|Year : 2017 | Volume
| Issue : 2 | Page : 50-55
A single-center, cross-sectional, observational study of heart failure patients
UM Nagamalesh, K C Karthik Naidu, VS Prakash, Anupama V Hegde, P Kamaldeep
Department of Cardiology, MS Ramaiah Memorial Hospital, MS Ramaiah Medical College, Bengaluru, Karnataka, India
|Date of Web Publication||31-Mar-2017|
U M Nagamalesh
Department of Cardiology, MS Ramaiah Memorial Hospital, MS Ramaiah Medical College, MSRIT Post, New BEL Road, Bengaluru - 560 054, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: Heart failure (HF) is an important emerging public health problem of the modern world. The scenario of HF in developing and underdeveloped countries is largely unknown. This study was carried out to understand the clinical profile of HF patients treated at a tertiary care center.
Methods: It was a single-center, prospective, observational study carried out during the period 2011–2012 at MS Ramaiah Memorial Hospital, Bengaluru. All the patients admitted to the cardiology unit with a diagnosis of HF were selected, and baseline patient characteristics were noted. Patients were investigated as per the clinical need and data documented.
Results: Of the 97 patients included, 41 (42.3%) were female, and 56 (57.7%) were male. Majority belonged to 65–79 years age group (59.79%) and octogenarians constituted 15.46% of our study participants. Almost all the males (94.64%) were overweight (body mass index between 25 and 29.9 kg/m2), whereas 48.78% females were overweight, 12.19% belonged to obesity Class I. 85.37% females had the waist circumference >80 cm and 73.21% males >90 cm. Hypertension (79.38%), diabetes mellitus (DM) (62.89%), and coronary artery disease (CAD) (44.33%) were the commonly associated comorbidities. Among other factors studied, anemia was seen in 24.39% female, and 32.14% of male patients.
Conclusion: This study showed that a significant proportion of inpatients belonged to elderly age group. Octogenarians also formed a sizeable proportion of patients. Hypertension, CAD, DM, overweight, and anemia were identified as the commonly associated comorbidities and understanding the complex interplay of these factors to plan optimal treatment strategy is of great challenge to the physician, especially when dealing with the elderly and very elderly group.
Keywords: Anemia, diastolic, epidemiology, heart failure, systolic
|How to cite this article:|
Nagamalesh U M, Naidu K C, Prakash V S, Hegde AV, Kamaldeep P. A single-center, cross-sectional, observational study of heart failure patients. J Clin Prev Cardiol 2017;6:50-5
|How to cite this URL:|
Nagamalesh U M, Naidu K C, Prakash V S, Hegde AV, Kamaldeep P. A single-center, cross-sectional, observational study of heart failure patients. J Clin Prev Cardiol [serial online] 2017 [cited 2019 Aug 25];6:50-5. Available from: http://www.jcpconline.org/text.asp?2017/6/2/50/203531
| Introduction|| |
Heart failure (HF) is a complex clinical syndrome resulting from any structural or functional impairment of ventricular filling or ejection of blood. It causes substantial morbidity, mortality, and health-care expenditure. The data from the American Heart Association (AHA) estimated a prevalence of 5.1 million individuals with HF in the United States alone between 2007 and 2012. Projections show that the prevalence will increase by 46% between 2012 and 2030, resulting in more than 8 million individuals above the age of 18 years by 2030 to be living with HF. The recent Indian data are largely lacking in this regard although one report estimated the prevalence to range from 1.3 to 4.6 million, with an annual incidence of 491,600–1.8 million. This void of epidemiological data further imposes greater challenge toward implementing an effective health-care delivery system to manage this clinical condition resulting in significant morbidity, mortality, and health-care costs.
We set out to understand the clinical profile of patients with HF admitted in our institution during the period 2011–2012.
| Methods|| |
It was a single-center, prospective, observational study conducted at M. S. Ramaiah Memorial Hospital, Bengaluru, India, during the period 2011–2012. During the study period, we chose all the newly diagnosed cases of HF admitted in the Department of Cardiology with the symptoms of HF. We excluded patients with an established diagnosis of HF before admission and patients who were evaluated elsewhere and put on treatment before referral to our center. We also excluded patients who left the hospital or died before a complete evaluation or patients with incomplete data. A total of 97 patients were finally included in our study after meeting the inclusion-exclusion criteria. Informed consent was taken from all the patients included in the study.
