Small "functional" size after mechanical aortic valve replacement: no risk in young to middle-age patients

Background. The impact of a valve prosthesis-patient size mismatch is still controversial. In most studies, the inclusion of a large proportion of poorly active old patients with low cardiac output requirements may be misleading, due to the close correlation between trans-prosthetic gradients and cardiac output. The aim of this study was to assess the impact of small "functional" prosthesis sizes in active young to middle-age patients. Methods. Eighty-three active patients with a mean age of 46 ± 8 years and a high health survey questionnaire score were followed for 80 ± 34 months after isolated aortic valve replacement with a mechanical prosthesis. Results. Patients with an indexed, Doppler derived, effective orifice area index less than 0.85 cm 2/m2 (0.77 ± 0.1 cm2/m2) showed higher early trans-prosthetic gradients (peak, 34 ± 11 vs 26 ± 8 mm Hg; P = 0.001) than patients with a larger effective orifice area index. However, significant regression of the left ventricular mass index and improvement of the left ventricular ejection fraction were observed in both groups at follow-up (119.8 ± 26 vs 165.2 ± 38 g/m2 and 128.5 ± 25 vs 181.8 ± 5 0 g/m2; P < 0.001; 58 ± 6 vs 52 ± 11% and 58 ± 7 vs 53 ± 10%; P < 0.001), with no differences between groups (P = 0.4 and P = 0.7, respectively). At multiple linear regression, the final left ventricular mass index was positively related to the preoperative left ventricular mass index (P = 0.004) and was unaffected by the effective orifice area index (P = 0.4). Symptomatic improvement (New York Heart Association class 1.3 ± 0.4 vs 2.4 ± 0.8 and 1.2 ± 0.4 vs 2.2 ± 0.8; P < 0.001) and freedom from late cardiac death (93 ± 3% and 95 ± 6%) were comparable between groups (P = 0.6 and P = 0.7, respectively). Conclusions. Our findings indicate that small "functional" prosthesis sizes with modern mechanical valves may not adversely affect outcomes of aortic valve replacement in young patients with high cardiac output requirements. © 2005 by The Society of Thoracic Surgeons.