Clinical epidemiology of heart failure

Abstract

he aim of this paper is to review the clinical epidemiology of heart failure.The last paper comprehensively addressing the epidemiology of heart failure in Heart appeared in 2000.w1 Despite an increase in manuscripts describing epidemiological aspects of heart failure since the 1990s, 1 additional information is still needed, as indicated by various editorials.w2 w3The evaluation and management of heart failure is schematically depicted in fig 1.Following some methodological considerations, most issues indicated in fig 1 (risk factors, aetiology, prevalence, incidence, prognosis, prevention) will be discussed.The therapeutic management of patients diagnosed with heart failure is beyond the scope of this paper, as is detailed information about the possible diagnostic tests and strategies to establish or rule out heart failure, although the prevailing definitions and categorisations of the syndrome will be discussed.The guidelines of the European Society of Cardiology and selected reviews provide up to date information on the diagnosis and therapeutic management of heart failure. 2 w4 w5 DEFINITION AND CLASSIFICATION OF HEART FAILURE cHeart failure is a syndrome with symptoms and signs caused by cardiac dysfunction, resulting in reduced longevity.To establish a diagnosis of heart failure, the European Society of Cardiology guidelines warrant the presence of symptoms and signs (tables 1 and 2), objective evidence of cardiac dysfunction (preferably by echocardiography), and, in case of remaining doubt, a favourable response to treatment directed towards heart failure.w5 To support the failing heart numerous compensatory mechanisms occur, including activation of the neurohormonal system. 2 An increase in natriuretic peptide concentrations (particularly B type natriuretic peptide) is considered a hallmark of heart failure.The diagnosis of heart failure, especially when relying solely on symptoms and signs (which is often the case in primary care), is fraught with difficulties.3 Many patients deemed to have heart failure will simply be found to be obese, have a poor physical condition, pulmonary disease, or ischaemia on further examination.Evidence is accumulating that normal natriuretic peptide levels and a normal electrocardiogram should lead to a reconsideration of a diagnosis of heart failure.4 w6Acute versus chronic heart failure Heart failure generally is a chronic condition (chronic heart failure-CHF) in which bouts of worsening symptoms and signs can occur that may require hospitalisation or more frequent doctor visits (decompensation of CHF).Alternatively, heart failure may present acutely, with occurrence of severe symptoms and signs within 24 h.Acute heart failure clinically presents in several forms: c acute pulmonary oedema secondary to cardiac dysfunction c cardiogenic shock, usually in the setting of an acute coronary syndrome, characterised by hypotension, oliguria, and peripheral vasoconstriction c acute worsening (decompensation) of CHF.Systolic versus diastolic heart failure, impaired versus preserved left ventricular ejection fraction Heart failure traditionally was seen to result from impairment in ability of the heart to pump sufficient amounts of blood into the circulation during systole-that is, left ventricular systolic dysfunction.Echocardiography is most often employed to assess left ventricular systolic function, an ejection fraction of (40% indicating impaired left ventricular systolic function.Heart failure can also occur in patients with normal left ventricular systolic function in whom higher filling pressures are needed to obtain a normal end-diastolic volume of the left ventricle, so called heart failure with preserved left ventricular ejection fraction (PLVEF) or ''diastolic'' heart failure.w7