Clinical profile of all the patients admitted with HF was recorded. Patients were subjected to the following investigations: Complete blood count, renal function tests, serum electrolytes, fasting lipid profile, electrocardiogram, two-dimensional (2D) echocardiogram (ECG), and chest X-ray. Other investigations such as serum troponin, N-terminal pro-B type natriuretic peptide (NT Pro BNP), anemia profile, and coronary angiogram were done as per the clinical need.
The diagnosis of HF was confirmed clinically by applying Framingham criteria., Once diagnosed the severity and staging of HF were made using the New York Heart Association (NYHA) and ACC/AHA  classification criteria, respectively.
Data were tabulated and analyzed using SPSS software version 20.0 (IBM) and results were reported.
| Results|| |
Of the 97 patients included, 41 (42.3%) were female, and 56 (57.7%) were male. The majority of the patients belonged to 65–79 years age group (59.79%). Octogenarians constituted 15.46% of the admitted patients (11 males and 4 females) [Table 1].
The range, mean, and median of weight (in kg) and height (in cm) for females were 45–90 kg, 61.54 kg, and 58 kg and 100–165 cm, 150.85 cm, and 151 cm, respectively [Table 2]. Similarly, the range, mean, and median of weight (kg) and height (cm) or male patients were 54–104 kg, 71.34 kg, and 71.5 kg and 150–190 cm, 161.95 cm, and 160 cm, respectively [Table 2]. Almost all the males (94.64%) were overweight with body mass index (BMI) between 25 and 29.9 kg/m 2. 48.78% females were overweight and 12.19% belonged to obesity Class I. Waist circumference measurement showed that 85.37% females had the waist circumference >80 cm and 73.21% males had waist circumference >90 cm (abdominal obesity cutoff as per the International Guidelines for South Asian Population) [Table 3].
Hypertension and diabetes mellitus (DM) were the most commonly identified comorbidities in our study population occurring in 79.38% and 62.89% patients, respectively. 44.3% of our study participants had coronary artery disease (CAD). Valvular heart disease was reported in 5.15% of patients and tachycardiomyopathy was reported in 3.1% of total patients (Refer [Figure 1]).
In addition, we also analyzed other common medical comorbidities such as chronic airway disease, asthma, anemia, renal failure, and others. The details on the incidence of these comorbidities in our study group are presented in [Table 4].
Symptom analysis of the study population showed that dyspnea and chest pain were the two most common symptoms. Ninety-five percent (n = 39) of female patients and 92.85% (n = 52) of male patients reported dyspnea in this study. Among the female patients, 66.67% reported dyspnea of NYHA Class III and above at the presentation, and the symptom was predominantly noticed in the elderly group (58.97%, n = 23). Out of the 52 males who reported dyspnea, 57.89% (n = 33) had dyspnea of NYHA Class III and above at presentation with 38.46% (n = 20) being >65 years. A total of 19 (19.58%) patients reported chest pain as a symptom at the initial presentation, of which 17 (17.52%) were diagnosed as having angiographically proven CAD. The decision to subject them for coronary angiography was based on a combination of clinical assessment, ECG, cardiac troponin test, and 2D echocardiography.
Analysis of patients with anemia was another important component of our study design. As per the WHO definition, hemoglobin level <12 g/dL for females and <13 g/dL for males was considered as the presence of anemia. The analysis showed that 24.39% (n = 10) of the total female population and 32.14% (n = 18) of the males were anemic at the time of admission, and all of them were over 65 years of age. It was also observed that the severity of anemia was directly associated with severity of HF symptoms at presentation. Four of our patients with hemoglobin levels <8 g/dL presented with NYHA Class III or > symptoms at the first clinical assessment. Patients with hemoglobin levels <10.9 g/dL were subjected to anemia profile and peripheral smear examination. All these patients had lower mean serum total iron and percent transferrin saturation with normal serum ferritin and total iron binding capacity (TIBC) levels [Table 5].
NT Pro-BNP levels were assessed in all the patients at the time of initial assessment, and it was observed that it varied widely from as low as 300 pg/mL to as high as 35,000 pg/mL in both the subsets of patients.
The data on lipid profile was available in 25 (60.97%) female and 36 (64.28%) male patients [Table 6]. No serious dyslipidemia was noted in any of the patients with the average values being within the clinically desirable and acceptable limits. This could be partly because majority of the patients were already on diet and lifestyle modifications with or without statins.
