13th July 2022, Dr Chee L Khoo
Have you noticed we don’t hear about congestive cardiac failure (CCF) anymore? Its’ just plain heart failure (HF) now. It makes sense because not all heart failures are congestive in nature. Of course, you are aware of the new terms – heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF). Guess what, there are more categories of HF defined now. There are also more stages of heart failure defined as well. A number of international heart failure societies have come together with a consensus statement defining the different categories and stages of HF. We need to know these definitions so that we can diagnose, initiate and intensify treatment early as there are huge implications for the morbidity and mortality of HF. More importantly, the new consensus statement reinforces the role of the GP in the management of HF.
Why do we need a new universal definition of HF?
HF is a clinical syndrome with different aetiologies and pathophysiology rather than a specific disease. The definition varies widely according to what the definition is used for. This can range from clinical trials to research to clinical care. Thus, everyone defines HF differently. This makes clinical efficacy trials and data interpretation difficult to compare. This makes the funding of new therapies by government difficult too.
A syndrome that is based solely on symptoms can be confusing for clinicians and patients, both because they are often not specific to a single disease (eg, fatigue and dyspnea) and because they are highly subjective, for example, with the same objective limitation being considered disabling by 1 person and perceived as being normal for age by another.
The traditional textbook definition of HF is usually defined as a “condition in which the heart cannot pump enough blood to meet the body’s needs” 1 or an “abnormality of cardiac structure or function leading to failure of the heart to deliver oxygen at a rate commensurate with the requirements of the metabolising tissues”(1). That definition is not precise and is difficult to verify in practice. Besides, the inability to meet the metabolic requirements of tissues is not always present even in advanced HF (2).
The Heart Failure societies of America, Europe and Japan published a Universal Definition of HF in January 2021 (3). This has been endorsed by the heart failure experts from Australia and NZ, Canadian, India and China. The Australian HF guidelines last published in 2018 is being updated as we speak.
The New Definition of HF
The new universal definition has two elements:
- Symptoms and or signs caused by a structural and/or functional cardiac abnormality (as determined by an EF of <50%, abnormal cardiac chamber enlargement, E/E’ of >15, moderate/severe ventricular hypertrophy or moderate/severe valvular obstructive or regurgitant lesion) and
- Corroborated by at least one of the following:
Elevated natriuretic peptide levels or Objective evidence of cardiogenic pulmonary or systemic congestion by diagnostic modalities, such as imaging (eg, by chest radiograph or elevated filling pressures by echocardiography) or hemodynamic measurement (eg, right heart catheterisation, pulmonary artery catheter) at rest or with provocation (eg, exercise).
Note that the use of BNP and NTproBNP to confirm the diagnosis of HF appears to be encouraged even though Medicare is yet to fund the ordering of the tests.
The 4 Categories of HF
The defining ejection fraction (EF) threshold used to be 50%. Now, for HFrEF, the EF needs to be <40%. HFpEF is still kept at EF >50%. As a result, there is a new category, heart failure with mildly reduced ejection fraction (HFmrEF) for EF between 40-49%. It is uncertain whether this represent a new entity of HF or a category which is transitioning towards HFrEF or HFpEF.
There is a further category of HF, HfImpEF or heart failure with improved EF. This covers patients whose EF has improved at least 10% with HF treatment. This category is necessary because patients whose EF has improved are still in danger of falling back into HF and developing the complications of HF.
The 4 Stages of HF
The universal definition of HF also added two new stages of HF:
- Patients at high risk for HF but without structural heart disease or symptoms of HF
- Structural heart disease but without signs or symptoms of HF
- Structural heart disease with prior or current symptoms of HF and
- Refractory HF requiring specialised interventions.
The universal definition of HF document also reinforced the role of ARNI and SGLT2 inhibitors in the management of HFrEF as more data have come in. We explored their roles when we discussed Quadruple Therapy in HF just 6 months ago here.
The universal definition of HF also highlighted the important role GPs play in early diagnosis, early initiation and intensification of quadruple therapy in patients with HFrEF. Remember, we should incorporate all 4 classes of medications early and rapidly and not wait for complications to occur before intensifying treatment. We should be titrating the doses to their maximal tolerated doses of each class within weeks. We need not wait for the patient to see the specialist at their next appointment. We discussed and explored the issue of treatment inertia in the management of heart failure a little more than 12 months ago here.
Reference:
- Wagner S, Cohn K. Heart failure. A proposed definition and classification. Arch Intern Med 1977;137:675–8.
- Adamo L, Nassif ME, Novak E, LaRue SJ, Mann DL. Prevalence of lactic acidaemia in patients with advanced heart failure and depressed cardiac output. Eur J Heart Fail 2017;19:1027–33.
- Bozkurt B, Coats AJS, et al. Universal definition and classification of heart failure. Journal of Cardiac Failure. 2021;27(4): P387–413