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Introduction Drug-induced long QT syndrome (DI-LQTS) is a clinical entity with prevalence and arrhythmic risk not well defined. Purpose To determine the clinical characteristics of patients with DI-LQTS diagnosed in the setting of a tertiary hospital center. Methods Prospective observational study with consecutive inclusion of patients with the diagnosis of DI-LQTS as per standard criteria, in a tertiary hospital, between 2018 and 2022. Results Eighty-five patients were included (age 65±15 years, 59% male). The mean corrected QT interval (QTc) of the entire cohort was 545±56 ms. The drugs responsible for QTc prolongation were: psychotropic drugs 51%, antiarrhythmics 38%, anesthetics 29%, antibiotics 15%, antineoplastics 3%, other 2%. QTc prolongation was due to the combination of ≥2 responsible drugs in 46 (54%) patients, and to the use of a single drug in 39 (46%). Twenty-one patients (25%) presented ventricular arrhythmias at the time of drug-induced QT prolongation: 10 (12%) ventricular fibrillation, 7 (8%) sustained ventricular tachycardia, 3 (3%) non-sustained ventricular tachycardia, 1 (1%) frequent ventricular extrasystole. Patients with ventricular arrhythmias were older (73±12 vs 62±15 years, p Conclusion The DI-LQTS is a rare clinical entity but may be cause of clinically-relevant ventricular arrhythmias. Older age and greater prolongation of the QTc interval are associated with an increased risk of ventricular arrhythmic events. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Health Institute Carlos III, Spain

Introduction Remote monitoring (RM) is commonly used in the follow-up of patients with cardiac implantable devices (CID). However, there are a significant amount of automatic alerts of low clinical relevance. An alert classification model designed to optimize the management of RM alert in CID receivers can improve the analysis. Purpose Assess the effectiveness of a local protocol for review and classification of MR alerts. Methods Retrospective study, single center. We included all patients with ICD +/− CRT in the RM program between september 2016 and december 2019. All transmission received were analyzed. The priority of the transmissions was established based on clinical criteria and device parameters, classified into 3 categories from lowest to highest priority: green, yellow and red. Each category involved a specific action protocol (Figure 1). The categorization by colors was initially carried out by a remote support center, based on data from the devices; and later, reviewed by arrhythmia nurse team who incorporated clinical information data. In case of discrepancy, the alert was again evaluated together with the cardiologist. The degree of concordance in the categorization of alerts was analyzed, as well as the transmission response time (TRT): support center- care team. Results In our center a total of 1013 patients were included (68±14 years old, 76% male), who completed 8755 remote transmissions. The initial classification of transmissions by the support center was: 6890 (78.7%) green, 1497 (17.1%) yellow and 368 (4.2%) red. Only 0.62% of transmissions required reclassification by the healthcare team. No alert initially classified as yellow or green should be reclassified to red. The TRT was 3.35 hours for the red transmissions and 5.6 hours for the yellow ones. Conclusion The categorization of alerts in our RM system allows an efficient and safe organization of assitance to patients with CID. Funding Acknowledgement Type of funding source: None

Funding Acknowledgements NA OnBehalf NA Background High-density activation maps during complex atrial reentrant tachycardias are challenging to interpret as they include the activation patterns of active and passive circuits. Entrainment mapping provides the identification of the active tachycardia circuit. However, current electroanatomic mapping systems are not capable to color-coded the information obtained from entrainment maneuvers. Objectives We sought to describe a mapping approach for ablation of complex atrial reentrant tachycardias in which high-density activation maps are transformed into low-density activation maps only displaying the active part of the tachycardia circuit. Methods We included consecutive patients with atypical atrial flutter. A high-density activation map was acquired during the index tachycardia. Subsequently, entrainment maneuvers were performed to generate a low-density activation map in which only the activation of the atria directly involved in the flutter circuit was displayed. Results Seventeen patients were included 82% male, mean age was 62 ± 7 years. Structural heart disease was present in 59% and 53% had a prior left atrial ablation procedure. Low-density activation maps were successfully generated from an average of 14 ± 3 entrainment points. Twenty circuits (95%) were identified in the left atrium and 1 (5%) in the right atrium. Ablation guided by low-density mapping successfully terminated all ARTs in 267 ± 353 seconds of radiofrequency application. Conclusion Low-density mapping based on entrainment maneuvers provides a precise delineation of the active circuit during complex ARTs and resulted in successful arrhythmia termination. This approach can be easily incorporated into clinical practice.

