A At risk of heart failure due to conditions such as hypertension, diabetes, coronary artery disease

B Pre-heart failure with no symptoms but evidence for structural heart disease including reduced ejection fraction, increased left ventricular wall thickness, valvular disease

C Symptomatic heart failure with structural heart disease and heart failure symptoms

D Advanced heart failure with marked symptoms despite attempts at optimization of guideline-directed medical therapy

I No symptoms

II Symptoms with moderate exertion

III Symptoms with mild exertion

IV Symptoms with minimal exertion or at rest

• Reduced: ≤ 40%

• Mildly reduced: 41%–49%

• Preserved: ≥ 50%

• Improved: > 40% after initially being ≤ 40%