Mechanical versus biological aortic valve implants in the elderly. A comparison of early and mid-term results

OBJECTIVE

Our aim was to compare, in a non randomized study, the surgical outcome in elderly patients with mechanical (Group 1; n=83) and bioprosthetic valve implants (Group 2; n=136).

METHODS

During a three year period, 219 patients >75 years underwent Aortic Valve Replacement. The groups matched according to age, sex, comorbidity, valve pathology and concomitant Coronary Artery Bypass Surgery. Follow-up was a total of 469 patient-years (mean follow-up 2.1 years, maximum 4,4 years).

RESULTS

Operative mortality was zero and the overall early mortality was 2.3 % (within 30 days). Actuarial survival was 87.5 +/- 4.0% and 66.1 +/- 7.7% (NS) at 4 years in Group 1 and Group 2, respectively. Freedom from valve-related death was 88.9 +/- 3.8% in Group 1 and 69.9+/-7.9% (NS) in Group 2 at 4 years.

CONCLUSION

Aortic Valve Replacement in the elderly (>75 years) is a safe procedure even in cases where concomitant coronary artery revascularization is performed. Only a few anticoagulant-related complications were reported and this may indicate that selected groups of elderly patients with significant life expectancy may benefit from mechanical implants.

Mitroflow pericardial bioprosthesis in the aortic position. Low incidence of structural valve deterioration in elderly patients during an 11-year follow-up

Aortic valve replacement with Mitroflow pericardial bioprosthesis, with or without concomitant bypass surgery was performed on 403 consecutive patients between March 1984 and December 1994. The mean age was 74 (range 10-92) years, with male/female ratio 183/220. Early mortality was 3.5% (14/403) and late mortality 25% (99/389). Actuarial survival was 35.4%+/-9.4% at 10 years and freedom from valve-related mortality 86.2%+/-9.6% at 8 years (total follow-up 1 270 years). The thromboembolic rate was 6.5% (fatal 0.7%)/patient year. The incidence of prosthetic valve endocarditis was 0.6% (fatal 0.3%)/patient year. Structural valve deterioration was found in 0.8%/patient year (no fatality). Actuarial freedom from all reoperations at 8 years was 92.4+/-8%. The Mitroflow pericardial heart valve is proposed as a good choice for aortic valve replacement in elderly patients, in view of the low rates of reoperation, anticoagulant treatment and valve-related thromboembolism.

Aortic valve replacement with and without concomitant coronary artery bypass surgery in the elderly: risk factors related to long-term survival

AIM

Preoperative coronary angiography often reveals significant coronary artery lesions in elderly people (>75 years of age) referred to hospital for aortic valve replacement (AVR). However, the possible benefit of concomitant coronary artery bypass grafting (CABG) in elderly is still under debate. In an effort to contribute to this discussion, we evaluated our data on elderly patients after aortic valve replacement.

METHODS

Between January 1990 and December 1993, 219 patients, aged 75 years and older, underwent AVR with or without concomitant CABG at our Department. There were 121 patients in the AVR group and 98 patients in the AVR+CABG group. There was no significant difference between the two groups in their age, sex valve type, valve size, and presence of diabetes. Five variables (concomitant CABG, age, sex, and type and size of prosthesis) were investigated with regard to long-term survival assessed by the Kaplan-Meier analysis. Group comparisons of survival were made with the Cox-Mantel log-rank test.

RESULTS

Early mortality (<30 days) was 0.8% in the AVR group and 4.1% in the AVR+CABG group. Overall actuarial survival was 77.7+/-4.4% at 52 months. There was significantly longer survival in patients with mechanical valve implant in the AVR group. None of the other 5 investigated variables had a significant influence on the long-term survival.

CONCLUSION

Our results suggest that AVR done in elderly is a treatment with excellent surgical results. We could not identify concomitant CABG as a predictor of poor long-term surgical outcome.

Open-heart surgery in a growing geriatric population: patient selection and risk factors to be considered

AIMS

This report describes our experience with cardiac surgery in elderly patients and aims to ascertain predictors of poor outcome.

PATIENTS

Five hundred and ninety-eight (598) consecutive patients aged 75 years and older underwent cardiac surgery at the Department of Cardiothoracic Surgery, University Hospital of Lund, Sweden, between January 1980 and December 1993. There were 324 men (54%) and 274 women (46%); their age varied between 75 and 91 years (mean age +/- SD, 77.8 +/- 2.6 years). One hundred and twenty-nine patients underwent aortic, mitral or combined valve replacement, 273 patients underwent exclusive coronary revascularization (CABG) alone and 109 underwent a surgical procedure which included valve replacement and concomitant CABG. The remainder (87 patients) underwent other, more complex surgical procedures.

