Congestive heart failure (CHF) is the clinical syndrome resulting from the structural or functional inability of the heart to meet the body’s basic metabolic needs at normal pressures. CHF can occur with the left or right ventricle, and frequently both.
Isolated right heart failure is seen less frequently than left heart failure. The most common cause for right heart failure is left heart failure. Other common causes for right heart failure include pulmonary problems such as chronic obstructive pulmonary disease, pulmonary hypertension, valve disease, and coronary artery disease.
Left-sided heart failure can be the consequence of any of a number of temporary or progressive disorders that affect the pericardium, myocardium, or endocardium. The most common cause is coronary artery disease. Other common causes include longstanding hypertension, diabetes mellitus, obstructive sleep apnea, and valve disease.
CHF can range from an asymptomatic condition to one requiring intensive hospital care. It may lead to inadequate perfusion to the body’s peripheral tissues as well as to pulmonary edema (left heart failure), buildup of pressure in the venous system (right heart failure), or both.
In the US, about 5.8 million people suffer from CHF. Acute decompensated CHF leads to about 1 million hospitalizations per year, and about 30% of patients discharged from the hospital with CHF will be readmitted within 90 days. Heart failure incidence increases with age.
Left-sided CHF is typically classified as:
The terms systolic and diastolic failure are still in use, but the above terms are preferred.
Several treatments (medication and devices) reduce mortality in patients with heart failure with reduced ejection fraction and will be discussed later in this chapter. However, no specific treatments have been shown to decrease mortality in patients with heart failure with preserved ejection fraction. Treatment for those with heart failure with preserved ejection fraction is aimed at preventing hospitalizations, slowing progression of symptoms, and improving quality of life.
As noted above, CHF can also be classified as primarily right-sided or left-sided. Signs and symptoms of right-sided failure include increased jugular venous pressure, right upper quadrant or abdominal discomfort, hepatomegaly, ascites and/or jaundice, and peripheral edema. Left-sided failure is characterized by dyspnea, orthopnea, and paroxysmal nocturnal dyspnea, attributable to elevated pulmonary pressure with or without pulmonary edema or effusion. Acute exacerbation of left-sided heart failure often presents with prominent dyspnea, diaphoresis, tachycardia, and pale, cold extremities.
Low-output heart failure is marked by decreased cardiac output and is most often caused by hypertension, myocardial infarction (MI), or chronic coronary artery disease. High-output heart failure is often caused by anemia, sepsis, obesity, or hyperthyroidism. In these cases, long-term excessive demands on the heart due to a decrease in blood volume, oxygen-carrying capacity, or systemic vascular resistance lead to a clinical syndrome similar to that seen with typical low-output heart failure. The heart may initially be able to respond with appropriate or increased cardiac output, but left untreated, ventricular remodeling and impaired ejection fraction can occur.
The most common etiology of heart failure with reduced ejection fraction is ischemic heart disease. Heart failure with preserved ejection fraction is usually multifactorial, with the most common causes being uncontrolled hypertension, diabetes, and coronary artery disease. It is worth noting that the left ventricle also becomes less compliant with age. With heart failure with preserved ejection fraction, myocardial stiffness and impaired relaxation lead to elevated ventricular filling pressures. The ventricle is still able to contract (and therefore the ejection fraction remains preserved), but stroke volume is reduced. To maintain or increase cardiac output, the heart rate must increase. If persistent, this increased stress on the heart can lead to failure. Heart failure with preserved ejection fraction accounts for approximately half of heart failure diagnoses and is more common in women.
Complications of CHF include activity-limiting symptoms, syncope, arrhythmias (which may be fatal), progressive systolic or diastolic dysfunction, thromboembolism (usually strokes), and circulatory collapse.
Age. The incidence of heart failure and left-ventricular dysfunction increases with age.
Race. CHF occurs more frequently in Black Americans than in white Americans. This is thought to be due to socioeconomic factors as well as higher prevalence of resistant hypertension and type 2 diabetes.
