter could be introduced through the same sheath employed for the LP. On the contrary, risk of dislocation/electrical variations could represent a shortcoming. Objective We aim to report 1) feasibility of concomitant AVNA after a LP implantation and 2) long-term outcomes. Methods Single center, prospective and observational study of 256 consecutive patients with an indication for single-chamber pacemaker placement. The implantation procedure was carried out using a femoral approach and conventional technique. Successful implantation was accomplished in 255/256 patients referred for leadless implantation. In one patient, a complete obstruction of the inferior vena cava was documented, and a conventional unicameral pacemaker was implanted. Results 33 out of 255 patients underwent immediate AV ablation. Mean age was 75.2±8.3 years. Were predominantly females: 25 (75.7%) and indication was fast conduction atrial fibrillation (n=25), atypical flutter or atrial tachycardia (n=8). Mean acute “R wave” was 11.3mV, threshold of 0.55Vx0.24ms and impedance of 833Ω. Uneventful AV node ablation was performed in all of them immediately after LP implantation. Additional mean fluoroscopic time was 3.0 minutes. There were no vascular or arrhythmic complications after the implantation. After a mean follow-up of 27.9±12 months, all patients remained alive without notable event, and electrical parameters remained unchanged (Figure 1). Actuarial survival was shown in Figure 2. Conclusions Conconmitant AVN ablation after LP implantation seems feasible without remarkable complications in the long run. In our experience, this approach appears more comfortable for the patients and less time-consuming than conventional pacemaker implantation with sequential AV node ablation. There were no device macrodislodgements or unexpected device malfunctions in the follow-up period. Funding Acknowledgement Type of funding sources: None. Electrical performanceSurvival

Introduction Leadless pacemakers (LPM) have demonstrated adequate electrical performance and safety in patients with multiple commorbidities such as heart valve replacements at short-term follow-up. Purpose We present our experience in patients with LPM and heart valve replacements at long-term follow-up. Methods This was a prospective observational study including all consecutive LPM implantation from June 1 2005 to March 15 2021. Clinical, electrical, echocardiographic characteristics, related complications and electrical parameters were compared in 2 different groups with and with-out valve surgical procedure. Results A total of 255 LPM were implanted. Clinical, electrical and echocardiographic characteristics are described in table 1. Mean follow-up was of 24 months. There were no significant differences in electrical performance or related complications in between both groups (Figure 1). Conclusions Electrical performance and complications were no significantly different between both groups with and without heart valve replacements. Funding Acknowledgement Type of funding sources: None.

Background As more experience is obtained with leadless pacemakers systems (LPM), a great group of patients is considered for its implantation. There are issues that cannot be completely avoided with conventional transvenous pacemaker (VVI-PM) such as infectious or pocket related complications in which LPM are clearly superior. Purpose The aim of the study was to compare the clinical and device performance between LPM and VVIPM in the same period of time in a “real-world” population. Methods We performed a prospective, observational, one center study, including all patients with a single chamber pacemaker implantation within 3 years (June 2015-December 2018) and its mid-term follow-up. All clinical, electrical and echocardiographic characteristics, as well as implantation characteristics and complications, were described. Results We included a total of 339 patients with transvenous pacemakers, 195 patients with VVI-PM and 144 LPM. There were no significant differences in mortality between both groups during the follow-up (12,3±10 months), Figure 1. Although there were no significant differences in major complications (P-value 0,54), the number of total complications was lower in the LPM group (P-value 0,01) at the expense of fewer minor ones (P-value 0,02), Table 1. Table 1. Complications TVP (195) LPM (144) P value Major complications 11 (5.6%) 6 (4.2%) 0.54 Minor complications 10 (5.1%) 0 (0.0%) 0.01 Total Complications 21 (10.7%) 6 (4,2%) 0.02 Figure 1 Conclusions In our study, during the med-term follow-up, there were no significant differences in terms of mortality and the major complications between LMP and VVI-PM. Although, the number of minor complications were less with the LMP.

