Background Diastolic function assessment in patients with hypertrophic hearts and preserved ejection fraction (EF) is a rather challenging task. Combined plotting of deformation parameters against other indices, especially left ventricular (LV) volume, may reflect diastolic function components of the hypertrophic myocardium. Purpose Aim of this study was i) to apply strain-volume loops (SVLs) in hypertrophic cardiomyopathy (HCM) patients based on simultaneous frame-by-frame strain and volume changes' recordings acquired by means of three-dimensional (3D) speckle tracking imaging and ii) to investigate potential correlations between these loops, traditional diastolic function indices and phenotypic features of HCM (thickness, obstruction and fibrosis) that may also reflect myocardial “stiffness”. Methods We included 40 HCM patients (54.1±14.3 years, 82.5% male, maximum wall thickness 19.3±4.8mm) who have consecutively undergone 3D-speckle tracking echocardiography and cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE). Values of 3D strain were plotted vs. volume for each frame to build an SVL. Peak of radial, longitudinal and circumferential systolic strain (Rsp, Lsp, and Csp, respectively), systolic slopes of the loops (RsSl, LsSl, CsSl), strain to end-diastolic volume (EDV) ratios (Rs/V, Ls/V, Cs/V) as well as the extent of systolic-diastolic uncoupling (difference between systolic and diastolic strain for the same volume) (panel A) were computed for the analysis. Left atrial volume index (LAVI), E/E' and tricuspid regurgitation velocity (TRvel) were measured to define diastolic dysfunction (DD) stage. Burden of fibrosis was evaluated by LGE extent in CMR slices. Results All HCM patients had preserved EF (60.5±5,7%), while 16 (40%) had LV outflow tract obstruction (LVOTO>30 mm Hg at rest). Mean LV mass index was 78.9±14.5 g (evaluated by 3D echocardiography). LGE was observed in 23 patients (57.5%) occupying 5.2±4.5% of LV mass. Concerning SVLs the following values were recorded for radial (Rsp 30.8±9.8%, RsSl 0.4±0.13 and Rs/V 0.25±0.09), longitudinal (Lsp −9.4±3.7%, LsSl 0.12±0.06 and Ls/V 0.08±0.04) and circumferential deformation (Csp −14.2±3.5%, CsSl 0.18±0.05 and Cs/V 0.11±0.03). Traditional isolated diastolic indices (E/E', LAVI, TRvel and DD stage) did not present significant correlations with SVL parameters or HCM phenotypic features. However, potentially “stiffer” hearts (combination of increased LVMI and fibrosis) presented a leftward transition of longitudinal SVLs, which also became wider (greater uncoupling) (panel B). Conclusions Traditional diastolic indices show modest only correlations with SVLs or HCM phenotypic characteristics, necessitating new approaches to DD of HCM patients. SVLs seem to be a promising-innovative tool for indirect assessment of myocardial “stiffness” and diastolic function. Funding Acknowledgement Type of funding sources: None. Figure 1

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Funding Acknowledgements Type of funding sources: None. Background The ongoing COVID-19 pandemic is a major public health crisis of great risk to patients with cardiovascular comorbidities. Heart failure (HF) is a deadly chronic disease, a leading cause of hospitalizations worldwide and a great detriment to patients’ quality of life. HF therapy guidelines suggest prescribing physical activity to improve long-term outcomes. Self- or government- imposed behavioral modifications in response to COVID-19 ranging from avoiding social interactions to outright restrictions of movement (lockdowns) could compromise regular PA in HF patients, who constitute an extremely high-risk group. Purpose Investigate the effect of the national lockdown in Greece 23rd March – 4th May 2020) on the PA levels of patients suffering from HF with reduced ejection fraction (HFrEF) and cardiac implantable electronic devices (CIEDs). Methods HFrEF patients with CIEDs were included in the study. Participants answered the Physical Activity Questionnaire (PAQ) regarding the period before, during and after the 42-day national lockdown. CIED-derived daily activity levels for the corresponding periods were recorded through CIED telemetry. The differences in PAQ- and CIED-derived PA levels and sedentary time before, during and after the lockdown period were investigated. Results 67 HFrEF patients participated in the study (mean age 69 ± 10.2y, 85% male). Activity levels fell in 55 (82%) of patients. The median PAQ-derived PA level decreased by 28% during lockdown, from 840.5 (944) METmin/week to 602 (1054) METmin/week during the lockdown (p = 0.01). A 53% increase was observed after the lockdown, to 924 (1214) METmin/week (p = 0.004). The CIED-derived activity level was 2.38 (1.3) hours/day pre-lockdown, 1.78 (1.1) hours/day during the lockdown (25% decrease, p < 0.001) and 2.69 (1.5) hours/day post-lockdown (51% increase, p < 0.001). Time spent on sedentary activities also increased to 9 (3) hours per day during the lockdown, up from 6.5 (4) hours before lockdown (p = 0.001). Conclusions All measures examined in this study indicate that the COVID-19 lockdown period was associated with a significant decrease in HFrEF patients’ PA. All efforts must be made on the part of clinicians and public health organizations to promote safe exercise in this subgroup of the population that is particularly vulnerable to the effects of a sedentary lifestyle. Abstract Figure. Patient activity around COVID lockdown