History of coronary artery disease. Left ventricular dysfunction often results from ischemic injury to the myocardium.
History of cardiomyopathy. Family or personal history of dilated, hypertrophic, or restrictive cardiomyopathy.
Diabetes. Diabetes accelerates the progression of coronary artery disease as well as left ventricular remodeling, both of which contribute to systolic as well as diastolic dysfunction.
Smoking. Smoking dramatically raises risk for atherosclerotic cardiovascular disease and thus heart failure.
History of rheumatic fever or valvular heart disease.
Hypertension. Pulmonary hypertension generally leads to right-sided heart failure, whereas systemic hypertension leads to left-sided heart failure.
Alcohol abuse. Alcohol may lead to dilated cardiomyopathy.
Obesity. Hypertension, type 2 diabetes, and left ventricular hypertrophy are commonly found in patients with a body mass index (BMI) > 30 kg/m². Heart failure incidence increases by 5% for men and 7% for women for every 1-point increase in BMI above 25 kg/m². Surprisingly, however, BMI appears to have an inverse association with CHF-related mortality in most studies. In a study of more than 7,500 individuals, a linear increase in CHF mortality has been found to occur with a BMI below 30 kg/m². Persons with heart failure and a BMI of 25 to 29.9, 22.5 to 24.9, and < 22.5 had a mortality risk approximately 120%, 145%, and 170% greater than those with a BMI > 30 kg/m².
Obstructive sleep apnea (OSA). Untreated obstructive sleep apnea causes frequent nighttime apneic episodes, which in turn cause periods of deoxygenation. Over time, this process leads not only to irreversible pulmonary disease, but also both right- and left-sided systolic failure. Systolic heart failure due to OSA is thought to be one of the least reversible causes of CHF.
Diagnosis is based on history and physical examination. Imaging and lab results are used to support the diagnosis. The New York Heart Association classification system describes the functional limitations of heart failure:
Class I: Symptoms (e.g., fatigue, dyspnea, palpitations) are experienced on heavy exertion.
Class II: Symptoms occur with mild to moderate levels of exertion.
Class III: Symptoms occur with less than ordinary exertion.
Class IV: Symptoms occur with any exertion or at rest.
2D and Doppler echocardiogram is the most common imaging modality for assessing cardiac function. Echocardiography can evaluate left and right ventricular systolic function, diastolic function, valvular structure and function, and cardiac chamber sizes. It also identifies possible heart failure etiologies, such as MI, valvular disease, and cardiomyopathies.
Chest x-ray can identify intrinsic pulmonary disease, pulmonary edema, and pleural effusions. It can also estimate the degree of cardiac enlargement but is much less accurate than echocardiography.
Electrocardiogram may reveal MI, dysrhythmias, conduction abnormalities, or left ventricular hypertrophy.
Measurement of circulating concentrations of brain natriuretic peptide (BNP), which is produced by the heart, is increasingly used to diagnose and assess the degree of heart failure and monitor treatment effects.
Blood tests, such as a complete blood count and comprehensive metabolic panel, are usually standard. Additional tests should be ordered when clinically appropriate to help determine the etiology. Heart failure without an identifiable cause usually requires an evaluation for coronary heart disease, such as exercise stress testing, noninvasive imaging, or cardiac catheterization.
Treatment of chronic heart failure should target the underlying disorder: hypertension, coronary artery disease, diabetes, etc.
See relevant chapters for specific information. Certain medications (e.g., Calcium channel blockers, NSAIDs, metformin, thiazolidinediones) may worsen heart failure.
Heart failure with preserved ejection fraction is more difficult to treat. Treatment strategies overlap with systolic failure in some cases (i.e., treatment of hypertension, diuretic use for pulmonary symptoms, rate control in atrial fibrillation, and treatment of ischemic CHD), but additional treatment strategies are still being researched.
