Valvuloarterial impedance does not improve risk stratification in low-ejection fraction, low-gradient aortic stenosis: results from a multicentre study.

OBJECTIVES: In a multicentre series of patients with low-ejection fraction/low-gradient aortic stenosis (LEF/LGAS), we evaluated the prognostic impact of valvuloarterial impedance (Zva). BACKGROUND: Zva in AS, a measure of global afterload taking into account systemic arterial compliance, has been proposed for risk stratification in paradoxical LGAS. We hypothesized that Zva could help risk stratification in LEF/LGAS. METHODS AND RESULTS: We retrospectively calculated Zva (5.6 ± 1.7 mmHg/mL/m(2)) of 184 consecutive patients (mean age: 71 ± 10 years) with severe symptomatic LEF/LGAS (valve area ≤1 cm2;, EF ≤40%, mean transaortic pressure gradient ≤40 mmHg) included between 1995 and 2005 in a multicentre registry. Zva was higher in patients with LVEF at rest ≤20% (6.6 ± 2.3 vs. 5.5 ± 1.6; P = 0.05) and correlated negatively with LVEF at rest (R = -0.25; P = 0.001). Zva was lower in patients without contractile reserve (CR) on dobutamine stress echocardiography (DSE) compared with patients with true severe AS (5.3 ± 1.3 vs. 5.8 ± 1.8 mmHg/mL/m(2); P = 0.048). Zva and the variation in stroke volume during DSE were positively correlated (P = 0.0001) but Zva did not allow distinction between true and pseudo-severe AS (5.8 ± 1.8 vs. 5.3 ± 1.8 mm Hg/mL/m(2); P = 0.30). In the total population, Zva was not predictive of long-term mortality. In the 128 patients who underwent aortic valve replacement, Zva was not predictive of operative death and of long-term mortality. CONCLUSIONS: Increased Zva is related to low LVEF and more frequent CR on DSE in LEF/LGAS. However, Zva did not allow an accurate distinction between true and pseudo-severe AS and failed to predict operative and long-term mortality after aortic valve replacement, in LEF/LGAS.

Influence of preoperative left ventricular contractile reserve on postoperative ejection fraction in low-gradient aortic stenosis.

BACKGROUND: Dobutamine stress hemodynamics (DSH) has the potential to stratify operative risk in low-gradient aortic stenosis (AS), but little is known about the relation between left ventricle contractile reserve and postoperative left ventricular ejection fraction (LVEF). We sought to assess the value of DSH to predict postoperative improvement in LVEF. METHODS AND RESULTS: Sixty-six consecutive patients with symptomatic severe AS (aortic valve area < or =1 cm2), LVEF < or =40%, and mean pressure gradient < or =40 mm Hg prospectively enrolled in the French multicenter study on low-gradient AS and who survived to aortic valvular replacement (AVR) were included. Preoperative contractile reserve was present in 46 patients (group I; 70%) and absent in 20 patients (group II; 30%). In the overall sample, 58% of patients improved by 2 New York Heart Association (NYHA) classes after AVR. Mean LVEF improved from 29+/-6% to 47+/-11% (P<0.0001). LVEF improved by > or =10 EF units in 38 patients (83%) in group I and in 13 patients (65%) in group II. Mean LVEF improvement was similar in the 2 groups (19+/-10% versus 17+/-11%; P=0.54). On multivariable analysis, multivessel coronary artery disease (P=0.05) and baseline mean transaortic pressure gradient (P=0.01) were related to LVEF improvement, whereas contractile reserve was not. CONCLUSIONS: LVEF increases in the majority of patients with low-gradient AS who survive after AVR. Although the absence of contractile reserve on DSH is related to high operative mortality, it does not predict the absence of LVEF recovery in patients surviving to AVR. These data further support the concept that surgery should not be contraindicated on the basis of absence of contractile reserve alone.

Low-gradient aortic stenosis: operative risk stratification and predictors for long-term outcome: a multicenter study using dobutamine stress hemodynamics.

BACKGROUND: The prognostic value of dobutamine stress hemodynamic data in the setting of low-gradient aortic stenosis has been addressed in small, single-center studies. Larger studies are needed to define the criteria for selecting the patients who will benefit from valve replacement. METHODS AND RESULTS: Six centers prospectively enrolled 136 patients with aortic stenosis (96 men; median age, 72 years [range, 65 to 77 years]; median aortic valve area, 0.7 cm2 [range, 0.6 to 0.8]; mean transaortic gradient, 29 mm Hg [range, 23 to 34 mm Hg]; cardiac index, 2.11 L x min(-1) x m(-2) [range, 1.75 to 2.55 L x min(-1) x m(-2)]). Left ventricular contractile reserve on the dobutamine stress Doppler study was present in 92 patients (group I) and absent in 44 patients (group II). Operative mortality was 5% (3 of 64 patients) in group I compared with 32% (10 of 31 patients) in group II (P=0.0002). Predictors for operative mortality were the lack of contractile reserve (odds ratio, 10.9; 95% confidence interval [CI], 2.6 to 43.4; P=0.001) and a mean transaortic gradient < or =20 mm Hg (odds ratio, 4.7; 95% CI, 1.1 to 21.0; P=0.04). Predictors for long-term survival were valve replacement (hazard ratio, 0.30; 95% CI, 0.17 to 0.53; P=0.001) and left ventricular contractile reserve (hazard ratio, 0.40; 95% CI, 0.23 to 0.69; P=0.001). CONCLUSIONS: In the setting of low-gradient aortic stenosis, surgery seems beneficial for most of the patients with left ventricular contractile reserve. In contrast, the postoperative outcome of patients without reserve is compromised by a high operative mortality. Thus, dobutamine stress Doppler hemodynamics may be factored into the risk-benefit analysis for each patient.