Survival of people with valvular heart disease in the community (OxVALVE-Survive)
Problem
More than half of all adults aged over 65 years have some form of valvular heart disease (VHD). Significant VHD, defined as stenosis or regurgitation that impacts upon cardiac function, is associated with impaired quality of life and increased hospitalisation. However, many existing studies of VHD prognosis are confounded by being hospital-based, with likely greater co-morbidity. In addition, most people with VHD have mild disease, which has been linked to poorer outcomes in hospital-based studies but is of uncertain clinical significance in community populations. Furthermore, degenerative valve changes are also common findings on echocardiogram and have traditionally been deemed of little clinical significance as they do not have a functional impact on the heart, but their prognostic significance is also unclear. In this study we aimed to investigate the association between VHD and its subtypes with all-cause and cause-specific mortality in a community population.
Approach
We linked data from the OxVALVE study to the Office for National Statistics mortality registry. OxVALVE used echocardiography to screen over 4,000 participants aged over 65 years from seven general practices in Oxfordshire for presence and severity of VHD. We examined the association between VHD and mortality alone and in relation to mitral annular calcification and aortic sclerosis. We hypothesized that these degenerative forms of valve disease may be associated with an adverse prognosis given that they are markers of atherosclerosis. Kaplan-Meier curves, log rank tests, Cox regression and the Fine-Gray competing risks model were used for the analysis.
Findings
Mortality data were available for 3,511 participants, of whom 361 (10.3%) died (median 6.49 years follow-up). Most had some form of valve abnormality (n=2,645, 70.2%), including either aortic sclerosis or mitral annular calcification. VHD without degenerative disease was present in 1,760 (50.1%) and 182 (5.2%) had significant disease. Mild and significant VHD were associated with increased all-cause mortality in the unadjusted analysis but not the multivariable model (mild VHD: HR 1.20, 95% CI: 0∙96-1.51; significant VHD: HR 1.47, 95% CI: 0.94-2.31). Aortic sclerosis and mitral annular calcification were common findings and both were independently associated with an increased risk of death. Mortality was highest for people with a combination of significant VHD and significant valve degeneration (HR 4.38, 95% CI 1.99-9.67).
Consequences
These results are important in changing the way that echocardiogram results are interpreted. Most older people detected with VHD (over 90%) will have mild disease that it is not associated with increased risk of death, and they can be reassured. However, degenerative valve changes, particularly in people with significant VHD, are associated with increased mortality, and represent potentially important prognostic indicators, the significance of which may currently be overlooked in clinical practice. Their presence should prompt clinicians to consider intensive treatment of modifiable cardiovascular risk factors.