Heart failure is a clinical syndrome that affects nearly two million people in the United States today. Moreover, approximately 400,000 people are diagnosed with congestive heart failure each year. The number of people who die in the United States as a result of heart failure, either directly or indirectly, totals nearly 250,000 per year. People who live with a diagnosis of congestive heart failure understand, too, that a failing heart can be the cause of poor quality of life due to symptoms of fatigue and shortness of breath that limit daily activities.
Management of heart failure with a combination of medications has long been the mainstay of treating this syndrome. Medications are prescribed for patients with heart failure to reduce the chance of death as well as to reduce symptoms and improve functioning. In this article, I will discuss the current regimen of drug therapies recommended by the Heart Failure Society of America, and used most often by physicians and nurse practitioners who participate in the ongoing care of people with heart failure due to systolic dysfunction. I will also mention some newer medications that are currently being added to the armamentarium of heart failure treatments.
Diagnosing Heart Failure
If a physician suspects that a patient has heart failure, the next step in diagnosis is determining whether there is systolic or diastolic dysfunction. Basically, this determination is made by obtaining an echocardiogram (an ultrasound of the heart) to directly visualize the overall function of the heart muscles.
If you have heart failure, but the walls of your heart are contracting vigorously and have not become too dilated (thinned-out), then you have preserved systolic ventricular function. This means that the heart failure probably stems from diastolic dysfunction, which is the inability of the heart muscles to relax properly after contracting. If your heart muscles are not contracting well, then you probably have systolic dysfunction.
The ejection fraction
The overall contracting function of the heart muscle can be quantified with the ejection fraction. The ejection fraction measures the amount of blood that is "ejected" from the heart with each beat, and compares it to the total amount of blood that is in the left ventricle just prior to ejection. If your heart muscles are not contracting well, then your ejection fraction will be lower than normal.
Your ejection fraction can help your physician differentiate between systolic and diastolic dysfunction. Generally, an ejection fraction of 40 percent or less indicates that your heart muscles are not contracting normally. This is systolic dysfunction. An ejection fraction of greater than 40 percent means that your systolic function, or overall contractile ability of your heart, is relatively preserved.
The good news is that your ejection fraction can improve with appropriate medical therapy as well as compliance with diet and exercise recommendations. Heart failure is a challenging clinical syndrome for the physician to treat because although we think of heart failure in terms of congestion and shortness of breath, not all patients will have these symptoms. Sometimes a heart failure patient will have vague symptoms of fatigue and a sense of not feeling like him- or herself. Luckily, the last decade has seen many studies on the recognition and treatment of heart failure.
Current Drug Therapy for Systolic Dysfunction
The following medications are considered standard in the treatment of heart failure due to systolic dysfunction.
Diuretics
Diuretics are sometimes referred to as water pills because they are helpful in reducing the symptoms of fluid overload by promoting diuresis, or the removal of extra fluid through urination. Patients with symptoms of shortness of breath, trouble breathing while lying flat (orthopnea), and awaking at night because of trouble breathing (paroxysmal nocturnal dyspnea) can benefit from a diuretic.
In general, diuretics are started when a patient with heart failure first develops these signs of fluid overload. If you suffer from marked fluid overload and congestion of the lungs, you may be given intravenous diuretics initially. As the extra fluid is eliminated from the body through urination, the diuretic can then be administered orally. If you have mild heart failure, your physician may have you take your diuretic on alternating days or when needed.
Generic-brand diuretics
Some common generic diuretics that are used in the treatment of heart failure are furosemide and hydrochlorothiazide. It is important to remember that potassium depletion can occur when patients are chronically treated with diuretics. Therefore, if you are taking a diuretic, your potassium levels should be carefully monitored. If low potassium levels are a persistent problem, then oral supplements of potassium can be prescribed or alternative diuretics, called potassium-sparing diuretics, can be used. Diuretics can also lead to magnesium depletion (this often accompanies depletion of potassium) when higher doses are used.
Digoxin
Digoxin, otherwise known as digitalis, has been used to treat symptoms of heart failure for a very long time—more than 200 years! It is generally agreed that digoxin improves physical function and decreases symptoms in most patients with heart failure by improving heart muscle contraction, but its effect on mortality is less clear. Nonetheless, for patients with systolic dysfunction, digoxin is routinely used in combination with a diuretic and an ACE inhibitor.
It is important to note that your daily dose of digoxin will be reduced if you have poor kidney function. Generally, levels of digoxin are checked once yearly after a regular dose has been established. However, if your heart failure or kidney function worsens or if additional medications are added to your medical regimen that could affect the digoxin level, your physician may decide to check your digoxin level more frequently.
ACE inhibitors
ACE inhibitors are angiotensin-converting enzyme inhibitors. They have many effects on the heart, but most important, they lead to improved functioning of the heart muscle. ACE inhibitors are also involved in the salt-retaining system of the kidneys.
