Seven and one-half years' experience with the Medtronic-Hall valve

Morbidity in Valvular Heart Replacement: Risk Factors of Systemic Emboli and Thrombotic Obstruction

A study on a cohort of 839 patients with valvular heart replacement between June 1977 and May 1985 showed that the linearized rates of systemic emboli and thrombotic obstruction were 1.4/100 pts/year for Aortic Valve Replacement (AVR), 2.2/100 pts./year for Mitral Valve Replacement, and 3.00/100 pts./year for Double Valve Replacement (DVR).

The 5-year free-from-thromboembolism (TE) survival was 95% for AVR and 92% for MVR. The hazard function (the instantaneous risk) for TE peaked in the first six months after operation for AVR and MVR.

Another analysis using the Cox regression model to estimate risk factors of systemic emboli and thrombotic obstruction pinpointed two factors in the AVR group: presence of aortic regurgitation (AR) and age at operation. In the MVR group the sole predictor covariate was sex of the patients, with a higher hazard for females. Our results underline the importance of patient-related factors besides the type of prosthesis as predictors of morbidity from TE.

Up to eight years' follow-up of 997 patients receiving the CarboMedics prosthetic heart valve

BACKGROUND

The aim of the study was to evaluate our clinical experience with the CarboMedics Heart Valve Prosthesis.

METHODS

Nine hundred ninety-seven consecutive patients underwent mechanical valve implantation (aortic, 771; mitral, 169; double, 52; tricuspid, 5) with this prosthesis from September 1987 through December 1993. The mean age was 62.3+/-13.7 years (range, 0.4 to 84 years); 56.6% (564 patients) were men. Four hundred seventy patients (47.1%) underwent additional surgical procedures. Mean follow-up was 4.1+/-2.2 years (range, 0 to 8.3 years) with a total of 4,040 patient-years.

RESULTS

Early mortality was 5.0% (50/997; aortic, 4.4%; mitral, 6.4%; double, 9.6%). Late mortality was 14.8% (140/947). Survival at 7 years was 75.9%+/-1.8% (aortic, 78.4%+/-2%; mitral, 70.7%+/-4.5%; double, 60.8%+/-7.4%). When matched for sex and age and compared with the normal Norwegian population, our patients had an increased standard mortality ratio in both men (1.9+/-0.4) and women (2.9+/-0.6). The linearized rate of major thromboembolism was 0.9% per patient-year, valve thrombosis 0.2% per patient-year, major bleeding event 0.6% per patient-year, paravalvular leak needing reoperation 0.5% per patient-year, prosthetic valve endocarditis 0.1% per patient-year, and of all reoperations 0.6% per patient-year.

CONCLUSIONS

The CarboMedics Heart Valve Prosthesis has incidences of morbid events comparable with or better than reported for other mechanical valves.

Mid-term surgical results after valve replacement with the CarboMedics valve prosthesis

We present herein a review of 95 patients who underwent valve replacement with the CarboMedics (CM) valve prosthesis between April 1990 and December 1992. The operative mortality for the entire group was 4.2%: 0% following aortic valve replacement (AVR), 2.7% following double valve replacement (DVR). All patients were prescribed warfarin and bucolome for anticoagulation, and were followed up for a mean period of 29.9 months. Late mortality was 8.4%; 3.1% following AVR, 10.8% following MVR, and 12.5% following DVR. There were no cases of mechanical prosthetic valve failure, significant hemolysis, infective prosthetic valve endocarditis, or bleeding complications. After 44 months of follow-up, the actuarial freedom from complications was calculated as: thromboembolism, 97.8 +/- 1.6%; valve thrombosis, 97.8 +/- 1.1%; paravalvular leak, 96.7 +/- 1.9%; and reoperation, 98.9 +/- 1.1%. The overall survival rate was 84.3 +/- 6.3% and all survivors showed a significant improvement in NYHA functional class, from 81% in classes III and IV preoperatively to 99% in classes I and II postoperatively. The CM valve exhibited no significant differences in hemolytic parameters or hemodynamic performance after isolated AVR or MVR compared with the similar type of St. Jude Medical bileaflet valve. The evidence provided by the present study therefore suggests that the CM valve prosthesis can achieve excellent mid-term clinical results and hemodynamic performance with a low incidence of thromboembolism and valve thrombosis.

Five-year experience with the Medtronic Hall prosthesis in isolated aortic valve replacement

We reviewed clinical data in 216 patients who underwent isolated aortic valve replacement with the Medtronic Hall prosthesis. Between January 1983 and December 1990, a total of 216 prosthetic valves were implanted in 180 males and 36 females. Preoperatively, 45.5% of patients were in New York Heart Association (NYHA) Class III to IV. Cumulative follow-up was 682 years, and 3.2% of patients were lost to follow-up. The actuarial 5-year survival rate was 90% for the whole group. All the patients were anticoagulated with aceno-coumarol (Sintrom). There were no cases of structural dysfunction and one patient presented with valve thrombosis. The Medtronic Hall valve has a low rate of thromboembolic events without structural failure. It is an excellent device for aortic valve replacement.

