As the life expectancy of Americans has increased, so has the prevalence of heart failure, which now accounts for approximately 20 percent of all hospitalizations for patients more than 65 years of age. A substantial number of changes have emerged in the management of heart failure over the past decade. Jessup and Brozena summarize these changes in a broad-based review of this common disease.
The authors note that symptomatic heart failure has a worse prognosis than most types of cancer in the United States, with a one-year mortality rate of approximately 45 percent. Although study results have shown that deaths related specifically to heart failure have decreased with modern management, the overall survival rate has not significantly improved.
The pathophysiology of heart failure is quite complex. In addition to the well-known structural and functional abnormalities of the heart itself, there are a host of abnormally activated neurohormonal systems (e.g., changes in renin-angiotensin-aldosterone axis, sympathetic nervous system, natriuretic peptides, and endogenous vasodilators and other agents). Furthermore, most patients with heart failure are elderly and have at least one coexisting chronic illness.
Remodeling of the left ventricle is common in patients with heart failure. First, the chamber hypertrophies, then dilates and becomes more spherical, which has deleterious effects on diastolic and systolic function. Elevated end-diastolic pressures can lead to mitral regurgitation and atrial stretch, which then can cause atrial fibrillation, compounding the ventricular dysfunction.
The authors review a staged approach to the management of this complex disease. In this approach, patients with stage A heart failure are at high risk of heart failure, but they do not have symptoms of heart failure or evidence of structural heart disease. This stage includes patients with hypertension, diabetes, coronary artery disease, previous exposure to cardiotoxic drugs, or a family history of cardiomyopathy. Control of hypertension, coronary artery disease, and diabetes are the chief targets for early intervention. The authors recommend the use of angiotensin-converting enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs) in patients who are at risk, in order to prevent the maladaptive remodeling that is the hallmark of early disease.
At stage B, structural heart disease is apparent (ventricular remodeling, with diastolic dysfunction or depressed ejection fraction), but symptoms have not yet developed. Patients in this stage would be considered to have New York Heart Association (NYHA) class I symptoms, including those with left ventricular hypertrophy, previous myocardial infarction, valvular heart disease, or left ventricular systolic dysfunction. The use of ACE inhibitors or ARBs is indicated in all patients in this stage. The authors note that no particular ACE inhibitor and no specific high or low dose has been proved superior in the treatment of heart failure. Modification of lifestyle factors, such as weight monitoring, medication compliance, moderation of alcohol consumption, avoidance of nonsteroidal anti-inflammatory drugs, and scheduled exercise, is emphasized.
Patients in stage C have symptoms that could be classified as NYHA class I, II, III, or IV. Beta blockers are now widely advocated for use in all patients with symptomatic heart failure and also in many presymptomatic patients. The authors note that short-term exacerbations of heart failure symptoms may initially occur with the use of beta blockers, but studies have uniformly shown improvement in long-term survival with the use of these agents. Diuretics and dietary sodium restriction are commonly employed to deal with the volume overload that accompanies advancing heart failure.
Aldosterone antagonists (e.g., spironolactone) and digoxin are other options for medical treatment of heart failure after ACE inhibitors and beta blockers have been appropriately employed. The authors discuss non-pharmacologic measures, such as cardiac resynchronization for patients with significant interventricular conduction defects; coronary revascularization for ischemic patients; and ventricular assist devices in end-stage patients who are candidates for transplantation.