Introduction Atrial fibrillation (AF) is a highly prevalent heart disease, affecting a significant proportion of patients over 65 years old. The CHA2DS2-VASc score predicts 1 year risk of a thromboembolic (TE) event and is well validated against several populations. However, calibration may vary if there is subgroup heterogeneity. Purpose To compare the CHA2DS2-VASc score calibration, in patients with or without anticoagulation (AC) in a real population of AF patients in our healthcare area. Methods Patients with an episode with atrial fibrillation/flutter were selected from a general population in a healthcare area (383,000 subjects), with 21/12/2013 as a cut-off date. Patients with valve disease, anticoagulation or antiplatelet therapy were identified. The CHA2DS2-VASc score was calculated as stipulated in the European Society of Cardiology guidelines. A CHA2DS2-VASc score of 0 is considered to be low risk for TE events (0% at 1 year), score of 1 intermediate risk (0.6% rate at 1 year), and greater than 1 high risk (3% rate at 1 year). Quantitative variables are presented as mean and standard deviation (SD). Categorical variables were presented as frequencies and percentages. A logistic regression was fitted to predict 1-year risk TE outcomes with CHA2DS2-VASc as the only covariate. Model calibration was assessed using the predicted versus actual probabilities of TE events. All analyses were performed using R v.3.4 (R Core Team, Vienna, Austria) with the packages rms and ggplot2. Results CHA2DS2-VASc was calculated in 7990 patients with AF. A total of 1824 patients were excluded either due to valvular disease (846) or due to previous antiplatelet treatment (1047). From them, 143 patients were excluded for an incomplete follow-up time ( As of December 31, 2015, 67 stroke cases had been notified from 6023 patients (1.1%) (Table 1). Mortality rate was 181 (3%) at 1 year. Patients presented overall low risks of stroke with a poor score calibration. Higher scores presented risks that were lower than predicted by CHA2DS2-VASc. Event rate at 1 year was similar regardless of the AC regime at the initial date, and also similar to a previous cohort of anticoagulated patients (Lip et al.). This similarity may indicate confounding by later AC therapy initiation, before the final assessment date. Table 1. Comparison of thromboembolic event rates in several studies % (No-AC) % (AC) % Lip 2010 % Poli 2011 % Friberg 2012 % Okumura 2014 0.01 0.01 0.02 4.5 4.5 1 AC: anticoagulation. CHA2DS2VASc score calibration Conclusion Higher CHA2DS2-VASc scores are not associated to higher risks of stroke in our healthcare area, in patients with non-valvular AF and without antiplatelet therapy.

Background Real-world data reinforce positive results in different implant locations of leadless pacemaker (LPM). LPM have special characteristics regarding accelerometer programmation. Purpose The purpose of the study was to describe our experience with LPM different implantation location and its programmation according the vector accelerometer. Methods We performed a prospective observational one center study including all patients with LPM implantation within 3 years (June 2015-December 2018). Location of deployment was classified as apicalseptal, midseptal or right ventricle outflow tract (RVOT). Vector programmation was performed from the second visit in patients with acceptable mobility and heart rate below 80 bpm, with the abbreviated protocol recommended by the brand. Clinical evaluation according to vector programmed was performed 3 to 6 months later. Results We include a total of 144 LPM, and exercise test was performed in 86 patients. There were 86 men (59.7%) with a mean age of 79.1±6.9 years-old (54 to 89). Location of deployment was distributed as follows: 32.4% in apicalseptal, 54.5% in midseptal and 13.1% in RVOT. Vector 1 was the more frequent programmation, specially in apicalseptal position. Correlation between location and vector of programmation could not be predicted (p=0.2381), but there was a non-significant tendency (p=0.08) between patients with LPM in RVOT location and Vector 3 programmation. Table 1 and Figure 1. Table 1. Micra Location and Activity Vector Apicalseptal Midseptal RVOT P Value Test Vector 39 (84.8%) 40 (58.5%) 7 (46.7%) NS Vector 1 22 (56.4%) 26 (65.0%) 2 (28.6%) NS Vector 2 8 (20.5%) 4 (10.0%) 1 (14.3%) NS Vector 3 9 (23.1%) 10 (25.0%) 4 (57.1%) 0.08 Figure 1 Conclusions In our series, Vector 1 was the predominant accelerometer programmation specially in apicalseptal LPM position and Vector 3 in RVOT position.