Abstract 9883: Impact of Low Transvalvular Gradient on Early and Late Outcomes After Aortic Valve Replacement for Aortic Stenosis

Abstract

Background: Few data are available concerning the results of aortic valve replacement (AVR) for low-gradient severe aortic stenosis (AS). Aim of this study was to assess the hypothesis that low-gradient is an independent predictor of early and late results after AVR. Methods: We retrospectively analyzed a series of 340 consecutive AS patients (area≦1.0cm 2 ) who underwent AVR from 2002 to 2012. Low-gradient AS was defined by the mean transvalvular gradient <40mmHg (n=68, 20%). The outcome measures included hospital mortality, major postoperative complication, prolonged length of hospital stay, and late survival. Results: Hospital mortality was 3.2% (n=11) (low-gradient 8.8%; high-gradient 1.8%; p=0.01). Low-gradient AS was an independent predictor for hospital mortality (odds ratio [OR] 6.0, 95% confidence interval [CI]: 1.6 to 21.2, p=0.006), but did not predict any postoperative major complication. NYHA class III/IV was another independent predictor of hospital mortality (OR 19.3, 95%CI: 2.4 to 155.1, p=0.005). In the patients with low-gradient AS who were in NYHA class III/IV (n=25), hospital mortality was significantly higher (24%) compared to those in NYHA class II (n=43, hospital mortality 0%). Multivariable predictors of late mortality (excluding hospital death) included NYHA class III/IV (OR 9.6, 95%CI: 1.2 to 76.7, p=0.03) and creatinine >2mg/dl (OR 6.9, 95%CI: 2.1 to 22.8, p=0.002). Low-gradient was no longer a risk of late mortality in operative survivors. The survival rate at 7 years after AVR was 84±10% in low-gradient and 95±2% in high-gradient patients (p=0.42). We also calculated propensity score for low-gradient status (C-statistic: 0.71), and 37 low-gradient were matched to 41 high-gradient patients. No statistically significance was observed in late survival between propensity matched low and high-gradient patients (83% vs 95% at 7 years, p=0.86). Conclusions: Low-gradient AS was an independent predictor of increased hospital mortality, but did not predict late mortality in operative survivors. Surgical risk was very high in low-gradient patients with advanced NYHA class. However, AVR could be performed safely if low-gradient AS patients were in NYHA class II, and good long-term survival was seen in operative survivors.