RELATIONSHIP BETWEEN REDUCED EJECTION FACTION AND RENAL DYSFUNCTION IN PATIENTS WITH CHF

ABSTRACT

Relevance: The increasing prevalence of CHF is an urgent problem for public health due to economic costs, multiple hospitalizations and high mortality rates. Impaired contractile function of the left ventricular myocardium (LV) increases renal dysfunction in patients with CHF. However, the degree of renal dysfunction is not indicated in the diagnosis and its correction is not carried out. Objective: to study clinical and laboratory characteristics and analyze cardiorenal relationships in patients with CHF with a reduced ejection fraction (EF). Materials and methods. This is a retrospective analytical study. An analysis of the medical records of 342 inpatient patients with a diagnosis of CHF of the "Ust-Kamenogorsk Hospital No.4" for the period 2021-2023 conducted. The clinical, laboratory and echocardiographic characteristics of patients with CHF are considered. Results. A decrease in the left ventricular ejection fraction occurs in most patients with CHF, this is 59.5%, and the remaining 40.5% of patients showed preserved LVEF. Renal dysfunction has a significant (80.6%) prevalence among patients with CHF. Renal dysfunction progresses during CHF and is a serious comorbid condition of CHF. Conclusions. A decrease in the contractility of the myocardium, that is, a decrease in the ejection fraction of the left ventricle, leads to a deterioration in the functional state of the kidneys in patients with CHF.

АННОТАЦИЯ

Актуальность: Возрастание распространенности ХСН – актуальная проблема для общественного здравоохранения из-за экономических затрат, многократных госпитализаций и высокого уровня смертности. Нарушение сократительной функции миокарда левого желудочка (ЛЖ) усиливает почечную дисфункцию у больных с ХСН. Но степень почечной дисфункции не указывают в диагнозе и не проводят её коррекцию. Цель: изучить клинико-лабораторные характеристики и проанализировать кардиоренальные взаимосвязи у пациентов с ХСН со сниженной фракцией выброса (ФВ). Материалы и методы. Проведено ретроспективное аналитическое исследование медицинских карт 342 стационарных больных, кардиологического отделения КГП на ПХВ «Городская больница №4 г. Усть-Каменогорск» УЗ ВКО за период 2021–2023 гг. c диагнозом ХСН. Рассмотрены клинико-лабораторные и эхокардиографические характеристики больных с ХСН. Результаты. Снижение фракции выброса левого желудочка встречается у большинства больных с ХСН, это 59,5%, а у остальных 40,5% пациентов выявлена сохранная ФВЛЖ. Почечная дисфункция имеет значительную (80,6%) распространенность среди больных с ХСН. Дисфункция почек прогрессирует течение ХСН и является серьезным коморбидным состоянием ХСН. Выводы. Снижение сократительной способности миокарда, то есть снижение фракции выброса левого желудочка, приводит к ухудшению функционального состояния почек у больных с ХСН.

Keywords: chronic heart failure, kidney dysfunction, glomerular filtration rate, left ventricular ejection fraction, mortality, morbidity.

Ключевые слова: хроническая сердечная недостаточность, дисфункция почек, скорость клубочковой фильтрации,  фракция выброса левого желудочка, смертность, заболеваемость.

