Major clinical characteristics of patients surviving 24 months or more after hospitalization due to decompensated heart failure

Abstracts

OBJETIVO: Estudar as principais características clínicas dos pacientes com insuficiência cardíaca sobreviventes há mais de 24 meses após hospitalização para compensação. MÉTODOS: Estudados 126 pacientes com insuficiência cardíaca, em classe funcional III ou IV, com idade média de 51,7 anos, a maioria homens (73%), com fração de ejeção (FE) média de 0,36 e diâmetro diastólico (DD) do VE de 7,13 cm. Avaliaram-se as principais características clínicas e laboratoriais e no seguimento identificaram-se 25 (19.8%) pacientes que sobreviveram mais de 24 meses após a alta hospitalar. Compararam-se os dados dos sobreviventes (G1) aos dos que faleceram (G2) antes de 24 meses. RESULTADOS: No G1 encontraram-se níveis mais elevados do sódio sérico (138,3±3,4 vs 134,5±5,8 mEq/l; p=0,001), da pressão arterial (120,0 vs 96,7 mmHg; p=0,003) e da FE do VE (0,40±0,08 vs 0,34±0,09; p=0,004) e valores menores da uréia (59,8 vs 76,3 mg/dl; p=0,007), do tempo de protrombina (12,9 vs 14,8s; p=0,001), do DDVE (6,78±0,55 vs 7,22±0,91; p=0,003) e do diâmetro do AE (4,77 vs 4,99cm; p=0,0003). Houve mais sobreviventes entre os portadores de cardiomiopatia idiopática e hipertensiva do que entre os chagásicos e doença coronariana. Na análise multivariada permaneceram como variáveis preditoras independentes da mortalidade o DDVE > 7,8 cm (HR 1,95), o Na < 132 mEq/l (HR 2,30) e o tempo de protrombina > 14 seg (HR 1,69). CONCLUSÃO: O estudo permite predizer quais os pacientes com insuficiência cardíaca que poderão apresentar uma boa sobrevida após a alta e os com maior possibilidade de longa sobrevivência após a alta.

insuficiência cardíaca avançada; disfunção sistólica ventricular; sobrevida; hiponatremia e choque

ORIGINAL ARTICLE

Major clinical characteristics of patients surviving 24 months or more after hospitalization due to decompensated heart failure

Mucio Tavares de Oliveira Jr; Manoel Fernandes Canesin; Robson Tadeu Munhoz; Carlos Henrique Del Carlo; Airton Scipioni; José Antonio Franchini Ramires; Antonio Carlos Pereira Barretto

São Paulo, SP - Brazil

Instituto do Coração do Hospital das Clínicas da FMUSP

^{Correspondence}

ABSTRACT

OBJECTIVE: To study the major clinical characteristics of patients with heart failure who survived more than 24 months after hospitalization for compensation.

METHODS: The study comprised 126 patients with heart failure in functional class III or IV, with a mean age of 51.7 years. Most patients were men (73%), had a mean ejection fraction (EF) of 0.36 and left ventricular diastolic diameter (DD) of 7.13 cm. The major clinical and laboratory characteristics were assessed, and, on follow-up, 25 (19.8%) patients, who survived more than 24 months after hospital discharge, were identified. Data of survivors (G1) were compared with those of patients who died (G2) before 24 months.

RESULTS: In G1, the following levels were greater: serum sodium (138.3±3.4 vs 134.5±5.8 mEq/L; P=0.001); blood pressure levels (120.0 vs 96.7 mm Hg; P=0.003); and LVEF levels (0.40±0.08 vs 0.34±0.09; P=0.004); and the following levels were lower: urea (59.8 vs 76.3 mg/dL; P=0.007); prothrombin time (12.9 vs 14.8 seconds; P=0.001); LVDD (6.78±0.55 vs 7.22±0.91; P=0.003); and LA diameter (4.77 vs 4.99cm; P=0.0003). More survivors were found among patients with idiopathic cardiomyopathy and arterial hypertension than among patients with Chagas' disease and coronary artery disease. In multivariate analysis, the following variables remained as independent predictors of mortality: LVDD > 7.8 cm (HR 1.95); Na < 132 mEq/L (HR 2.30); and prothrombin time > 14 seconds (HR 1.69).

