In this series of HT recipients with uneventful postoperative course, LV and RV GLS values were significantly reduced early after HT and improved progressively until their complete normalization two and 1 year after HT, respectively. This is the first study to show a full recovery of LV and RV deformation parameters and offers "normal" strain values that, if confirmed in larger studies, could be useful for monitoring the evolution of HT recipients.

Sudden cardiac death (SCD) is the most devastating complication in hypertrophic cardiomyopathy (HCM). The implantable cardioverter–defibrillator (ICD) has proven to be effective in SCD prevention in several clinical scenarios. In HCM population, it has demonstrated to successfully abort life-threatening ventricular arrhythmias despite the extreme morphology characteristic of HCM, often with massive degrees of left ventricular hypertrophy and/or LV outflow tract obstruction. Studies showed a high rate of appropriate intervention in secondary prevention and in primary prevention of patients considered at high risk. This appropriate intervention rate is even more significant considering the young and otherwise healthy patients that compose HCM population. Since SCD incidence in HCM is relatively low, optimal identification of patients at high risk is crucial. Classical strategy of risk stratification based on clinical risk factors has several limitations and has proven to overestimate risk. A new risk prediction model that provides individual 5-year estimated risk appears to be superior to traditional models based on bivariate risk factors. Perioperative complications seem to be similar to those related to the implant of other cardiac devices, while long-term complications have been traditionally in the spotlight. HCM patients are considered more vulnerable to ICD-related complications and inappropriate ICD therapy because of their young age at implant and increased prevalence of atrial fibrillation, but long-term follow-up data on ICD-related complications in general practice is limited. The subcutaneous implantable cardioverter defibrillator seems to be a safe and effective alternative in HCM, although long-term data are scarce.

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Introduction Permanent pacing is often needed in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) due to new onset conduction disorders. Nevertheless, continuous right ventricular pacing may deteriorate left ventricular ejection fraction (LVEF) and lead to poor outcomes. Thus, in last years, more physiological forms of pacing, such as left bundle branch pacing (LBBP) have been developed to prevent pacing induced cardiomyopathy. Purpose The aim of our study is to describe the initial experience in our center, evaluate the safety and feasibility of LBBP after TAVI and describe electrophysiological outcomes in the first months of follow-up. Methods We designed a prospective registry that collected all patients from the TAVI program of our center who developed conduction abnormalities in the immediate postoperative and received LBBP. We analyzed baseline characteristics, complications and procedure time, electrophysiological parameters after the procedure and final QRS interval. During follow-up LVEF, electrophysiological parameters and adverse clinical events (readmissions for heart failure, cardiovascular mortality and all-cause of mortality) were also evaluated at 3rd, 6th and 12th month. Results Between January 2020 and January 2022, twenty patients who developed conduction abnormalities after TAVI underwent LBBP. Seven patients (35%) had a complete atrioventricular block, two patients (10%) alternating bundle branch block and 11 (55%) had a new left bundle branch block. HV electrophysiology study was performed in 8 patients, with a median value of 68ms (66–72). Of the 20 patients, 3 out of 4 patients were male and had history of hypertension. 40% had previous ischemic heart disease and one patient had transthyretin cardiac amyloidosis. Median age was 79 years-old (76–83.5). Balloon-expandable prosthesis was implanted in 11 patients while 9 received a self-expandable prosthesis. Median basal LVEF was 59% (41.5–60) and median NTproBNP was 1722pg/ml (535–5848). LBBP was successful in all of the 20 patients. The median time of the procedure was 60 minutes (45–80) without suffering any complications. The median QRS interval before the procedure was 155ms (140–158) and 116ms (105–125) post-implant. To date, two patients have died of non-cardiac cause 3 and 8 months after LBBP. There have been no readmissions for heart failure. LVEF (pre and post-LBBP) and electrophysiological parameters post-implant and three-month follow-up are shown in Table 1. Conclusions In our experience, LBBP after TAVI is a safe and feasible procedure. Despite the small sample size and short follow-up period, our first results indicate stability of LVEF and pacemaker parameters. Funding Acknowledgement Type of funding sources: None.

Funding Acknowledgements Type of funding sources: None. Introduction Paroxysmal supraventricular tachycardias (PSVT) are common arrhythmias and catheter ablation is considered its first-line treatment. However, the duration of the episodes frequently precludes ECG documentation. Thus, patients may not be referred for ablation until the tachycardia is documented, leading to recurrences, emergency room visits and often unnecessary tests or treatments. Our objective was to evaluate the results of electrophysiological study (EPS) followed or not by ablation in patients with suspected but not documented PSVT. Methods Multicenter, retrospective, observational registry of consecutive patients undergoing EPS due to clinical suspicion of PSVT, but with no prior ECG documentation. Collection of clinical and EPS data, along with data regarding ablation, when performed. Results 427 patients of 12 centers were included. Mean age was 46.3 ±16.1 and 297 (69.6%) were females. Most frequent symptoms consisted on sudden onset (n = 360; 84.9%) and abrupt end (n = 304; 72.0%), with median episode duration of 10 minutes (interquartile range 5-20 min). Sustained arrhythmias were induced in most patients (n = 255; 59.7%). Specific types are summarized in Table 1. Ablation was performed in 274 (64.2%) patients. A total of 10 complications (2.3% of procedures) were reported: 3 transient AV block, 2 PR interval prolongation, 2 puncture-related hematoma, 2 painful site of puncture and 1 catheter entrapment in mitral chordae. Conclusions Electrophysiological study in patients with palpitations highly suggestive of PSVT is an effective and safe diagnostic and therapeutic tool that may be considered as a first-choice even in the absence of documented tachycardia. Results of EP study Results of electrophysiological study Typical AVNRT 183 (42.9%) Orthodromic AVRT 38 (8.9%) Dual AV nodal physiology 30 (7.0%) 1 nodal echo beat 21 (4.9%) Atrial tachycardia 19 (4.5%) >1 nodal echo beat 17 (4.0%) Atrial fibrillation 7 (1.6%) Atypical AVNRT 7 (1.6%) Atrial flutter 1 (0.2%) No abnormal findings 104 (24.4%) AVNRT atrioventricular nodal reentran tachycardia AVRT atrioventricular reentrant tachycardia