Relationship Between the Kansas City Cardiomyopathy Questionnaire Score and New York Heart Association Class in Patients With Hypertrophic Cardiomyopathy: Insights From EXPLORER-HCM

Background: Treating hypertrophic cardiomyopathy (HCM) aims to improve health status. Given the importance of accurately assessing health status and the limitations of the New York Heart Association (NYHA) Class, the Kansas City Cardiomyopathy Questionnaire (KCCQ) has gained interest. Thus, frameworks for interpreting the KCCQ in the context of the NYHA are needed. Methods: EXPLORER-HCM (NCT03470545) randomized patients with NYHA class II-III HCM to mavacamten or placebo and collected the NYHA and KCCQ. We pooled subjects for analyses who had KCCQ scores and NYHA class at baseline and 30-weeks. KCCQ scores, stratified by class at baseline, 30 weeks, and by change in class were reported as means±standard deviations. We generated two unadjusted models predicting the probability of NYHA class attribution for a given KCCQ-Overall Summary Score (OSS) at 30 weeks and for change in NYHA class by changes in KCCQ-OSS. Results: Of 196 participants, mean age was 57.9±12.2 years, 120 (61.2%) were male, and the baseline mean LVOT gradient was 51.5±30 mm Hg. Mean KCCQ scores by NYHA classes at baseline and 30 weeks are included in Table 1. Figure 1 maps the probability of NYHA Class by KCCQ. KCCQ-OSS Scores <40 mapped to Class III, scores from 40-85 mapped to Class II, and >85 mapped to Class I. Reductions of >25 points on the KCCQ-OSS aligned with worsening class and increases by >8 points on the KCCQ-OSS reflected improvement in class. Conclusion: NYHA Class is concordant with KCCQ, but there is variability in health status within class and changes in class. These analyses may help clinicians interpret both cross-sectional and changes in KCCQ scores for patients with obstructive HCM.