Echocardiography suggestive of HF with preserved ejection fraction (EF) (diastolic dysfunction) was noted in 28 (28.88%) patients. Out of these, 75% (n = 21) had Grade I left ventricular (LV) diastolic dysfunction while the remainder had Grade II LV diastolic dysfunction. Totally, 29, i.e., 29.9% patients had regional wall motion abnormalities on echocardiography predominantly involving the anterior, septal, and lateral wall. Global hypokinesia on echocardiography was observed in 15.46% and inferior and posterior wall hypokinesia seen in 6.2% patients. Echocardiographic EF ranged from 25% to 58%.
The most commonly used drugs for HF were diuretics (mainly loop diuretic furosemide) (100%), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (80%), and beta-blockers (75%). Some patients were also given vasodilators and/or calcium channel blockers.
Majority of patients, i.e., 90 (92.78%) reported improvement in functional class at the time of discharge. During the study period, 4 mortalities were reported, and all were due to systemic sepsis and multiorgan failure.
| Discussion|| |
HF is a major and growing public health problem worldwide, with high morbidity, mortality, and health-care cost due to repeated hospitalization. This is probably attributed to the paradigm shift in the epidemiology of CAD which was once a disease of the elderly is now affecting even younger population. Further, the therapeutic advances with increased longevity have resulted in increased incidence of HF.
The prevalence and incidence of HF progressively increase with age. In the US population-based study, the prevalence of HF was 0.7% in persons aged between 45 and 54 years, but it was 8.4% in those older than 75 years. The Framingham Heart Study found higher prevalence of HF in men and also reported favorable prognosis among women after the onset of symptomatic HF., In our study, we found that elderly (59.79%) and octogenarians (15.46%) constituted a significant proportion of those treated. These octogenarians are a very important subset of the population because of cooccurrence of multiple medical comorbidities sometimes masking or mimicking the symptoms of HF.
Overweight and obesity are the established risk factors for cardiovascular disease. In the Framingham Heart Study, risk of HF increased 5% in men and 7% in women per 1 kg/m 2 higher BMI, with obese participants (BMI ≥30.0 kg/m 2) having double the risk. Two other studies have shown, abdominal adiposity as measured by waist circumference seemed a better predictor for HF incidence than overall obesity., Both BMI and waist circumference have been shown to predict HF to a similar extent. In a study of elderly individuals with a history of CAD, waist circumference, but not BMI, was a risk factor for HF incidence. Evidence also suggests that Asians (including Indians) have more body fat for a given BMI than the Western population and thus at a higher risk of developing metabolic complications at a lower BMI.,, In our study, 48.78% of female patients and 94.64% of male patients were overweight with waist circumference of >80 cm in 85.37% females and >90 cm in 73.21% males. By 2015, 75% of the US adult population is projected to be overweight or obese. The data from our study shows that our study patients have already crossed the Western predictions with 94.64% males and 48.78% females being overweight with BMI between 25 and 29.9 kg/m 2.
The study also showed that hypertension, DM, and CAD were some of the common comorbid conditions in HF patients at the time of admission. Others were valvular heart diseases, cardiac dysrhythmias, myocarditis, and cardiomyopathies. Hypertension and valvular heart disease are significant risk factors, with relative risks of 1.4 and 1.46, respectively. DM which has already reached epidemic proportions in India, doubles the risk of HF by directly leading to cardiomyopathy and significantly contributing to CAD. It is also a strong risk factor for HF in women with CAD. HF is often considered a clinical syndrome with numerous associated medical comorbidities, especially in the elderly. A typical geriatric patient with HF usually has varied combination of CAD, hypertension, DM, atrial fibrillation, chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), depression and is usually on multiple medications. Our study population showed that hypertension and DM were observed in 79.38% and 62.89%, respectively. 44.3% patients had CAD while 9.28% had dilated cardiomyopathy. Tachycardiomyopathy was common in younger patients and was reported in 3.1% of patients with HF. Other comorbidities such as COPD (17.5%), anemia (28.86%), hypothyroidism (6.2%), and CKD (7.21%) were also common (Refer [Figure 1]).
Dyspnea as a symptom is reported in nearly all the patients with HF and is one of the most commonly used symptom to assess the severity of HF using NYHA scale. HF accounts for only 30% of the causes of dyspnea in the primary care setting. However, the absence of this symptom only slightly decreases the probability of HF and the presence of it adds a small probability benefit of diagnosing it (positive likelihood ratio [LR] = 2.2 and 2.6)., In our study, nearly 95% (n = 39) of female patients and 92.85% (n = 52) of male patients reported the symptom of dyspnea at presentation. A gender difference was also noticed in the patient population with respect to severity of dyspnea with nearly all the females over 65 years of age having NYHA Class III dyspnea at presentation as against males (38.46%) in the same age group. This could be partly due to the higher incidence of diastolic HF in this subset of the female population as 12 (36.36%) female patients (total n = 33) over 65 years were diagnosed with diastolic HF. It is reported that patients with diastolic HF are more likely to be women, to be older, and to have hypertension, atrial fibrillation, and LV hypertrophy, but no history of CAD.