Introduction Women are frequently underrepresented in clinical trials for heart failure. Differences on cardiovascular background may imply differences on indications, device election and outcomes in patients receiving cardiac devices (CRT and ICD). We sought to compare sex-related differences in a real-life cohort. Methods We analyzed all subjects who underwent a cardiac resynchronization therapy (CRT) implantation (with or without ICD) between 2016 and 2019 in a single center, all of them followed by remote monitoring. Baseline characteristics and outcomes were compared according to gender. Response to resynchronization was defined as clinical improvement in NYHA class or an increase of > =10% in LVEF. Results A total of 430 devices (ICD or CRT) were implanted. 149 (35%) of them were CRTs: 116 (88%) CRT-D and 33 (22%) CRT-P. Of the whole cohort, 43 (29%) were women and the mean age was similar in both sex (70+/-9 years). Women had more likely non-ischemic cardiomyopathy (86% vs 49%, p 0.05) and no difference on optimal medical treatment was observed. Women trend to receive more frequently CRT-P than men (33% vs 18%, p 0.054). After a mean follow-up of 3 years, a four-fold higher response to CRT was observed in women (OR 4.0, 95% CI 2.0-10.7, p 0.002), after adjustment by the etiology of the myocardiopathy. No differences on all-cause mortality (6% in men vs 1% in women, p 0.2) or ventricular arrhythmias (10% in men vs 2% in women, p 0.3) were observed. Conclusions in a real-life cohort, CRT implantation showed a sex-disparity: the proportion of women receiving a CRT was lower than in men, but a CRT without defibrillation was more frequently implanted in women, reflecting a higher prevalence of ischemic cardiomyopathy in men. The underlying myocardial substrate in women and a lower prevalence of AF may explain a more favorable response to CRT, despite more pronounced symptoms of heart failure at the moment of implantation.

Introduction Remote monitoring (RM) of cardiac devices is a technology established in clinical practice. The early activation of RM is associated with greater survival. The RM of leadless pacemakers consists of a non-automatic remote interrogation (RI), however factors such as age, the monitoring center and the type of device delivered can condition the adequate adherence to the system. Purpose Describe the results of RM in patients with leadless pacemakers in the clinical practice of a tertiary referral hospital. Methods All patients with leadless pacemakers were included. Since October 2017, RM was offered to all new patients and to previously implanted patients who had an elevated threshold. Clinical and demographic characteristics were analyzed. The following variables were evaluated: Activation (first RI), early activation (activation occurring before 90 days from the implant or from the medical order), premature activation (activation before 15 days), and adherence to follow-up (patients with almost one RI after 12 months from activation). Results A total of 142 patients have been implanted with a leadless pacemaker, of which 56 patients were offered RM, being accepted in 96% of the cases (54 patients, 88±6 years old, 54% males). A 54% patients received a RM using App based technology. During a mean follow-up of 200 days, 7 deaths occurred (13%). 100% of the patients have performed the activation, being in all cases an early activation, and in 50% (26 patients) it has been premature activation. 32 patients have follow-up longer than 12 months and all are adherent to RM. There are no differences in the percentage of activation or adherence depending on the type of monitor. Conclusions The implementation of RM program in old patients with a leadless pacemaker has a high acceptance rate, achieving an early activation in all patients. The adherence to this technology remains high despite the limitation of a non automatic transmission. RM using App based technology is possible in spite of the age.

The prognosis of postmyocardial infarction (post-MI) patients depends in particular upon the interaction between ischemia, left ventricular dysfunction, and electrical instability. The risk can be found in the center of an imaginary triangle formed by these three factors. These factors interact bidirectionally (Fig. 1), so that any of the apices affects the next directly or indirectly, and the modification of any one of these factors consequently alters the other two. Ischemia, therefore, affects left ventricular dysfunction either directly or indirectly through the electrical instability pathway and the sames happens with other two factors. We should also emphasize that the three angles of the triangle, electrical instability, left ventricular dysfunction, and ischemia, include different parameters as we can see in Fig 2. In Tables 1–3 we summarize the most important relationships between these three parameters.