Until recently heart failure was only described in terms based on the degree of symptoms a patient presented with. This approach misses patients with heart failure without symptoms and those at risk for developing heart failure, two groups who represent the vast majority of the heart failure population. The AHA staging system sought to correct this nomenclature deficit and follows the convention of oncology nomenclature for cancer. The use of stages of heart failure captures the notion that this is a progressive condition and it is not enough to treat symptoms but also efforts should be made to stop progression.
What is confusing to clinicians-especially those new to heart failure management-is how the AHA stages fit in with the old New York Heart Association (NYHA) classes and the profiles used by Interagency Registry of Mechanically Assisted Circulatory Support (INTERMACS) to stratify advanced patients. The best way to remember the relationships is to again go back to the CHF continuum above. Stage A and B patients do not have heart failure symptoms. When a patient develops symptoms they become stage C (even if those symptoms are treated and later go away).
The NYHA classes are used to describe the degree of symptoms experienced by patients in stage C and range from no symptoms (Class I), mild symptoms (class II), moderate symptoms (class III) or severe symptoms at rest (class IV). Patients with persistent severe symptoms (class IV) despite treatment are no longer considered stage C and are grouped into stage D. These patients with advanced heart failure symptoms sometimes need consideration of mechanical circulatory support and INTERMACS profiles were developed to further stratify patients. Unfortunately, unlike AHA stages and NYHA classes, INTERMACS profiles are numbered in reverse progression where profile 1 are the sickest patients and profile 7 are relatively stable patients.
[tab title=”AHA Stages”]
American Heart Association HF Stages
Stage A: High risk for developing heart failure due to presence of one or more risk factors (CAD, hypertension, diabetes, obesity, etc)
Stage B: Asymptomatic heart failure despite presence of damaged myocardium and LV dysfunction
Stage C: Symptomatic heart failure (from very little symptoms all the way to severe limitation with minimal exertion and at rest)
Stage D: Refractory end-stage heart failure (persistent symptoms at rest despite medical treatment)
[tab title=”NYHA Classes”]
New York Heart Association Symptom Classes
The New York Heart Association class system identifies patients in AHA stage C (symptomatic heart failure) according to their physical limitations.
Class I: No limitations of physical activity, no symptoms with ordinary activities
Class II: Slight limitation, symptoms with ordinary activities
Class III: Marked limitation, symptoms with less than ordinary activities
Class IV: Severe limitation, symptoms of heart failure at rest
[tab title=”INTERMACS Profiles”]
Interagency Registry of Mechanically Assisted Circulatory Support Profiles
Interagency Registry of Mechanically Assisted Circulatory Support or INTERMACS created a system of profiles that assesses the comprehensive status of patients with advanced heart failure takes into consideration therapeutic interventions and extenuating circumstances (modifiers). The profiles allow more uniform decision making with regard to which patients are in need of mechanical circulatory support and the immediacy of such need. The profiles range from 1 to 7 and are in reverse numerical progression with increasing numbers representing more stability.
(Definitions from INTERMACS worksheet)
INTERMACS 1: Critical cardiogenic shock
Describes a patient who is “crashing and burning”, in which a patient has life-threatening hypotension and rapidly escalating inotropic pressor support, with critical organ hypoperfusion often confirmed by worsening acidosis and lactate levels.
INTERMACS 2: Progressive decline
Describes a patient who has been demonstrated “dependent” on inotropic support but nonetheless shows signs of continuing deterioration in nutrition, renal function, fluid retention, or other major status indicator. Patient profile 2 can also describe a patient with refractory volume overload, perhaps with evidence of impaired perfusion, in whom inotropic infusions cannot be maintained due to tachyarrhythmias, clinical ischemia, or other intolerance.
INTERMACS 3: Stable but inotrope dependent
Describes a patient who is clinically stable on mild-moderate doses of intravenous inotropes (or has a temporary circulatory support device) after repeated documentation of failure to wean without symptomatic hypotension, worsening symptoms, or progressive organ dysfunction (usually renal).
INTERMACS 4: Resting symptoms
Describes a patient who is at home on oral therapy but frequently has symptoms of congestion at rest or with activities of daily living (ADL). He or she may have orthopnea, shortness of breath during ADL such as dressing or bathing, gastrointestinal symptoms (abdominal discomfort, nausea, poor appetite), disabling ascites or severe lower extremity edema. This patient should be carefully considered for more intensive management and surveillance programs, which may in some cases, reveal poor compliance that would compromise outcomes with any therapy.
INTERMACS 5: Exertion Intolerant
Describes a patient who is comfortable at rest but unable to engage in any activity, living predominantly within the house or housebound. This patient has no congestive symptoms, but may have chronically elevated volume status, frequently with renal dysfunction, and may be characterized as exercise intolerant.
INTERMACS 6: Exertion Limited
Describes a patient who is comfortable at rest without evidence of fluid overload, but who is able to do some mild activity. Activities of daily living are comfortable and minor activities outside the home such as visiting friends or going to a restaurant can be performed, but fatigue results within a few minutes of any meaningful physical exertion. This patient has occasional episodes of worsening symptoms and is likely to have had a hospitalization for heart failure within the past year.
INTERMACS 7: Advanced NYHA Class 3
Describes a patient who is clinically stable with a reasonable level of comfortable activity, despite history of previous decompensation that is not recent. This patient is usually able to walk more than a block. Any decompensation requiring intravenous diuretics or hospitalization within the previous month should make this person a Patient Profile 6 or lower.