Introduction. The mortality rate due to diseases of the circulatory system ranks first in the world, which is 52-55% of all mortality rates [1]. Today, according to the World Health Organization, people in Kazakhstan die from diseases of the circulatory system almost twice as often as, for example, in European countries. Over the past decade, the prevalence of cardiovascular diseases (CVD) has increased almost 2.5 times, from 1204.3 to 2755.4 cases per 100,000 population [1]. The incidence of CVD among the adult population in 2019 amounted to 2811.7 cases in the Republic, and the East Kazakhstan region (East Kazakhstan region) ranked second by region – 3406.5 cases per 100 thousand people, after the city of Almaty (3758.3 cases) [1]. If compared with previous indicators, in 2015, East Kazakhstan Region appeared in fourth place among other regions of the Republic of Kazakhstan in terms of mortality from diseases of the circulatory system [2]. In terms of mortality from CVD, the East Kazakhstan region also ranked second among all regions of the country in 2019, it amounted to 255.81 cases per 100 thousand a person [1].  The outcome of diseases of the cardiovascular system such as arterial hypertension, coronary heart disease, myocardial infarction, etc. is a chronic heart failure (CHF). The high prevalence of CHF is an actual problem for the country's healthcare because of the economic costs and multiple hospitalizations, as well as the high level of disability and mortality. In turn, a decrease in the contractility of the myocardium leads to a deterioration in the functional state of the kidneys [4]. However, the degree of renal dysfunction is not specified in the diagnosis and its correction is not carried out [7]. So, there is a problem of studying the relationship between reduced systolic heart function and increased risk of renal failure in patients with CHF in East Kazakhstan region. The purpose of the study is to study clinical and laboratory characteristics and analyze cardiorenal relationships in patients with CHF with a reduced ejection fraction (EF).

Chronic heart failure is a pathological condition when the cardiovascular system is unable to provide the body with the necessary amount of oxygen [10]. As a result of the CHF development, the heart muscles are damaged and lose the ability to stretch and pump the necessary amount of blood for the body. CHF is not an independent disease, it is a complication of cardiac diseases [8]. Thus, CHF is a symptom complex of severe shortness of breath at rest or during exercise, fatigue, palpitations and decreased physical activity. Due to insufficient blood supply to organs and tissues, with the progression of heart failure (HF), fluid retention in the body is observed (the presence of edematous syndrome). HF develops slowly and in the initial stages manifests itself only with physical exertion, and if the above symptoms manifest themselves at rest, then the stage of the disease is severe [6]. Progressing, CHF leads to a decrease in renal function [5].

Echocardiography (EchoCG) is necessary for the CHF diagnostics. It allows us to see the work of all heart parts and gives possibility to assess the systolic function [7]. The ejection fraction (EF) is the most important parameter in the diagnosis of CHF. Normally, EF corresponds to 60-70%, and in case of heart failure it decreases to 40%. The lower the ejection fraction, the more severe the degree of cardiac dysfunction. Thus, echocardiography helps to diagnose the severity and etiology of CHF.

Moreover, there is a biomarker for diagnosing the severity of CHF, such as brain natriuretic propeptide (NT-proBNP) [3]. NT-proBNP is a protein that forms in the myocardium when it is overstretched and overloaded. An increase in the level of NT-proBNP in the blood shows that cardiac overload is stronger [9]. This is how the severity of heart failure is determined.

Methods and materials. A cross-sectional study of the adult population of Oskemen city. The sample consisted of 342 inpatient patients hospitalized in the cardiology department of the “Hospital No.4 of Oskemen” for the period 2021-2023 with a diagnosis of CHF.

Inclusion criteria: inpatient patients with CHF 35-85 years old, men and women. Exclusion criteria: diabetes mellitus, primary pathology of the kidneys and urinary tract, oncological and systemic diseases with manifestations of nephropathy.

Ethical issues of the study: Informed consent was obtained from the participants of the study, patients are aware of the methods and possible consequences of the study. Before the start of the study, the conclusion of the local ethics committee of the "Semey medical university" was received (Protocol No.1 from 10/22/2022). During retrospective analytical study, the analysis of medical records carried out, the clinical and laboratory characteristics of inpatient patients with CHF analyzed.

The socio-demographic and anthropometric (height, weight, body mass index (BMI)) data of patients were evaluated. General clinical studies conducted: a survey (the presence of shortness of breath in patients), a physical examination (the presence of peripheral edema), blood pressure (BP) measurement on both hands using the Korotkov method.

