BACKGROUND Left ventricular pressure-strain-derived myocardial work index (LVMWI) is a novel, noninvasive method for left ventricular (LV) function evaluation in relation to LV pressure dynamics. LV global longitudinal strain (LVGLS) has proven benefit for diagnosis and risk stratification in patients with cardiac amyloidosis (CA), but LVGLS does not adjust for loading conditions. The aim of the present study was to characterize LVMWI at rest and during exercise in patients with CA. METHODS A total of 155 subjects were retrospectively included. These subjects comprised 100 patients with CA and 55 healthy control subjects. All patients had previously undergone comprehensive two-dimensional echocardiographic examinations at rest. Furthermore, a subgroup 27 patients with CA and 41 control subjects was examined using semisupine exercise stress echocardiography. RESULTS Patients with CA had significantly lower LVGLS, LVMWI, and LV myocardial work efficiency (LVMWE) than control subjects (P < .0001 for all). The reduction in LV myocardial performance was more pronounced in the basal segments, which led to significant alterations in the average apical-to-basal segmental ratios between patients with CA and control subjects (LVGLS, 2.6 [1.9 to 4.1] vs 1.3 [1.2 to 1.5]; LVMWI, 2.6 [1.7 to 3.8] vs 1.3 [1.1 to 1.5]; LVMWE, 1.1 [1.0 to 1.3] vs 1.0 [1.0 to 1.1]; P < .0001 for all). The average increase in LVMWI from rest to peak exercise was 1,974 mm Hg% (95% CI, 1,699 to 2,250 mm Hg%; P < .0001) in control subjects and 496 mm Hg% (95% CI, 156 to 835 mm Hg%; P < .01) in patients with CA. The absolute numeric LVGLS increase was 5.6% (95% CI, 3.9% to 7.3%; P < .0001) in control subjects and only 1.2% (95% CI, -0.9% to 3.3%; P = .26) in patients with CA (between groups, P < .0001) from rest to peak exercise. The LVMWI increase in patients with CA was mediated by improvement in the apical segments (P < .0001), whereas there was no significant LVMWI alterations in the midventricular or basal segments. LVMWE remained stable during exercise in control subjects (Δ -0.6%; 95% CI, -2.5% to 1.2%; P = .50) but decreased significantly in patients with CA (Δ -2.5%; 95% CI, -4.8% to -0.2%; P < .05). CONCLUSIONS Patients with CA have significantly reduced magnitude of LVMWI compared with healthy control subjects. With exercise, the differences are even more pronounced. Even though LVMWI increased with exercise, LVMWE decreased, suggesting inefficient myocardial energy exploitation in patients with CA.

中文翻译：

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心脏淀粉样变性患者在静息和运动期间的左心室压力应变衍生心肌功。

背景左心室压力应变衍生的心肌工作指数 (LVMWI) 是一种新颖的非侵入性方法，用于评估与 LV 压力动态相关的左心室 (LV) 功能。LV 整体纵向应变 (LVGLS) 已证明对心脏淀粉样变性 (CA) 患者的诊断和风险分层有益，但 LVGLS 并未根据负荷条件进行调整。本研究的目的是表征 CA 患者在休息和运动期间的 LVMWI。方法回顾性纳入155名受试者。这些受试者包括 100 名 CA 患者和 55 名健康对照受试者。所有患者之前都在静息状态下接受了全面的二维超声心动图检查。此外，使用半卧位运动负荷超声心动图检查了一个亚组 27 名 CA 患者和 41 名对照受试者。结果 与对照组相比，CA 患者的 LVGLS、LVMWI 和 LV 心肌工作效率 (LVMWE) 显着降低（P < .0001）。LV 心肌功能的降低在基底段更为明显，这导致 CA 患者和对照受试者之间的平均心尖与基底节段比率发生显着变化（LVGLS，2.6 [1.9 至 4.1] vs 1.3 [1.2 至 4.1] 1.5]；LVMWI，2.6 [1.7 至 3.8] 与 1.3 [1.1 至 1.5]；LVMWE，1.1 [1.0 至 1.3] 与 1.0 [1.0 至 1.1]；所有 P < .0001）。LVMWI 从休息到运动峰值的平均增加为 1,974 mm Hg%（95% CI，1,699 至 2,250 mm Hg%；P < .0001），对照组为 496 mm Hg%（95% CI，156 至 835 mm Hg） %; P < . 01) 在 CA 患者中。对照组的绝对数值 LVGLS 增加为 5.6%（95% CI，3.9% 至 7.3%；P < .0001），而患者仅为 1.2%（95% CI，-0.9% 至 3.3%；P = .26） CA（组间，P < .0001）从休息到运动高峰。CA 患者的 LVMWI 增加是由心尖节段的改善介导的（P < .0001），而心室中段或基底节段的 LVMWI 没有显着改变。LVMWE 在对照受试者运动期间保持稳定（Δ -0.6%；95% CI，-2.5% 至 1.2%；P = .50），但在 CA 患者中显着降低（Δ -2.5%；95% CI，-4.8%至 -0.2%；P < .05)。结论与健康对照受试者相比，CA 患者的 LVMWI 幅度显着降低。通过锻炼，差异更加明显。