Ten-year results with the St. Jude Medical prosthesis

The Edwards MIRAtm Heart Valve Prosthesis:. A 2-Year Study

BACKGROUND

The Edwards MIRA mechanical heart valve is designed to optimize hemodynamics, reduce thrombogenicity, and avoid mechanical failure with a special hinge mechanism. The purpose of the study was to investigate the clinical performance and postoperative hemodynamic results of the first European patients receiving Edwards MIRA mechanical heart valves.

METHODS

From March 1998 to March 1999 a total of 54 Edwards MIRA valves model numbers 3600 (aortic, n = 44) and 9600 (mitral, n = 10) were implanted in 52 (36 male, 16 female; mean age 61 +/- 10.1 years) consecutive patients undergoing mechanical valve replacement in a prospective study. Follow-up of the patients including physical examination, ECG, blood tests, and Doppler were performed prior to discharge, at 6 months, at 1 year, and at least 2 years postoperatively.

RESULTS

Through October 2001 a total of 172 follow-up examinations were completed (51 patients at discharge, 46 patients at 6 months, 43 patients at 12 months, 32 patients at 2 years or beyond). All patients were in NYHA class I and II at the 6-month and 2+-year follow-up. All the patients stated an improved quality of life. Hospital mortality was 1.9%. There were no complications related to anticoagulation. Mean international normalized ratio at 6 months was 3.2 (range 1.9 to 4.3); lactate dehydrogenase was slightly increased with 264 +/- 103 U/L on average (normal value 80 to 240 U/L). No signs of valvular dysfunction or paravalvular leakage were observed. Mean pressure gradients were related to valve diameter: after mitral valve replacement (size 27, 29, 31 mm: 4.8, 3.2, 2.1 mmHg); after aortic valve replacement (size 19, 21, 23, 25 mm: 12.1, 13.1, 9.3, 8.2 mmHg).

CONCLUSIONS

These preliminary data suggest good hemodynamic function and a low rate of valve-related complications of the Edwards-MIRA mechanical prosthesis.

Fifteen-Year Experience with Shanghai Disc Valve Prosthesis

Between 1983 and 1998, 168 Shanghai prosthetic heart valves were implanted in 122 patients (57 males, 65 females) aged 14 to 57 years (mean, 34 years). There were 69 mitral, 7 aortic, and 46 double valve replacements. Early mortality in each group was 8.7%, 14.3%, and 6.5%, respectively. Mean follow-up was 7.9 years (87.5% complete). There were 7 late deaths (5.7%); 2 in the mitral group, 5 in the double valve group. Five late deaths were considered valve-related. The 5-year actuarial survival rates were 96.8% for mitral, 100% for aortic, and 88% for double valve replacement. Preoperatively, 77.9% of patients were in New York Heart Association functional class III or IV, whereas postoperatively, 90.2% were in class I or II. No structural failure was observed. There were 3 cases of systemic and cerebral embolism, and 2 cases of valve thrombosis in patients who had ceased taking anticoagulants. Hemorrhage was the most frequent complication; 1 of 6 events was fatal. The very affordable Shanghai valve provided good hemodynamic performance with low thrombogenicity in patients receiving anticoagulants.

Hemodynamic performance of four mechanical bileaflet prosthetic valves in the mitral position: an echocardiographic study

OBJECTIVES

The CarboMedics, Duromedics, Sorin Bicarbon and the St. Jude Medical valves are bileaflet mechanical prostheses of modern but different design. Choosing a valve with the best hemodynamic profile is of clinical importance in patients with small ventricles and a small mitral annulus.

METHODS

The hemodynamic performance of these valves in the mitral position was compared in 76 asymptomatic, ambulatory patients with normally functioning prosthesis and left ventricle, using Doppler echocardiography. Of the 76 patients studied, 22 had the CarboMedics, 16 had the Duromedics, 17 had the Sorin Bicarbon and 21 had the St. Jude prosthesis. The patients ages ranged from 18 to 81 years. There were 44 women and 32 men. The time from implantation to echocardiographic study ranged from 1 to 55 months.

RESULTS

The echocardiographic study was performed earlier after surgery in the Sorin Bicarbon group. There was no significant difference in women/man ratio, incidence of atrial fibrillation, left ventricular or left atrial diameters between the four groups. The mean prosthesis size was significantly smaller for Sorin Bicarbon and Duromedics valves compared to the CarboMedics and the St. Jude valves (mean+/-SD, 27.2+/-1.3, 27.1+/-1.1 and 30.0+/-1.9 and 30.0+/-2.7 mm, respectively, P<0.001). Despite its smaller size the Sorin Bicarbon valve had significantly larger effective valve area by Doppler compared to the CarboMedics valve (290+/-40 vs 250+/-60 mm2, respectively, P=0.014). The ratio of effective valve area to prosthesis size was significantly larger for the Sorin Bicarbon valve when compared with any other type of prosthesis.

