NursingLink

Library >> Browse Articles >> Heart Disease

Reducing The Risk of Heart Failure

Currently 5 million people in the United States suffer from heart failure, a figure that is predicted to double by the year 2040. A total of 550,000 new cases of heart failure are diagnosed annually, and 74 million people have risk factors for developing this chronic disorder. The cost of caring for people with heart failure is between $27 and $38 billion per year; 10% of this cost is for medications alone. Because heart failure is primarily a disease of the elderly, the incidence of heart failure will continue to increase as the population ages, a concern not only in the United States but throughout Europe and the rest of the world as well.
As developing countries become more industrialized, unhealthy habits such as sedentary lifestyles, unhealthy diets, smoking, and obesity have created a pandemic of cardiovascular disease (CVD) that will lead to a global elevated risk of heart failure. These staggering facts are cause enough to pursue the prevention of heart failure, but an equally important reason is the poor quality of life experienced by individuals who live with heart failure.
Evolution of Heart Failure
Heart failure is complex. It does not originate from any single cause or pathology but is defined by the American College of Cardiology/American Heart Association (ACC/AHA) as a clinical syndrome resulting from any structural or functional cardiac disorder that impairs the ability of the ventricle to fill or eject blood. In describing the evolution of heart failure, Wingate says the key message in prevention is to maintain functional myocardial reserve by keeping myocytes intact and in shape.
In 2001, the ACC/AHA guidelines for diagnosis and management of chronic heart failure in adults (updated in 2005) offered staging classifications for heart failure that incorporated risk factors and structural prerequisites for the development of heart failure. The ACC/AHA stages complement but do not replace the New York Heart Association's class I through class IV function-based system. Dr. Wingate focused on the 4 stages of heart failure that take into account both the development and progression of the disease.
Stages of Heart Failure
Stage A. These patients are at high risk for developing heart failure but are without structural heart disease or symptoms. Their risk factors, which include hypertension, atherosclerotic disease, diabetes, obesity, metabolic syndrome, use of cardiotoxins, or a family history of cardiomyopathy, can change the shape or function of myocytes.
Stage B. These patients have progressed from stage A to asymptomatic structural heart disease, such as valvular disease, a previous myocardial infarction (MI), left ventricular (LV) remodeling (LV hypertrophy [LVH] and low ejection fraction).
Stage C. These patients have structural heart disease and previous or current symptoms. Stage C includes patients with known structural heart disease and symptoms such as shortness of breath, fatigue, and reduced exercise tolerance.
Stage D. These patients have refractory heart failure requiring special intervention. Rehospitalized frequently, stage D patients have marked symptoms at rest despite therapy and require special interventions before they can be safely discharged.
Progression of Heart Failure
The ACC/AHA guidelines for the prevention of heart failure are unique because they include a "pre-heart failure" category (stage A) and a long latent period (stage B) during which structural heart disease is present without symptoms of heart failure. Stage A and stage B present ideal opportunities to intervene to prevent heart failure. The risk factors of a patient in stage A heart failure, if not controlled, lead to cellular pathophysiology such as myocardial hypertrophy, infarction, accelerated apoptosis, and fibrosis. Progressive maladaptive ventricular remodeling causes LVH, dilatation, or both, leading to systolic and/or diastolic ventricular dysfunction. A patient with these progressive changes is at stage C or D and most certainly is symptomatic.
The goal, Wingate said, is to prevent the risk factors for heart failure in the first place (what she calls primordial prevention) or to intervene early. Cardiac pathology will worsen unless there is early intervention. Early intervention in stages A and B will slow or stop progression to stage C. According to Wingate, once a person has progressed to stage C, there is no going back. Progression to stage D is inevitable. Her message to health professionals is, "we can and must prevent or slow this progression."
Lifetime Risk of Heart Failure
Lifetime risk is defined as the absolute cumulative risk of an individual developing a given disease in his or her remaining lifetime. Findings from the Framingham studies reveal that the lifetime risk for heart failure is 1 in 5 for both men and women. However, Wingate reminds us that lifetime risk for heart failure is altered depending on the presence of other risk factors such as hypertension or MI.
Wingate discussed short-term risk for heart failure and how it compares with lifetime risk. For example, a 40-year-old man has a 0.2% chance over a 5-year period of developing heart failure but a 21% lifetime risk. A 40-year-old woman has short-term and lifetime risks of 0.1% and 20.3%, respectively. In contrast, an 80-year-old man has a 5-year risk of 8.3% but his lifetime risk is 20.2%, very similar to an 80-year-old woman (7.8% 5-year risk and 19.3% lifetime risk).[6] Because of their shorter life spans, elderly individuals have higher short-term risks of developing heart failure.
A younger individual, particularly one with risk factors or a previous MI, may fail to appreciate his or her increased risk unless it is phrased in terms of lifetime risk. Lifetime risk, for this patient population, may be more meaningful and beneficial when trying to explain the need for prevention and therapy. The risk factors of hypertension and history of MI can increase lifetime risk for heart failure beyond the degree of risk related to advancing age alone.
MI and Lifetime Risk of Heart Failure
MI stimulates cardiac remodeling and is an important risk factor for the development of heart failure, increasing the risk 2- to 3-fold. In the Framingham studies of 3757 men and 4472 women, the lifetime risk for a 40-year-old man, without a previous MI, decreases from 21% to 11.4%, and a woman's risk decreases from 20% to 15.4%. Decreases in lifetime risk for an 80-year-old man or woman without an MI are similar .
Hypertension and Lifetime Risk of Heart Failure
Below is the same scenario with and without hypertension. The 40-year-old man, with a blood pressure lower than 140/90, has a lifetime risk for the development of heart failure of 15.6%, but a blood pressure equal to or higher than 160/100 elevates the lifetime risk to 27.4%. A 40-year-old woman without hypertension has a 12.0% lifetime risk that increases to 29.5% if her blood pressure rises to 160/100 or higher. The lifetime risk for an 80-year-old man with the same level of hypertension is 27% and with normal blood pressure is 16.6%. For women, the risks with and without hypertension are 17.1% and 24.4%, respectively.[6] These data once again drive home the message of the importance of aggressive management of patients in stage A and B heart failure or, better yet, before they reach those stages!
Treatment Strategies for Heart Failure
In addition to the major risk factors of stage A, other risk factors can contribute either directly or indirectly (by increasing the risk for MI or LVH) to the development of heart failure. Treatment strategies geared toward the patient's stage of heart failure are outlined here.
Stage A -- High Risk Without Symptoms
-1. Risk factor reduction and patient education:

