Cardiopulmonary Exercise Testing in Patients with Asymptomatic or Equivocal Symptomatic Aortic Stenosis: Feasibility, Reproducibility, Safety and Information Obtained on Exercise Physiology

Abstract

Objective: The aim of this study was to determine the feasibility, reproducibility, safety and information obtained on exercise physiology from cardiopulmonary exercise testing (CPX) in patients with aortic stenosis. Methods: Patients with an aortic valve area (AVA) <1.3 cm ² who were judged asymptomatic or equivocal symptomatic underwent CPX and an inert gas rebreathing test. Only those where comprehensive evaluation of CPX results indicated haemodynamic compromise from aortic stenosis were referred for valve replacement. Results: The mean patient age was 72 (±9) years; an AVA index <0.6 cm ²/m ² and equivocal symptomatic status were found in 90 and 70%, respectively. CPX was feasible in 130 of the 131 patients. The coefficients of repeatability by test-retest were 5.4% (pVO ₂) and 4.6% (peak O ₂ pulse). A pVO ₂ <83% of the expected was predicted by a lower stroke volume at exercise, lower peak heart rate and FEV ₁, and higher VE/VCO ₂, but not by AVA index. Equivocal symptomatic status and a low gradient but high valvulo-arterial impedance were associated with a lower pVO ₂, but not with an inability to increase stroke volume. In total, 18 patients were referred for valve replacement. At 1 year, no cardiovascular deaths had occurred. Conclusions: CPX was feasible and reproducible and provided comprehensive data on exercise physiology. A CPX-guided treatment strategy was safe up to 1 year.