Dataset related to the publication "Mapelli M, Romani S, Magri D, Merlo M, Cittar M, Mase M, et al. Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy". Heart.

Objectives: Reduced cardiac output (CO) has been considered crucial in symptoms' genesis in hypertrophic cardiomyopathy (HCM). Absolute value and temporal behaviour of O2-pulse (oxygen uptake/heart rate (VO2/HR)), and the VO2/work relationship during exercise reflect closely stroke volume (SV) and CO changes, respectively. We hypothesise that adding O2-pulse absolute value and kinetics, and VO2/work relationship to standard cardiopulmonary exercise testing (CPET) could help identify more exercise-limited patients with HCM.

Methods: CPETs were performed in 3 HCM dedicated clinical units. We retrospectively enrolled non-end-stage consecutive patients with HCM, grouped according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva manoeuvre (72% of patients with LVOTO <30; 10% between 30 and 49 and 18% ≥50 mm Hg). We evaluated the CPET response in HCM focusing on parameters strongly associated with SV and CO, such as O2-pulse and VO2, respectively, considering their absolute values and temporal behaviour during exercise.

Results: We included 312 patients (70% males, age 49±18 years). Peak VO2 (percentage of predicted), O2-pulse and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety-six (31%) patients with HCM presented an abnormal O2-pulse temporal behaviour, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106±45 vs 130±49 W), VO2 (21.3±6.6 vs 24.1±7.7 mL/min/kg; 74%±17% vs 80%±20%) and O2-pulse (12 (9-14) vs 14 (11-17) mL/beat), with higher VE/VCO2 slope (28 (25-31) vs 27 (24-31)) (p<0.005 for all). Only 2 patients had an abnormal VO2/work slope.

Conclusion: None of the frequently used CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal temporal behaviour of O2-pulse during exercise, which is strongly related to inadequate SV increase, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, identifying more advanced disease irrespectively of LVOTO.

研究目的：心输出量（cardiac output, CO）降低被认为是肥厚型心肌病（hypertrophic cardiomyopathy, HCM）症状发生的关键致病机制。运动过程中氧脉搏（O2-pulse，即摄氧量/心率（VO2/HR））的绝对值与动态变化，以及摄氧量（VO2）与做功量的关联，可分别紧密反映每搏输出量（stroke volume, SV）和心输出量的变化。本研究假设，在标准心肺运动试验（cardiopulmonary exercise testing, CPET）中纳入氧脉搏绝对值、动态变化及VO2与做功量的关联参数，可帮助识别更多存在运动受限的肥厚型心肌病患者。

研究方法：本研究于3个肥厚型心肌病专科临床中心开展心肺运动试验。我们回顾性纳入了非终末期的连续性肥厚型心肌病患者，并根据静息状态或瓦氏动作（Valsalva manoeuvre）下的左心室流出道梗阻（left ventricle outflow tract obstruction, LVOTO）程度进行分组：其中72%的患者LVOTO压力梯度<30 mmHg，10%介于30~49 mmHg，18%≥50 mmHg。本研究针对肥厚型心肌病患者的心肺运动试验应答情况进行评估，重点关注与每搏输出量和心输出量强相关的参数，即分别对应氧脉搏与摄氧量的绝对值及其运动过程中的动态变化。

研究结果：本研究共纳入312例患者（男性占70%，年龄49±18岁）。不同左心室流出道梗阻分组的峰值摄氧量（预测值百分比）、氧脉搏及通气量/二氧化碳生成量（VE/VCO2）斜率均无显著差异。共有96例（31%）肥厚型心肌病患者出现氧脉搏动态变化异常，且这一异常与左心室流出道梗阻程度无关。与无该异常的患者相比，此类患者的峰值收缩压、做功量（106±45 vs 130±49 W）、摄氧量（21.3±6.6 vs 24.1±7.7 mL·min⁻¹·kg⁻¹；预测值百分比74%±17% vs 80%±20%）及氧脉搏（12（四分位距9~14）vs 14（11~17）mL·beat⁻¹）均更低，而通气量/二氧化碳生成量斜率更高（28（25~31）vs 27（24~31）），所有指标的组间差异均具有统计学意义（p<0.005）。仅2例患者出现VO2与做功量斜率异常。

研究结论：临床常用的心肺运动试验参数，无论是绝对值还是动态关联指标，均与左心室流出道梗阻程度无关联。与之不同的是，运动过程中氧脉搏的动态变化异常（该异常与每搏输出量增加不足密切相关），与患者运动功能受损（峰值摄氧量、无氧阈摄氧量及做功量降低）及通气量/二氧化碳生成量斜率升高相关，可在不考虑左心室流出道梗阻程度的情况下，识别出病情更严重的肥厚型心肌病患者。