Department of Cardiology, Nuclear Medicine & PET Research, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
Department of Radiology, Nuclear Medicine & PET Research, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
JACC Cardiovasc Imaging. 2020 Mar;13(3):746-756. doi: 10.1016/j.jcmg.2019.06.013. Epub 2019 Aug 14.
The current substudy of the PACIFIC (Prospective Comparison of Cardiac PET/CT, SPECT/CT Perfusion Imaging and CT Coronary Angiography With Invasive Coronary Angiography) trial explores the impact of computed tomography (CT)-derived unfavorable plaque features on both hyperemic and non-hyperemic flow indices.
Next to lesion severity, plaque vulnerability as assessed using coronary CT angiography affects fractional flow reserve (FFR), which is associated with imminent acute coronary syndromes. Instantaneous wave-free ratio (iFR) has recently emerged as an alternative for FFR to interrogate coronary lesions for ischemia. It is, however, unknown whether vasodilator-free assessment with iFR is associated with plaque stability similarly as FFR.
Of 120 patients (62% men, age 58.3 ± 8.6 years) with suspected coronary artery disease, 257 vessels were prospectively evaluated. Each patient underwent 256-slice coronary CT angiography to assess stenosis severity and plaque features (positive remodeling [PR], low attenuation plaque [LAP], spotty calcification [SC], and napkin ring sign [NRS]), as well as intracoronary pressure measurements (FFR, iFR, Pd/Pa, and pressure ratio during adenosine within the wave-free period [iFRa]). CT-derived plaque characteristics were related to these invasive pressure measurements.
Atherosclerotic plaques were present in 170 (66%) coronary arteries. On a per-vessel basis, luminal stenosis severity was significantly associated with impaired FFR, iFR, Pd/Pa, and iFRa. Multivariable analysis revealed that FFR and iFR were independently related to ≥70% stenosis (-0.10, p < 0.001 and -0.09, p = 0.003, respectively) and plaque volume (-0.02, p = 0.020 and -0.02, p = 0.030, respectively). Additionally, PR and SC were also independent predictors of an impaired FFR (-0.10, p < 0.001 and -0.07, p = 0.021, respectively), but adverse plaque characteristics were not independently related to the vasodilator-free iFR.
CT-derived vulnerable plaque characteristics are independently associated with hyperemic flow indices as assessed with FFR and iFRa, but not with non-hyperemic indices such as iFR and Pd/Pa. These findings suggest that the effects of hyperemia on pressure-derived indices might depend not only on hemodynamic stenosis severity but also on plaque characteristics.
PACIFIC（前瞻性比较心脏 PET/CT、SPECT/CT 灌注成像与 CT 冠状动脉造影与有创冠状动脉造影）试验的本次亚研究旨在探讨计算机断层扫描（CT）衍生的不利斑块特征对充血和非充血血流指数的影响。
除了病变严重程度外，使用冠状动脉 CT 血管造影评估的斑块脆弱性会影响与急性冠状动脉综合征相关的血流储备分数（FFR）。瞬时无波比（iFR）最近作为 FFR 的替代方法出现，用于检测缺血性冠状动脉病变。然而，iFR 无需血管扩张剂评估是否与 FFR 一样与斑块稳定性相关仍未知。
在 120 名（62%为男性，年龄 58.3±8.6 岁）疑似冠心病患者中，前瞻性评估了 257 个血管。每位患者均接受 256 层冠状动脉 CT 血管造影检查，以评估狭窄严重程度和斑块特征（正性重构[PR]、低衰减斑块[LAP]、点状钙化[SC]和围边征[NRS]），以及冠状动脉内压力测量（FFR、iFR、Pd/Pa 和无波期腺苷内压力比[iFRa]）。CT 衍生的斑块特征与这些有创压力测量值相关。
170 个（66%）冠状动脉存在动脉粥样硬化斑块。在血管水平上，管腔狭窄严重程度与 FFR、iFR、Pd/Pa 和 iFRa 受损显著相关。多变量分析显示，FFR 和 iFR 分别与≥70%狭窄（-0.10，p<0.001 和-0.09，p=0.003）和斑块体积（-0.02，p=0.020 和-0.02，p=0.030）独立相关。此外，PR 和 SC 也是 FFR 受损的独立预测因子（-0.10，p<0.001 和-0.07，p=0.021），但不利的斑块特征与无血管扩张剂的 iFR 无关。
CT 衍生的易损斑块特征与 FFR 和 iFRa 评估的充血血流指数独立相关，而与 iFR 和 Pd/Pa 等非充血指数无关。这些发现表明，充血对压力衍生指数的影响不仅取决于血流动力学狭窄严重程度，还取决于斑块特征。