As CAD is one of the common risk factors for HF, it is not uncommon for these patients to report the chest pain symptom. Often it is one of the primary reasons for these patients to seek medical attention. The presence of angina warrants a careful assessment of these patients as failure to diagnose CAD may lead to continuing myocardial damage, thus adversely affecting disease progression and prognosis. Our report shows that 19 (19.58%) patients reported chest pain as a symptom at the initial presentation, of which 17 (17.52%) had classical angina type of chest pain who on further evaluation had angiographically proven CAD requiring intervention.
The prevalence of anemia in HF ranges widely from 4% to 61% (median 18%). Our study used the WHO definition of anemia, taking into account known gender differences in the distribution of hemoglobin values. Most studies have shown an increased prevalence of anemia in HF populations with comorbid kidney disease and advanced age. These patients have more severe symptoms (range, 30%–61%) when compared with less symptomatic ambulatory populations (range, 4%–23%). We found a prevalence of anemia at 24.39% (n = 10) in females and 32.14% (n = 18) in the males, and it was very common in the elderly subset. Iron deficiency was present in <30% of anemic patients with congestive HF, so the majority of observed anemia was normocytic, often classified as anemia of chronic disease. About 16 (41.81%) patients had Hb <10.9 g/dL of the total 28 anemic patients in the study. The mean iron levels and transferrin saturation were low in this subset of the population. The females had a mean of 39.94 μg/dL (normal: 50–170 μg/dL) and 11.75% (normal: 15%–50%) of serum Iron levels and transferrin levels, respectively, whereas males had a mean of 43.8 μg/dL (normal: 65–177 μg/dL) and 17.12% (normal: 20%–50%), respectively. However, the mean TIBC and serum ferritin levels in females were 257.71 μg/dL (normal: 250–370 μg/dL) and 175.15 μg/L (normal: 15–150 μg/L) respectively, and in males, 275.91 μg/dL (normal: 250–370 μg/dL) and 245.84 μg/L (normal: 20–250 μg/L), respectively. The low serum iron and transferrin saturation and normal TIBC and serum ferritin levels suggested that these patients had both iron deficiency anemia and anemia of chronic illness.
NT-Pro BNP level estimation is an important bedside investigation to establish the diagnosis of HF with average cutoff levels for HF being 642 pg/mL. Multiple systematic reviews have concluded that NT pro-BNP levels can effectively rule out a diagnosis of HF, because of their NPV (negative LR = 0.1 and 0.14). NT-Pro BNP levels increases with age, are higher in women and blacks, and can be elevated in patients with renal failure, whereas obesity may result in unexpectedly lower BNP or NT-Pro BNP concentrations, even in those with HF., Among HF syndromes, systolic dysfunction and HF with preserved EF may cause elevated BNP or NT-Pro BNP although HF with preserved EF may be associated with lower values of both peptides than HF due to systolic dysfunction. In our study, NT Pro BNP levels ranged from 300 to 35,000 pg/mL. In patients with lower level of NT-Pro BNP, clinical judgment was an aid to establish the diagnosis of HF. We found that a rise in the levels of NT Pro BNP was a good indicator for HF, but the degree of rise in its levels was poorly correlated with clinical severity. No age or gender difference was noticed in our population, which was in disagreement with general consensus; however, the levels over 15,000 pg/ml were observed in patients with sepsis and renal failure. Although the exact reason for this disparity could not be elucidated, but a small sample size and lack of uniformity in sample collection time may be one possible explanation.
Dyslipidemia is considered as another important risk factor in HF resulting in increased morbidity, mortality, and frequent hospitalization rates. In our study, lipid profile estimation showed normal mean total cholesterol, low-density lipoprotein (LDL), and very LDL levels slightly decreased the levels of high-density lipoprotein. This was mainly because the majority of patients have been already on statin therapy at the time of evaluation.
