Global Longitudinal Strain Predicts Poor Functional Capacity in Patients with Systolic Heart Failure

Abstract Background: Left ventricular global longitudinal strain value (GLS) can predict functional capacity in patients with preserved left ventricular ejection fraction (LVEF) heart failure (HF) and to assess prognosis in reduced LVEF HF. Objetive: Correlate GLS with parameters of Cardiopulmonary Exercise Test (CPET) and to assess if they could predict systolic HF patients that are more appropriated to be referred to heart transplantation according to CPET criteria. Methods: Systolic HF patients with LVEF < 45%, NYHA functional class II and III, underwent prospectively CPET and echocardiography with strain analysis. LVEF and GLS were correlated with the following CPET variables: maxVO2, VE/VCO2 slope, heart rate reduction during the first minute of recovery (HRR) and time needed to reduce maxVO2 in 50% after physical exercise (T1/2VO2). ROC curve analysis of GLS to predict VO2 < 14 mL/kg/min and VE/VCO2 slope > 35 (heart transplantation’s criteria) was performed. Results: Twenty six patients were selected (age, 47 ± 12 years, 58% men, mean LVEF = 28 ± 8%). LVEF correlated only with maxVO2 and T1/2VO2. GLS correlated to all CPET variables (maxVO2: r = 0.671, p = 0.001; VE/VCO2 slope: r = -0.513, p = 0.007; HRR: r = 0.466, p = 0.016, and T1/2VO2: r = -0.696, p = 0.001). GLS area under the ROC curve to predict heart transplantation’s criteria was 0.88 (sensitivity 75%, specificity 83%) for a cut-off value of -5.7%, p = 0.03. Conclusion: GLS was significantly associated with all functional CPET parameters. It could classify HF patients according to the functional capacity and may stratify which patients have a poor prognosis and therefore to deserve more differentiated treatment, such as heart transplantation.

摘要 背景：左心室整体纵向应变（left ventricular global longitudinal strain, GLS）可用于预测左心室射血分数（left ventricular ejection fraction, LVEF）保留型心力衰竭（heart failure, HF）患者的功能容量，并评估LVEF降低型HF患者的预后。目的：探讨GLS与心肺运动试验（cardiopulmonary exercise test, CPET）参数的相关性，并评估二者能否依据CPET标准，筛选出更适合接受心脏移植的收缩性HF患者。方法：前瞻性纳入LVEF＜45%、纽约心脏协会（New York Heart Association, NYHA）功能分级Ⅱ~Ⅲ级的收缩性HF患者，所有患者均接受CPET检查及带应变分析的超声心动图检查。将LVEF及GLS与以下CPET变量进行相关性分析：最大摄氧量（maxVO2）、VE/VCO2斜率、恢复初期1分钟内心率下降值（heart rate reduction, HRR）以及运动结束后最大摄氧量下降50%所需时间（T1/2VO2）。采用受试者工作特征（receiver operating characteristic, ROC）曲线分析GLS对VO2＜14 mL/kg/min及VE/VCO2斜率＞35（心脏移植判定标准）的预测价值。结果：共纳入26例患者，年龄为47±12岁，男性占比58%，平均LVEF为28±8%。LVEF仅与maxVO2及T1/2VO2存在相关性。GLS与所有CPET变量均存在显著相关性（maxVO2：r=0.671，P=0.001；VE/VCO2斜率：r=-0.513，P=0.007；HRR：r=0.466，P=0.016；T1/2VO2：r=-0.696，P=0.001）。以-5.7%作为截断值，GLS预测心脏移植判定标准的ROC曲线下面积为0.88（灵敏度75%，特异度83%），P=0.03。结论：GLS与所有CPET功能参数均存在显著相关性。其可依据功能容量对HF患者进行分层，能够识别预后较差的患者，从而为这类患者制定更具针对性的治疗方案，例如心脏移植。