Loop diuretics (furosemide, torsemide, budesemide) are mainstays of symptomatic treatment for patients with both heart failure with preserved ejection fraction and heart failure with reduced ejection fraction. Although they do not reduce mortality for either group of patients, they prevent volume overload, reduce the need for hospitalization, and improve quality of life. It should be noted that patients do develop tolerance to these medications, so upward titration is often necessary. Therefore, dietary restrictions and lifestyle changes are important in order to avoid excessive use of these medications.
Angiotensin-converting enzyme inhibitors (ACEIs) (e.g., enalapril, lisinopril) are first-line heart failure treatments. They decrease mortality in patients with heart failure with reduced ejection fraction primarily by decreasing blood pressure and inhibiting the renin-angiotensin axis, thus preventing cardiac remodeling and worsening heart function.
Beta-blockers are a first-line treatment for all categories of heart failure and are not limited to patients with coronary artery disease or hypertension. Carvedilol, metoprolol succinate, and bisoprolol have all been shown to decrease heart failure mortality.
Angiotensin II receptor blockers (ARB) (e.g., losartan, candesartan, irbesartan) are generally equivalent to ACEIs and often used if side effects (usually cough) limit ACEI use. It is not recommended to combine an ACEI and an ARB as this can result in renal impairment and potentially dangerous electrolyte imbalances.
Hydralazine and nitrates. Evidence suggests that patients who self-identify as Black and have class III or IV heart failure as defined by the New York Heart Association may have improved response to the addition of hydralazine and isosorbide dinitrate when initial therapy is not successful.
Aldosterone blockers (e.g., spironolactone, eplerenone) have been shown to decrease heart failure mortality when added to usual therapy, but patients must be monitored for hyperkalemia and impaired renal function.,
Angiotensin receptor neprilysin inhibitor (ARNi) (e.g., Sacubitril). Sacubitril, in combination with valsartan (an angiotensin receptor blocker), was approved in 2015 for treatment of heart failure with reduced ejection fraction. It can be used in place of ACEIs to decrease mortality and heart failure hospitalizations (Paradigm-HF trial). Sacubitril must be used with caution in patients prone to renal failure or hypotension.
Anticoagulants (e.g., warfarin, aspirin, clopidogrel) are typically not recommended for routine use in cases of reduced ejection fraction unless there is a specific indication such as concomitant atrial fibrillation or left ventricular thrombus. In clinical trials, anticoagulation decreased the rate of thrombotic events, but this benefit was outweighed by increased risk of significant bleeding. When coronary artery disease is present along with left ventricular dysfunction, it is recommended to follow the coronary artery disease guidelines regarding anticoagulation.
Digoxin is an oral inotropic agent that provides symptomatic relief, but no improvement in overall mortality, in patients with decompensated heart failure. Its therapeutic window is narrow. A high serum digoxin concentration may increase mortality and cause a wide array of arrhythmias. It may be useful for patients who remain symptomatic despite optimal treatment with diuretics, ACEI or ARB, and beta-blockers, especially if atrial fibrillation is present. Digoxin is not useful for diastolic dysfunction. Dosage must be adjusted for older patients and those with renal dysfunction, as well as in the presence of many drugs that influence digoxin levels.
Calcium channel blockers (e.g., verapamil, amlodipine) are contraindicated for patients with significant impairment in ventricular function.
Statins. There are currently no studies showing any reduction in mortality or symptomatic improvement from statin therapy when prescribed solely for treatment of heart failure.
In general, intravenous therapies for heart failure decompensation are intended to relieve symptoms and facilitate hospital discharge. They are not generally used for prolonging survival beyond the short term. The following drugs are used for treatment of decompensation:
Dobutamine is an inotropic and vasoactive agent administered intravenously for symptom relief and systolic function improvement. It requires close monitoring, as it may produce dysrhythmias or abrupt blood pressure changes. It is sometimes given to end-stage heart failure patients for home infusion, in conjunction with amiodarone, to provide symptomatic relief and to decrease the need for hospitalization.
