Limitations of the New York Heart Association functional classification system and self-reported walking distances in chronic heart failure

Background: Two ways to evaluate the symptoms of heart failure are the New York Heart Association (NYHA) classification and asking patients how far they can walk (walk distance). The NYHA system is commonly used, although it is not clear how individual clinicians apply it. Aim: To investigate how useful these measures are to assess heart failure and whether other questions might be more helpful. Methods: 30 cardiologists were asked what questions they used when assessing patients with heart failure. To assess interoperator variability, two cardiologists assessed a series of 50 patients in classes II and III using the NYHA classification. 45 patients who had undergone cardiopulmonary testing were interviewed using a specially formulated questionnaire. They were also asked how far they could walk before being stopped by symptoms, and then tested on their ability to estimate distance. Results: The survey of cardiologists showed no consistent method for assessing NYHA class and a literature survey showed that 99% of research papers do not reference or describe their methods for assigning NYHA classes. The interoperator variability study showed only 54% concordance between the two cardiologists. 70% of cardiologists asked patients for their walk distance; however, this walk distance correlated poorly with actual exercise capacity measured by cardiopulmonary testing (r = 0.04, p = 0.82). Conclusion: No consistent method of assessing NYHA class is in use and the interoperator study on class II and class III patients gave a result little better than chance. Some potential questions are offered for use in assessment. Walking distance, although frequently asked, does not correlate with formally measured exercise capacity, even after correction for patient perception of distance, and has never been found to have prognostic relevance. Its value is therefore doubtful.