While its use is widespread, the NYHA score is not very reproducible and does not reliably predict the walking distance or exercise tolerance on formal testing.In its 2001 guidelines, the American College of Cardiology/American Heart Association working group introduced four stages of heart failure:
Stage A: People at high risk for developing HF in the future, but no functional or structural heart disorder
Stage B: A structural heart disorder, but no symptoms at any stage
Stage C: Previous or current symptoms of heart failure in the context of an underlying structural heart problem, but managed with medical treatment
Stage D: Advanced disease requiring hospital-based support, a heart transplant, or palliative careThe ACC staging system is useful since 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. The degree of coexisting illness: i.e. heart failure/systemic hypertension, heart failure/pulmonary hypertension, heart failure/diabetes, heart failure/kidney failure, etc. 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 heart failure)

Histopathology
Histopathology can diagnose heart failure in autopsies. The presence of siderophages indicates chronic left-sided heart failure, but is not specific for it.
Remote monitoring can be effective to reduce complications for people with heart failure. Lifestyle
Behavior modification is a primary consideration in chronic heart failure management program, with dietary guidelines regarding fluid and salt intake. Fluid restriction is important to reduce fluid retention in the body and to correct the hyponatremic status of the body. The evidence of benefit of reducing salt, however, is poor as of 2018. Exercise and physical activity
Exercise should be encouraged and tailored to suit individuals capabilities. A meta-analysis found that centre-based group interventions delivered by a physiotherapist are helpful in promoting physical activity in HF. There is a need for additional training for physiotherapists in delivering behaviour change intervention alongside an exercise programme. An intervention is expected to be more efficacious in encouraging physical activity than the usual care if it includes Prompts and cues to walk or exercise, like a phone call or a text message. It is extremely helpful if a trusted clinician provides explicit advice to engage in physical activity (Credible source). Another highly effective strategy is to place objects that will serve as a cue to engage in physical activity in the everyday environment of the patient (Adding object to the environment; e.g., exercise step or treadmill). Encouragement to walk or exercise in various settings beyond CR (e.g., home, neighbourhood, parks) is also promising (Generalisation of target behaviour). Additional promising strategies are Graded tasks (e.g., gradual increase in intensity and duration of exercise training), Self-monitoring, Monitoring of physical activity by others without feedback, Action planning, and Goal-setting.