HF is a complex condition where by the heart is not able to pump blood effectively in order to meet the demands of the body.

Stages of HF can be defined by signs and symptoms, structural abnormalities, and left ventricular ejection fraction (LVEF).

Symptoms including shortness of breath, reduced exercise tolerance, and oedema. Structural abnormality such as thickened walls and reduced ejection fraction can be viewed under echocardiogram. Blood tests for biomarkers - NP and troponins, indicate heart disease.

Stages

Stage A: No symptoms nor signs of HF but the patient has high risk factors

Stage B: No signs/symptoms but some abnormal tests or structural abnormalities can be seen.

Stage C: Patient has HF with signs and symptoms on physical exertion.

Stage D: Advanced HF - patients has symptoms at rest and requires recurrent hospitalisation.

New York Heart Association (NYHA) Classification

The NYHA classification is used to characterize functional capacity and symptoms of patients with stage C or stage D, and used to help track the patient's condition.

Class I: No limitation of physical activity.

Class II: Slight limitation of hard physical activity, comfortable at rest.

Class III: Limitation of moderate physical activity, comfortable at rest.

Class IV: Symptoms even at rest.

Although a patient at stage C at may become asymptomatic with treatment (NYHA class I), that patient will still be categorized as stage C HF. 

Classification according to LVEF

Different prognosis and treatments given according to the patient's LVEF. LVEF is a spectrum, and there is overlap between classes and which drug regimen will work for a patient under a LVEF classification.

HFrEF (HF with reduced EF)LVEF ≤40%

HFimpEF (HF with improved EF) Previous LVEF ≤40% and a follow-up measurement of LVEF >40%

HFmrEF (HF with mildly reduced EF) LVEF 41%–49%

HFpEF (HF with preserved EF) LVEF ≥50%

ACC/AHA