CONCLUSIONS

(1) The Sorin Bicarbon bileaflet valve offered the best hemodynamic results that may be explained by the valve's large leaflet opening angle and small thickness of the leaflets. (2) Since the Sorin Bicarbon is the newest bileaflet valve, durability of this valve remains uncertain.

Mitral valve replacement with the St. Jude Medical prosthesis: a 15-year follow-up

BACKGROUND

A retrospective study was conducted to analyze the results of St. Jude Medical mitral valve replacement.

METHODS

From January 1979 to December 1989, 870 patients (54% women, 46% men; mean age, 55.8 +/- 6.2 years) underwent mitral valve replacement with the St. Jude Medical prosthesis. Of these operations 616 were isolated mitral valve replacements and 254 were double valve replacements. Coronary artery bypass grafting was performed concomitantly in 55 patients (6.3%).

RESULTS

Overall, early mortality was 5.05%, with 4.2% for the isolated mitral valve procedure and 7.08% for the double valve replacement. Follow-up at 15 years was complete in 859 patients (98.74%). Mean follow-up time was 93.5 months, for a total of 6,436 years. Actuarial survival at 15 years was 59.5% +/- 5%, 60.5% +/- 6%, and 56.9% +/- 9%, for the entire group, the isolated mitral valve and double valve procedures, respectively. Multivariate analysis identified age, sex, hospital stay, and preoperative mitral regurgitation as independent prognosis factors for overall mortality. Of 606 patients alive at the latest follow-up, the New York Heart Association class improved significantly (from 67% class III/IV before the operation to 88% class I/II after the operation). All patients received warfarin to maintain an international normalized ratio between 3.5 and 4. The linearized rates (% per patient-year) of thrombosis, thromboembolism, and major hemorrhage were, respectively, 0.21, 0.75, and 0.94 for the entire group; 0.18, 0.67, and 0.88 for the isolated mitral valve operation; and 0.15, 0.92, and 1.08 for the double valve replacement. For the entire group the freedom from thrombosis and thromboembolism at 15 years was 98.1% +/- 1% and 88% +/- 4%, respectively. No case of structural dysfunction occurred. The freedom from paravalvular leak and endocarditis at 15 years was 95.3% +/- 2% and 97.3% +/- 2.4%, respectively. The probability of remaining free from reoperation at 15 years was therefore 95.6% +/- 2.5%.

CONCLUSIONS

These results confirm that the St. Jude Medical valve is a reliable prosthesis with very low thrombosis and thromboembolism rates, allowing the use of a low dose of anticoagulation with an international normalized ratio of about 3.

Controversies in Antithrombotic Therapy in Cardiovascular Diseases

Antithrombotic treatment became an important point in human medical treatment. Dicoumarols, heparin, aspi rin, and more recently, direct antithrombins and platelet glyco protein IIb/IIIa receptor blockers are the most frequent medi cations used as antithrombotics. The role of these drugs in the treatment of cardiovascular diseases remains controversial. Low-dose aspirin (80-100 mg/day) should be used for second ary prevention in patients with a history of coronary disease. Primary prevention in patients with no risk factors is not rec ommended. Studies using oral anticoagulant therapy indicated that long-term therapy achieves substantial benefit in arterial complications in patient survivors of myocardial infarction. Combined therapy of aspirin and a higher dose of oral antico agulant than that used in the CARS trial seem necessary after myocardial infarction, and further studies should be under taken. In the treatment of unstable angina, the combined use of aspirin and unfractioned heparin (UFH) is widely accepted. Low molecular weight heparin (LMWH) was also proposed for the treatment of these patients, but the beneficial effect of LMWH over UFH is a matter of discussion, and more prospec tive studies with different LMWHs should be undertaken be fore reaching a definitive answer. The use of hirudin needs additional studies because its superiority over heparin is un- proved. The initial clinical experience with blockers/inhibitors of platelet glycoprotein IIb/IIIa receptors has been promising, although some increase of bleeding was reported. According to published trials on the use of antiplatelet drugs and antithrom botic therapy in the prevention of acute closure after PTCA or after stent implantation, antithrombotic therapy decreased the incidence of abrupt closure or reocclusion at 30 days postan gioplasty, but neither antiplatelet agents nor other pharmaco logical agents have been shown to reduce significantly the rate of restenosis. Finally, oral anticoagulant in a target INR of 2.0 to 3.0 together with aspirin 100 mg/day provide good protec tion from thromboembolism and diminish the rate of minor bleeding complications in patients with cardiac valve replace ment.

