['After aortic valve replacement, the effects of a small functional prosthesis on the extent and pattern of regression of left ventricular hypertrophy and on clinical outcomes may be less significant in older patients with low cardiac output requirements. The objective of this study was therefore to determine whether patient-prosthesis mismatch affects left ventricular mass regression in the elderly.', 'The population studied was made up of 88 patients over 65 years of age with pure aortic stenosis who underwent mechanical aortic valve replacement. The effective orifice area index was calculated for each patient on the basis of the projected prosthesis in vivo effective orifice area. It was considered a continuous variable and influence of its entire range of values on the extent of left ventricular mass regression was analyzed in a multivariate prediction model.', 'Even though, in the group with prosthesis-patient mismatch there was a trend for lower postoperative left ventricular mass index (115+/-24 g/m(2) vs 102+/-27 g/m(2), p=0.24) and postoperative peak trans-prosthetic gradients (32+/-9.8 mmHg vs 28.9+/-7.79 mmHg, p=0.35) these differences were not statistically significant. The prevalence of residual left ventricular hypertrophy at follow-up was 50% in the group with patient-prosthesis mismatch and 50% in the group without patient-prosthesis mismatch (p=0.83). In multivariate analysis the only factors associated with indexed left ventricular mass were the follow-up time (p=0.015, r(2)=0.22) and preoperative indexed left ventricular mass (p=0.0012, r(2)=0.11).'] Does indexed effective orifice area after mechanical aortic valve replacement affect left ventricular mass regression in elderly?