Phosphodiesterase inhibitors (e.g., amrinone, milrinone) increase contractility by modulating calcium influx into cardiac cells. They also facilitate both arterial and venous dilation, reducing preload and afterload. They are not used for chronic therapy, as this has resulted in increased mortality for heart failure patients.
Implantable cardioverter-defibrillator (ICD) use has been shown to decrease mortality from lethal dysrhythmias for high-risk patients, particularly those with documented dysrhythmias and/or severe systolic dysfunction, typically with ejection fraction less than 30-35%.
Cardiac resynchronization therapy (CRT) devices are implantable devices designed to allow the right and left ventricles to beat in synchrony, allowing for improved cardiac output, and in some cases, an increase in ejection fraction. These devices are often placed in conjunction with ICDs (CRT-D) to reduce the hospitalization and mortality rates for people with heart failure with reduced ejection fraction.
An intra-aortic balloon pump (IABP) is used to treat refractory cases of cardiogenic shock, which can be due to acute, decompensated heart failure. An IABP assists the heart by decreasing afterload and improving cardiac output. After insertion into the aorta via catheter, the balloon inflates at the beginning of diastole to enhance coronary perfusion. It deflates at the beginning of systole, thereby increasing cardiac output. An IABP is often used after acute myocardial infarction to support the left ventricular function as the ventricle heals from the insult.
Cardiac transplant may be necessary for patients with end-stage heart failure. Left ventricular assist devices are used in severely ill patients as a bridge to cardiac transplantation.
Cardiac rehabilitation should be approved by a physician and overseen by an exercise physiologist. Exercise and conditioning have been shown to improve functional status, decrease hospitalization, and improve quality of life, but has not been shown to reduce mortality.
Leg elevation above the heart should be done during rest.
Compression stockings may help control leg edema and improve fluid removal. Results are variable, and a therapeutic trial will help determine usefulness for individual heart failure patients.
Previously, the focus of heart failure prevention and treatment was a restriction of excess sodium intake in order to prevent fluid overload. While controlling sodium remains important, macronutrient nutrition may be more important in the prevention than previously thought, and a particular role for the avoidance of foods containing saturated fat has emerged. Healthy dietary patterns high in fruits and vegetables and the inclusion of fish also appear important in preventing heart failure, and the benefit of certain dietary supplements (thiamine, coenzyme Q10) has been further confirmed.
Avoidance of saturated fat and fried foods. The risk for heart failure increased with higher amounts of red meat intake in the Physicians Health Study, with or without previous MI. Men in the highest compared to lowest intake groups had a roughly 25% greater risk for heart failure. Similarly, daily consumption of eggs was found to increase the risk for heart failure by 30% when compared with individuals who didn’t eat eggs or limited them to 3 per month. These results were similar to those of the Atherosclerosis Risk in Communities study that found a 23% greater risk for heart failure in individuals eating the most compared to the fewest eggs. The Physicians Health Study also found a graded increase in risk for heart failure in persons consuming fried foods, with a 2-fold increased risk for those consuming them at least daily compared with those eating them less than once per week. Meat, eggs, and fried foods are all sources of advanced glycation end products, which have been related to the severity of heart failure and are an independent predictor for cardiac events in these patients.
A health-promoting dietary pattern. Diets following both Mediterranean and DASH (Dietary Approaches to Stop Hypertension) style, as well as dietary patterns that are lower in meat, higher in unsaturated fat, and higher in fish (discussed further below), have all been associated with significant reductions in the risk for heart failure.,,,,
Eating a minimum of 5 fruits and vegetables per day. In a study of over 34,000 women, total fruit and vegetable consumption was inversely related to the incidence of heart failure. Although vegetables appeared to be more protective against heart failure than fruits, the intake of 5 or more daily servings combined was associated with a 20% lower risk when compared with those eating half that amount.
