AbstractPurposeMechanisms leading to heart failure (HF) symptoms in aortic valve stenosis (AS) are contentious. We examined the impact of secondary mitral regurgitation (MR) on the symptomatic status in patients with AS.MethodsOutpatients performing echocardiography with any degree of AS, without organic mitral valve disease, mitral valve intervention, or aortic insufficiency were enrolled. MR was quantitatively defined through mitral effective regurgitant orifice area (EROA) using the proximal isovelocity surface area method. Patients were divided into two groups (New York Heart Association [NYHA] class I–II vs. NYHA class III–IV).ResultsFive hundred and eighty‐four patients were enrolled (484 NYHA I–II, 100 NYHA III–IV). More symptomatic patients had smaller aortic valve area (AVA), lower left ventricular ejection fraction (LVEF) and stroke volume, higher E/E’, and LV global afterload. MR was present in 178 (30%) patients and EROA was <.20 cm2 in 158 (89%). NYHA III–IV patients showed higher prevalence of MR (78% vs 21%, P < 0.0001) and larger EROA (.13±.08 cm2 vs .09±.07 cm2, P < 0.0001). An association between EROA and symptoms was present in the total cohort and in subgroups with preserved LVEF, AVA ≥ 1 and <1 cm2, EE’ 8–14 and ≥14 (P < 0.05 for all). EROA was associated with severe symptoms after adjustment for LVEF, E/E’, and AVA in the overall population (OR 1.10 [1.06–1.15]; P < 0.0001) and in the 516 patients with preserved LVEF (OR 1.13 [1.08–1.19]; P < 0.0001).ConclusionIn patients with AS, greater EROA values are associated with HF symptoms, even though MR degree is far from the threshold of MR severity. Therefore, even a mild MR represents a supportive marker of HF symptoms presence.