Funding Acknowledgements Type of funding sources: None. INTRODUCTION Both angina and dyspnea symptoms are the most common clinical manifestations of cardiac ischaemia. Nevertheless, cardiac ischaemia may be detected on control functional tests of patients with ischaemic dilated cardiomyopathy despite being asymptomatic. The aim of this study was to assess the effect of elective myocardial revascularization on patient’s prognosis  depending on baseline clinical symptoms. METHODS All consecutive patients with ischaemic left ventricular dysfunction (LVEF <40% determined by gated-SPECT) who underwent stress-rest SPECT in our hospital between January 2010 and February 2018 were included. Baseline patients’ clinical presentation (angor pectoris, dyspnea or asymptomatic) and major adverse events (myocardial infarction, heart failure hospitalization and cardiovascular death) were retrospective recorded.  RESULTS A total of 748 patients with multiple comorbid conditions (smoking habit 69%, hypertension 78,7%, diabetes mellitus 49,5%, atrial fibrillation 22,1%, previous myocardial infarction 69% and previous heart failure hospitalization 24,9%) were included. Nonemergent coronary intervention during the first year (17,9% of patients) was associated with a reduction in the composite event (HR 0.69 [0.5-0.95]) but the multivariate analysis showed a prognostic benefit of revascularization in symptomatic patients (HR = 0.59 [0.37 - 0.94]) that was not observed among asymptomatic patients. The relative risk of the composite endpoint was RR = 0.63 (p <0.001) for asymptomatic vs. symptomatic non-revascularized patients and RR = 1.09 (p = 0.60) for asymptomatic vs. symptomatic revascularized patients. Finally, asymptomatic patients presented more necrosis (17.3 vs. 20.2%, p <0.01) and less ischemia (9.7 vs. 5.7%, p <0.001) than symptomatic patients.  CONCLUSION Patients with ischaemic dilated cardiomyopathy without symptoms of dyspnea or angina present less ischaemia and more necrosis in stress-rest SPECT than symptomatic patients. Moreover, unlike symptomatic patients, asymptomatic patients do not benefit from elective revascularization. Therefore, the clinical presentation should be considered when deciding revascularization of patients with ischaemic dilated cardiomyopathy and a positive SPECT test. Abstract Figure. Kaplan-Meyer curves

Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Hospital Universitari Vall d"Hebron - Vall d"Hebron Institut de Recerca. CIBERCV BACKGROUND Patients with structural heart disease (SHD) or bundle branch block (BBB) are at high risk of having an arrhythmic syncope (AS).  In patients with recurrent syncope episodes (RSE)  complete work-up including electrophysiological study (EPS) and/or implantation of a loop recorder (ILR) is recommended, however patients with their first episode may also be at risk of an AS. AIM To determinate if the patients with SHD or BBB with a single syncope episode (SSE) are at high risk of having an AS and compare it with patients with recurrent episodes (RSE). METHODS Cohort study carried out in a tertiary hospital that is a reference centre for syncope. From January 2008 to August 2020 patients with SHD or BBB with syncope of unknown origin after the initial evaluation and without direct indication of an ICD were included. They were managed according the current ESC guidelines. RESULTS 417patients were included  (74 ±11 y. o; 39% female). Mean follow up was 2.5 ±1 y. 223 patients were diagnosed from an AS [113 (53%) in SSE group and 110 (54%) in RSE group, p = 0.9], 210 were due to bradyarrhythmia (AV block or sinus arrest). No differences in baseline characteristics where found comparing both groups, except that BBB was slightly more prevalent in patients with RSE (81% vs 90%, p = 0.01) (FIGURE- PANEL A). Risk of AS was 53% in patients with SE and 54% (p = 0.9). RSE were not associated with an increased risk of AS in univariate analyses (OR 1.01 IC95% 0.7-1.5) neither in the multivariate (FIGURE- PANEL B). EPS and ILR diagnostic yield was 45% / 32% respectively in SSE group and 44% / 33% in RSE group (p = 0.8) (FIGURE - PANEL C).  After appropriate treatment, recurrence syncope rate was 10% in SSE group and 9% in RSE group (p = 0.8). No significant differences in mortality rate were found. CONCLUSIONS Patients with SHD or BBB and single syncope episode are at a high risk of having AS, and similar to those with RSE. EPS and ILR offer a similar diagnostic yield in both groups. Complete syncope work-up must be recommended in these patients despite having had only a single episode. Abstract Figure

Introduction The arrhythmic risk stratification of patients with repaired Tetralogy of Fallot (TOF) is still controversial. The performance of an electrophysiologic (EP) study before pulmonary valve replacement (PVR), regardless of patient's risk factors, is an extended practice in some centers that is not recommended in current guidelines. The aim of our study was to explore the differences in ventricular tachycardia (VT) inducibility in patients with TOF during programmed ventricular stimulation (PVS) depending on the clinical indication. Methods All patients with repaired TOF who underwent an EP study with PVS between January 2001 and October 2020 were included. EP studies performed in the context of ventricular or supraventricular tachycardia ablations that had been previously diagnosed were excluded. We defined two clinical scenarios for performing the EP study: pre-PVR (performed previous to pulmonary valve replacement) or diagnostic EP study (performed due to high risk symptoms which included palpitations, syncope or presyncope). Baseline clinical information, electrocardiogram, echocardiogram and cardiac MRI parameters were retrospective recorded. Results A total of 139 EP studies with PVS were included; 87 in the pre-PVR group and 52 in the diagnostic EP study group. There was a greater incidence of palpitations, syncope and presyncope in the “Diagnostic EP study” group. Moreover, there were statistical significant differences in right ventricle dimensions and function between groups. The repair surgical approach was similar in both groups. It was detected a statistical significant difference in VT induction between the pre-PVR group and the diagnostic indicated group (16,1% vs 34,6%, p=0,012). Conclusions Differences in VT induction are observed during PVS performing in TOF patients depending on the clinical indication. Symptomatology is an important parameter that must be taken into account in order to decide whether to perform an EP study in this population. FUNDunding Acknowledgement Type of funding sources: None.