Abstract 4694: Prognostic Value of the Contractile Reserve on Exercise Echocardiography in Asymptomatic Aortic Stenosis
Abnormal exercise test defined as the occurence of exercise limiting symptoms or of blood pressure drop, is useful to predict clinical events in asymptomatic patients with aortic stenosis (AS). Whether exercise stress echocardiographic data, especially the response of LV systolic function to exertion, have an added predictive value is unclear. to determine if the behaviour of LV systolic function during exercise test can predict maximum exercise capacity and clinical outcomes in patients with asymptomatic AS. 48 patients with asymptomatic AS (aortic peak velocity: 3.4 ±0.7 m/s) and preserved LV ejection fraction (≥50%) were assessed by echocardiography at rest and during a maximum ramp semi-supine bicycle exercise test. 18 (38%) patients had an abnormal exercise test (occurrence of exercise limiting symptom: angina: 1, severe dyspnea: 14; drop in systolic blood pressure: 1; ventricular arrhythmias: 2). Compared to patients with normal test, these patients had smaller LV end-diastolic volumes (87±15 vs 100±21, p=0.02), smaller indexed aortic valve area at peak stress (0.52±0.18 vs 0.63±0.15, p=0.02) and smaller increase in LVEF during exercise (ΔLVEF: 6±4% vs 11±6%, p=0.008). Absent or limited contractile reserve defined as ΔLVEF <10% was observed in 66% of patients with abnormal test vs 33% in those with normal test, p=0.02. The most important predictors of an abnormal exercise test were an AVA at peak stress<1cm2 (p=0.03; NPV=91%, PPV=62%) and ΔLVEF <10% (p=0.016, NPV=83%, PPV=54%). At a mean follow up of 14±6 months, 4 patients developed cardiac symptoms and 9 were referred for AVR. At one year, the event (AVR or symptom)-free survival was markedly lower in patient with abnormal vs normal test (65±11% vs 96±3%, p≤0.001) and in patients with ΔLVEF <10% vs ΔLVEF ≥10% (70±9 % vs 96±4%, p=0.03). An abnormal test was associated with 3.6-fold (p=0.0003) and ΔLVEF <10% with a 1.9-fold (p=0.04) increase in the risk of cardiac events. Exercise-limiting symptoms, fall in blood pressure or ventricular arrhythmias as well as no or minimal increase in LVEF during exercise predicts the onset of symptoms and need for AVR. Stress exercise echocardiography may be helpful to improve risk stratification in asymptomatic AS.