Treat hypertension;

Smoking cessation;

Treat lipid disorders;

Lifestyle changes (regular physical activity, weight loss, and maintenance of ideal body weight); and

Address excessive alcohol intake and illicit drug use.
Pharmacotherapy -- for patients with asymptomatic LV dysfunction, hypertension, coronary artery disease (CAD), vascular disease, and diabetes:

Angiotensin-converting enzyme (ACE) inhibitors; or

Angiotensin receptor blockers (ARBs) in patients with vascular disease or diabetes.
Stage B -- Structural Heart Disease Without Symptoms
All measures for stage A patients, including beta-blockers in appropriate patients.

Devices for selected patients (implantable defibrillator).
Stage C -- Structural Heart Disease With Previous or Current Symptoms
All measures for stage A and stage B patients, plus dietary salt restriction.

. Pharmacotherapy for routine use:

Diuretics;

ACE inhibitors; and

Beta-blockers.
. Pharmacotherapy for selected patients:

Aldosterone antagonist;

ARBs;

Digitalis; and

Hydralazine/nitrates.
Devices in selected patients:

Biventricular pacing; and

Implantable defibrillator.
Stage D -- Refractory Symptoms Requiring Special Intervention
All measures for stages A, B, and C.

. Decisions regarding appropriate level of care:

Mechanical assist devices; and

Compassionate end-of-life care.
. Extraordinary measures:

Heart transplantation;

Chronic inotropes;

Permanent mechanical support; and

Investigational surgery or drugs.

Heart Failure Prevention vs Treatment
More benefit can be gained from preventing heart failure than from treating it. Currently, however, there is more research involving the treatment than the prevention of heart failure in high-risk populations. Wingate explains that treating a patient for several years with heart failure drugs can potentially prolong survival by 3 to 4 years. Applying preventive measures (reducing obesity, lowering blood pressure) in high-risk patients could produce similar results but has the benefit of being applicable to more people and prolonging more lives. Existing prevention research is the basis of current guidelines for preventing the development or progression of heart failure.
Coronary Artery Disease and Myocardial Infarction
More than 15 million people have a history of MI, symptomatic coronary heart disease, or both. An MI confers a 2-3 times increased risk for heart failure. According to the ACC/AHA scientific statement on prevention of heart failure, the contribution of CAD to heart failure is not limited to the initial ischemic injury.

---