Background-The first generation of pericardial valves had a high rate of premature deterioration. The aim of this study was to compare the outcome after aortic valve replacement with second generation pericardial prostheses (Pericarbon and Carpentier-Edwards). Methods and Results-Between 1987 and 1994, 162 patients underwent aortic valve replacement with either a Pericarbon (nϭ81, 69Ϯ11 years) or a Carpentier-Edwards (nϭ81, 70Ϯ11 years) pericardial prosthesis. Mean follow-up was 4.4Ϯ2.7 years for Pericarbon and 4.8Ϯ2.4 years for Carpentier-Edwards valves (Pϭ0.27), giving a total follow-up of 745 patient-years. Thirty-day mortality and 5-year actuarial survival were, respectively, 6.2% and 63.2Ϯ5.7% in the Pericarbon group and 6.2% and 63.5Ϯ5.6% in the Carpentier-Edwards group. At 8 years, freedom from (and linearized rates per patient-year) thromboembolism, structural failure, and all valve-related events were, respectively, 91.8Ϯ3.6% (1.4%), 76.9Ϯ8.7% (2.5%), and 58.4Ϯ9.3% (5.6%) in the Pericarbon group and 94.4Ϯ2.7% (1%), 100% (0%, PϽ0.01), and 88.8Ϯ3.7% (2%, PϽ0.05) in the Carpentier-Edwards group. There were 9 (11.1%) Pericarbon structural failures related predominantly to severe calcification and stenosis. The actual reoperation rate was 7.4% (1.6% per patient-year) in the Pericarbon group for fibrocalcific degeneration (nϭ3), periprosthetic leak (nϭ1), endocarditis (nϭ1), and aortic dissection (nϭ1). There was neither structural valve failure nor valve reoperation in the Carpentier-Edwards group. Echocardiographic review of 70 patients from 85 survivors (82.3%) found 4 additional Pericarbon valves with signs of early structural failure but no Carpentier-Edwards valve with such changes. Conclusions-Eight years after aortic valve replacement, Pericarbon pericardial prostheses compared unfavorably with Carpentier-Edwards pericardial prostheses, with a high incidence of structural valve failure and reoperation. (Circulation. 1999;100[suppl II]:II-11-II-16.) Key Words: valves Ⅲ surgery Ⅲ prosthesis Ⅲ complications F irst generation pericardial valves have been abandoned because of poor clinical results and a high rate of deterioration characterized by leaflet tears and valve incompetence. 1-6 Second generation pericardial valves (Carpentier-Edwards, Pericarbon) have now been available for over 10 years but little is known about their mid-term comparative results. The main advantages of pericardial valves are their low thrombogenicity, permitting the avoidance of oral anticoagulation, and their alleged improved hemodynamic performance compared with porcine bioprostheses. 7-11 The aim of this retrospective study was to compare mid-term outcome in patients with 2 different types of pericardial valves (Carpentier-Edwards, Pericarbon) implanted in the aortic position between 1987 and 1994 in our institution. Methods Patients We retrospectively reviewed the medical records of all patients who underwent isolated aortic valve replacement with second generation pericardial valves in our institution between July 1987 (fir...