In our study, 68.3% (n = 28) of the total female participants had EF <45% while 73.21% (n = 41) of the total males had EF <45%. Both regional wall motion abnormalities and global hypokinesia were commonly noted in our study population, indicating that LV systolic dysfunction was common in a significant proportion of patients and was commonly attributed to CAD. Echocardiographic diagnosis of diastolic HF was made in 29.26% (n = 12) female patients, and 28% (n = 16) males and all these patients were over the age of 65 years.
During the study period, four patients died due to severe sepsis (one patient) and multiorgan dysfunction (three Patients). The presence of cardiac dysfunction in sepsis has been associated with a very high mortality rate of 70%–90% compared with 20% in septic patients without cardiovascular impairment. Numerous studies have shown the relationship between sepsis and cardiac dysfunction. Due to the lack of adequate data from this subset of patients, no significant conclusions could be drawn.
Our study had several limitations. Small sample size was one of the biggest limiting factors to draw any conclusion. Cause and effect relationship between some of the comorbid medical condition and HF could not be drawn. Our study being a cross-sectional observational study, the etiological role of hypertension, DM, CAD, and other comorbid illness in HF could not be established. Lack of control population and long-term follow-up data further posed limitations in studying the relationship between comorbid medical illness and HF and the final outcome.
Inclusion of treatment naïve newly detected cases of HF in our study was another limitation as we excluded a significant proportion of established cases of HF. Our findings or results cannot be generalized to a real world population scenario. However, our study gives a fair idea of the clinical profile of an HF patient across various age groups and sex encountered in a hospital setting. A long-term follow-up study with a control population will reflect more details on predictors and outcomes for HF.
| Conclusion|| |
HF is becoming an increasingly common problem encountered in clinical practice. There is a significant lacuna in understanding the common mode of presentation of HF in the hospital setting, and the comorbidities that can predict the outcome.
Our study showed that the prevalence of HF is significant in elderly population with both systolic and diastolic dysfunction being common. Hypertension, DM, CAD, and anemia have been shown to be commonly associated with HF. NT Pro BNP, ECG, and 2D echocardiography have been valuable tools in helping establish the diagnosis and determine the clinical severity.
The significant number of elderly patients and octogenarians indicates that this new subset of patients would soon be posing a great challenge to medical community catering to their care due to the occurrence of several medical comorbidities that can impact the outcome of HF.
We would like to thank the Department of Statistics and Medical Records division for compiling and analyzing the necessary data for the study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Go AS, Mozaffarian D, Roger VL, Benjamin EJ, Berry JD, Blaha MJ, et al.
Heart disease and stroke statistics – 2014 update: A report from the American Heart Association. Circulation 2014;129:e28-292.
Huffman MD, Prabhakaran D. Heart failure: Epidemiology and prevention in India. Natl Med J India 2010;23:283-8.
Ho KK, Pinsky JL, Kannel WB, Levy D. The epidemiology of heart failure: The Framingham study. J Am Coll Cardiol 1993;22 4 Suppl A:6A-13A.
Marantz PR, Tobin JN, Wassertheil-Smoller S, Steingart RM, Wexler JP, Budner N, et al.
The relationship between left ventricular systolic function and congestive heart failure diagnosed by clinical criteria. Circulation 1988;77:607-12.
Hunt SA, Abraham WT, Chin MH, Feldman AM, Francis GS, Ganiats TG, et al.
2009 focused update incorporated into the ACC/AHA 2005 guidelines for the diagnosis and management of heart failure in adults a report of the American college of cardiology foundation/American heart association task force on practice guidelines developed in collaboration with the international society for heart and lung transplantation. J Am Coll Cardiol 2009;53:e1-90.
Bayes-Genis A, Lloyd-Jones DM, van Kimmenade RR, Lainchbury JG, Richards AM, Ordoñez-Llanos J, et al.
Effect of body mass index on diagnostic and prognostic usefulness of amino-terminal pro-brain natriuretic peptide in patients with acute dyspnea. Arch Intern Med 2007;167:400-7.
Redfield MM, Jacobsen SJ, Burnett JC Jr., Mahoney DW, Bailey KR, Rodeheffer RJ. Burden of systolic and diastolic ventricular dysfunction in the community: Appreciating the scope of the heart failure epidemic. JAMA 2003;289:194-202.
Ho KK, Anderson KM, Kannel WB, Grossman W, Levy D. Survival after the onset of congestive heart failure in Framingham Heart Study subjects. Circulation 1993;88:107-15.
McKee PA, Castelli WP, McNamara PM, Kannel WB. The natural history of congestive heart failure: The Framingham study. N Engl J Med 1971;285:1441-6.
