There are many different ways to categorize right , which includes whether the abnormality is due to insufficient contraction (systolic dysfunction); or due to insufficient relaxation of the heart (diastolic dysfunction), or to both; whether the problem is primarily increased venous back pressure (preload), or failure to supply adequate arterial perfusion (afterload); whether the abnormality is due to low cardiac output with high systemic vascular resistance or high cardiac output with low vascular resistance (low-output heart failure vs. high output cardiac failure); degree of functional impairment conferred by the abnormality (as reflected in the New York Heart Association Functional Classification^[1]); and the degree of coexisting illness: i.e. heart failure/systemic hypertension, heart failure/pulmonary hypertension, heart failure/diabetes, heart failure/chronic renal failure, etc.

• Right heart failure can be functionally classified according to the New york heart association functional classification – NYHA (I-IV) or structurally according to the American College of Cardiology/ American Heart Association – ACC/AHA (stage A, B, C and D).
• The ACC staging system is useful in that Stage A encompasses “pre-heart failure” — a stage where intervention with treatment can presumably prevent progression to overt symptoms. ACC Stage A does not have a corresponding NYHA class. ACC Stage B would correspond to NYHA Class I. ACC Stage C corresponds to NYHA Class II and III, while ACC Stage D overlaps with NYHA Class IV.

According to the New york heart association functional classification, the classes (I-IV) are:

According to the American College of Cardiology/American Heart Association working group, the stages (A-D) are:^[2]