. After adjustment for several risk factors, moderate prosthesis-patient mismatch was associated with increased midterm mortality in patients with baseline left ventricular ejection fraction<50% (HR: 1.80, p=0.02), but with normal prognosis in those with preserved LV function. Younger age (cut off value=65 years) was not an independent predictor of increased midterm mortality and valve-related complications in patients with moderate prosthesis-patient mismatch.