Simches Cardiovascular Research Center, Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston.
MIT Critical Data, Laboratory for Computational Physiology, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge.
JAMA Cardiol. 2021 Jun 1;6(6):653-660. doi: 10.1001/jamacardio.2021.0292.
Heart failure with preserved ejection fraction (HFpEF) is a joint metabolic and cardiovascular disorder with significant noncardiac contributions.
To define and quantify the metabolic cost of initiating exercise in individuals with and without HFpEF and its functional consequences.
DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study included individuals with hemodynamically confirmed HFpEF from the Massachusetts General Hospital Exercise Study (MGH-ExS) and community-dwelling participants from the Framingham Heart Study (FHS). Analysis began April 2016 and ended November 2020.
Internal work (IW), a measure of work equivalents required to initiate movement.
Using breath-by-breath oxygen uptake (V̇o2) measurements and V̇o2-work rate associations, cost of initiating exercise (IW) in patients with HFpEF (MGH-ExS) and in community-dwelling individuals (FHS) was quantified. Linear regression was used to estimate associations between IW and clinical/hemodynamic measures.
Of 3231 patients, 184 (5.7%) had HFpEF and were from MGH-ExS, and 3047 (94.3%) were community-dwelling individuals from FHS. In the MGH-ExS cohort, 86 (47%) were women, the median (interquartile range) age was 63 (53-72) years, and the median (interquartile range) peak V̇o2 level was 13.33 (11.77-15.62) mL/kg/min. In the FHS cohort, 1620 (53%) were women, the median (interquartile range) age was 54 (48-60) years, and the median (interquartile range) peak V̇o2 level was 22.2 (17.85-27.35) mL/kg/min. IW was higher in patients with HFpEF and accounted for 27% (interquartile range, 21%-39%) of the total work (IW + measured external workload on the cycle), compared with 15% (interquartile range, 12%-20%) of that in FHS participants. Body mass index accounted for greatest explained variance in patients with HFpEF from MGH-ExS and FHS participants (22% and 18%, respectively), while resting cardiac output and biventricular filling pressures were not significantly associated with variance in IW in patients with HFpEF. A higher IW in patients with HFpEF was associated with a greater increase in left- and right-sided cardiac filing pressure during unloaded exercise, despite similar resting hemodynamic measures across IW.
This study found that internal work, a new body mass index-related measure reflecting the metabolic cost of initiating movement, is higher in individuals with HFpEF compared with middle-aged adults in the community and is associated with steep, early increases in cardiac filling pressures. These findings highlight the importance of quantifying heterogeneous responses to exercise initiation when evaluating functional intolerance in individuals at risk for or with HFpEF.
射血分数保留的心力衰竭（HFpEF）是一种联合代谢和心血管疾病，具有重要的非心脏贡献。
定义和量化有和没有 HFpEF 的个体开始运动的代谢成本及其功能后果。
设计、设置和参与者：这项前瞻性队列研究包括来自马萨诸塞州总医院运动研究（MGH-ExS）的血流动力学确诊 HFpEF 患者和来自弗雷明汉心脏研究（FHS）的社区居民参与者。分析于 2016 年 4 月开始，2020 年 11 月结束。
内部工作（IW），一种衡量启动运动所需工作量的指标。
使用逐次呼吸耗氧量（V̇o2）测量和 V̇o2-工作速率关联，量化了 HFpEF 患者（MGH-ExS）和社区居民（FHS）开始运动的成本（IW）。线性回归用于估计 IW 与临床/血液动力学指标之间的关联。
在 3231 名患者中，有 184 名（5.7%）患有 HFpEF，来自 MGH-ExS，3047 名（94.3%）是来自 FHS 的社区居民。在 MGH-ExS 队列中，86 名（47%）为女性，中位（四分位间距）年龄为 63（53-72）岁，中位（四分位间距）峰值 V̇o2 水平为 13.33（11.77-15.62）mL/kg/min。在 FHS 队列中，1620 名（53%）为女性，中位（四分位间距）年龄为 54（48-60）岁，中位（四分位间距）峰值 V̇o2 水平为 22.2（17.85-27.35）mL/kg/min。HFpEF 患者的 IW 更高，占总工作量（IW+在自行车上测量的外部工作负荷）的 27%（四分位间距，21%-39%），而 FHS 参与者的 IW 占 15%（四分位间距，12%-20%）。在 MGH-ExS 和 FHS 参与者中，身体质量指数（BMI）解释了 HFpEF 患者 IW 中最大的差异（分别为 22%和 18%），而静息心输出量和双心室充盈压与 HFpEF 患者 IW 的差异无显著相关性。HFpEF 患者的较高 IW 与在无负荷运动期间左、右心充盈压力的更大增加相关，尽管 IW 之间的静息血液动力学测量相似。
本研究发现，内部工作（一种新的与 BMI 相关的指标，反映了启动运动的代谢成本）在 HFpEF 患者中高于社区中年成年人，并且与心脏充盈压力的急剧、早期增加有关。这些发现强调了在评估有或没有 HFpEF 风险的个体的功能不耐受时，量化对运动起始的异质反应的重要性。
