NYHA Functional Classification of Heart Failure

The NYHA (New York Heart Association) functional class is the standard clinical severity scale for chronic heart failure. It has been in use since 1928, with the most recent revision in 1994. It divides patients into 4 functional classes based on the degree of limitation in physical activity.

Class I: ordinary physical activity does not cause symptoms. Class II: slight limitation - ordinary activity is accompanied by dyspnea, fatigue, or palpitations. Class III: marked limitation - symptoms occur with less than ordinary activity, but the patient is comfortable at rest. Class IV: symptoms at rest; any activity increases discomfort.

The scale is subjective, but this is also its main strength: its correlation with prognosis and quality of life is stronger than that of objective measures (LVEF, NT-proBNP) used in isolation. The ESC 2021 heart failure guidelines use NYHA class as a key criterion for clinical decisions: ICD/CRT indications, therapy escalation (initiation of SGLT2 inhibitors or sacubitril/valsartan), and referral for transplantation.

• Any patient with an established diagnosis of heart failure - at every visit.
• Decisions on specific therapy (beta-blockers, ACE inhibitors/ARBs/ARNI, mineralocorticoid receptor antagonists, SGLT2 inhibitors).
• Indications for device implantation (ICD, CRT-D) - typically Class II-IV.
• Assessment of treatment efficacy - improvement of 1 functional class is clinically significant.

• Subjectivity - two physicians may rate the same patient differently. Accuracy improves when the assessment is anchored to the patient's specific everyday activities.
• Not well suited to patients with limited mobility or who are immobilized.
• Status can fluctuate within a week in the same patient - document the patient's 'average' status over the past month.
• Does not reflect structural cardiac changes - echocardiography is needed.