Flow-gradient patterns in severe aortic stenosis with preserved ejection fraction: clinical characteristics and predictors of survival

Abstract

Background: Among patients with severe aortic stenosis (AS) and preserved ejection fraction, those with low gradient (LG) and reduced stroke volume may have an adverse prognosis. We investigated the prognostic impact of stroke volume using the recently proposed flow-gradient classification.

Methods and results: We examined 1704 consecutive patients with severe AS (aortic valve area <1.0 cm(2)) and preserved ejection fraction (≥50%) using 2-dimensional and Doppler echocardiography. Patients were stratified by stroke volume index (<35 mL/m(2) [low flow, LF] versus ≥35 mL/m(2) [normal flow, NF]) and aortic gradient (<40 mm Hg [LG] versus ≥40 mm Hg [high gradient, HG]) into 4 groups: NF/HG, NF/LG, LF/HG, and LF/LG. NF/LG (n=352, 21%), was associated with favorable survival with medical management (2-year estimate, 82% versus 67% in NF/HG; P<0.0001). LF/LG severe AS (n=53, 3%) was characterized by lower ejection fraction, more prevalent atrial fibrillation and heart failure, reduced arterial compliance, and reduced survival (2-year estimate, 60% versus 82% in NF/HG; P<0.001). In multivariable analysis, the LF/LG pattern was the strongest predictor of mortality (hazard ratio, 3.26; 95% confidence interval, 1.71-6.22; P<0.001 versus NF/LG). Aortic valve replacement was associated with a 69% mortality reduction (hazard ratio, 0.31; 95% confidence interval, 0.25-0.39; P<0.0001) in LF/LG and NF/HG, with no survival benefit associated with aortic valve replacement in NF/LG and LF/HG.

Conclusions: NF/LG severe AS with preserved ejection fraction exhibits favorable survival with medical management, and the impact of aortic valve replacement on survival was neutral. LF/LG severe AS is characterized by a high prevalence of atrial fibrillation, heart failure, and reduced survival, and aortic valve replacement was associated with improved survival. These findings have implications for the evaluation and subsequent management of AS severity.

Keywords: echocardiography; heart valves; surgery; survival; valves.

Figure 1

Overall survival. NF groups had similar survival, while LF/LG had the worst survival (p<0.0001). Abbreviations: HG, high gradient; LF, low flow; LG, low gradient; NF, normal flow. Numbers at bottom of figure indicate percent survival (number of patients) at each time point for each group.

Figure 2

Survival to AVR. LF/LG group had the lowest survival to AVR compared to the other groups, while NF/LG had the highest survival (p<0.0001). Abbreviations: HG, high gradient; LF, low flow; LG, low gradient; NF, normal flow; AVR, surgical or transcatheter aortic valve replacement. Numbers at bottom of figure indicate percent survival (number of patients) at each time point for each group.

Figure 3

Survival in medically managed patients (censored at AVR). NF/LG had the best survival, while LF/LG had the worst survival with conservative medical management (p<0.0001). Abbreviations: HG, high gradient; LF, low flow; LG, low gradient; NF, normal flow; AVR, surgical or transcatheter aortic valve replacement. Numbers at bottom of figure indicate percent survival (number of patients) at each time point for each group.

Figure 4

Overall survival according to symptoms at baseline. The presence of symptoms at baseline was not strongly associated with survival in any of the groups. Abbreviations: Asym, asymptomatic; Symp, symptomatic.