Background It is well documented that prolonged intense exercise such as a marathon, transitorily alters cardiac function. However, the impact of ultra-endurance (UE) exercise on global and segmental longitudinal deformation of all cardiac chambers and on inter-chamber functional relationships has not yet been thoroughly investigated. Purpose The aim of the study was the evaluation of the acute effects of UE exercise on longitudinal deformation of all cardiac chambers and on intra-, inter- and atrioventricular functional relationships. Methods Echocardiographic assessment was performed the day before and at the finish line of “Spartathlon”: a 246 Km ultra-marathon. 2D speckle-tracking echocardiography was performed in all 4 chambers during the same cardiac cycle, allowing a simultaneous strain-time data display of all cardiac chambers (Figure 1). Peak global deformation values and temporal parameters adjusted for the heart rate were extracted from the derived curves, while a segmental analysis for left (LV) and right ventricle (RV) was also performed. Results Out of 60 participants initially screened, 27 athletes (17 male, age 45±7 years) finished the race in 33:34±1:59 hours. Both LV (−20.9±2.3 pre- to −18.8±2% post-, p=0.009) and RV global strains (−22.9±3.6 pre- to −21.2±3% post-, p=0.04) decreased post-race, even though remained within normal range for the 85% of the participants. Peak atrial strains [right (RA) and left (LA)] did not change (p=0.12 and 0.95). Basal and mid segmental strain values significantly decreased post-race, while both LV and RV apical strain values remained unaffected (p=0.899 and p=0.46, accordingly) (Figure). Concerning interchamber relationships, RV and RA strain curves were constantly larger in magnitude than those of the LV and LA, with RV/LV, LV/LA, RV/RA and RA/LA peak values' ratios remaining unchanged from pre- to post-race. Finally, although right chambers' time-to-peak values were shorter compared to the left ones, all chambers' strain curves peaked later post-race (p<0.001 for all). Conclusions Despite subtle changes in LV and RV strain, 4-chamber deformation values remained within normal range even after running a 246 km ultra-marathon. Following a segmental analysis, this finding could be explained for both ventricles by a preservation of apical deformation. Additionally, inter- and atrioventricular concordance was also maintained. Figure 1 Funding Acknowledgement Type of funding source: None

Background Catheter ablation has emerged as an effective therapy in patients with atrial fibrillation (AF). Despite high success rates of the method, there is still heterogeneity of outcomes and complications across Europe. A center's volume of AF ablations performed per year might also play an important role in the success rate of the procedure as compared to other confounding factors which may be different among centers (such as type of AF ablated, patient selection criteria, referral bias and/or ablation strategy). Purpose Aim of the study was to investigate differences in clinical outcomes and complication rates among European AF ablation centers related to the volume of ablations performed annually. Methods Data for this analysis were extracted from the European AF Ablation Long-Term Study, a prospective registry designed to describe the clinical epidemiology of patients undergoing AF ablation. Based on 33th and 67th percentiles of number of AF ablations performed, the participating centers were classified into high volume (HV) (≥180 procedures/year), medium volume (MV) (<180 and ≥74/year) and low volume (LV) (<74/year). One-year success was defined as patient survival free from any atrial arrhythmia, from the end of the 3-month blanking period to 12 months following the ablation procedure. Results A total of 91 centers in 26 European countries enrolled 3368 patients. There was a significantly higher reporting of cardiovascular complications in LV centers (5.2%), especially pericarditis and cardiac perforation, while the HV and MV centers reported cardiovascular complications in 3.0 and 4.3% of cases, respectively (p=0.039). Additionally, stroke incidence after ablation was significantly higher in LV centers (0.5% of cases vs 0% in HV and MV centers, p=0.008). One-year success after AF ablation ranged from 77.8% in HV vs 70.5% in LV vs 77.3% in MV centers (p<0.001). Despite these unadjusted differences, Kaplan-Meier survival analysis based on adjusted data demonstrated, however, that there were not significant differences in complication and recurrence rates according to volume's center (p=0.328 and p=0.476 accordingly, Figure A). This result was mainly driven by a proportional increase in severity/risk of cases ablated (as evidenced by CHA2DS2-VASc score and AF type) in relation to a center's procedural volume (Figure B). Conclusions Low volume centers present slightly higher cardiovascular complications' and stroke incidence and a lower unadjusted success rate after AF ablation. On the other hand, adjusted overall complication and recurrence rates are non-significantly different among different volume centers, a fact reflecting inhomogeneity of patient and procedural profiles and a counterbalance between expertise and risk level among participating centers. Funding Acknowledgement Type of funding source: None