Exercise capacity in moderate aortic stenosis: a cardiopulmonary stress echocardiography study

Background: Patients with moderate aortic stenosis (AS) may experience symptoms and adverse outcomes. The aim of this study was to determine whether patients with moderate AS exhibited objective evidence of exercise limitation, compared with age and sex matched controls and if so, to determine which echocardiographic parameters predicted exercise ability. Methods: This was a prospective case control study of patients with moderate AS (peak velocity (Vmax) 3.0–3.9 m/s, mean gradient (MG) 20-39mmHg, aortic valve area (AVA)1.1-1.5cm²) and left ventricular ejection fraction (LVEF) ≥ 55%. All patients underwent cardiopulmonary stress echocardiography. Results: 25 patients with moderate AS (Vmax 3.5 ± 0.2mmHg, mean gradient 28 ± 5mmHg, AVA 1.2 ± 0.1cm², LVEF 61 ± 4%) were compared with 25 controls. % predicted oxygen uptake efficiency slope (OUES), % predicted O₂ pulse and VO₂ at anaerobic threshold (AT) were significantly lower in patients compared with controls (OUES 79 ± 15 vs. 89 ± 15%, p = 0.013). VO₂ did not significantly differ between cases and controls. Conclusion: Objective measures of exercise capacity including OUES, O₂ pulse and VO₂ at AT are significantly lower in patients with moderate AS compared with controls, suggesting that these parameters may be more useful than VO₂ where patients may be unable to complete a maximal exercise test. Risk stratification using cardiopulmonary exercise echocardiography may help to identify patients with moderate AS who are at increased risk of cardiovascular events and should be considered for more intensive surveillance and intervention. Trial registration: Clinical trial number MRC 0225 IRAS 207395.