Predictors of Mortality and Symptomatic Outcome of Patients With Low-Flow Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

Abstract

Background: Impaired left ventricular (LV) ejection fraction is a common finding in patients with aortic stenosis and serves as a predictor of morbidity and mortality after transcatheter aortic valve replacement. However, conflicting data on the most accurate measure for LV function exist. We wanted to examine the impact of LV ejection fraction, mean pressure gradient, and stroke volume index on the outcome of patients treated by transcatheter aortic valve replacement.

Methods and results: Patients treated by transcatheter aortic valve replacement were primarily separated into normal flow (NF; stroke volume index >35 mL/m²) and low flow (LF; stroke volume index ≤35 mL/m²). Afterwards, patients were divided into 5 groups: "NF-high gradient," "NF-low gradient" (NF-LG), "LF-high gradient," "paradoxical LF-LG," and "classic LF-LG." The 3-year mortality was the primary end point. Of 1600 patients, 789 (49.3%) were diagnosed as having LF, which was characterized by a higher 30-day (P=0.041) and 3-year (P<0.001) mortality. LF was an independent predictor of all-cause (hazard ratio, 1.29; 95% confidence interval, 1.03-1.62; P=0.03) and cardiovascular (hazard ratio, 1.37; 95% confidence interval, 1.06-1.77; P=0.016) mortality. Neither mean pressure gradient nor LV ejection fraction was an independent predictor of mortality. Patients with paradoxical LF-LG (35.0%), classic LF-LG (35.1%) and LF-high gradient (38.1%) had higher all-cause mortality at 3 years compared with NF-high gradient (24.8%) and NF-LG (27.9%) (P=0.001). However, surviving patients showed a similar improvement in symptoms regardless of aortic stenosis entity.

Conclusions: LF is a common finding within the aortic stenosis population and, in contrast to LV ejection fraction or mean pressure gradient, an independent predictor of all-cause and cardiovascular mortality. Despite increased long-term mortality, high procedural success and excellent functional improvement support transcatheter aortic valve replacement in patients with LF severe aortic stenosis.

Keywords: aortic stenosis; low flow; outcome; transcatheter aortic valve implantation; transcatheter aortic valve replacement.

Figure 1

All‐cause (A) and cardiovascular (B) mortality according to low flow (LF) vs normal flow (NF). HR indicates hazard ratio.

Figure 2

All‐cause (A) and cardiovascular (B) mortality according to mean pressure gradient (MPG). All‐cause (C) and cardiovascular (D) mortality according to left ventricular ejection fraction (LV‐EF). HR indicates hazard ratio.

Figure 3

All‐cause (A) and cardiovascular (B) mortality according to 5 different aortic stenosis entities: normal flow–high gradient (NF‐HG), NF–low gradient (NF‐LG), low flow–HG (LF‐HG), classic LF‐LG (cLF‐LG), and paradoxical LF‐LG (pLF‐LG).

Figure 4

A, Percentage of patients with respective New York Heart Association (NYHA) functional class for each entity at baseline and at 1 year. B, Percentage of patients with NYHA class III or higher for each entity before and after treatment. C, Percentage of patients in each group with NYHA improvement of ≥1 classes after treatment. cLF‐LG indicates classic low flow–low gradient; LF‐HG, low flow–high gradient; NF‐HG, normal flow–high gradient; and pLF‐LG, paradoxical low flow‐low gradient.