RESULTS

The 30-day or in-hospital mortality rate was 5.5% (0.8% for valve replacement, 5.1% for CABG, 5.5% for valve replacement with concomitant CABG, and 12.6% for other procedures). Concomitant severe diseases occurred in 34.9% of the patients. All surviving patients were evaluated during June 1994. None of the patients was lost to follow-up. The 566 long-term survivors have been followed for an average of 23.0 months (median 21; range 1-53 months). Late mortality was 12.0% in the 566 hospital survivors. Only 17 patients experienced late complications (after hospital discharge), as an adverse effect linked to heart surgery.

Aortic valve replacement in patients older than 85 years: outcomes and the effect on their quality of life

PURPOSE

The aim of this study was to investigate the outcome of aortic valve replacement (AVR) and the effect on quality of life in patients aged over 85 who had symptomatic aortic stenosis.

METHODS

We performed a retrospective analysis of 21 patients, aged 85-91 years (mean age 86.5), who underwent AVR, 10 of whom underwent concomitant coronary artery bypass grafting (CABG) between 1989 and 1995. All patients were categorized as New York Heart Association (NYHA) functional class III and IV. A questionnaire was used to evaluate heart symptoms and quality of life among the 13 patients who were alive at follow-up (9-83 months).

RESULTS

Eighteen patients were categorized as NYHA functional class I and II for 1 year (9 months for one patient) after AVR. Three patients, all undergoing concomitant CABG, died early. The overall 1-, 2- and 3-year actuarial survival rate was 85%, 64% and 53% (among the patients undergoing only AVR the figures were 100%, 100% and 85%). Follow-up questionnaire results showed an improvement in the patients' symptoms of heart disease, dyspnea (P = 0.017) and angina (P = 0.03). An improvement in the patients' physical functioning (P = 0.025), satisfaction with physical ability (P = 0.005), sleep (P = 0.025), health status (P = 0.025) and perception of general health (P = 0.005) was also observed.

CONCLUSIONS

Our results show that AVR can be performed on patients > or = 85 years of age or older, with an improvement in heart symptoms and quality of life.

An in vitro study of mechanical heart valve sound loudness

The purpose of the study was to measure the valve sound loudness of eight 25 mm aortic mechanical heart valve prostheses under controlled laboratory conditions in an isolated acoustic environment. A specially designed single-chamber pulse duplicator was constructed within an anechoic box that isolated the sounds of the valve from external noise. The valves were closed with a stimulated aortic pressure waveform of three different amplitudes. Valve sound loudness was measured with ISO-532/B (Zwicker method), which is based on a model of loudness perception that is better than dB(A), the traditional A-weighted sound pressure level. The average loudness for each valve was St. Jude Medical, 0.97 sones; CarboMedics, 0.98 sones; Sorin Biomedica Bicarbon, 1.08 sones; Edwards Tekna, 1.92 sones; Edwards Duromedics, 2.36 sones; Monostrut, 2.48 sones; Sorin Biomedica Carbocast, 3.17 sones; and Medtronic Hall, 3.57 sones. There was a positive trend between valve sound loudness and aortic drive pressure for most valves in the study.

Strut fracture with Björk-Shiley 70 degrees convexo-concave valve. An international multi-institutional follow-up study

Between 1980 and 1983, 831 Björk-Shiley 70 degrees convexo-concave prosthetic heart valves were implanted at five institutions in Sweden, Germany. The Netherlands, and Canada. As of January 1991, there were 34 outlet strut fractures occurring from 0.2 to 10.1 years (median = 4.6 years) after implantation. In addition, there were 28 sudden, unexplained deaths. The mortality after strut fracture was 84%. The mortality after emergency valve replacement for strut fracture was 50%. The 10-year actuarial fracture rate (standard error) was 10.5 (2.4)% for large (29-33 mm) valves vs. 3.3 (1.2)% for 21-27 mm valves (P less than 0.001). Within valve size groups, fracture rates for aortic and mitral valves were similar. Cox regression analysis found only valve size to be significantly associated with strut fracture. There is a further subgrouping of the valves according to the manufacturer: group I are the earlier large 29-33 mm) valves; group II are the later large valves; group III are the small size (21-27 mm) valves. The risk of strut fracture was highest in group I (12.3% at 10 years) with an approximatively constant hazard (1.4% per year). A comparison was made with a statistical model incorporating all cases reported to the manufacturer. This model estimates fracture rates approximately 63%-73% of those found in the present study. These findings lead us to recommend that group I patients should be considered for elective reoperation on an individual basis, giving careful attention to risk factors and contraindications.

