Most patients with hypertrophic cardiomyopathy (HCM) usually complain of a reduced exercise capacity, and several factors have been advocated as possible causes of this clinical feature. The present single-center study was designed to investigate exercise capacity and its main clinical determinants in HCM patients. One hundred ninety seven patients of 223 evaluated underwent a complete clinical assessment, including Doppler echocardiography, cardiopulmonary exercise test (CPET) and, in most cases, cardiac magnetic resonance. The HCM population (male 75 %; age 47 ± 16 years; NYHA class I or II 95 %; left ventricular ejection fraction 61 ± 3 %; resting left ventricular outflow tract gradient ≥30 mmHg 22 %; late gadolinium enhancement presence 58 %) showed slightly reduced mean peak oxygen uptake values (pVO2 75 ± 15 %, 23.2 ± 6.7 ml/kg/min) with a significant reduction of the achieved percentage of peak heart rate reserve (%pHRR 65 ± 20 %). Adopting a pVO2 <80 % cut-off value, 59 % of HCM patients showed a reduced exercise capacity. Age, male gender, left atrial size, chronotropic and systolic blood pressure response, ventilatory efficiency, late gadolinium enhancement presence and β-blocker therapy were independently associated with pVO2 (R (2)-adjusted index 0.738). A %pHRR cut-off value of 74 % appeared to most accurately predict an impaired exercise capacity (area under curve 0.90). A great prevalence of reduced exercise capacity is present in NYHA class I-II HCM patients. Notwithstanding its multifactorial genesis, few parameters might be adopted in identifying this feature. In this context, %pHRR value might represent a reliable and easy-to-obtain tool for the clinical evaluation of HCM patients.

Funding Acknowledgements Type of funding sources: None. Background – Wave front inhomogeneous propagation is crucial for reentry circuit generation. Bipolar EGM duration is indicative of local conduction delay and may identify areas of low conduction as a functional substrate. This study aimed to create a map of EGM duration during the VT (VEDUM Map) to identify the area of the slowest conduction and to verify if RF delivery at this area allows to rapidly interrupt the VT. Methods – 24 high-density VTs maps (21 patients) were analyzed. Activation maps and voltage maps during SR were performed. An offline remap confirmed with MathLab software was customized to visualize the longest duration electrogram during VT. Results – All of the VTs were interrupted during the first RF delivery (mean time 7,3 ± 5,4 sec (range 3-25 sec)) at the area with the longest EGM duration (212 ± 47 ms (range 113-330 ms)). . In 9 pts (37,5%) the longest EGM was located at the entrance or exit area of the activation maps while in 5 pts (21%) the EGM covered the full diastolic phase. Finally, in 10 pts the longest EGM occurred in the mid-exit-diastolic phase. Conclusions - A novel Ventricular map of Electrograms DUration (VEDUM Map) is highly accurate in defining a conductive vulnerable zone of the VT circuit. The longest EGM duration within the isthmus is highly predictive of rapid VT termination. Quantitative variablesQualitative variablesMeanMedianStandard DeviationAge71738.40BMI26.624.54.02LV EDV16315442.7LV EDD61.2629.9LV EF38.7369.74VT cycle lenght (TCL)35537556.4EGM max. duration in VT21220847EGM max dur / TCL58.260.512Maximum EGM duration localization in CLProto = 12.5%Meso = 33.3%Tele = 25%Full = 20.8%Myocardium voltage characteristics in VEDUM EGMHealthy = 25%Transition = 20.8%Scar = 41.7%Critical Isthmus area12.3107.3VT Interruption during RFYes = 79.2%No = 20.8%Time (seconds) to interruption765Access typeEndo = 58.3%Epi = 29.2%Clinical and procedural dataAbstract Figure.

Funding Acknowledgements Type of funding sources: None. OBJECTIVES This study aimed to describe the results of a modified sympathicotomy (uniportal VATs with stellate ganglion sparing) for cardiac sympathetic denervation (CSD) in the setting of untreatable ventricular tachycardia. BACKGROUND. CSD, in patients with refractory ventricular tachycardia (VT), is comprehensively recognized as an important treatment option for patients with structural heart disease as well as congenital inherited arrhythmia syndrome. A recent case series demostrated  the feasibility of the modified technique. METHODS We consecutively enrolled 8 patients with refractory VT. Baseline demographic, medical, and surgical data as well as arrhythmia outcomes and procedural complications were evaluated. RESULTS A total of 8 patients ( 7 pts NIDCM, 1 pt IDCM with mean age:68+-8 years) were enrolled for the treatment of refractory VT with a modified CSD technique. Mean sympathicotomy length were 7.3 (SD 3) min per side. 3/8 patients underwent monolateral (LCSD) sympathicotomy due to strong adesion in the right pleural cavity. Mean follow up was 13 months (SD 6). No complication occurred during the sympathicotomy. An overall reduction in VT burden and VT number was observed after the CSD despite an in-hospital early recurrence in 3 patients. CONCLUSIONS A modified CSD (sympathicotomy T2–T5) with stellate ganglion sparing and the use of unipolar radiofrequency is feasible, effective, and safe in the setting of untreatable VT. Abstract Figure. VT trend

