2. Definitions of Heart Failure

HF is a complex clinical syndrome in which abnormal heart function results in, or increases the subsequent risk of, clinical symptoms and signs of reduced cardiac output and/or pulmonary or systemic congestion at rest or with stress. While this has traditionally focused on patients with predominant left ventricular (LV) systolic dysfunction (LVSD), there is an increased awareness of the syndrome spanning patients with acute and chronic HF, right-sided HF, and HF across a spectrum of ventricular or valvular function. We have refrained from using other terms, often older descriptive terms (e.g., dilated, congestive), unless a specific definition exists. The term “stable” is not considered to be clinically appropriate given the inherent risk for future clinical events. We have not adopted a staging system1 or alternative systems2 for describing HF.

Chronic HF is the preferred term representing the persistent and progressive nature of the disease. Acute HF (AHF) is defined as a gradual or rapid change in HF signs and symptoms resulting in the need for urgent therapy. Advanced HF is the term often used clinically, yet has no widely-accepted definition. In the context of the guidelines, we have outlined some of the key considerations for this term in 7.1.4 Advanced HF Management Strategies as it pertains to selecting advanced mechanical devices, transplant or palliative therapies.

2.1 Ejection fraction (EF) terminology

This guideline uses the following terms:

  • HF with preserved ejection fraction (HFpEF): LVEF ≥ 50%;
  • HF with a mid-range ejection fraction (HFmEF): LVEF 41-49%;
  • HF with a reduced ejection fraction (HFrEF): LVEF ≤ 40%.

This recognizes the uncertainty that often occurs in the measurement of left ventricular ejection fraction (LVEF), the evolving landscape of current clinical trials enrolling patients with different LVEF cutoffs, and evolving ways to evaluate cardiac function. Echocardiography is the most accessible method to evaluate LVEF in Canada. Estimates of ejection fraction (EF) may vary due to patient or technical factors, as well as therapy or clinical deterioration. The previously stated EF cutpoints recognize that there is a large body of evidence related to treatment for patients with HFrEF and emerging evidence for patients with HFpEF and HFmEF. HFmEF may represent many different phenotypes, including patients transitioning to and from HFpEF.

The term “recovered EF” has also been added to the literature,3 referring to patients who previously had HFrEF and now have an EF > 40%. These patients might eventually be classified in the HFmEF or HFpEF group but deserve recognition that despite their recovered imaging parameters, they might still carry additional risk for adverse clinical events. Uncertainty exists on strategies for management of individuals with HFmEF including surveillance, treatment and prognosis.

2.2 Symptoms terminology

Symptoms are described using the New York Heart Association (NYHA) functional class I-IV Table 1.

Table 1: New York Heart Association functional classification and other symptom descriptors



Other descriptor


No symptoms



Symptoms with ordinary activity

Mild symptoms


Symptoms with less than ordinary activity

Moderate symptoms


Symptoms at rest or with any minimal activity

Severe symptoms

Data from the Criteria Committee of the New York Heart Association.4



1. Hunt SA, Baker DW, Chin MH, et al. ACC/AHA Guidelines for the Evaluation and Management of Chronic Heart Failure in the Adult: Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1995 Guidelines for the Evaluation and Management of Heart Failure): Developed in Collaboration With the International Society for Heart and Lung Transplantation; Endorsed by the Heart Failure Society of America. Circulation 2001;104:2996-3007.

2. Arbustini E, Narula N, Dec GW, et al. The MOGE(S) classification for a phenotype-genotype nomenclature of cardiomyopathy: endorsed by the World Heart Federation. J Am Coll Cardiol 2013;62:2046-72.

3. Kalogeropoulos AP, Fonarow GC, Georgiopoulou V, et al. Characteristics and Outcomes of Adult Outpatients With Heart Failure and Improved or Recovered Ejection Fraction. JAMA cardiology 2016;1:510-8.

4. Dolgin M, Committee NYHAC. Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels: Little, Brown; 1994.

Cite this page content

Ezekowitz, Justin A. et al. 2017 Comprehensive Update of the CCS Guidelines for the Management of Heart Failure. Can J Cardiol 2017;33:1342-1433.