Inability to execute internal logistics to begin enrollment

Severe aortic stenosis is a condition with poor life expectancy once it becomes symptomatic. There are no prospective studies illustrating the utility of cardiopulmonary stress (CPX) testing in diagnosing and prognosticating patients with paradoxically low gradient and low flow severe aortic stenosis. We aim to prospectively investigate the utility of CPX in this patient population with the hypothesis that utilizing CPX parameters would better identify higher risk patients warranting further evaluation and possibly intervention sooner.

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.

Inclusion Criteria:

• Aortic valve area <1 cm2
• Mean aortic pressure gradient <40 mmHg,
• Left ventricular ejection fraction >50% by 2D transthoracic echocardiography

Exclusion Criteria:

• Ischemic heart disease
• Severe mitral valve disease (regurgitation or stenosis)
• Moderate or severe aortic regurgitation
• Pulmonary hypertension (PA pressure >50 mmHg)
• COPD
• Uncontrolled hypertension (Systolic BP or Diastolic BP greater than 150/90)
• Inability or unwillingness to exercise.

Patients with paradoxical low flow low gradient aortic stenosis