Weatherhead PET Center For Preventing and Reversing Atherosclerosis, Division of Cardiology, Department of Medicine, University of Texas Medical School and Memorial Hermann Hospital, Houston, Texas, USA.
JACC Cardiovasc Imaging. 2011 Sep;4(9):990-8. doi: 10.1016/j.jcmg.2011.06.015.
This study aimed to determine the quantitative low-flow threshold for stress-induced perfusion defects with severe angina and/or significant ST-segment depression during dipyridamole hyperemia.
Vasodilator stress reveals differences in regional perfusion without ischemia in most patients. However, in patients with a perfusion defect, angina, and/or significant ST-segment depression during dipyridamole stress, quantitative absolute myocardial perfusion and coronary flow reserve (CFR) at the exact moment of definite ischemia have not been established. Defining these low-flow thresholds of angina or ST-segment changes may offer insight into physiological disease severity in patients with atherosclerosis.
Patients underwent rest-dipyridamole stress positron emission tomography (PET) with absolute flow quantification in ml/min/g. Definite ischemia was defined as a new or worse perfusion defect during dipyridamole stress with significant ST-segment depression and/or severe angina requiring pharmacological treatment. Indeterminate clinical features required only 1 of these 3 abnormalities. The comparison group included patients without prior myocardial infarction, or angina or electrocardiographic changes after dipyridamole.
In 1,674 sequential PET studies, we identified 194 (12%) with definite ischemia, 840 (50%) studies with no ischemia, and 301 (18%) that were clinically indeterminate. A vasodilator stress perfusion cutoff of 0.91 ml/min/g optimally separated definite from no ischemia with an area under the receiver-operator characteristic curve (AUC) of 0.98 and a CFR cutoff of 1.74 with an AUC = 0.91, reflecting excellent discrimination at the exact moment of definite ischemia.
Thresholds of low myocardial vasodilator stress perfusion in ml/min/g and CFR sharply separate patients with angina or ST-segment change from those without these manifestations of ischemia during dipyridamole stress with excellent discrimination. Stress flow below 0.91 ml/min/g in dipyridamole-induced PET perfusion defects causes significant ST-segment depression and/or severe angina. However, when the worst vasodilator stress flow exceeds 1.12 ml/min/g, these manifestations of ischemia occur rarely.
本研究旨在确定在双嘧达莫（潘生丁）充血时伴有严重心绞痛和/或显著 ST 段压低的应激性灌注缺损的定量低流量阈值。
血管扩张剂应激可在大多数患者中揭示无缺血的区域性灌注差异。然而，在双嘧达莫应激时存在灌注缺损、心绞痛和/或显著 ST 段压低的患者中，尚未确定确切发生缺血时的定量绝对心肌灌注和冠状动脉血流储备（CFR）。确定这些与心绞痛或 ST 段变化相关的低流量阈值可能有助于深入了解动脉粥样硬化患者的生理疾病严重程度。
患者行静息-双嘧达莫应激正电子发射断层扫描（PET）检查，并用毫升/分钟/克绝对血流量进行定量。明确的缺血定义为在双嘧达莫应激时出现新的或更严重的灌注缺损，伴有显著的 ST 段压低和/或严重的心绞痛，需要药物治疗。不确定的临床特征只需要这 3 种异常中的 1 种。对照组包括无先前心肌梗死、或双嘧达莫后无心绞痛或心电图改变的患者。
在 1674 项连续的 PET 研究中，我们确定了 194 项（12%）有明确的缺血，840 项（50%）无缺血，301 项（18%）临床不确定。血管扩张剂应激灌注的截断值为 0.91ml/min/g，最佳地将明确的缺血与无缺血分开，其受试者工作特征曲线下面积（AUC）为 0.98，CFR 截断值为 1.74，AUC=0.91，反映了在明确的缺血发生的确切时刻具有出色的区分能力。
在双嘧达莫应激 PET 灌注缺损中，以毫升/分钟/克为单位的低心肌血管扩张剂应激灌注的阈值可以极好地区分在双嘧达莫应激时伴有心绞痛或 ST 段改变的患者与无这些缺血表现的患者。在双嘧达莫诱导的 PET 灌注缺损中，当应激血流低于 0.91ml/min/g 时，会引起显著的 ST 段压低和/或严重的心绞痛。然而，当最差的血管扩张剂应激血流超过 1.12ml/min/g 时，这些缺血表现很少发生。
