"Impact of Aortic Valve Replacement on Outcome of Symptomatic Patients With Severe Aortic Stenosis With Low Gradient and Preserved Left Ventricular Ejection Fraction" 
Circ Jun 27
http://circ.ahajournals.org/content/128/6/622.full 
"Conclusions—AVR is associated with better survival than medical therapy in patients with symptomatic low-gradient severe AS and preserved left ventricular ejection fraction."