CarboMedics mechanical prosthesis: performance at eight years

The bileaflet St. Jude Medical mechanical prosthesis has been implanted for over 20 years. The purpose of this study was to evaluate the clinical performance of the bileaflet CarboMedics (CM) prosthesis, which was introduced in 1986.

The CM prosthesis was implanted in 1,258 patients (709 males, 549 females; mean age 60.9 +/- 12.3 years) between 1989 and 1997. The prosthesis distribution was aortic valve replacement (AVR) 613; mitral valve replacement (MVR) 447; and multiple replacement (MR) 231. Coronary artery bypass (CAB) was performed in 334 (26.6%) patients; previous procedures had been performed in 346 (27.5%). The age distribution was <60 years (n = 527), 61-70 years (n = 424) and >70 years (n = 307). Risk factors assessed were age or age groups, gender, CAB, previous surgery, rhythm, valve position, status and NYHA functional class. The total follow up was 4,765.0 patient-years (pt-yr), and was 98.4% complete.

The early mortality rate was 5.6% (AVR 4.8%, MVR 3.7%, MR 11.5%). The late mortality rate was 3.7%/pt-yr (n = 174), and valve-related mortality 1.1%/pt-yr (n = 50). The total thromboembolism (TE) rate was 4.1%/pt-yr (n = 195) (p = NS by valve position); the major TE rate was 1.9%/pt-yr and fatal TE rate 0.31%/pt-yr (n = 15). The valve thrombosis rate was 0.31%/pt-yr (n = 15; 11 MVR, four MR). The fatal thrombosis rate was 0.06%/pt-yr (n = 3; two MVR, one MR). The hemorrhage rate was 2.7%/pt-yr (n = 128) and fatal hemorrhage rate 0.4%/pt-yr (n = 20). The reoperation rate was 1.0%/pt-yr (n = 46), fatal 0.1%/pt-yr (n = 5). The actuarial freedom from overall TE at eight years was 77.3 +/- 2.8%; major TE 88.5 +/- 1.6%, and hemorrhage 76.4 +/- 3.2% (all p = NS by valve position). There were no independent predictors of overall TE and TE exclusion of early events. The only predictor for TE major was status (emergency > urgent > elective). The actuarial freedom from valve-related mortality at eight years was 91.4 +/- 1.8% (p = NS by position) (actual freedom 93.0 +/- 1.3%). The actuarial freedom from valve-related reoperation was 91.1 +/- 2.4% (p <0.05; AVR > MVR and MR, MVR > MR) (actual freedom 92.2 +/- 2.7%). Overall survival rate at eight years was 68.2 +/- 2.3% (p <0.05; AVR > MVR and MR, MVR > MR).

The clinical performance of the CarboMedics mechanical prosthesis is satisfactory when implanted in the mitral, aortic and multiple positions.