Funding Acknowledgements Type of funding sources: None. Background. Atrial fibrillation (AF) is the most frequent sustained arrhythmia worldwide and Cryoballoon ablation (CB) has become a consolidated alternative to the radiofrequency pulmonary vein (PV) isolation. However, CB requires fluoroscopy and dye injections to verify the occlusion grade. The accuracy of the earlier version of the Kodex Occlusion Tool software has been studied. Purpose. The purpose of this study was to verify the accuracy of the second generation Kodex Occlusion Tool Software of a new dielectric system imaging compared to its first generation to detect PV occlusion during CB ablation in patients with AF. Methods. 15 consecutive patients with paroxysmal AF were enrolled in the study and underwent the procedure with the guidance of the first generation version (1.4.6) of the Kodex Occlusion Tool software. The Kodex recorded procedural data were used to replay the case using the Kodex second generation version (1.4.7) of the Occlusion Tool software when clinically available. After transseptal access, a detailed image reconstruction of left atrium and PVs was achieved with an octa-polar circular mapping catheter, PV occlusion was assessed with the Occlusion Tool Software and compared with standard dye injection and angiography, the cryoablation was then performed with a cryoballoon catheter. Results. A total of 72 PVs CB occlusions were tested. The old version showed 90.7% sensitivity and 76.5% specificity in assessing a complete PV occlusion verified with contrast medium injection. The positive predictive value was 80.3%, and the negative predictive value was 88.6%. The new version showed 94.8% sensitivity and 93.7% specificity in assessing a complete PV occlusion verified with same contrast medium injection data. The positive predictive value was 98.2%, and the negative predictive value was 93.7%. Acute isolation was achieved in all PVs and no 30-day complication was observed. Conclusion. This study demonstrates an increased accuracy of new Occlusion Tool software of the Kodex dielectric imaging system to assess the degree of PV occlusion during a CB ablation. Abstract Figure. Occlusion tool software 1.4.6 vs 1.4.7

Funding Acknowledgements Type of funding sources: None. Background Limited data exist on factors associated with radiation exposure during ablation procedures when a high definition mapping technology is used. Purpose To report factors associated with radiation exposure and data on feasibility and safety of a minimal fluoroscopic approach using the Rhythmia mapping system in supraventricular tachycardia (SVT) ablation procedures. Methods Consecutive patients indicated for arrhythmia ablation were enrolled in the CHARISMA study at 12 centers. We included in this analysis consecutive right-side procedures performed through a minimal fluoroscopy approach with the Rhythmia mapping system were analyzed. A 3D geometry of chambers of interest was reconstructed on the basis of the electroanatomic information taken from the mapping system. Fluoroscopy was used only if deemed necessary. The effective dose (ED) was calculated using accepted formula. For our purpose high dose exposure was defined as an ED greater than the median value of ED of the population exposed to radiation. Results This analysis included 325 patients (mean age = 56 ± 17 years, 57% male) undergoing SVT procedures (152 AVNRT, 116 AFL, 41 AP and 16 AT). During the study, 27481 seconds of fluoroscopy was used (84.6 ± 224 seconds per procedure), resulting in a mean equivalent ED of 1.1 ± 3.7 mSv per patient. The mean reconstructed RA volume was 99 ± 54 ml in a mean mapping time of 12.2 ± 7 min. The mean number of radiofrequency ablations (RFC) to terminate each arrhythmia was 9.4 ± 9 (mean RFC delivery time equal to 6.7 ± 6 min). 192 procedures (59.1%) were completed without any use of fluoroscopy; during the remaining 133 procedures (39.9%), 206.6 ± 313.4 seconds of fluoroscopy was used (median ED = 1.2 mSv). In a minority of the cases (n = 25, 7.7%) the fluoroscopy time was higher than 5 minutes (median ED = 6.5 mSv), whereas radiologic exposure time greater than 1 minute occurred in ninety cases (27.7%, median ED = 2.1 mSv). On multivariate logistic analysis adjusted for baseline confounders the RFC application time (OR = 1.0014, 95%CI: 1.0007 to 1.0022; p = 0.0001) was independently associated to an ED greater than 1.2 mSv, whereas female gender had an inverse association (0.54, 0.29 to 0.98; p = 0.0435). Acute success was reached in 97.8% of the cases. During a mean of 290.7 ± 169.6 days follow-up, no major adverse events related to the procedure were reported. Overall, the recurrence rate of the primary arrhythmia during follow-up was 2.5%. Conclusions In our experience, arrhythmias ablation through minimal fluoroscopy approach with the use of a novel ablation technology is safe, feasible, and effective in common right atrial arrhythmias. High-dose exposure occurred in a very limited number of cases, without any reduction of the safety and acute and long-term effectiveness profile.