Severe aortic stenosis (AS) is the most common valvular heart disease in developed countries. Heart failure (HF) is a frequent comorbidity of this condition and represents a diagnostic and therapeutic challenge. The spectrum of both conditions has gradually expanded over the past decade; HF was divided into three groups according to left ventricular ejection fraction (LVEF) and severe AS was reclassified into four groups according to aortic valve (AV) gradient, AV flow measured by stroke index LV and LVEF. Although all four types of AS can be found in patients with signs and symptoms of IC, low-flow AS with a low or normal gradient is the most common type in these patients. Several studies have documented that patients with severe low-flow AS have a higher mortality risk than patients with normal-flow and high-gradient AS, not only during natural disease progression, but also after replacement. Interventional or surgical AV. Existing data support transcatheter AV replacement (TAVR) in patients with severe AS, regardless of AV gradient, AV flow, and LVEF. Controversial issues, however, are still present on this subject, which has not been sufficiently addressed by large studies and trials. This clinical review summarizes the epidemiology of different types of IC in patients with severe AS, as well as the impact of IC and LVEF on the clinical outcomes of untreated AS patients or after AV replacement. In particular, we addressed the influence of AV gradient and AV flow on all-cause and cardiovascular mortality in AS patients after TAVR.