For the laboratory and instrumental stage: biochemical studies were performed on the Mindray BS-200 analyzer: creatinine concentration was determined using laboratory kits Bеckman (norm – men: 53-106 mmol/l; women: 44-97 mmol/l); the level of terminal propeptide natriuretic hormone (NT-proBNP) in blood serum was determined on an automatic enzyme immunoassay the Finecare FIA Meter analyzer (the norm is from 0 to 125 pg/ml). The functional ability of the kidneys in patients was determined by the level of creatinine in the blood and the glomerular filtration rate (GFR). GFR was calculated by creatinine level according to the formula CKD-EPI (2021). This equation was used to calculate GFR, when compared with other formulas, CKD-EPI shows fewer false-positive results indicating chronic kidney disease. Ultrasound of the heart was performed on a LOGIQ e R8 device from General Electric (USA) according to a standard procedure. LV systolic function was considered to be preserved (normal) with an ejection fraction (EF) of more than 50%.

The statistical analysis was carried out using the statistical software package SPSS 20 (IBM Statistical) for Windows (USA), MS Excel XP. The results are presented in the form of arithmetic mean (M) and mean standard deviation (SD).

Results and discussions. The average age of patients with CHF was 59.51±11.85 years old; the number of respondents over 60 years old was 81.6%, so CHF is more common in adults over 60 years old. Men (54.8%) and women (45.2%) in the sample made up an almost equal number. Arterial hypertension was the leader in terms of the frequency of concomitant pathology – 53.8%, obesity as a concomitant disease occurred in 41.2% of patients, coronary heart disease, a history of heart attack, atrial fibrillation, and heart defects also occurred in the group of patients with CHF.

Now Echocardiography (EchoCG) is a mandatory and main method of CHF diagnostics. However, the results of echocardiography should always be compared with the clinical picture of the disease and data from other laboratory and other instrumental research methods. According to the results of EchoCG, the maximum number of patients 40.5% (n=138) belonged to the group with preserved (normal) LVEF (>50%), 31.9% (n=109) of patients with moderately reduced LVEF (41-49%), and 94 (27.6%) of patients with patients with low LVEF. Thus, a decrease in the left ventricular ejection fraction was noted in the majority of 247 (59.5%) patients with CHF, while the remaining 138 (40.5%) patients showed preserved LVEF. And also, almost all (83%) patients with CHF had quantitative signs of left ventricular hypertrophy.

GFR calculated and distributed by levels: the maximum number of patients n=121 (36%) belongs to the group with a slight decrease in GFR (60-89 ml/min/1.73m²), 19.3% patients (n=65) are with normal or elevated (>90 ml/min/1.73m²), and in 113 patients (33.6%) the average degree of calculated GFR showed a decreased level (30-59 ml/min/1.73 m²). Also, 8.3% of patients (n=28) had a sharp decrease in GFR (15-29 ml/min/1.73m²), 8 patients (2.4%) were diagnosed with terminal renal insufficiency with GFR <15ml/min/1.73m². Also, the average GFR was calculated using the CKD-EPI formula: in men 72.7±28.35 ml/min/m² and in women 56.6±24.97 ml/min/m², whereas in patients with low LVEF, the average GFR was 64.2±29.1 ml/min/m². Renal dysfunction has a significant (80.6%) prevalence among patients with CHF. And a decrease in GFR calculated according to the CKD-EPI formula <60 ml/min/1.73m² was detected in 149 patients (43.5%). Renal dysfunction progresses during CHF and is a serious comorbid condition of CHF.

According to the results of laboratory data, the average level of NT-proBNP in the blood of patients with reduced LVEF (<49%) was 7769.08±8181.26 pg/ml, whereas in patients with preserved LVEF (>50%) it showed 5255.18±7694.84 pg/ml. Thus, if the data are closer to normal concentrations of NT-proBNP, we exclude the chronic course of HF and are more inclined to acute HF, but if we observe a high level of NT-proBNP, this tells us about the chronic stage of HF.

Conclusions. Elderly and senile people prevailed among patients with renal dysfunction on the background of CHF. Most patients with CHF in our study had signs of RD, even if there were no clinical manifestations. Thus, we were unable to trace what is the cause and what is the effect. With a pronounced violation of the contractility of the LV myocardium, there is a tendency to decrease GFR.

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