Morbidity (the frequency of new cases of the state of interest over a period of time in a population in which it was originally absent). The only way to directly estimate the incidence is to organize a cohort study. When it is carried out, a group (cohort) is formed, into which persons without CHF are included. Then this cohort is observed for a certain period, in order to establish which of its participants the outcome of the study [11] arises. Since the organization and conduct of a large-scale cohort study involves significant material and time costs, it is not surprising that in most countries of the world there is no accurate data on the prevalence of CHF.
Most authors describe the incidence of CHF beginning with a discussion of the results of a classical epidemiological study, which was started as early as 1948 in Framingham (Table 2.1) [5, 13, 14]. In this study, the annual number of new cases of CHF was 2 per 1,000 in the 45-54-year-old population, and increased more than 10-fold among the elderly. In women, the incidence rate was lower (incidence of CHF in women and men of all ages was 1.4 ‰ and 2.3 ‰, respectively).
In a later study [15], the incidence of CHF is lower: in the 25-34-year-old age group, the incidence was 0.02 cases per 1000 population per year, and among those who reached the age of 85, 11.6 (the ratio of men to women with the newly established diagnosis of CHF was defined as 1.75: 1). But these seemingly low rates of morbidity are unlikely to be comforted by anyone. After all, only in the United States for such abstract figures are about 500,000 patients who for the first time for the first time diagnosed CHF.
Prevalence (the frequency of the state of interest in the population). The results of the Framingham and other epidemiological studies performed in America and Europe convincingly confirm the well-known fact that CHF affects mainly the elderly. If the prevalence of CHF among adult residents of the city under the age of 50 does not exceed 1%, in the population over 65 it reaches 6-10%.
Today, we see an increase in the prevalence of CHF, the situation of which resembles a non-infectious
epidemic. The impressive successes achieved in recent decades in the treatment of the most common cardiovascular diseases (primarily acute coronary catastrophes) concerned mainly the immediate results of pharmacological and surgical interventions. Thus, a significant reduction in mortality in myocardial infarction (MI), observed in the last three decades in most economically developed countries, was not accompanied by an equivalent reduction in overall cardiovascular mortality. This paradoxical situation, which was designated as “an ironic failure of success,” is explained by an increase in the number of people suffering from CHF.
There are three main causes of increased incidence of CHF:
- Increase in the life expectancy of the population of the developed countries of the world. Aging of the population leads to “accumulation” of risk factors for CHF (coronary heart disease, arterial hypertension, diabetes, etc.).
- Improving the quality of diagnosis and treatment of acute cardiovascular diseases, primarily MI. Although not all cardiologists and epidemiologists find a convincing link between the decrease in the mortality of patients with MI and the increase in the incidence of CHF.
- Early diagnosis and effective surgical treatment of vices and coronary heart disease (IHD). The comprehension of the phenomenon of an increase in the prevalence of CHF on the background of a general improvement in the situation with cardiovascular diseases led to the creation of the theory of a single cardiovascular continuum at the end of the 20th century.
The paradoxical situation is that the better we treat patients with underlying cardiovascular diseases, the greater the number of patients who survive to the older age and the stage of development of the disease, in which the likelihood of developing CHF is high. Yu. N. Belenkov point out that “an increasing number of patients with IHD survive only in order to” wait “for the development of heart failure in a later period of the disease. To the same extent, this applies to patients with rheumatic heart defects, as well as dilated cardiomyopathy. ”
In the United States, the number of patients discharged from a clinic with CHF diagnosis has increased by 155% over the past 20 years, and a total of about 5 million patients in this country have CHF (approximately 2% of the 270 million population). In a review article Yu.N. Belenkov gives a comparative description of the results of studies of the prevalence of CHF in Europe and Russia, often indicative of an even greater number of cases of this pathological condition in the Old World. At the same time estimates of the prevalence of CHF in Russia significantly exceed those presented by European cardiologists (1.5% in the MONICA study, 4% in the Rotterdam study). If we are guided by these figures, in Europe, with a population of 900 million people, the prevalence of CHF is approximately 18 million. In Russia, about 4-5% of the population, that is, about 6-8 million people, is involved.
As the results of the MONICA study conducted under the aegis of WHO show, the prevalence of asymptomatic LV dysfunction can exceed that of the manifest forms of CHF.
The immediate future promises only an aggravation of the problem: the incidence and prevalence of CHF will increase due to an increase in life expectancy. Even the most optimistic scientifically based forecasts look like depressingly. Taking into account the latter, Yu. N. Belenkov warned that “it is necessary to be prepared for the fact that in 10-20 years every second or third patient after visiting a cardiologist (or therapist) will leave his office with this diagnosis.”