P0382 - Comparison of Exercise Capacity in Patients with Bicuspid Aortic Valve with and without Aortic Stenosis

Background: Bicuspid Aortic Valve (BAV) is a common congenital heart defect with a risk for progressive worsening of aortic stenosis (AS). Severe symptomatic AS is associated with poor prognosis and therefore, exercise capacity (XC) testing is routinely performed in BAV. While correlation of exercise limitation with AS severity has been established in adults, similar data in the pediatric population are lacking.

Objective: Our aim was to compare XC in patients with BAV with and without Aortic Stenosis.

Methods: This single center retrospective chart review included patients with BAV who underwent treadmill XC testing and spirometry. Patients who had valve replacement, abnormal left ventricle function or history of coarctation repair were excluded. AS severity was based on resting mean echo Doppler gradient across the aortic valve: moderate AS (21–39 mmHg), mild AS (5-20 mmHg), and no AS (≤ 5 mmHg). Demographic data collected included age, height, and weight at the time of exercise. Peak oxygen uptake (VO2 in ml/kg/min) during the test, an indicator of maximal aerobic capacity, was collected. Other parameters studied were a) Percentage of predicted VO2 (%VO2) based on age, weight, height and gender b) Work(watts) c) % oxygen pulse, d) Anaerobic threshold (% of Predicted VO2 max) ( AT %) e) Metabolic equivalents (METS), f) % Forced Vital capacity, g) % Forced expiratory volume (FEV1) and h) Blood pressure response. Statistical analyses (SPSS version 20.0) included ANOVA to compare the various exercise parameters between the groups.

Results: A total of 95 patients met our inclusion criteria (No AS=17, Mild AS=55, Moderate AS=23). There were no differences in the age, or gender distribution among the three groups.
Moderate AS patients had statistically significant differences, when compared with no AS, in VO2 (mean difference 8.5 ± 3.1, p=0.02), %VO2 (mean difference 18.7 ±7.2, p=0.03), AT% (mean difference 16.1 ±5.9, p=0.02) and METS (mean difference 2.4 ±0.9, p=0.02). Other assessed parameters were comparable between groups. There were no differences in various XC parameters between the mild vs. moderate AS groups.

Conclusions: Our data demonstrates decreased aerobic capacity, anaerobic threshold and METS in patients with BAV with moderate stenosis, compared to those without stenosis. No significant differences were found in any of the exercise parameters between mild and moderate AS subgroups. Our data suggest an association between moderate aortic stenosis in BV and diminished exercise capacity, which may merit close longitudinal follow up.