Age-related complications and optimal choice of artificial heart valves in elderly patients

The use of bioprosthetic heart valves in elderly patients is presently advocated by many since implanting mechanical valves are considered to result in unacceptable rates of thromboembolism and bleeding. However the somewhat limited durability of bioprostheses has to be acknowledged since a group of elderly patients will eventually require a reoperation due to tissue failure. We have evaluated our policy to implant mechanical heart valve prostheses even in elderly patients based on the conception that we believe that anticoagulation in this group of patients can be handled with a low rate of complications.

Perception of mechanical heart valve sounds

Most currently used mechanical heart valve prostheses generate a distinct sound when they close. This sound is sometimes disturbing to the patient, and may impair quality of life. In a study of 285 patients followed up for a mean of 2.5 years after mechanical heart valve replacement, one-third were sometimes disturbed by sounds emanating from the prosthesis. Older patients were less disturbed than young ones, but whether this could be explained by age-related impairment of hearing ability (presbyacusis) was not possible to determine. Prosthetic size, implantation site, patient's weight, body surface area and type of prosthesis did not statistically differ according to experience of prosthetic sounds. Although few patients were seriously disturbed by these sounds, it is hoped that mechanical heart valves of the future will function more quietly.

An in vitro study of prosthetic heart valve sound

Patients with an implanted mechanical heart valve sometimes experience the closing sounds of the valve as disturbing. To study the generation of valve sounds in general, a pulse duplicator study was carried out, testing eight commonly used types of prosthetic valves in the aortic position. Pulse rate was set at 70 beats/min, stroke volume at 70 ml and mean 'aortic' pressure at 100 mmHg. Despite the controlled conditions, there was great variability of the closing sound, in both intensity and spectral composition, making noise comparisons and spectral characterization ('sonoprint') difficult. In general, bileaflet mechanical valves produced less noise than did tilting disc valves, particularly those with large opening angles. One small-size (23 mm) tilting disc valve produced 50% less noise than large types. The plastic ball valve, the porcine and the polyurethane trileaflet valve all were very quiet.

Heart valve replacement with the Björk-Shiley Monostrut valve: early results of a multicenter clinical investigation

To evaluate the clinical performance of the Björk-Shiley Monostrut prosthesis, five centers combined their early experience. Between May, 1982, and June, 1985, 537 prostheses were implanted in 486 patients at these centers: 246 patients had aortic valve replacement (AVR), 163 underwent mitral valve replacement (MVR), and 47 had double-valve replacement (DVR). Thirty patients underwent other, more complex procedures. Concomitant cardiac procedures were performed in altogether 25%. Overall hospital (30 days) mortality was 5.1% (3.6% for AVR, 4.3% for MVR, 8.3% for DVR, and 16.6% for other procedures). The patients were followed up at 6- to 9-month intervals from 6 to 48 months (mean follow-up, 33 months). Follow-up was 99.6% complete. Late mortality was 7.2%. The three-year survival rate was 91.0% for AVR, 92.3% for MVR, and 76.2% for DVR. There was no structural failure of the prosthesis. No instances of valve thrombosis and fatal thromboembolism occurred in anticoagulated patients. The three-year incidence of freedom from thromboembolic events (including TIA) was 89.8% for AVR, 94.9% for MVR, and 90.2% for DVR. Preoperative and postoperative data for the assessment of mechanical hemolysis was available in 60% of the patients. The degree of mechanical hemolysis was low and did not change with time. Although the follow-up is still short, the Björk-Shiley Monostrut prosthesis appears to represent an improvement over previous Björk-Shiley models, particularly with regard to durability.

Cineradiographic functional evaluation of the Björk-Shiley monostrut prosthesis. A follow-up study of 46 consecutive patients

In 46 patients, 51 Björk-Shiley monostrut valves were studied with high-speed cineradiography 9 months after implantation. Each valve was viewed in lateral, frontal and oblique projections for 10-12 heart beats. In the aortic valves the opening time was 0.04-0.067 (mean 0.052) and closing time 0.04-0.067 (mean 0.046) sec. In all these valves the maximum opening angle was 70 degrees. Disc rotation could be monitored in 29/31 valves, and during 10 heart beats averaged 20 degrees. Disc slide of 2.0-2.5 mm was seen in 27/31 valves. It occurred during the last 40-50 degrees of opening and the first 20-40 degrees of closing. In mitral valves with sinus rhythm (12/20), the opening time was 0.053-0.106 (mean 0.073) and closing time 0.040-0.106 (mean 0.061) sec. Mean disc rotation (recorded in 17/20 valves) during 10 heart beats was 25 degrees, and disc slide of 2.0-2.5 mm was found in all but one case, mainly during the last 50 degrees of opening and the first 30 degrees of closing. The valve opened to 70 degrees in all but one patient, in whom the disc clearly impinged against the left ventricular wall and opened only to 35-50 degrees at rest. At reexamination a year later the patient was asymptomatic, in sinus rhythm, and the disc had regained full movement with 70 degrees opening.