Aortic valve replacement (AVR) in the small aortic root has been reported to be associated with obstruction of left ventricular output. This study was designed to investigate the determinants of long-term survival after the implantation of small size prostheses. From September 1961 to December 1993, 2,977 patients underwent isolated aortic valve replacement at our institution. Of these patients, 447 who were older than 18 years received small size (21 mm or less) prostheses. Long-term survival was investigated in the 404 patients who survived operation (more than 30 days) with 92% follow-up completeness (mean +/- deviation 7.1 +/- 6.4; maximum, 31 years). The age was younger than 50 years in 62 patients, 50 to 59 years in 60, 60 to 69 years in 99, 70 to 79 years in 138, and 80 to 94 years in 45; 67% were men. Thirty patients (7%) had previous AVR. prosthesis usage included early Starr-Edwards models in 130 (32%), current Starr-Edwards (model 1260 since 1969) in 50 (12%), Carpentier-Edwards (porcine) in 113 (28%), and other prostheses in 111 patients (27%). One hundred sixteen patients (26%) had concomitant coronary artery bypass grafting (CABG). Eleven variables (age divided as above, sex, preoperative functional class, body surface area [BSA], small BSA [less than 1.6, 1.7, 1.8, or 1,9 m(2)], period of operation, previous AVR, type of prosthesis, size of prosthesis, concomitant CABG, and re-replacement) were investigated with regard to the long-term survival by the Kaplan-Meier method, and age, concomitant CABG, and type of prosthesis were significant. Multivariable analyses (Cox proportional hazard regression) were performed for the whole group as well as subsets of patients. The multivariable analyses reveal that concomitant CABG and age are independent variables to determine the long-term survival. In the subgroup of patients without concomitant CABG, age was the only independent variable found to determine long-term survival and in the subgroup of the patients with concomitant CABG, BSA less than 1.7 m(2) is the only independent variable. We conclude that patients with small aortic root and small BSA may have satisfactory long-term results after isolated AVR and that old age and concomitant CABG are the risk factors for long-term survival in those patients. However, mismatch between body size and prosthesis size is a negative determinant for long-term survival in the subgroup of patients who receive small size of prostheses with concomitant CABG.
