Relationship between symptom assessment and cardiopulmonary exercise testing in patients with obstructive...

In obstructive hypertrophic cardiomyopathy (oHCM), peak oxygen consumption (pVO₂) by cardiopulmonary exercise testing (CPET) and patient-reported outcomes with Kansas City Cardiomyopathy Questionnaire (KCCQ), are increasingly utilized to assess efficacy in clinical trials. However, in clinical practice, treatments have historically been based on physician assessment of symptoms with New York Heart Association (NYHA) classification. We aimed to evaluate relationship between NYHA classification, pVO₂ and KCCQ in oHCM.

Consecutive patients with oHCM undergoing CPET and KCCQ at two HCM-centers. Correlations were assessed between continuous measures and according to subgroups of pVO₂ (<14, 14-20, >20 mL/kg/min), KCCQ-overall summary score (OSS) (≤50, 51-75, >75) and NYHA class (III/IV, II, I) to reflect moderate to severe, mild to moderate, and little to no limitations.

Clinical evaluation and CPET were performed in 75 patients: 59 ± 13 years, resting LVOT gradient 81 ± 29 mmHg, pVO₂ 17.6 ± 4.5 mL/kg/min, with 88 % NYHA class ≥II and 83 % with KCCQ-OSS <75. NYHA classification was moderately associated with KCCQ-OSS (ρ = -0.596, p < 0.001) and borderline correlated with pVO₂ (ρ = -0.223, p = 0.055). pVO₂ showed a weak correlation with KCCQ-OSS (r = 0.361, p = 0.002). On patient level, a discordance in the severity of limitations between each test was present: 55 % between pVO₂ and NYHA, 53 % between pVO₂ and KCCQ-OSS and 40 % between KCCQ-OSS and NYHA class.

Poor correlation and substantial differences were observed between physician assessed symptom burden, objective measures of exercise capacity, and patient-reported measures. These findings provide insight for considered in the context of clinical management decisions and clinical trials in oHCM.