This will be a prospective crossectional, longitudinal study recruiting patients by invitation with paradoxical low flow low gradient severe aortic stenosis. Patients with PLFLG AS will have been identified in other studies and these patients will be approached for enrollment in the study. Patients deemed appropriate for enrollment will undergo recumbent bicycle stress testing with concomitant measure of gas exchange. The bicycle will be at 30 degrees with initiation of minimal resistance for 3 minutes, followed by an increase in work-rate of 25 watts every two minutes until the patient reaches a sign/symptom-limited maximum exertion or test limiting symptoms develop. Charts will be reviewed for baseline medical conditions and demographics. CPX protocol will be standard HFH protocol supervised by exercise physiologist. The first phase of the study will be investigating if these asymptomatic patients will be reclassified to symptomatic as defined by reduced V02 Max. The second phase will be following these patients for long term adverse events and if V02 max correlates with a higher risk.
