ArticlesSymptomatic and asymptomatic left-ventricular systolic dysfunction in an urban population
Introduction
Despite the falling trend for other cardiovascular disorders, the incidence and prevalence of chronic heart failure (CHF) are predicted to rise substantially over the next 10 years.1 Already, increasing rates of hospital admission for CHF have been reported from Europe and the USA,2, 3, 4 and the disorder now accounts for 1–2% of all health-care expenditure.5
In developed countries CHF is mainly attributable to left-ventricular systolic dysfunction (although some patients have diastolic dysfunction). The substantial morbidity and mortality6, 7, 8 can be greatly reduced by appropriate treatment.8, 9 Moreover, treatment at the asymptomatic stage can delay or prevent progression to symptomatic left-ventricular systolic dysfunction and its consequences.10, 11
Little is known, however, about the epidemiology of CHF and less still about its probable precursor, asymptomatic left-ventricular systolic dysfunction. Most population surveys have relied on a clinical diagnosis of CHF.5, 12, 13 However, Wheeldon and colleagues14 found that many patients with a diagnosis of CHF do not have left-ventricular systolic dysfunction or, indeed, any significant cardiac abnormality. In addition, previous population surveys have been unable to identify people with asymptomatic left-ventricular systolic dysfunction.
We report a large-scale epidemiological study that used two-dimensional echocardiography to investigate the prevalence and predictors of both symptomatic and asymptomatic left-ventricular systolic dysfunction in men and women aged 25–74 years, randomly sampled from a geographically defined urban population.
Section snippets
Methods
All 2000 people (200 men, 200 women, in each 10-year age band from 25 to 74 years) who had attended the third Glasgow MONICA coronary-risk-factor survey in 1992 (response rate 67%)15, 16 were invited to take part in this study; 1640 reattended (response rate 83%). This sample is representative of the original cohort in all relevant criteria, except that the attenders were more affluent and there were fewer smokers. The frequencies of coronary heart disease and hypertension were the same as
Results
The ejection fraction was measurable in 1467 (89·5%) of the 1640 participants; the proportion with measurable ejection fractions ranged from 86·2% in men aged 65–74 to 94·8% in women aged 25·34. Participants with measurable ejection fractions were significantly younger than those without a measurement, lower proportions had diabetes and hypertension, and the mean body-mass index was lower. The difference in the proportion with angina almost reached significance (table 1).
Left-ventricular
Discussion
In this first study of symptomatic and asymptomatic left-ventricular systolic dysfunction in the general population, we found that a low ejection fraction is common; 2·9% of the population had definite left-ventricular systolic dysfunction, of whom about 50% were asymptomatic.
Since left-ventricular ejection fraction was normally distributed in the population without cardiovascular disease, the first question our study raises is “What is normal left-ventricular function?”. Our decision to choose
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