Kenchaiah S, Evans JC, Levy D, Wilson PW, Benjamin EJ, Larson MG, et al.
Obesity and the risk of heart failure. N Engl J Med 2002;347:305-13.
Nicklas BJ, Cesari M, Penninx BW, Kritchevsky SB, Ding J, Newman A, et al.
Abdominal obesity is an independent risk factor for chronic heart failure in older people. J Am Geriatr Soc 2006;54:413-20.
Dagenais GR, Yi Q, Mann JF, Bosch J, Pogue J, Yusuf S. Prognostic impact of body weight and abdominal obesity in women and men with cardiovascular disease. Am Heart J 2005;149:54-60.
Ingelsson E, Sundström J, Arnlöv J, Zethelius B, Lind L. Insulin resistance and risk of congestive heart failure. JAMA 2005;294:334-41.
McKeigue PM, Shah B, Marmot MG. Relation of central obesity and insulin resistance with high diabetes prevalence and cardiovascular risk in South Asians. Lancet 1991;337:382-6.
Rush EC, Freitas I, Plank LD. Body size, body composition and fat distribution: Comparative analysis of European, Maori, Pacific Island and Asian Indian adults. Br J Nutr 2009;102:632-41.
Snehalatha C, Viswanathan V, Ramachandran A. Cutoff values for normal anthropometric variables in Asian Indian adults. Diabetes Care 2003;26:1380-4.
Wang Y, Beydoun MA. The obesity epidemic in the United States – Gender, age, socioeconomic, racial/ethnic, and geographic characteristics: A systematic review and meta-regression analysis. Epidemiol Rev 2007;29:6-28.
He J, Ogden LG, Bazzano LA, Vupputuri S, Loria C, Whelton PK. Risk factors for congestive heart failure in US men and women: NHANES I epidemiologic follow-up study. Arch Intern Med 2001;161:996-1002.
Bibbins-Domingo K, Lin F, Vittinghoff E, Barrett-Connor E, Hulley SB, Grady D, et al.
Predictors of heart failure among women with coronary disease. Circulation 2004;110:1424-30.
Mulrow CD, Lucey CR, Farnett LE. Discriminating causes of dyspnea through clinical examination. J Gen Intern Med 1993;8:383-92.
Wang CS, FitzGerald JM, Schulzer M, Mak E, Ayas NT. Does this dyspneic patient in the emergency department have congestive heart failure? JAMA 2005;294:1944-56.
Madhok V, Falk G, Rogers A, Struthers AD, Sullivan FM, Fahey T. The accuracy of symptoms, signs and diagnostic tests in the diagnosis of left ventricular dysfunction in primary care: A diagnostic accuracy systematic review. BMC Fam Pract 2008;9:56.
King M, Kingery J, Casey B. Diagnosis and evaluation of heart failure. Am Fam Physician 2012;85:1161-8.
Silverberg DS, Wexler D, Blum M, Keren G, Sheps D, Leibovitch E, et al.
The use of subcutaneous erythropoietin and intravenous iron for the treatment of the anemia of severe, resistant congestive heart failure improves cardiac and renal function and functional cardiac class, and markedly reduces hospitalizations. J Am Coll Cardiol 2000;35:1737-44.
McCullough PA, Lepor NE. Anemia: A modifiable risk factor for heart disease. Introduction. Rev Cardiovasc Med 2005;6 Suppl 3:S1-3.
Tang YD, Katz SD. Anemia in chronic heart failure: Prevalence, etiology, clinical correlates, and treatment options. Circulation 2006;113:2454-61.
Daniels LB, Clopton P, Bhalla V, Krishnaswamy P, Nowak RM, McCord J, et al.
How obesity affects the cut-points for B-type natriuretic peptide in the diagnosis of acute heart failure. Results from the Breathing Not Properly Multinational Study. Am Heart J 2006;151:999-1005.
O'Donoghue M, Chen A, Baggish AL, Anwaruddin S, Krauser DG, Tung R, et al.
The effects of ejection fraction on N-terminal ProBNP and BNP levels in patients with acute CHF: Analysis from the ProBNP Investigation of Dyspnea in the Emergency Department (PRIDE) study. J Card Fail 2005;11 5 Suppl:S9-14.
Parker MM, Shelhamer JH, Bacharach SL, Green MV, Natanson C, Frederick TM, et al.
Profound but reversible myocardial depression in patients with septic shock. Ann Intern Med 1984;100:483-90.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]