LF-LG Aortic StenosisMulticenter Prospective Study of Low-Flow Low-Gradient Aortic Stenosis (TOPAS Study)

Low-flow, low-gradient (LF-LG) aortic stenosis (AS) may occur with depressed (i.e. Classical LF; CLF) or preserved (i.e. Paradoxical LF; PLF) LV ejection fraction (LVEF) and both situations are amongst the most challenging encountered in patients with valvular heart disease. Although, CLF-LG AS is recognized has an important clinical entity, current ACC/AHA-ESC guidelines however do not provide precise recommendations for clinical management of these patients . PLF-LG AS is a new entity recently described by our group, which is characterized by more pronounced LV concentric remodeling with smaller LV cavity size and a restrictive physiology leading to impaired LV filling, altered myocardial function, and a low-flow state. Up to recently, this entity was often misdiagnosed, leading to underestimation of AS severity and inappropriate delays for aortic valve replacement surgery (SAVR). The two main challenges in patients with CLF- or PLF- LG AS are to distinguish between a true-severe (TS) versus a pseudo-severe (PS) stenosis and to accurately quantify the extent of myocardial impairment. Unfortunately, the traditional resting and stress echocardiographic parameters currently used to assess the severity of valvular and myocardial dysfunction in patients with LF-LG AS are far from being optimal, and as a consequence, quantification of disease severity and therapeutic management may not be appropriate in a substantial proportion of these patients.

THE GENERAL OBJECTIVES of the TOPAS study are to develop and validate new parameters and biomarkers to improve the assessment of stenosis severity and myocardial impairment, the risk-stratification, and the clinical decision making in patients with LF-LG AS and to assess the impact of the different therapeutic strategies on patient outcomes.