CONCLUSION: The study allowed predicting which patients with heart failure will have a good survival after hospital discharge and those with a greater chance of a long survival after discharge.

Key words: advanced heart failure, ventricular systolic dysfunction, survival, hyponatremia, shock

Heart failure is currently recognized as a disease with a poor prognosis ^1-5. Initially, the disease evolves insidiously, but as patients become symptomatic, the prognosis becomes poor. Its advanced form has characteristics of malignancy and results in a shorter survival than different types of cancer ⁶.

In the natural history of heart failure, the need for hospitalization for compensation is associated with a greater heart impairment and failure of the mechanisms of compensation. The patients are hospitalized, have a poorer evolution, and their mortality is 2 to 3 times greater than that of those who require no hospitalization ^3,7-10. At our institution, we treat patients with heart failure who need hospitalization for compensation, a group with disease of greater severity and a worse prognosis.

We have observed that the survival of those patients, even with the new therapeutic schedules, remains small with less than 50% survival in the first year after hospital discharge ^11,12. However, some patients seem to challenge those results, surviving several years after hospitalization.

This study aimed at assessing the characteristics of patients with advanced heart failure hospitalized for compensation who survived longer (more than 2 years).

Methods

This study comprised 126 patients with heart failure in NYHA functional class IV nonconsecutively treated at the emergency unit of InCor. They were hospitalized for compensation at the Hospital Auxiliar de Cotoxó during the period 12/12/1993 to 09/25/1995. The patients had left ventricular dysfunction, signs of pulmonary and hepatic congestion, lower limb edema, and had been medicated at the emergency unit. Because their symptoms were not controlled with the therapy administered, they were hospitalized.

The inclusion criterion was the presence of systolic ventricular dysfunction of any etiology identified by values below 55% (cube method). The exclusion criteria were as follows: patients who died within the first 24 hours and those with acute coronary syndrome, valvular heart diseases with a surgical indication, congenital heart diseases, chronic renal failure or serum creatinine > 2.5 mg/dL, and fatal noncardiac diseases. All patients were clinically assessed on the day of hospitalization and underwent laboratory and echocardiographic assessments.

The major clinical characteristics of the population studied are shown in table I.

Table II

Most patients were of the male sex (73%). The patients' mean age was 51.1±14.2 years. Chagas' disease was the major etiology of ventricular dysfunction (44.4%). Shock was present in 31.7% of patients. On echocardiography, the mean left ventricular diameter was 7.14±0.9 cm, the ejection fraction was 0.36± 0.09, and 80.9% of patients had moderate or important mitral regurgitation.

The renal function was reduced in most patients, with mean levels of urea and creatinine of 73.1±29.4 mg/dL and 1.48±0.39 mg/dL, respectively.

The patients were followed up at the outpatient care clinic of InCor after hospital discharge. All those who were not followed up at InCor were contacted (or their relatives) at the end of 1998 for assessing their clinical situation or death. The mean follow-up time was 15.3 ± 13.8 months.

As the study's objective was to assess the basal clinical characteristics of the patients who survived more than 2 years, the patients were divided into 2 groups: 1) group 1, comprising those who remained alive after 2 years; and group 2, comprising those who died within 2 years of follow-up.

The statistical analysis comprised the calculation of the mean, standard deviation, and minimum and maximum values of the continuous variables. The categorical variables were presented as frequency and percentage.

