Integrating the 6-Minute Walk Test Into New York Heart Association Functional Classification

The New York Heart Association (NYHA) Functional Classification System is integral to guiding management of patients with heart failure. However, reproducibility remains a challenge due to subjective assessment of patient functional capacity based on self-reported symptoms and clinical interpretations. The 6-minute walk test (6MWT), involving walking as far as possible in 6 minutes, represents a simple, objective functional assessment tool. The objective of this study was to determine the clinical utility of the 6MWT in improving reproducibility of cardiologist-assigned NYHA classification. This was a prospective observational study. After performing a 6MWT, adults with hypertrophic cardiomyopathy, heart failure, or pulmonary hypertension were reassessed for NYHA classification. Of 56 participants, 25 were classified as NYHA Class I, 21 as NYHA Class II, 9 as NYHA Class III, and 1 as NYHA Class IV at baseline. The 6MWT resulted in redistribution of 15 participants in NYHA Class I, 21 participants in NYHA Class II, 16 participants in NYHA Class III, and 4 participants in NYHA Class IV. Participants were predominantly reclassified to higher NYHA classes (25/56 (45%)) while 4/56 (7%) received a lower NYHA Class. 6-minute walk distance was negatively correlated with NYHA Class, particularly between NYHA Classes I and II which are often difficult to differentiate. Traditional cardiac risk factors (age, sex, dyslipidemia, diabetes, hypertension, and smoking) or history of invasive procedures (pacemakers, stents, valve replacements) were not associated with effect on the 6MWT. In conclusion, the 6MWT reveals more severe functional impairment than expected by relying solely on patient-reported symptoms and clinical judgment.