The heart failure epidemic


Cardiology Department
Hospital Universitario La Paz
Madrid, SPAIN

The heart failure epidemic

by J . López-Sendón, Spain

Heart failure constitutes an important medical, social, and economic problem. Although reliable estimates are lacking in many countries, the prevalence of heart failure is estimated as 2%-3% of the adult population and increases with age. Over 26 million people suffer from heart failure around the world and over 3.5 million people are newly diagnosed with heart failure every year in Europe alone. The long-term prognosis associated with heart failure is worse than that associated with the majority of cancers, with 50%mortality after 4 years. Patients suffer disabling symptoms that often become refractory to treatment and need hospitalization, having the greatest negative impact on quality of life compared with other chronic conditions. The cost ofmedical care ismeasured in billions of dollars. The prevalence of heart failure progressively increased from the early 1950s onwards for 30 years, eventually reaching a plateau. However, it is likely we will observe a new increase in the future mainly because of the aging of the population and because of the trend showing an increasing prevalence of major heart risk factors, including obesity and diabetes. The challenge of preventing a heart failure pandemic in the future is important for all countries, but especially those with economies in transition, where traditional healthy lifestyles are quickly changing. The only way of avoiding this new pandemic is through prevention, which is the collective responsibility of everyone: physicians, education and health authorities, and patients.

Medicographia. 2011;33:363-369 (see French abstract on page 369)

Although not a heart disease itself, heart failure (HF) is a heart condition with a high social, sanitary, and economic impact. Reliable estimates of HF are lacking in many countries because of the absence of reliable surveillance programs to track the incidence, prevalence, outcomes, as well as the key causes of HF. According to estimates from the European Heart Failure Association, 26 million people have HF worldwide and 3.6 million people are newly diagnosed with HF every year in Europe alone. Similar figures are reported by the National Institute of Health in the United States, and an absolute increase is expected in future years.

The long-term prognosis associated with HF is poor. Half of all patients diagnosed with HF die within 4 years, and the 5-year survival rate is lower than that associated with myocardial infarction and the majority of major malignancies. HF has the greatest negative impact on quality of life compared with other major chronic disease, such as diabetes, arthritis, and hypertension. Patients with HF suffer disabling symptoms, especially after their first hospitalization, the most common of which are fatigue and dyspnea, while in terms of disability, the end stage of the disease is comparable to that of terminal cancer.

The economic cost of HF is estimated in billions of dollars per year, the need for repeated hospitalization being the most powerful contributing factor to direct costs associated with the disease. The longer life expectancy of the population, better treatment of heart diseases, and increase in risk factors for ischemic heart disease, particularly in countries with economies in transition, account for a growing incidence and prevalence of HF around the world. The only way to decrease the oncoming pandemic is by reducing the risk factors for cardiovascular diseases and HF through treatment, education of the population, and legislation for a healthier lifestyle. This is a responsibility that concerns not only physicians, but also teachers, health care providers, and patients.

Figure 6
Figure 1. The progression of heart failure.

Heart failure is a progressive disorder, ranging from normal ventricular function in the absence of heart
disease in the presence of risk factors to severe ventricular dysfunction with symptoms refractory to
treatment. An elusive clinical diagnosis and the lack of reliable, universal tools for diagnosis in epidemiologic
studies explain discrepancies in heart failure prevalence and incidence between different studies.
Abbreviations: HF, heart failure; LV, left ventricular; NYHA, New York Heart Association (classification).

The difficulties of defining and classifying heart failure

HF is a complex syndrome, clinically characterized by signs and symptoms secondary to abnormal cardiac function.1,2 It includes patients with impaired (systolic HF) or preserved systolic left ventricular function (diastolic HF). Left ventricular function is below normal limits in a significant number of otherwise normal individuals (asymptomatic left ventricular dysfunction),3,4 and the process itself may be considered as a progressive disorder ranging from risk factors to heart disease, asymptomatic impaired ventricular function, symptomatic HF, and finally refractory or advanced HF (Figure 1).1,2 In some epidemiological studies, the most representative being the Framingham Study,5 patients were considered as having HF when 2 major criteria or 1 major and 2 minor criteria of HF (major criteria: rales, jugular ingurgitation and third heart sound; minor criteria: dyspnea, peripheral edema, and hepatomegaly) were present.

None of the above clinical manifestations are pathognomonic of HF and may be related to other conditions, some of which are common comorbidities associated with HF. Other studies used algorithms and scores based on clinical data, physical findings, and chest x-ray or even specific drug treatments3- 9 with different sensitivity and specificity results,8,10 ICD-9 codes,11 or even the simple, direct opinion of physicians.6 There is no agreement over a simple definition of HF for epidemiologic studies.