The 2 groups were compared; the Student t test was used for the continuous variables and the chi-square test was used for the categorical variables. For determining the predictors of mortality during the follow-up period, multiple regression analysis was performed with the Cox proportional hazards model, which was adjusted according to the clinical and laboratory characteristics of that population. The criterion used for selecting the variables in the multiple model was P<0.200 in the univariate analysis. The final model was constructed according to the Stepwise Forward technique, and the variables were maintained in the final model when the P value was <0.050. The Kaplan-Meier method was used for describing the survival rates for the relevant variables determined by regression analysis. The difference of survival between the groups was determined by the log-rank test. In all steps of the analysis, the significance level of 5% was adopted.

Results

On follow-up, 25 (19.8%) patients who survived more than 24 months after hospital discharge were identified. The major characteristics of the 2 groups are shown in table III.

No difference was found between the groups regarding age and sex. On univariate analysis, the following conditions were identified as predictors of mortality: Chagas' disease; reduced systolic blood pressure; reduced mean blood pressure; shock; left ventricular diastolic diameter greater than 7.8 cm; left atrial diameter greater than 5.7 cm; ejection fraction lower than 0.30; plasma sodium lower than 132 mEq/L; urea level greater than 55 mg/dL; and prothrombin time greater than 14 seconds (tab. IV).

No patient with ventricular diameter greater than 7.80 cm, left atrial diameter greater than 5.70 cm, ejection fraction lower than 0.30, and sodium level below 132 mEq/L was alive 24 months after hospital discharge (fig. 1, 2, and ³).

On multiple regression analysis using the proportional hazards model, the following variables remained in the model as independent variables: left ventricular diastolic diameter greater than 7.8 cm (HR 1.95; P=0.009); plasma sodium lower than 132 mEq/L (HR 2.30; P<0.001); and prothrombin time greater than 14 seconds (HR 1.69; P=0.014) (fig. 4).

Discussion

Patients with heart failure who require hospitalization for compensation usually have the advanced form of the disease, and evolve with higher mortality rates than that of those who remained compensated on an outpatient care basis only ^{1-5, 7-10}.

In population-based studies, 10% to 20% of patients with heart failure die in the first year of evolution, and this number may reach 50% in a 5-year follow-up ^1-5. When analyzing the survival of patients hospitalized with heart failure, the numbers are not encouraging, with a 30 to 40% mortality in the first year of follow-up ^7-10.

The patients in this study originated from the emergency unit and were transferred to the ward when not compensated after emergency medication. The nonresponse to diuretics in the emergency treatment indicated the most severely ill patients. In this study, 60% of the patients died during the first year of follow-up, evidencing a population with severe disease. Our findings are in accordance with the literature that signals that the advanced form of heart failure is a disease with malignant characteristics ⁶.

The population in this study seems more severely ill than those usually described in epidemiological studies, or even in large assays, because no study reported mortality greater than 50% ^{1-5,7-10,13,14}.

Although the population had great cardiac impairment, 19.8% of the patients survived more than 2 years. The survivors differed from those who died because, on clinical and laboratory examination on admission, they had higher blood pressure, a lower incidence of shock or hypotension, smaller left ventricular and atrial dilation, greater left ventricular ejection fraction, normal sodium levels, [Which is better? See change.] minor impairment in renal function, and normal prothrombin time.

The predictive factors of good or poor evolution are related to the pathophysiology of heart failure and to the mechanisms of disease progression ^15-18.

The result of this study is relevant, because it shows that, through clinical assessment and routine laboratory tests, the population could be stratified and the patients with better evolution potential could be identified. This information has great practical connotations, because, as the patients with good evolution potential are identified, those with poor evolution potential are also identified. The latter are those who should be carefully followed up and who are the major candidates for heart transplantation or more aggressive procedures, necessary for trying to change the evolution of the disease.

The presence of hypotension or shock was an important predictor of poor outcome. The patients who manage to maintain arterial blood pressure signal a greater cardiac reserve, a fact associated with a better prognosis. In the literature, the reduction in blood pressure is identified as an independent prognostic factor in the studies with a population of patients hospitalized due to heart failure ^3,7,19. Blood pressure levels < 100 mm Hg are associated with greater mortality ^3,7,19.

