Raw data of paper entitled: "Cardiopulmonary exercise testing in hypertrophic cardiomyopathy: the role of reduced O2 pulse and chronotropic incompetence in myocardial adaptation"

Aims: Hypertrophic cardiomyopathy (HCM) is associated with functional limitations during exercise. We aimed to evaluate oxygen pulse (O2p) as a stroke volume (SV) surrogate and to propose a new HCM classification (RoMa) based on haemodynamic profiles during exercise: predicted peak O2p (O2pp) and peak heart rate (HRpp). Methods and results: This multicentre, prospective study included 90 clinically stable HCM patients who underwent cardiopulmonary exercise testing with simultaneous impedance cardiography (PhysioFlow®). We assessed the relationship between SV and O2p. Patients were stratified into four groups based on HRpp (≥80% predicted) and O2pp (≥100% predicted): RoMa I (high HRpp-high O2pp), RoMa II (high HRpp-low O2pp), RoMa III (low HRpp-high O2pp), and RoMa IV (low HRpp-low O2pp). Oxygen uptake (VO2), minute ventilation-to-carbon dioxide production (VE/VCO2) slope, SV, and mitral regurgitation (MR) were analysed. Patients (80% male, 53 [42-64] years) had preserved left ventricular ejection fraction (62 [58-68]%) and peakVO2 (23.1 ± 7.8 mL/min/kg = 81 ± 21% predicted). SV correlated with O2p (r = 0.48, P < 0.001; β = 3.59, P < 0.001). Resting moderate to severe MR was more prevalent in RoMa class IV (41%) vs. RoMa I (18%, P = 0.038). PeakVO2 declined across groups, from 29.7 ± 8.3 (RoMa I) to 16.2 ± 5.1 mL/min/kg (RoMa IV, P < 0.001). VE/VCO2 slope increased from 26.4 ± 4.5 (RoMa I) to 38.6 ± 6.0 (RoMa IV, P = 0.002). Peak SV decreased from 128.7 ± 24.8 (RoMa I) to 104.7 ± 28.0 mL (RoMa IV, P = 0.019), while rest to peak SV difference dropped from 38.6 (30.4-52.8) to 15.8 (8.2-27.9) mL (P = 0.002). Conclusion: SV and O2p are significantly related, and the RoMa classification effectively distinguished HCM patients.