Adams, Jonathon

Introduction- Recent studies based on echocardiographic data have described an entity termed paradoxical low-flow, low-gradient severe aortic stenosis (AS) with preserved ejection fraction (EF). It is not clear whether this condition is also seen in patients who undergo hemodynamic catheterization. Objective- To determine the prevalence of low-flow in patients with low mean gradient (MG) severe AS despite preserved EF as determined by echocardiography who subsequently undergo hemodynamic catheterization. Methods- We retrospectively reviewed medical records of 259 patients who underwent hemodynamic catheterization at Mayo Clinic from 2000-2009 to assess the severity of AS within 6 months of their echocardiographic study. Results- A total of 35 patients (mean age 75±9yrs; 49% males) had MG (≤ 40 mm Hg) and aortic valve area (AVA ≤ 1 cm2) despite preserved EF (≥50%) as determined by echocardiography. A total of 7/35 patients (20%) had low flow by echocardiography, defined as stroke volume index (SVI) ≤ 35 ml/m2 (median SVI of 32 ml/m2, inter-quartile range 30-33 ml/m2). Among the same 35 patients, there were 23 patients who had both low MG (≤ 40 mm Hg) and severe AS (AVA ≤ 1 cm2), while a total of 14/35 patients (40%) had low MG, severe AS as well as low flow (median SVI of 32 ml/m2, inter-quartile range 29-33 ml/m2) as determined by hemodynamic catheterization. A statistically significant correlation with modest association was observed between invasive and noninvasive measurements of MG, SVI, and AVA (r=0.48 ; p = 0.003; r=0.48; p = 0.004 ; r=0.36; p=0.03 respectively) in our study group of 35 patients. In most patients (94%) MG by catheterization was also ≤ 40 mm Hg. However, agreement between echocardiography and catheterization to identify patients with paradoxical low-flow, low MG, severe AS was poor (kappa = 0.03). Conclusions- 1) Paradoxical low flow, low-gradient severe aortic stenosis is also observed in patients who undergo hemodynamic catheterization. 2) Further studies are needed to better understand the pathophysiology, best method for diagnosis and true prevalence of this entity.