Introduction

Congestive heart failure is a condition caused by impaired cardiac pumping ¹. It can be caused by ischemic heart diseases, myocardial infarction, hypertension, valvular heart diseases, alcoholism, infections, among others ². It is a costly and high-mortality disease with a risk of death similar to that of some neoplasms ³. Its prevalence rates are increasing worldwide, thus being considered a global epidemic with 17 million deaths per year ⁴. It affects approximately 64 million people ⁵, mainly in developed countries such as the United States, where almost 6 million people and 550,000 new cases per year suffer from this disease ⁶. However, in developing countries, its occurrence increasingly growing due to the higher rate of life expectancy and diseases such as diabetes, hypertension, dyslipidemia and obesity ⁷. Its prevalence is increasing in Peru, especially in adults aged over 65 years, with high mortality rates in the first year (70 %) ⁸.

The adverse role of anemia in heart failure, which leads to a hyperhemodynamic state, has been widely studied ⁹. In addition, the excess of compensatory cardiac work to provide oxygen to the body affects the sympathetic nervous activity and tone ¹⁰, thus contributing to myocardial remodeling ¹¹.

Additionally, it has been suggested that gastrointestinal edema affects iron absorption ¹², which is also affected by inflammatory cytokines—including interleukins 1 and 6— together with tumor necrosis factor alpha ¹³, which promote iron storage in the reticuloendothelial system ¹⁴ and affect its utilization. Moreover, interleukin 6 would affect erythropoiesis in the bone marrow ¹⁵. On the other hand, it has been observed that folic acid or vitamin B12 deficiency does not significantly contribute to anemia associated with heart failure ¹⁶. Likewise, the role of angiotensin II in red blood cell production—either by stimulation of erythropoiesis or by direct effects on erythropoiesis in the bone marrow—has been proposed, although there is still no consensus on this topic ¹⁷. The coexistence of heart failure and chronic renal disease increases the risk of anemia; it has been observed that reduced hemoglobin levels are similar to reduced glomerular filtration rates ¹⁸. Possible iatrogenic mechanisms such as the use of antithrombotic drugs, which might cause minor gastrointestinal bleeding that could contribute to anemia, have also been proposed ¹⁹.

In spite of several studies on the influence of anemia on morbidity and mortality in heart failure, there is no agreement on the prognostic value of this disease ²⁰. Research on congestive heart failure in Peru, mainly aimed at understanding the clinical course of the disease, has increased in the last 20 years ²¹. Therefore, the objective of the present research is to determine the risk of death from congestive heart failure among patients with anemia. This will allow us to establish its impact on mortality among patients with low red blood cell count: an issue that is still in search of consensus in the international medical community and that has been little researched in the Peruvian population.

Materials and methods

Results

Congestive heart failure was the immediate cause of death in 62.80 % of patients with anemia in contrast to 13.20 % of those who died without recorded anemia (Table 1).

The variables were statistically related and, according to phi and Cramér's V correlation coefficients, there was a moderate relationship. People with anemia had 11.14 times higher risk of dying from underlying congestive heart failure (Table 2).

Discussion

Anemia was moderately and positively associated with death from congestive heart failure, and the rate of death was high compared with that of patients with comorbidities other than anemia. This agrees with Abebe et al. who, in a study on the prevalence of anemia among patients with heart failure and on the outcomes of patients with severe heart failure with and without anemia admitted to a hospital in Ethiopia, found a prevalence of 45 % of patients with anemia and heart failure ²⁴. Ikama et al., in a study on the prevalence of anemia among patients with heart failure conducted in a university hospital in Congo, estimated a prevalence of 42 % ²⁵. Cleland et al., in a study on the prevalence and outcome of anemia and hematinic deficiencies

among patients with chronic heart failure, found that 68 % of the patients had anemia and congestive heart failure ²⁶. In general, the actual frequency of anemia among patients with heart failure depends on the definition and ranges according to the particular population and demographics of each country. The cut-off point for delimiting normal values and anemia is the one defined by the World Health Organization (WHO) ²⁷, which is a generalized value that does not consider a specific adjustment for congestive heart failure; i.e., the definition of anemia by the WHO has not been validated for patients with congestive heart failure.

Patients with anemia had a high risk of dying from underlying heart failure. The results agree with the study by Casas et

al. who, in an article on anemia as a predictor of heart failure mortality in a hospital in Lima, Peru, found 2.82 times higher probability of death from congestive heart failure in those who had anemia ²⁸. Armas et al., in an article aimed to determine the association between anemia and cardiovascular mortality 30 days after admission for heart failure in an emergency hospital in Peru, found 3 times higher risk of death in the presence of anemia ²⁹. Romero et al., in a study on anemia as a risk factor for mortality among patients with heart failure hospitalized in Trujillo, Peru, found 5 times higher risk of death among patients with anemia ³⁰. The preceding research works agreed that a relationship exists. However, the absolute and relative risks were lower than those found in the present study, where there was an 11 times higher absolute risk of death. This could be due to the methodological design and the sample size of this research since it consisted of a population of 35,724 people, out of whom 1,003 had anemia, compared to the abovementioned studies whose sample size was around 100 patients.

The limitations of this study were related to the methodological design: there was no sample calculation since the entire available population was included in the research based on the inclusion criteria; i.e., convenience sampling was used. Moreover, due to the nature of the data source, it is possible that there were other comorbidities in addition to anemia and heart failure which were not recorded in the SINADEF and could have caused complications and accelerated death.

In conclusion, anemia increases the risk of death from congestive heart failure in the Peruvian population. It is necessary to monitor iron, hemoglobin and red blood cell levels among patients with heart failure, as well as to identify the causes of these deficiencies, in order to reduce morbidity and mortality associated with congestive heart failure in this group of patients.