St. Jude Medical valve prosthesis: an analysis of long-term outcome and prognostic factors

Between 1979 and 1984, 321 patients received 354 St. Jude Medical prostheses (194 aortic, 94 mitral, 1 tricuspid, and 32 multiple valve replacements). Follow-up was 96% complete (2967 patient-years; mean 9.5 years per patient). Actuarial event-free rates at 10 years and linearized rates (in parentheses) of late complications were as follows: embolism, 85.0% +/- 2.3% (2.3% per patient-year); anticoagulant-related hemorrhage, 74.8% +/- 2.7% (3.3% per patient-year); cerebrovascular accident, 81.8% +/- 2.5% (2.6% per patient-year); prosthesis thrombosis, 98.5% +/- 0.7% (0.1% per patient-year); endocarditis, 97.2% +/- 1.1% (0.4% per patient-year); prosthesis dysfunction, 97.1% +/- 1.0% (0.4% per patient-year); hemolytic anemia, 98.5% +/- 0.7% (0.1% per patient-year); reoperation, 97.4% +/- 1.0% (0.4% per patient-year); overall mortality, 63.3% +/- 2.7% (4.2% per patient-year); and valve-related death (including sudden death), 84.7% +/- 2.2% (1.4% per patient-year). Independent preoperative risk factors were as follows: (1) for embolism, cardiac failure as indication for operation and history of prior systemic embolism; (2) for cerebrovascular accidents, the same two factors and age; (3) for endocarditis, diabetes, chronic alcoholism, and aortic valve replacement; (4) for overall mortality, age, ejection fraction (or cardiac index or cardiothoracic index), chronic alcoholism, and history of systemic embolism; and (5) for valve-related death, chronic alcoholism, degenerative cause of valve disease, and prosthetic diameter 23 mm or smaller. Ninety percent of survivors were in New York Heart Association functional class I or II at the end of follow-up. In conclusion, this study confirms the excellent durability of the St. Jude Medical valve and the remarkable functional benefit for the majority of the patients. However, prosthesis-related complications are still common, particularly for small-diameter prostheses. Outcome is strongly related to the patient's preoperative cardiac condition and to the adequacy of anticoagulation control.

Six-Year Experience with CarboMedics Prosthetic Heart Valves

Between July 1989 and July 1995, 89 CarboMedics prosthetic heart valves were implanted in 70 patients (38 males, 32 females) ranging in age from 13 to 54 years (mean 33 years). Forty-one of these patients underwent mitral valve replacement, 10 had aortic valve replacement, and 19 had double aortic and mitral valve replacement. Early mortality was 4.9%, 0%, and 15.8% respectively in these groups. Mean follow-up time was 3.4 years and was 95.4% complete (3 lost). There were 5 late deaths (7.7%); 1 in the mitral group, 1 in the aortic group, and 3 who had double valve replacements. Three of these late deaths were considered valve-related. The 5-year actuarial survival rates, hospital mortality excluded, were 97% for mitral, 88% for aortic, and 88% for double valve replacement. Preoperatively, 80% of the patients were in New York Heart Association functional class III or IV, whereas postoperatively, 99.5% of the patients were in class I or II. No structural failures were observed. There was 1 case of systemic embolism and 1 case of valve thrombosis, neither of these patients were taking anticoagulants. Hemorrhage was the most frequent complication; 1 of 4 events was fatal. A less intensive warfarin regimen and improvement in hepatic function may reduce hemorrhagic risk while maintaining thromboembolic protection. On the basis of this experience, the CarboMedics prosthetic heart valve appears to be an excellent mechanical prosthesis for cardiac valve replacement, in terms of hemodynamic performance and low thrombogenicity, in patients receiving anticoagulants.

