Left ventricular systolic dysfunction is common in elderly patients in general practice. About 1 in 20 patients aged 70-74 and 1 in 10 patients aged 75-84 have left ventricular dysfunction. There are no comparable data for patients aged over 75 years, but for patients aged 65-74 years our estimate is consistent with the estimated prevalence of ventricular dysfunction of 5.6% reported from a Glasgow study (Glasgow has a substantially higher standardised mortality ratio for cardiovascular disease, but the sample assessed was limited to a selected population of responders to a questionnaire).15
The prevalence of ventricular dysfunction in a smaller sample from Rotterdam, aged
70 years, was considerably lower at 4.2%.18
Patient selection and a lower response rate could account for the low prevalence in this Dutch population, which was described as relatively healthy.
A key finding of our study is the higher prevalence of disease in men than in women. This is consistent with gender differences in the prevalence of ischaemic heart disease, but runs contrary to the general practice stereotype of an elderly breathless woman with swollen legs. Interestingly, previous prevalence estimates in the United Kingdom, which have relied on review of general practice records based on assessment of clinical features, electrocardiograms, and chest x
have shown no apparent gender difference in prevalence in elderly age groups. This may reflect the difficulty of making a reliable diagnosis of heart failure without echocardiography, particularly in patients who may have peripheral oedema and breathlessness for a variety of non-cardiac causes.21
At the design stage of our study we agreed that prevalence should be reported on the basis of categorical grading of global left ventricular systolic function rather than quantitative measurement of ejection fraction. This decision was made partly in the knowledge of the difficulty of making reliable measurements of ejection fraction in this age group (especially in subjects most likely to have abnormal left ventricular function), and partly because we anticipated that global assessment was likely to be the best predictor of outcome and benefit from treatment in elderly patients. Without longer follow up we lack data to justify the assertion that global assessment is likely to be the best predictor of outcome and benefit from treatment in elderly patients, but the clear separation and gradient of mean ejection fraction for each category indicates that qualitative categorisation and quantitative assessment of ejection fraction are broadly consistent with each other.22
The number of abnormal echocardiograms not reviewed by the cardiologist was small, and thus even if all were false positive diagnoses these would only have inflated the prevalence by 1.3%.
The high response rate, the use of home assessment, and the similar demographic characteristics of responders and non-responders encourages us to believe that our prevalence estimates are robust. It seems unlikely that the lower assessment rate among women can account for more than a small part of the observed gender difference. Our study was, however, set in a desirable retirement area, which is likely to have had inward migration of more affluent and possibly fitter elderly people. Thus our prevalence estimate may be lower than in less privileged areas and may underestimate the prevalence of left ventricular dysfunction in the United Kingdom.
Only half of our patients with left ventricular dysfunction had a previous record of heart failure in their medical records. This was confirmed by the observed levels of prescribing of diuretics and angiotensin converting enzyme inhibitors. There are a substantial number of elderly individuals who have asymptomatic or misdiagnosed left ventricular dysfunction, which is likely to be due to the very limited sensitivity and specificity of clinical history taking and examination in general practice. Only 11% of patients with left ventricular dysfunction will have a raised jugular venous pressure. Bilateral ankle oedema has the unfortunate characteristic of relatively high prevalence in the general population and relatively low specificity. Although these clinical findings are useful in acute severe heart failure at the time of hospitalisation, they have only a small role in detecting left ventricular dysfunction in the community.23,24
Our study extends and explains the findings of Remes, that the clinical diagnosis of left ventricular dysfunction in primary care is not accurate or easy.21
Clinical diagnosis based on raised jugular venous pressure, bilateral ankle oedema, or basal crepitations will very often be misleading.
On the evidence of our study, targeting individuals for more detailed assessment on the basis of gender, age, and a history of ischaemic heart disease would detect a substantial proportion of the currently unrecognised left ventricular dysfunction. However, it would be unwise to embark on a screening programme in elderly people (whether or not selected by age, sex, or medical history) until we have better evidence of its cost effectiveness in this elderly patient group.