Hypertrophic Cardiomyopathy Center of Excellence, Johns Hopkins University, Baltimore, MD, USA.
Division of Cardiology, Taipei Veterans General Hospital, Taipei, Taiwan.
J Nucl Cardiol. 2020 Dec;27(6):2031-2043. doi: 10.1007/s12350-018-01521-x. Epub 2018 Nov 19.
Vasodilator-induced transient left ventricular cavity dilation (LVCD) by positron emission tomography (PET) is associated with microvascular dysfunction in hypertrophic cardiomyopathy (HCM). Here we assessed whether HCM patients who develop LVCD by PET during vasodilator stress also develop LV cavity dilation by echocardiography (ECHO-LVCD) following exercise stress.
A retrospective analysis of cardiac function and myocardial blood flow (MBF) was conducted in 108 HCM patients who underwent perfusion-PET and exercise-ECHO as part of their clinical evaluation. We performed a head-to-head comparison of LV volumes and ejection fraction (LVEF) at rest and stress (during vasodilator stress, post-exercise), in 108 HCM patients. A ratio > 1.13 of stress to rest LV volumes was used to define PET-LVCD, and a ratio > 1.17 of stress to rest LVESV was used to define ECHO-LVCD. Patients were divided into 2 groups based on the presence/absence of PET-LVCD. MBF and myocardial flow reserve were quantified by PET, and global longitudinal strain (GLS) was assessed by ECHO at rest/stress in the two groups.
PET-LVCD was observed in 51% (n = 55) of HCM patients, but only one patient had evidence of ECHO-LVCD (ratio = 1.36)-this patient also had evidence of PET-LVCD (ratio = 1.20). The PET-LVCD group had lower PET-LVEF during vasodilator stress, but ECHO-LVEF increased in both groups post-exercise. The PET-LVCD group demonstrated higher LV mass, worse GLS at rest/stress, and lower myocardial flow reserve. Incidence of ischemic ST-T changes was higher in the PET-LVCD group during vasodilator stress (42 vs 17%), but similar (30%) in the two groups during exercise.
PET-LVCD reflects greater degree of myopathy and microvascular dysfunction in HCM. Differences in the cardiac effects of exercise and vasodilators and timing of stress-image acquisition could underlie discordance in ischemic EKG changes and LVCD by ECHO and PET, in HCM.
正电子发射断层扫描（PET）诱导的血管扩张剂诱发的左心室腔扩张（LVCD）与肥厚型心肌病（HCM）中的微血管功能障碍有关。在这里，我们评估了在血管扩张剂应激期间通过 PET 发生 LVCD 的 HCM 患者是否也会在运动应激后通过超声心动图（ECHO-LVCD）发生 LV 腔扩张。
对 108 例接受灌注-PET 和运动-ECHO 检查的 HCM 患者进行了心脏功能和心肌血流（MBF）的回顾性分析，这些患者是其临床评估的一部分。我们对 108 例 HCM 患者在静息和应激时（在血管扩张剂应激时、运动后）的 LV 容积和射血分数（LVEF）进行了直接比较。使用应激与静息 LV 容积之比>1.13 来定义 PET-LVCD，使用应激与静息 LVESV 之比>1.17 来定义 ECHO-LVCD。根据是否存在 PET-LVCD 将患者分为两组。通过 PET 量化 MBF 和心肌血流储备，通过 ECHO 在两组的静息/应激时评估整体纵向应变（GLS）。
在 51%（n=55）的 HCM 患者中观察到 PET-LVCD，但只有 1 例患者出现 ECHO-LVCD（比值=1.36）-该患者也存在 PET-LVCD（比值=1.20）。在血管扩张剂应激时，PET-LVCD 组的 PET-LVEF 较低，但两组在运动后 ECHO-LVEF 均增加。PET-LVCD 组的 LV 质量更高，静息/应激时 GLS 更差，并且心肌血流储备较低。在血管扩张剂应激时，PET-LVCD 组出现缺血性 ST-T 改变的发生率更高（42%比 17%），但在运动时两组相似（30%）。
PET-LVCD 反映了 HCM 中更严重的心肌病和微血管功能障碍。运动和血管扩张剂的心脏效应以及应激图像采集时间的差异可能导致 ECHO 和 PET 对缺血性心电图改变和 LVCD 的不一致。