Effects of dipyridamole in combination with anticoagulant therapy on survival and thromboembolic events in patients with prosthetic heart valves. A meta-analysis of the randomized trials

The addition of dipyridamole, an antiplatelet agent, to conventional anticoagulant regimens has been shown to reduce the frequency of embolization after valve replacement with a mechanical prosthesis. The purpose of this meta-analysis was to reevaluate the benefit of dipyridamole by analyzing the evidence from all randomized clinical trials. Summary data were extracted from the application to the Food and Drug Administration. Six randomized clinical trials had accrued 1141 patients, of whom 582 received anticoagulant therapy alone and 559 received additional dipyridamole at dosages ranging from 225 to 400 mg per day. The events analyzed were all thromboembolic events, both fatal and nonfatal; hemorrhagic events, both fatal and nonfatal; and the overall mortality. The combination of dipyridamole with anticoagulants reduced the risk of thromboembolic events (fatal or nonfatal) by 56% when compared with the use of anticoagulants alone (p = 0.0001). The risk reduction was seen in fatal and in nonfatal thromboembolic events (risk reduction for fatal events, 64%, p = 0.008; for nonfatal events, 50%, p = 0.005). The overall mortality rate was also significantly reduced by 40% in the group receiving dipyridamole (p = 0.013). There was no difference between treatment groups with respect to hemorrhagic events (risk reduction, -1%, p = 0.94). This meta-analysis supports the use of dipyridamole in this setting and warrants further trials with new antiplatelet agents.

Optimal oral anticoagulant therapy in patients with mechanical heart valves

BACKGROUND

The optimal intensity of oral anticoagulant therapy for patients with mechanical heart valves (i.e., the level at which thromboembolic complications are effectively prevented without excessive bleeding) is not known. We attempted to determine the optimal intensity by calculating the incidence of both complications at different levels of anticoagulation.

METHODS

Data were collected on all patients with mechanical heart valves who have been seen at four regional Dutch anticoagulation clinics since 1985. The primary outcome events were episodes of thromboembolism or major bleeding. The intensity-specific incidence of each type of event was calculated as the number of events that occurred at a certain intensity of anticoagulation (expressed in terms of the international normalized ratio [INR]) divided by the number of patient-years during which the INR was at this level in the total patient population.

RESULTS

A total of 1608 patients were followed during 6475 patient-years. Cerebral embolism occurred in 43 patients (0.68 per 100 patient-years) and peripheral embolism in 2 (0.03 per 100 patient-years). Intracranial and spinal bleeding occurred in 36 patients (0.57 per 100 patient-years) and major extracranial bleeding in 128 (2.1 per 100 patient-years). The optimal intensity of anticoagulation, at which the incidence of both complications was lowest, was achieved when the INR was between 2.5 and 4.9.

CONCLUSIONS

The intensity of anticoagulant therapy for patients with prosthetic heart valves is optimal when the INR is between 2.5 and 4.9. To achieve this level of anticoagulation, a target INR of 3.0 to 4.0 is recommended.

Modified conduit preparation creates a pseudosinus in an aortic valve-sparing procedure for aneurysm of the ascending aorta

Mechanical valved conduit replacement of the aortic root is a durable and appropriate procedure for many diseases of the ascending aorta, but may sacrifice an anatomically salvageable aortic valve. For young active patients and for patients with "systemic" arterial disease (atherosclerosis, Marfan's syndrome) who may require future operations, life-long anticoagulation with its attendant thromboembolic versus hemorrhagic risks is not ideal. Several techniques have been suggested as aortic valve-sparing options. Recently, a procedure was described that combines the freehand homograft techniques with the standard Bentall techniques (David procedure). This innovative technique replaces the ascending aorta with a Dacron cylinder, spares the aortic valve, and restores competence and thus offers an excellent alternative. The durability of this procedure that places the aortic valve inside a cylindrical conduit without sinuses of Valsalva is unknown. In selected patients, we have used this technique to spare the aortic valve. On the basis of experimental data and preliminary computer modeling, with the hope of improving the durability, we have modified the conduit to create a "pseudosinus" in our most recent nine patients. We have done the David procedure in 10 patients. The pseudosinus modification was done in the most recent nine patients. Patients' ages ranged from 37 to 71 years (mean 49.9 years). There were five female and five male patients. Five patients had Marfan's syndrome and five patients had annuloaortic ectasia. There has been no mortality and all patients have had both early and late follow-up echocardiography. Five patients have zero to trace aortic insufficiency, four patients have trace to mild aortic insufficiency, and one patient has mild or "1+" aortic insufficiency. Aortic insufficiency has not progressed in any patient during the 18 months of follow-up. The patient with 1+ aortic insufficiency has no activity limits, good ventricular function, and no evidence of congestive symptoms. One patient who had extensive thoracoabdominal aneurysmal disease has undergone subsequent replacement of the descending aorta to the level of the renal arteries and has done well. Aortic valve-sparing replacement of the aortic root is an excellent procedure for any patient with an ascending aortic aneurysm and an anatomically salvageable valve. We believe that by modifying the proximal conduit and creating a "pseudosinus" into which the leaflets can retract without contact of the cylindrical conduit we may increase the longevity of the native aortic valve in this procedure.