Many study results have shown the benefits of adding an ACE inhibitor to the medical regimens of patients who suffer from heart failure with an ejection fraction of 40 percent or less. For patients who suffer with only mild shortness of breath and who have no symptoms of fluid overload, an ACE inhibitor may be considered the sole therapy. Diuretics are added to the treatment when these patients develop worsening shortness of breath despite the ACE inhibitor.
Generic-brand ACE inhibitors
Some of the more commonly prescribed generic ACE inhibitors are enalapril, captopril, and lisinopril. During therapy with any of these agents, your physician will monitor your potassium levels, check your kidney function, and watch closely for the development of a cough (an uncommon side effect of ACE inhibitors).
There are patients, however, who should be started on an ACE inhibitor with caution:
- patients with a history of adverse reactions or intolerance to ACE inhibitors
- patients with high potassium levels
- patients with low blood pressure.
In contrast to diuretics, ACE inhibitors can cause the kidneys to hold onto potassium, leading to high potassium levels. In addition, those patients who have known renal artery stenosis (narrowing of the renal arteries) may not be eligible for treatment with an ACE inhibitor.
Beta-adrenergic receptor blockers
Beta-adrenergic receptor blockers, known simply as beta-blockers, were formerly considered to be of no use in patients with heart failure. In fact, it was thought that beta-blockers were potentially harmful in patients with heart failure. Over the last decade, however, more than 20 studies have shown that beta-blockers can actually reduce symptoms of heart failure and improve a patient's functioning. Moreover, beta-blockers can decrease the risk of death in patients with mild to moderate heart failure.
Generic-brand beta-adrenergic receptor blockers
Presently, the only beta-blocker that is approved for use in the treatment of heart failure is carvedilol. The current recommendation by the American College of Cardiology is that all patients who are in stable condition and have mild to moderate heart failure with an ejection fraction of 40 percent or less, start on a beta-blocker. The degree of heart failure is categorized under the New York Heart Association (NYHA) classification system. Mild to moderate heart failure is NYHA Class II or III. The NYHA functional classification of heart failure divides this cardiac condition into four categories:
Class I is reserved for those patients who have no limitation of physical activity. In other words, Class I patients experience no shortness of breath or fatigue with ordinary physical activity.
Class II patients, on the other hand, experience a slight limitation of activity; they have fatigue and shortness of breath with ordinary physical activity, but are comfortable at rest.
Class III patients are markedly limited in activity. They can experience fatigue and shortness of breath with less than ordinary activity. An example of Class III limited activity is shortness of breath when climbing stairs very slowly, one by one. It is important to note that Class III patients are also comfortable at rest.
Class IV indicates the most severe stage of heart failure. In this class, the symptoms of shortness of breath or fatigue are present even when the patient is at rest, and only exacerbated with any kind of physical exertion.
Remember that beta-blockers are often used to treat high blood pressure. So, if you are taking carvedilol for the treatment of your heart failure, your physician will monitor you for signs of low blood pressure. Additionally, beta-blockers are used to treat rapid heart rates. Your physician will also watch for signs that your heart rate is too slow as a result of taking a beta-blocker.
Therapies on the Horizon
New guidelines for managing heart failure are being developed all the time as newer drugs become available. A good example of the evolving process of heart failure treatment is the addition of beta-blockers (as described above) to the list of standard medications used to treat patients with mild to moderate heart failure. Additionally, there are new medications under investigation that may be useful in the management of heart failure. Note that these drugs are not presently recommended as routine therapy for heart failure patients.
Angiotensin II receptor inhibitors
Like ACE inhibitors, angiotensin II receptor inhibitors are involved with the salt-retaining system of the kidneys. The proper role of angiotensin II receptor inhibitors has yet to be determined. However, patients who are unable to tolerate ACE inhibitors because of side effects, such as a persistent cough, may be offered a trial of angiotensin II receptor inhibitors. At present, angiotensin II receptor inhibitors are not considered substitutes for ACE inhibitors.
Amiodarone
Amiodarone is a drug primarily used to treat arrhythmias (irregular heart rhythms). Patients who suffer from heart failure due to systolic dysfunction may also develop arrhythmias. Moreover, sudden cardiac death as a result of arrhythmias is a problem associated with systolic dysfunction.
A few preliminary studies on the use of amiodarone in patients with heart failure have shown a reduction in sudden cardiac death. At present, amiodarone is considered for patients who have arrhythmias that do not respond to the more commonly used agents (such as beta-blockers or digoxin) and which are not going to be managed with the placement of an implanted cardiac defibrillator (a device that delivers electrical currents to terminate dangerous arrhythmias).
Conclusion
The treatment of heart failure with medications remains an evolving process. I have described drugs that are currently considered essential for the optimal care of patients with heart failure due to systolic dysfunction. ACE inhibitors and diuretics have emerged as the two drugs that constitute the foundation of medical therapy for heart failure. Digoxin is widely used to further improve the function of heart muscle. Beta-blockers have been introduced as a useful medication in patients with mild to moderate heart failure. Newer drugs in the treatment of heart failure, such as amiodarone and angiotensin II receptor inhibitors, are currently under investigation.
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