New York Heart Association (NYHA) Classification for Breathlessness
The NYHA classification is a four-class system that grades heart failure symptom severity based on physical activity limitations: Class I (no limitation with ordinary activity), Class II (slight limitation with ordinary activity), Class III (marked limitation with less than ordinary activity), and Class IV (symptoms at rest). 1
The Four NYHA Classes
Class I: No limitation of physical activity. Ordinary physical exercise does not cause undue fatigue, dyspnea, or palpitations. 1
Class II: Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity results in fatigue, palpitations, or dyspnea. 1
Class III: Marked limitation of physical activity. Comfortable at rest, but less than ordinary activity causes fatigue, palpitations, or dyspnea. 1
Class IV: Unable to carry out any physical activity without discomfort. Symptoms of heart failure are present even at rest, with increased discomfort with any physical activity. 1
Critical Clinical Context
The NYHA classification is a subjective assessment by healthcare providers that can change frequently over short periods of time, and it correlates poorly with objective measures of cardiac dysfunction. 1 This means that symptom severity does not reliably predict the degree of left ventricular dysfunction or other structural cardiac abnormalities. 1
Important Caveats
Symptoms may be related to prognosis, particularly if persisting after therapy, but there is a poor relationship between symptoms and the severity of cardiac dysfunction. 1
The NYHA classification should be reassessed after each treatment adjustment throughout the continuum of care, recognizing that it can change rapidly. 2, 3
For NYHA Class I patients to fulfill the basic definition of heart failure, they must have objective evidence of cardiac dysfunction, a past history of heart failure symptoms, and be receiving treatment for heart failure. 1
Relationship to ACC/AHA Staging System
The NYHA classification is intended to complement, not replace, the ACC/AHA staging system (Stages A-D). 1, 4 The ACC/AHA stages represent disease progression that typically does not reverse (Stage A: at risk, Stage B: structural disease without symptoms, Stage C: structural disease with symptoms, Stage D: refractory/advanced heart failure), while NYHA class reflects current symptom status that can fluctuate with treatment. 1, 4
Management Implications
All patients with heart failure and reduced ejection fraction (HFrEF) should receive guideline-directed medical therapy with ACE inhibitors/ARBs, beta-blockers, and mineralocorticoid receptor antagonists regardless of NYHA class, as these therapies provide similar relative mortality reductions across all functional classes. 4, 2, 3
Class-Specific Considerations
NYHA Class I (Asymptomatic): Focus on aggressive optimization of guideline-directed medical therapy to prevent progression. These patients still have measurable mortality risk despite absence of symptoms. 2, 3
NYHA Class II (Mild symptoms): Initiate all guideline-directed medical therapies immediately and titrate to target doses. Consider ICD if LVEF ≤35% and life expectancy >1 year. 2, 3
NYHA Class III (Moderate symptoms): Maximize guideline-directed medical therapy and evaluate for cardiac resynchronization therapy (CRT) if LVEF ≤35% and QRS duration ≥120-150 ms. 2, 3
NYHA Class IV (Severe symptoms at rest): Corresponds to ACC/AHA Stage D (advanced heart failure) and requires evaluation for mechanical circulatory support, cardiac transplantation, or palliative care. 4, 2, 3
Supplementing NYHA Classification
NYHA classification should be supplemented with objective measures including NT-proBNP levels, 6-minute walk distance, quality of life scores (such as Kansas City Cardiomyopathy Questionnaire), and cardiopulmonary exercise testing when available. 1, 2, 3 Recent evidence shows that NT-proBNP level is a poor discriminator between NYHA Class I and II (with 93% overlap in distribution), and that physician-defined "asymptomatic" functional class can conceal patients at substantial risk for adverse outcomes. 5
Practical Assessment Points
Document NYHA class at every patient visit using standardized criteria. 1, 4
Assess breathlessness in different modes (effort-related and nocturnal), as symptoms may be difficult to interpret, particularly in elderly patients, obese individuals, and women. 1
Recognize that symptoms cannot guide the optimal titration of neurohormonal blockers—objective measures and target dosing should be used instead. 1