This methodological study aimed to validate the cardiac output (CO) measured by exercise-stress real-time phase-contrast cardiovascular magnetic resonance imaging (CMR) in patients with heart failure and preserved ejection fraction (HFpEF). 68 patients with dyspnea on exertion (NYHA ≥ II) and echocardiographic signs of diastolic dysfunction underwent rest and exercise stress right heart catheterization (RHC) and CMR within 24 h. Patients were diagnosed as overt HFpEF (pulmonary capillary wedge pressure (PCWP) ≥ 15mmHg at rest), masked HFpEF (PCWP ≥ 25mmHg during exercise stress but < 15mmHg at rest) and non-cardiac dyspnea. CO was calculated using RHC as the reference standard, and in CMR by the volumetric stroke volume, conventional phase-contrast and rest and stress real-time phase-contrast imaging. At rest, the CMR based CO showed good agreement with RHC with an ICC of 0.772 for conventional phase-contrast, and 0.872 for real-time phase-contrast measurements. During exercise stress, the agreement of real-time CMR and RHC was good with an ICC of 0.805. Real-time measurements underestimated the CO at rest (Bias:0.71 L/min) and during exercise stress (Bias:1.4 L/min). Patients with overt HFpEF had a significantly lower cardiac index compared to patients with masked HFpEF and with non-cardiac dyspnea during exercise stress, but not at rest. Real-time phase-contrast CO can be assessed with good agreement with the invasive reference standard at rest and during exercise stress. While moderate underestimation of the CO needs to be considered with non-invasive testing, the CO using real-time CMR provides useful clinical information and could help to avoid unnecessary invasive procedures in HFpEF patients.

这项方法学研究旨在验证通过运动-应激实时相位对比心血管磁共振成像 (CMR) 测量的心力衰竭和射血分数保留 (HFpEF) 患者的心输出量 (CO)。68 名劳力性呼吸困难 (NYHA ≥ II) 和舒张功能障碍超声心动图征象的患者在 24 小时内接受了休息和运动应激性右心导管检查 (RHC) 和 CMR。患者被诊断为显性 HFpEF（静息时肺毛细血管楔压 (PCWP) ≥ 15mmHg）、隐匿性 HFpEF（运动应激时 PCWP ≥ 25mmHg，但静息时 < 15mmHg）和非心源性呼吸困难。使用 RHC 作为参考标准计算 CO，在 CMR 中通过容积每搏输出量、常规相差以及休息和压力实时相差成像来计算。在静止状态下，基于 CMR 的 CO 与 RHC 表现出良好的一致性，传统相差测量的 ICC 为 0.772，实时相差测量的 ICC 为 0.872。在运动压力期间，实时 CMR 和 RHC 一致性良好，ICC 为 0.805。实时测量低估了静息时的 CO（偏差：0.71 L/min）和运动压力期间的 CO（偏差：1.4 L/min）。与隐匿性 HFpEF 和运动应激期间非心源性呼吸困难的患者相比，明显 HFpEF 患者的心脏指数显着较低，但在休息时则不然。实时相位对比 CO 的评估与静息和运动应激期间的侵入性参考标准具有良好的一致性。虽然非侵入性测试需要考虑适度低估 CO，但使用实时 CMR 的 CO 可以提供有用的临床信息，并有助于避免 HFpEF 患者不必要的侵入性操作。