Abstract
Background Mortality dramatically rises with the onset of symptoms in patients with severe aortic stenosis (AS). Surgery is indicated when symptoms become apparent or when there is ventricular decompensation. Cardiopulmonary exercise testing (CPET) in combination with exercise echocardiography can unmask symptoms and provides valuable information regarding contractile reserve. The aim of the present study was to determine the prevalence of reduced exercise tolerance and the parameters predicting adverse cardiovascular events.Methods Thirty-two patients with asymptomatic severe AS were included in this study. Patients were followed up as part of an enhanced surveillance clinic.Results Age was 69 ± 15.7 years, 75% of patients were male. Patients had a raised NT-ProBNP of 301 pg/mL. VO2peak was 19.5 ± 6.2 mL/kg/min. Forty-one percent of patients had a reduced %VO2peak and this predicted unplanned cardiac hospitalisation (P = 0.005). Exercise systolic longitudinal velocity (S′) and age were the strongest independent predictors for VO2peak (R2 = 0.76; P < 0.0001). Exercise S′ was the strongest independent predictor for NT-ProBNP (R2 = 0.48; P = 0.001).Conclusion A large proportion of patients had a lower than predicted VO2peak. The major determinant of exercise and NT-ProBNP is the ability of the left ventricle (LV) to augment S′ on exercise rather than the severity of aortic valve obstruction or resting structural remodelling of the LV. Reduced exercise tolerance and more adverse remodelling, rather than valve obstruction predicted unplanned hospitalisation. This study demonstrates that for those patients, in whom a watchful waiting is an agreed strategy, a detailed assessment should be undertaken including CPET, exercise echocardiography and biomarkers to ensure those with exercise limitation and risk of decompensation are detected early and treated appropriately.
Highlights
Aortic stenosis (AS) results in obstruction of blood flow through the aortic valve
The aims of the study were firstly to determine the level of reduced exercise tolerance in a cohort of patients with severe ‘asymptomatic’ aortic stenosis (AS) and secondly to determine if exercise tolerance in these symptom-free patients was defined by obstruction to the aortic valve, ventricular remodelling or left ventricular contractile reserve
This study demonstrated that a large proportion of supposedly asymptomatic patients had a lower than predicted %VO2peak suggesting that patients have exercise intolerance, this is in agreement with previous reports in the literature (10, 11)
Summary
Aortic stenosis (AS) results in obstruction of blood flow through the aortic valve. The ventricular response to chronic pressure overload and other consequences of AS such as subtle myocardial ischaemia (1) are important to understand. Studies have previously reported that over half of the included patients with ‘asymptomatic’ severe AS have a reduced VO2peak implying that a large proportion of self-reported asymptomatic patients are limited by symptoms (10, 11). The aims of the study were firstly to determine the level of reduced exercise tolerance in a cohort of patients with severe ‘asymptomatic’ AS and secondly to determine if exercise tolerance in these symptom-free patients was defined by obstruction to the aortic valve, ventricular remodelling or left ventricular contractile reserve. The major determinant of exercise and NT-ProBNP is the ability of the left ventricle (LV) to augment S′ on exercise rather than the severity of aortic valve obstruction or resting structural remodelling of the LV. Reduced exercise tolerance and more adverse remodelling, rather than valve obstruction predicted unplanned hospitalisation. This study demonstrates that for those patients, in whom a watchful waiting is an agreed strategy, a detailed assessment should be undertaken including CPET, exercise echocardiography and biomarkers to ensure those with exercise limitation and risk of decompensation are detected early and treated appropriately
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