Section 2: Conceptualization and Working Definition of Heart Failure

Heart failure (HF) remains a major and growing societal problem despite advances in detection and therapy.1-4 However, there is no widely accepted characterization and definition of HF, probably because of the complexity of the syndrome. The conceptualization and working definition of HF presented here emerged as these guidelines were developed. They are critical to understanding HF and approaching its treatment appropriately.

Conceptual Background. HF is a syndrome rather than a primary diagnosis. It has many potential etiologies, diverse clinical features, and numerous clinical subsets. Patients may have a variety of primary cardiovascular diseases and never develop cardiac dysfunction, and those in whom cardiac dysfunction is identified through testing may never develop clinical HF. In addition to cardiac dysfunction, other factors, such as vascular stiffness, dyssynchrony, and renal sodium handling, play major roles in the manifestation of the syndrome of HF.

Patients at risk for many cardiovascular diseases are at risk for HF. Early identification and treatment of risk factors is perhaps the most significant step in limiting the public health impact of HF.5-7 Emphasis on primary and secondary prevention is particularly critical because of the difficulty of successfully treating left ventricular (LV) dysfunction, especially when severe.5 Current therapeutic advances in the treatment of HF do not make prevention any less important.

Although HF is progressive, current therapy may provide stability and even reversibility. The inexorable progression of HF from LV remodeling and dysfunction is no longer inevitable. Prolonged survival with mild to moderate LV dysfunction is now possible. Therapy with angiotensin-converting enzyme inhibitors (or angiotensin receptor blockers), beta blockers, and cardiac resynchronization therapy can lead to slowing or to partial reversal of remodeling.

Because of this prolonged survival, comorbid conditions, such as coronary artery disease or renal failure, can progress, complicating treatment. Given this prolonged survival, considerable attention is devoted in this guideline to disease management, the use of multidrug therapy, and the management of patients with HF at the end of life.

Working Definition. Although HF may be caused by a variety of disorders, including valvular abnormalities and dysrhythmias, the following comprehensive guideline and this working definition focus on HF primarily from the loss or dysfunction of myocardial muscle or interstitium.

HF is a syndrome caused by cardiac dysfunction, generally resulting from myocardial muscle dysfunction or loss and characterized by either LV dilation or hypertrophy or both. Whether the dysfunction is primarily systolic or diastolic or mixed, it leads to neurohormonal and circulatory abnormalities, usually resulting in characteristic symptoms such as fluid retention, shortness of breath, and fatigue, especially on exertion. In the absence of appropriate therapeutic intervention, HF is usually progressive at the level of both cardiac function and clinical symptoms. The severity of clinical symptoms may vary substantially during the course of the disease process and may not correlate with changes in underlying cardiac function. Although HF is progressive and often fatal, patients can be stabilized and myocardial dysfunction and remodeling may improve, either spontaneously or as a consequence of therapy. In physiologic terms, HF is a syndrome characterized by either or both pulmonary and systemic venous congestion and/or inadequate peripheral oxygen delivery, at rest or during stress, caused by cardiac dysfunction.