Fish consumption. Meta-analytic reviews have concluded that omnivores consuming the most fish have slightly (roughly 15%) lower risk for heart failure compared with individuals consuming the least amount., However, in omnivorous populations, the ratio of omega-6 to omega-3 fats is high (20:1); in contrast, ratios ranging from 5:1 to 2:1 show risk reductions for several chronic diseases. The higher ratios predispose individuals to atherosclerosis and inflammation that are often precursors of heart failure. Thus, these studies do not suggest that fish consumption is preferable to the avoidance of meat altogether and are more indicative of the need to counterbalance a high omega-6 intake from animal products, an important consideration, given that plant-based diets are associated with improvements in major cardiac risk factors.
Sodium reduction. Restriction of excess sodium is important in reducing the risk for heart failure; however, the degree of sodium restriction in established CHF is a matter of some controversy. The most recent recommendations from the American College of Cardiology Foundation and the American Heart Association downgraded sodium restriction for patients with CHF from a class I (part of standard care) to a class IIa (reasonable to include in care) recommendation. In addition, the recommendation for stringent low salt intakes (to 1500 mg/day) was reserved for patients with Stage A and B CHF only. The Heart Failure Society of America recommends a salt restriction to less than 2,000 mg/day for patients with moderate to severe CHF.
Some experts are more permissive regarding sodium intake, because stringent sodium restriction can increase renin, aldosterone, epinephrine, and norepinephrine. Liberalizing sodium intake (while avoiding the high sodium intakes found in typical Western diets) may actually enhance response to diuretic therapy and predispose patients to more favorable long-term outcomes. Thus, most evidence supports a more moderate level of salt restriction to 2,000-3,000 mg/day (half of typical daily American sodium intake). This level of intake reduces hospital readmissions for CHF, while higher intakes increase the need for urgent transplantation.
Monitoring magnesium status. The importance of magnesium in patients with heart failure lies in its vasodilatory, anti-inflammatory, anti-ischemic, and antiarrhythmic properties, among others. The reported prevalence of hypomagnesemia in heart failure patients ranges from 7-52%, and replacement therapy is not uncommon. However, a review of magnesium status in these patients indicated that high blood levels were associated with an almost 40% greater risk for cardiovascular mortality, when compared with those with normal levels.
Thiamine supplements for patients treated with diuretics. Diuretic therapy, particularly furosemide, is responsible for increasing thiamine excretion. High-dose thiamine (300 mg/day) was found to significantly improve ejection fraction in heart failure patients.
Moderation in alcohol consumption. A dose-response meta-analysis found a 10% lower risk for heart failure in persons consuming 3 alcoholic drinks per week and a 13% and 14% lower risk, respectively, in persons consuming 7 and 10 drinks per week when compared with individuals who rarely or never consumed alcohol. No further benefit was found above this amount.
Coenzyme Q10 supplementation. A previous meta-analysis of controlled clinical trials with coenzyme Q10 found significant improvements in stroke volume, cardiac output, cardiac index, and end-diastolic volume in patients with heart failure, regardless of etiology (e.g., idiopathic, dilated, ischemic, hypertension, valvular heart disease, congenital heart disease). More recently, the Q-SYMBIO study documented significantly fewer cardiovascular deaths and hospital admissions for heart failure in heart failure patients given 300 mg of coenzyme Q10 per day, compared with placebo.
Diet: When heart failure is the result of heart disease, a cardiovascular-specific diet should be ordered (see Coronary Heart Disease chapter).
Sodium and fluid restriction as appropriate.
Nutrition consultation to help the patient adjust to the above diet.
Exercise physiologist, physical therapist, and occupational therapist consultations to prescribe exercise regimen and provide appropriate support for activities of daily living.
Heart failure is usually progressive. However, patients may be able to prolong survival, improve heart function, ameliorate chronic symptoms, avoid repeated episodes of decompensation, and decrease the need for hospitalization by following a low-sodium diet, restricting fluids, and taking medications as prescribed. Exercise conditioning is also important, as it can help improve exercise tolerance and oxygen uptake. The family may need to provide physical support as the patient attempts to recondition. Family support is also important to help the patient adhere to diet changes.