Mitral valve replacement: randomized trial of St. Jude and Medtronic-Hall prostheses

To better define the merits of the bileaflet and tilting-disc valves, we prospectively randomized 102 patients (mean age, 57 years; range, 11 to 85 years) to receive either the St. Jude (n = 55) or the Medtronic-Hall (n = 47) mitral valve prosthesis between September 1986 and May 1991. The two groups were not different with respect to preoperative New York Heart Association class, incidence of mitral stenosis and insufficiency, angina score, extent of coronary artery disease, ventricular function, completeness of revascularization, or cross-clamp or bypass time. The hospital mortality (14.5% versus 10.6%, St. Jude versus Medtronic-Hall) and late mortality (7.3% versus 2.1%) were not significantly different. Follow-up was complete in 84 of 89 hospital survivors (94%) with a mean of 26 months (range, 1 to 60 months). The linearized rates of valve-related events and the 3-year actuarial survival demonstrated no significant differences between both cohorts. Comparison of the clinical outcome and echocardiographic parameters obtained at the time of follow-up demonstrated no significant differences between the two prostheses. These data indicate that the Medtronic-Hall and St. Jude mitral prostheses are similar with respect to their rates of valve-related complications and hemodynamic profiles. This study suggests that there is no difference between the St. Jude and Medtronic-Hall prostheses with regard to early clinical performance or hemodynamic results and therefore does not support the preferential selection of either prosthesis.

Clinical experience with the Medtronic-Hall valve prosthesis

Medtronic-Hall valves were implanted during 204 procedures performed between 1982 and 1988. Mean population age was 54.4 years; 96% of patients were in New York Heart Association functional class III or greater. Emergency operations constituted 16% of the procedures. Rheumatic heart disease was the single most common indication for valve replacement. In 18% of patients, operation was performed to replace a previous prosthetic valve. The mean follow-up was 3.2 years. Overall operative mortality was 10.3%, the highest mortality being for double-valve replacements (24%). Valve-related mortality, by position, was 5.3% for aortic valves, 6.0% for mitral valves, and 4.0% for multiple-valve replacements. Actuarial 5-year freedom from events were: survival, 68%; thromboembolism, 90%; prosthetic valve endocarditis, 98%; paravalvular leak, 95%; and reoperation, 92%. Complications with the highest mortality were thromboembolism (36%) and endocarditis (33%). The complication rates in this series are high but the patients were more severely ill than in other reports, and operative survivors experienced a considerable improvement in New York Heart Association functional class.

Thrombotic and bleeding complications of prosthetic heart valves

A review of articles published since 1979 indicates that thrombotic and bleeding complications account for about 50% of valve-related complications in patients with bioprosthetic aortic and mitral valves and for approximately 75% of the complications in patients with mechanical valves. Although compromised by lack of standard definitions and by variability in reporting and follow-up, the data suggest that the linearized rate of both thrombotic and bleeding complications in patients with aortic bioprostheses is approximately half that for aortic mechanical prostheses (2% versus 4%), but is approximately equal for both bioprostheses and mechanical valves in the mitral position (approximately 4%), and for mechanical and bioprosthetic aortic and mitral valves in combination. However, linearized rates for fatal thrombotic and bleeding events are two to four times higher in patients with mechanical prostheses. The adequacy of warfarin anticoagulation is the most important factor affecting thrombotic and bleeding complications in patients with mechanical valves and over shadows the dubious importance of other phenomena such as atrial fibrillation and left atrial thrombus. Short-term warfarin anticoagulation or the use of long-term platelet inhibitors, or both, do not appear to reduce the incidence of thrombotic complications in patients with aortic bioprostheses but increase bleeding. For mitral bioprostheses, the postoperative use of warfarin for three months or aspirin indefinitely is as effective in preventing thromboembolism as long-term warfarin. Acute prosthetic valve endocarditis is associated with a 13 to 40% incidence of thrombotic complications. Likewise, the recurrence rate of cerebral emboli is high (20-30%) in patients with prosthetic valves who are not anticoagulated. Bioprostheses are strongly preferred for women who wish to bear children; fetal wastage occurs in 25 to 30% of pregnant women with mechanical heart valves who receive either warfarin or heparin, or a combination of the two. Heparin, however, greatly increases the risk of maternal bleeding. In children, the efficacy of platelet inhibitors without warfarin anticoagulation is unproven; nearly all serious strokes occur when warfarin is omitted; and permanent disability from warfarin-related bleeding is rare. All prosthetic cardiac valves initiate coagulation and affect the dynamic equilibrium between activated procoagulants and endogenous anticoagulants. Warfarin is the only available oral exogenous anticoagulant.(ABSTRACT TRUNCATED AT 400 WORDS)