Incidence and prevalence

Incidence (number of new cases per year) and prevalence (proportion of the general population with HF) figures reported in the medical literature vary widely, mainly because different sets of diagnostic criteria have been used. Contemporary studies estimate the overall prevalence of HF in the US population to be about 2%-3%.10,12-14 The prevalence is higher in men than in women and increases with age as shown in Figure 1.10 The prevalence of HF may be even higher in Europe.15,16 Although significant differences have been noted between studies in different countries (Figure 2),16-19 in general, HF prevalence in Western European populations is estimated to range from 0.4% to 2%.1,16

_ Systolic versus diastolic heart failure
Asymptomatic diastolic left ventricular dysfunction, manifested by severe left ventricular hypertrophy and/or abnormal echocardiographic parameters,20-22 is frequently found in patients with hypertension and other clinical conditions, such as ischemic heart disease. Although the majority of these patients never present signs or symptoms of HF,3,4 there is a clear relationship between diastolic functional abnormalities and long-term hospital admission for HF and, in general, worse outcomes compared with patients with normal diastolic function.22-27

If the diagnosis of HF with depressed systolic ventricular function is considered elusive, then the correct diagnosis of diastolic HF is a real clinical challenge. Both European and American cardiology associations offer recommendations for the correct diagnosis of diastolic HF that go well beyond the tandem of HF symptoms in the presence of normal left ventricular ejection fraction (LVEF).20,21 The relative complexity of the diagnosis may be a problem in everyday clinical practice, but it is a real challenge to ascertain the type of HF, either systolic or diastolic, when conducting epidemiologic studies. Accordingly, the information relative to this type of HF is found mainly in registries rather than in prospective, populationbased epidemiologic studies. With all the aforementioned limitations, the incidence and prevalence of diastolic HF is probably about the same as HF with depressed left ventricular contractility.16,22

Figure 2
Figure 2. Prevalence of heart failure by age and sex in the USA.

Prevalence, which increases with age, may affect as much as 10% of the elderly
population and is more frequent in men than in women.
Modified from reference 10: Lloyd-Jones et al; American Heart Association
Statistics Committee and Stroke Statistics Subcommittee. Circulation. 2010;121:
e46-e215. © 2010, American Heart Association, Inc.

_ Incidence
In the Olmsted County study (Minn, USA), 137 patients with new HF presenting in 1991 had a recent echocardiogram assessing LVEF, which showed that 43% of them had an LVEF above 50%, qualifying as HF with preserved systolic function.28 However, in another population-based study, Cowie et al in London18 performed an echocardiogram in 93% of all new, local cases of HF and only 16% presented a normal LVEF, while there was a mild to moderate reduction in LVEF in 68%, and a severe reduction in LVEF in 16%. Again there was the problem of defining normal limits of systolic function parameters.

Figure 3
Figure 3. Prevalence of heart failure.

Comparison of several cross-sectional, population-based, echocardiographic studies from the United States and Europe were examined to determine the relative proportion of cases with (grey bars) and without (red bars) preserved left ventricular systolic function. Differences between the studies may reflect different diagnostic criteria, and not necessarily different prevalences in different countries.
Abbreviation: LV, left ventricular.
Modified from reference 16: Hogg et al. J Am Coll Cardiol. 2004;43:317-327. © 2004, American College of Cardiology

_ Prevalence
In cross-sectional population studies, the proportion of patients with preserved systolic function HF range from 40% to 70%, with an average of about 50% (Figure 3).16 In the Euro- Heart Failure Survey I, 51% of men, but only 28% of women, had an LVEF <40%.29 In contrast, in the EuroHeart Failure Survey II in patients hospitalized with acute HF, preserved LVEF ≥45% was present in 34.3% of the whole study population (42.8% in de novo acute HF vs 29.6% in acutely decompensated chronic HF patients).30 In addition, patients with diastolic HF are older and present more comorbidities than patients with left ventricular systolic dysfunction, and treating patients with diastolic HF remains a diagnostic and therapeutic challenge in clinical practice.22,23,25

Figure 4
Figure 4. Low left ventricular ejection fraction in normal individuals with previously
unknown heart disease.

Left ventricular ejection fraction <30% in normal individuals with previously unknown heart disease, of whom about 50% were completely asymptomatic. After reference 3: McDonagh et al. Lancet. 1997;350:829-833. © 1997, Elsevier Ltd.

Table II
Table I. The heart failure pandemic in numbers.

Abbreviation: HF, heart failure.

_ Asymptomatic left ventricular dysfunction
A surprisingly large number of otherwise normal individuals in the general population present systolic function indexes well below the normal limits, the majority without signs or symptoms of HF. In the Glasgow study, part of the MONICA (MONItoring CArdiovascular disease) project, 2.9% of 1467 normal individuals without previously known heart disease, aged 25 to 75 years, presented a LVEF <30%, of whom about 50%were completely asymptomatic (Figure 4).3

In the Rotterdam study,4 which included 5540 participants aged over 55 years, the prevalence of HF was 3.9%, and 3.7% presented a left ventricular fractional shortening <25%, a measure of systolic left ventricular dysfunction. Curiously, only 20% of patients with systolic dysfunction presented clinical HF, and 60% of patients with left ventricular systolic dysfunction had no symptoms or signs of HF at all.3,4

A true epidemic

HF statistics all over the world are overwhelming (Table I). It is estimated that 26 million people have HF worldwide, up to 6 million American and as many Europeans suffer from HF, and 1 million people are newly diagnosed with HF every year in the USA and the European Union alone. These figures imply that the risk of having HF in a lifetime is 1 in 5.10,12-19

Past, present, and future prospects

The worldwide prevalence of HF has been increasing during the last few decades, something that could be attributed to several factors: an increase in the incidence of cardiovascular diseases; an aging population; better and more effective treatment of heart disease in general and acute coronary syndromes in particular, leading to a reduction in short-term mortality and HF occurring over a longer time frame.

