Low-gradient aortic stenosis: impact of prosthesis-patient mismatch on survival.

AIMS: To assess the prognostic impact of prosthesis-patient mismatch (PPM) in a large consecutive series of patients operated for low-gradient aortic stenosis (AS). METHODS AND
RESULTS: Outcomes after surgery for low-gradient AS were prospectively assessed in 152 consecutive patients from seven institutions. There were 113 men (74%); mean age was 72 years (64-76); valve area, 0.7 cm(2) (0.6-0.8); left ventricular (LV) ejection fraction 0.31 (0.25-0.37) and baseline mean transaortic pressure gradient (MPG), 30 mmHg (25-35) Among 139 patients with available prosthetic valve effective orifice area (EOA), PPM (defined by an indexed EOA < or = 0.85 cm(2)/m(2)) was present in 79 patients (57%) and had no significant impact on post-operative mortality. Independent predictors of overall mortality were LV contractile reserve [hazard ratio (HR) 0.52; 95% confidence interval (CI) 0.35-0.78; P = 0.002], associated coronary artery bypass grafting (HR 1.87; 95% CI 1.24-2.82; P =0.003), baseline MPG (per 1 mmHg decrease to 10 mmHg; HR 1.03; 95% CI 1.01-1.06; P = 0.021), previous cancer (HR 2.13; 95% CI 1.05-4.29; P = 0.037), and logistic EuroSCORE (per 1% increase; HR 1.02; 95% CI 1.01-1.04; P = 0.040). CONCLUSION In this large multicentre series of patients with low-gradient AS, we found that PPM (moderate in most cases) had no influence on post-operative mortality. Therefore, the performance of more complex interventions in order to avoid moderate PPM may not be justified in the setting of low-gradient AS, because their higher risk probably outweighs the expected benefit.