Abstract 2062: Predictors Of Outcome In Low Flow, Low Gradient Aortic Stenosis. Result Of The Multicenter Topas Study
Background: Patients with low flow aortic stenosis (AS) have a poor prognosis and a high operative mortality. Dobutamine stress echocardiography (DSE) has been used to assess LV contractile reserve and determine the “actual” severity of the stenosis. Recently, we proposed the projected aortic valve area at a normal flow rate (AVAproj) to better differentiate true-severe from pseudo-severe AS. The objective of this study was to identify the independent predictors of survival in low flow, low gradient AS.
Methods and results: 101 patients with low flow, low gradient AS (AVA≤1.2cm2, LV Ejection Fraction (LVEF) ≤40% and mean gradient (MG) ≤40 mmHg) underwent DSE and an assessment of functional capacity using the Duke Activity Status Index (DASI). A subgroup of 74 patients underwent a 6-minute walk test (6MWT). Overall survival was 70±5% at 1 year and 61±5% at 2 years. On univariate analysis, predictors of mortality were 6MWT ≤320m (p<0.0001), DASI ≤20 (p=0.0001), rest AVA ≤1cm2 p=(0.006), peak DSE LVEF (LVEFpeak) ≤35% (p=0.02), AVAproj≤1.2cm2 (p=0.04). After adjusting for age, gender, and the type of treatment (surgical vs. medical), significant predictors of mortality were DASI ≤20 (HR: 1.79, 95%CI: 1.28 –2.53 p=0.0006) and AVAproj ≤1.2cm2 (HR:1.64, 95%CI: 1.04 –2.87 p=0.03). In the subgroup of patients undergoing a 6MWT (n=74), independent predictors of mortality were: 6MWT ≤320m (HR: 2.49, 95%CI: 1.55– 4.30 p<0.0001), AVAproj ≤1.2cm2 (HR: 2.07, 95%CI: 1.18 – 4.08 p=0.01), and LVEFpeak ≤35% (HR: 1.64, 95%CI: 1.10 –2.51 p=0.016). In the subset of patients undergoing valve replacement (n=44), unvariate predictors of operative mortality (18%) were: 6MWT ≤180m (OR: 9.8, 95%CI: 3.7–35, p=0.0002), DASI ≤15 (OR: 3.21, 95%CI: 1.67– 6.48, p=0.011) and LVEFpeak ≤20% (HR:5.83, 95%CI: 2.6 –16.7 p=0.001).
Conclusion: In low flow, low gradient AS, the most significant risk factors for poor outcome were:
Impaired functional capacity documented by a reduced DASI or 6MWT,
More severe valve stenosis as documented by a smaller AVAproj, and
Reduced peak stress LVEF, a composite accounting for resting LV function and contractile reserve.
This new knowledge may assist in predicting the prognosis of patients with low flow AS and improve operative risk stratification.