The United Kingdom Heart Valve Registry: the first 10 years

Does preservation of the sub-valvular apparatus during mitral valve replacement affect long-term survival and quality of life? A Microsimulation Study

BACKGROUND

Techniques to preserve the sub-valvular apparatus in order to reduce morbidity and mortality following mitral valve replacement have been frequently reported. However, it is uncertain what impact sub-valvular apparatus preservation techniques have on long-term outcomes following mitral valve replacement. This study investigated the effect of sub-valvular apparatus preservation on long-term survival and quality of life following mitral valve replacement.

METHODS

A microsimulation model was used to compare long-term survival and quality-adjusted life years following mitral valve replacement after conventional valve replacement and sub-valvular apparatus preservation. Probabilistic sensitivity analysis and alternative analysis were performed to investigate uncertainty associated with the results.

RESULTS

Our Analysis suggests that patients survive longer if the sub-valvular apparatus are preserved (65.7% SD 1.5%, compared with 58.1% SD 1.6% at 10 years). The quality adjusted life years gained over a 10 year period where also greater after sub-valvular apparatus preservation. (6.54 QALY SD 0.07 QALY, compared with 5.61 QALY, SD 0.07 QALY). The superiority of preservation techniques was insensitive to patient age, parameter or model uncertainty.

CONCLUSION

This study suggests that long-term outcomes may be improved when the sub-valvular apparatus are preserved. Given the lack of empirical data further research is needed to investigate health-related quality of life after mitral valve replacement, and to establish whether outcomes differ between preservation techniques.

Antithrombotic therapy following bioprosthetic aortic valve replacement

The life expectancy of the general population is increasing. This has meant that more elderly patients are requiring aortic valve replacement (AVR). The choice of valve replacement and its durability are important. Bioprosthetic (tissue) heart valves were introduced into clinical use in the 1960s and were developed primarily to reduce the complications associated with thromboembolism (TE) and the need for lifelong oral anticoagulation, due to their low thrombogenicity compared to mechanical prostheses. This makes them suitable for use in elderly patients (aged>65 years) and in others where the risks of anticoagulation are higher or anticoagulation is contraindicated. There is thought to be a higher risk of TE for up to 90 days following bioprosthetic AVR. Guidelines for the management of patients with valvular heart disease published by the American College of Cardiology (ACC)/American Heart Association (AHA), the American College of Chest Physicians (ACCP) and the European Society of Cardiology (ESC) all recommend the use of an anticoagulation regimen for the first 3 months following bioprosthetic AVR. However, there is division of opinion and practice, despite these recommendations, and more recent studies have not supported the evidence for these guidelines. In this article, we review the literature on the use of anticoagulation in the first 90 days following bioprosthetic AVR.

Systematic review of the quality of surgical mortality monitoring

BACKGROUND

Mortality is the most tightly defined and used adverse event for audit and performance monitoring in surgery. However, to identify cause and therefore scope for improvement, accurate and timely data are required. The aim of this study was to perform a systematic review of the quality of measurement, reporting and monitoring of mortality as an outcome after surgery.

METHODS

A systematic review of published literature was undertaken for the 7-year interval 1993-1999. Grey and unpublished literature was obtained through the Royal College of Surgeons of England, from UK national audits and routine national hospital data collections.

RESULTS

Eligible monitoring systems included six UK national surgical audits, and cardiac and vascular surgery monitoring systems from North America and the UK. The definitions of 'surgical death' varied in several respects and deaths after discharge from hospital were rarely ascertained unless there was routine linkage to national death registers. There were very few published studies on validation of the completeness and accuracy of the data collection.

CONCLUSION

A comprehensive data collection system is needed for improving clinical performance, with ownership, but not necessarily data collection, resting with the surgeons concerned. Recording of risk factors and deaths after discharge from hospital is essential, whatever data collection system is used.

First redo heart valve replacement: a 10-year analysis

BACKGROUND

The United Kingdom Heart Valve Registry (UKHVR) has recently completed collecting information on 52 659 heart valve replacements (in 47 718 patients) performed during the period 1986 to 1995 in the whole of the United Kingdom. Information stored in the UKHVR's computer database was used for this study. Factors affecting the time from first prosthesis to first redo prosthesis were analyzed and provided useful predictive information. The association between prosthesis-induced local pathological processes and redo valve size was investigated.

METHODS AND RESULTS

This is a retrospective study of 43 301 patients (from among 47 718 in the database) undergoing single-site replacement of a diseased native mitral or aortic valve over a 10-year period from January 1986 to December 1995 in the United Kingdom. Of these patients, 1051 (2.43%) went on to have a first redo heart valve replacement. Valve survival analysis (Cox regression and Kaplan-Meier curves) was used to study the natural progression to the first redo heart valve replacement. Female sex and having a replacement at the aortic rather than the mitral position were both associated with a longer interval to the first redo operation. Regression analysis showed the size of the redo valve to be influenced by the interoperative time. This effect was more pronounced at the mitral position.

CONCLUSIONS

Females and patients having an aortic valve replacement exhibit a longer interval to the first redo operation than do males and patients having mitral valve replacements, respectively. The time from the first replacement to the first redo operation significantly affects the size of the first redo valve.