Introduction Despite the pivotal role of left atrial (LA) function in a variety of cardiac pathologies, it has been studied mainly at rest. Aim Aim of the study was to assess the effect of semisupine exercise ergometry (Ex) on LA function, by volumetric and strain parameters and to interrogate relationships with left ventricular (LV) function and noninvasive hemodynamics. Patients and methods Eighty-two patients (female 26, age: mean/SD 61/15) referred for Ex were studied. The following parameters were estimated by 2 D echo: LV systolic (LVvolsyst) and diastolic (LVvoldiast) volume, ejection fraction (LVEF), stroke volume (LVsv), LA minimum (LAvolmin) and maximal volume (LAvolmax), LA emptying fraction [LAEF), LA reservoir volume (LAvolres = LAvolmax − LAvolmin), LA reservoir fraction (LAresFR = LAvolres/LVsv), LA conduit volume (LAcondvol = LVsv − LAvolres) and LA conduit fraction (LAcondFR = LAcondvol/LVsv). LV strain (LVSR) and LA strain (LASR) were estimated by 2D analysis. Peak tricuspid gradient (TRpg) was also estimated. Parameters were measured at rest R and Ex and the respective % changes (%d) were calculated. Results SBE performance was efficient with a % achieved target heart rate 73/9 and workload Watts 96/21. Systolic blood pressure increased from 139/53 to 179/31. Parameters with significant change during Ex are in the table (all p<0.001). LVSRr and LVEFr were both related inversely with LAvolresR (r=−0.39/p=0.001 and r=−0.24/p=0.05) and LAresFRr (r=−0.34/p=0.001 and r=−0.25/p=0.04). LVEFr was related inversely with LAcondRFr r=−0.24/p=0.04). LVSR was related inversely with LAvolresEx (r=−0.43/p=0.001). LVSREx was related inversely with LAvolresR (r=−0.24/p=0.04) and LAcondRFr (r=−0.25/p=0.04). The %dLVSR was related inversely with LAEFr (r=−0.25/p=0.04). The %dLVEF was related inversely with LAresFREx (r=−0.27/p=0.03) and LAcondRFr (r=−0.27/p=0.03). The % increase in TRpg during SBE was positively related with LAresFREx r=0.30/p=0.04 and inversely with LAcondFREx (r=−0.30/p=0.04) (Figure 1). Conclusion SBE induces LA dynamic changes in a spectrum of volumetric and strain indices. Dynamic changes of LV are related with reservoir and conduit LA function. LA reservoir and conduit function during SBE are related with the induced dynamic changes of pulmonary pressure, thus further supporting the clinical relevance of the respective evaluation. Funding Acknowledgement Type of funding sources: None.

Funding Acknowledgements Type of funding sources: None. Introduction Risk stratification in the asymptomatic severe aortic stenosis (AS) remains a difficult task within the spectrum of its hemodynamic phenotypes, especially on aging demographics. Interplay of left ventricular function and AS hemodynamics may be studied using semisupine bicycle ergometry (SBE). Purpose Purpose of the study was to interrogate the prognostic relevance of SBE based evaluation of LV function and noninvasive hemodynamics in asymptomatic severe AS. Methods Seventy-eight asymptomatic severe AS patients (pts), followed up on valve clinic in a tertiary center (age 65±12 years, female 29), were referred for SBE. AS related cardiac events (independent decision for surgery, NYHA worsening) during a follow up of 33/21 months occurred in 25 pts (64% for age>65 vs 30% for age<65). Workload (Watts) and % achieved target heart rate (%targetHR) were considered surrogates for SBE efficiency. The following parameters (mean±SD) were estimated at rest(R) and SBE (Ex): Biplane LV ejection fraction (EF) and stroke volume (SV), 2D strain (SR), tricuspid peak gradient (TRPG), transmitral E/e, HR, systolic blood pressure (SBP), HR*SBP product and their respective % changes. Results Event group had a decreased SBE efficiency in workload (Watts: 59±16 vs 78±20, p<0.001), similar %target heart rate (73±13 vs 73±9), with differences among the continuous variables only in EFex (59±8 vs 63±7, p = 0.04) and %dLVEF (6±10 vs 12±10, p = 0.02). Categorical classification was performed for inadequate LV functional improvement at SBE, using the absolute cut off for <5% LVEF increase and the <3% for LVSR increase, as well as for an excessive increase in pulmonary hypertension at SBE, using the cut off for TRPG >55mmHg. Respective distribution of cases was similar for age category > or <=65 years (dEX <5: 46% vs 45%, dSR <3: 62% vs 87%, TRPGEx >55mmHg: 38% vs 48%, all p = ns). Kaplan Meier analysis for events using TRPG>55 was significant for females (log rank=3.2, p = 0.06/ figure1). Kaplan Meier analysis for events using dEF≥5 was significant for age <65 years (log rank =4.7, p = 0.03/figure2). LVSR cut off did not provide any difference in outcome. Conclusion SBE induced changes on LV function and pulmonary hypertension have an uneven risk stratification relevance according to age and gender. Dedicated algorithms to gender and age have to be applied for the improvement of prognostication in severe AS based on SBE.