A higher awareness of the problem and the widespread use ofmore reliable and sensible diagnostic tools, especially echocardiography, could certainly also explain a “false” increase in the incidence and prevalence of HF.

Figure 5A shows the hospitalization rates for congestive HF in USA over a span of 35 years.13 For people younger than 65 years, HF prevalence increased from 1971 to 1993 and remained stable until 2006. Rates for those 65 years and older increased from 1970 to 1998 and remained somewhat stable until 2006.13 In contrast, hospital mortality has progressively decreased during the last 25 years, contributing to the observed increase in the prevalence of HF (Figure 5B).

Figure  5A/5B
Figure 5A. Hospitalization rates for congestive
heart failure in the USA from 1971-2006.

After a steady increase in the hospitalization rate for congestive
heart failure in the elderly (≥65 years) in the USA
from 1971 to 1993, the rate then stabilized with minor
fluctuations until 2006.

Figure 5B. Mortality rates for congestive heart
failure in the USA from 1982-2006.

Hospital mortality declined steadily from 1982 to 2006 in
both heart failure patients ≥65 years and in those <65 years in the USA, which could help explain the increase in heart failure prevalence today. Modified from reference 13: National Institutes of
Health—National Heart, Lung, and Blood Institute. Morbidity
and Mortality: 2009 Chart Book on Cardiovascular,
Lung and Blood Diseases. © 2009, National Institutes of
Health—National Heart, Lung, and Blood Institute.

Despite an increasing prevalence, the majority of evidence indicates that the incidence of HF has plateaued and might even be decreasing in some groups.14,31,32 In Western countries, including Canada, the USA, and countries in Western Europe, the incidence and prevalence of HF as well as the hospital admissions for HF has decreased during the last decade when corrected for age.10,12-14,31 This trend has not been observed in many other countries where the prevalence of heart disease remains very high (as in Eastern European countries)32 or is still increasing (as in some Asian and South American countries).33,34

What is expected in future years is controversial and depends mostly on the success we have in controlling risk factors and on the change in life expectancy of the population. Most estimates predict a steady increase in the total number of cases, even in countries where cardiovascular diseases and cardiovascular mortality is declining.14,35 Again, the aging of thepopulation explains the otherwise contradictory epidemiologic predictions. Table II shows the predicted prevalence of HF, as well as the direct costs (medical care, hospitalization, treatments) and the indirect costs (loss of productivity) attributed to HF, for the years 2010 to 2030 in the United States.35 The increase in prevalence will be relatively small, but over a 20-year period is equivalent to 25%, a figure that implies a terrible social and economic burden, with a cost increase of over 200%. These estimates may be conservative; if changing lifestyles lead to an increase in risk factors that have a strong impact on HF, such as diabetes and obesity, we may see an even greater increase in cardiovascular diseases and HF and their associated costs.11,36-38

Table II
Table II. Projections of heart failure prevalence and the direct and
indirect costs of heart failure in the United States from 2010-2030.

Direct costs are medical care, hospitalization, and treatments, while indirect costs
include loss of productivity. Based on data from the American Heart Association
Advocacy Committee in reference 35.

In countries with an economy in transition, the possibilities are even more dramatic.33,34 The control of communicable diseases, the expected steep increase in life expectancy, and the changes in lifestyle (mainly due to a shift from rural to urban communities) may lead to a steady increase in cardiovascular diseases and HF, causing a pandemic that will be, put simply, global. The only hope is in the control of risk factors.

Preventing an epidemic outbreak

_ Risk factors
A number of risk factors, such as ischemic heart disease, hypertension, smoking, obesity, atrial fibrillation, diabetes, and tachycardia, among others, have been identified to both predict the incidence of HF as well as its severity.11,36-39

The risk of HF is particularly high in coronary disease (the incidence of HF is highest after myocardial infarction) and diabetes. Needless to say, prevention of cardiovascular diseases, changing lifestyle and diet (or maintaining healthy lifestyles and diets in some populations), and using appropriate medications are the best and most rewarding strategies to control the growing medical, social, and economic burden of HF.

_ Role of the patient
HF is a chronic disease, and the role of the patient in prevention and treatment is crucial. Although the awareness of the problem of HF is very low,40 the majority of citizens from developed countries are aware of the negative effects of major classic risk factors, such as obesity, hypercholesterolemia, smoking, hypertension, sedentary lifestyle, etc. In spite of this awareness, the control of some factors is lower than expected,41,42 while others are clearly increasing, especially obesity and diabetes, both of which are related to modern lifestyles and HF. Education and legislation will be crucial to control the growing global burden of cardiovascular heart diseases, HF included. _

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Keywords: heart failure; epidemic; life expectancy; prevention; risk factor