Observed change in peak oxygen consumption after aortic valve replacement and its predictors

OBJECTIVE: To assess the change in peak oxygen consumption (pVO(2)) and determine its outcome predictors after aortic valve replacement (AVR) for aortic stenosis (AS). METHODS: Patients with AS and preserved left ventricular ejection fraction who were referred for single AVR had cardiopulmonary exercise testing prior to and 9 months post-AVR. Predictors of outcome for pVO(2) were determined by multivariate linear and logistic regression analyses. A significant change in pVO(2) was defined as a relative change that was more than twice the coefficient of repeatability by test–retest (>10%). RESULTS: The pre-AVR characteristics of the 37 study patients included the following: median age (range) 72 (46–83) years, aortic valve area index (AVAI) 0.41 (SD 0.11) cm(2)/m(2), mean gradient (MG) 49.1 (SD 15.3) mm Hg and New York Heart Association (NYHA)≥II 27 (73%). Pre-AVR and post-AVR mean pVO(2) was 18.5 and 18.4 mL/kg/m(2) (87% of the predicted), respectively, but the change from pre-AVR was heterogeneous. The relative change in pVO(2) was positively associated with the preoperative MG (β=0.50, p=0.001) and negatively associated with brain natriuretic peptide > upper level of normal according to age and gender (β=−0.40, p=0.009). A relative increase in pVO(2) exceeding 10% was found in 9 (24%), predicted by lower pre-AVR AVAI (OR 0.18; 95% CI 0.04 to 0.82, p=0.027) and lower peak O(2) pulse (OR 0.94; 95% CI 0.88 to 0.99, p=0.045). Decreases in pVO(2) exceeding 10% were found in 11 (30%) and predicted by lower MG (OR 0.93; 95% CI 0.86 to 0.99, p=0.033). CONCLUSIONS: Change in pVO(2) was heterogeneous. Predictors of favourable and unfavourable outcomes for pVO(2) were identified.