Abstract
BACKGROUND: In order to identify candidacy and treatment response for patients with obstructive hypertrophic cardiomyopathy (oHCM), clinicians need an accurate means of assessing symptoms, function, and quality of life. While the New York Heart Association (NYHA) Classification is most often used for this purpose, the Kansas City Cardiomyopathy Questionnaire (KCCQ-23) is more accurate and sensitive to change, although less familiar to practicing clinicians. To support interpreting the KCCQ-23, we describe cross-sectional and longitudinal changes in KCCQ scores in the context of the NYHA. METHODS: Participants from the EXPLORER-HCM trial (NCT03470545) completed the KCCQ-23 and clinicians assigned NYHA classes at study visits. Participants were included if they had baseline and week 30 data for cross-sectional and longitudinal changes. Median KCCQ-23 scores were compared by NYHA class at baseline and week 30 and by change in NYHA class from baseline to week 30. RESULTS: Cross-sectionally, the KCCQ-23 Overall Summary Scores (KCCQ-23 OSS) and Clinical Summary Scores (KCCQ-23 CSS) had an inverse relationship with the NYHA class at baseline and 30 weeks, with marked variations in KCCQ-23 scores among patients assigned to the same NYHA class. When improving from NYHA class II to I, the median changes in KCCQ-23 OSS and KCCQ-23 CSS were 10 (IQR 4, 22) and 8 (IQR 2, 20), respectively. The changes were larger when improving from NYHA class III to II and from NYHA class III to I. CONCLUSION: KCCQ-23 scores are inversely related to NYHA classes, with significant variability within classes. Changes in scores are not linear, suggesting greater differences when patients move between NYHA Classes II and III than when moving between Classes I and II. These insights may help clinicians better understand cross-sectional and longitudinal changes in KCCQ scores.