Cardiac function is another important prognostic determinant^5,10,15,16. Our data show that patients with greater cardiac impairment, smaller cardiac dilation, and greater ejection fraction survive longer. This shows that for the population of patients with advanced heart failure, cardiac remodeling, which is more and more identified as a mechanism of disease progression, plays an unquestionable role in the natural history of the disease ^{5,10,15,16,20}. The patients with left ventricular diastolic diameter > 7.8 cm had a risk of death almost two times greater than that of patients with smaller dilation (HR 1.95) (fig. 1).

In laboratory tests, hyponatremia, an elevation in urea, and a more prolonged prothrombin time were associated with a worse prognosis. The surviving patients had no significant alterations in those tests. In the literature, hyponatremia and renal failure are frequently identified as independent predictors of the evolution of patients with heart failure ^{3,5,7,10,18-22}. Hyponatremia results from an increased neurohormonal stimulation, is always an important factor in prognostic stratification, and is frequently recognized as the most powerful factor for identifying those with the worst prognosis ^5,7,10,18-20. In the population studied, considering p level and the result of multivariate analysis, sodium was the factor with the greatest statistical expression, emphasizing the increased neurohormonal stimulation as an important prognostic determinant. Patients with hyponatremia had a 2.3-fold greater risk of death than those with normal sodium levels (fig. 2).

The presence of renal failure is frequently identified as an important prognostic factor in patients with heart failure, inducing an increase in mortality directly proportional to the degree of renal dysfunction ^{3,5,7,10,20-22}.

Both the elevation in urea level and the extension of the prothrombin time result from low cardiac output and hepatic congestion in association with the cardiac dysfunction characteristic of heart failure ^{3,5,7,10,19,20}. In multivariate analysis, a prothrombin time greater than 14 seconds identified patients with a 1.69-fold greater risk of death than those with a prothrombin time not so prolonged (fig. 4).

When comparing the values found in the 2 groups of patients (survivors and nonsurvivors), some of the variables showed nonoverlapping values, which allowed the selection of values that identified severely ill patients, because the values were not found in any survivor. Thus, left ventricular dilation greater than 7.8 cm identified patients who died without completing 2 years of survival; the same occurred for an ejection fraction lower than 0.30 and for a plasma sodium level lower than 132 mEq/L (fig. 1, 2 and ³).

Two studies, a Brazilian and a Canadian, that assessed the evolution of patients treated at an emergency unit also identified hyponatremia as an important independent predictor of poor evolution ^19,20. Hypotension, depressed renal function, and ventricular dilation were also identified as predictors of a bad evolution, suggesting that the variables identified are strong predictors of evolution in patients with decompensated heart failure and deserve the attention of the clinicians treating patients in this phase of the disease.

This study has limitations, such as the fact that most patients, although medicated with ACE inhibitors, were not receiving beta-blockers. Prescription of the latter might have allowed a greater number of patients to survive more than 24 months, and the variables identified as prognostic to have other values.

The recognition of the importance of the participation of cardiac remodeling, neurohormonal alterations, venous congestion and renal failure in determining the prognosis reinforces the role of the treatment for heart failure with neurohormonal blockers (angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, and aldosterone blockers) and beta-blockers, which are known to modify the identified factors, altering the evolution of the disease.

In conclusion, 19.8% of the patients with advanced heart failure survive more than 24 months after hospitalization for compensation. In patients hospitalized for decompensation, the parameters of cardiac remodeling, the sodium and urea levels, and the prothrombin time allow the identification of those with the greatest chances of surviving longer after hospital discharge. Assessment through clinical parameters and simple laboratory tests allows the stratification of patients with heart failure and the recognition of those who will have a better outcome.

References

Received for publication: 01/26/2004

Accepted for publication: 06/16/2004

English version by Stela Maris Costalonga

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Publication Dates

• Publication in this collection
  08 Mar 2005
• Date of issue
  Feb 2005

History

• Accepted
  16 June 2004
• Received
  26 Jan 2004