In patients (pts) with asymptomatic aortic stenosis (AS), exercise stress echocardiography (ESE) provides additional prognostic information beyond baseline. The coronary flow reserve (CFR) is impaired in AS but its link with exertion is missing in this setting. We hypothesize that CFR could predict exercise capacity and an abnormal exercise test in AS.

Methods .– Non-invasive CFR and symptom limited semi-supine exercise stress echocardiography (ESE) were performed the same morning in 20 consecutive pts with asymptomatic isolated severe AS (mean age 69 ± 12 years, 30% women, mean aortic valve area 0.8 ± 0.1 cm ² , mean LVEF 70 ± 6%). CFR was performed in the distal part of the left anterior descending artery using intravenous adenosine infusion (140 μg/kg/min over 2 minutes). An abnormal ESE was defined as onset of symptoms at less than 80% of maximum predicted workload, ECG ST-segment depression ≥ 2 mm during exercise, rise of systolic blood pressure < 20 mmHg or fall in blood pressure, complex ventricular arrhythmia.

Results .– When compared to pts with normal ESE, pts with an abnormal ESE ( n = 9) were older, had higher left atrial volume index (all, P ≤ 0.05), and lower CFR (2.1 ± 0.3 vs. 2.9 ± 0.7, P ≤ 0.01), whereas resting hemodynamic variables assessing AS severity were not significantly different between subgroups. Furthermore, CFR was significantly correlated to age, the change of transvalvular pressure gradient and LVEF with exercise, workload (in watts), and exercise duration (all, P < 0.05). After adjusting for age, and sex, CFR remained significantly correlated to exercise duration and workload (all, P < 0.05). Using a ROC curve analysis, a CFR < 2.17 was the best cut-off to predict an abnormal ESE with a sensitivity of 67%, a specificity of 90% (AUC = 0.8, P < 0.01).

Conclusion .– In pts with asymptomatic severe AS, non-invasive CFR is correlated to exercise duration and workload, and a low CFR predicts an abnormal ESE with a good accuracy.