Redgrave Jessica N, Gallagher Patrick, Lovett Joanna K, Rothwell Peter M
Stroke Prevention Research Unit, Department of Clinical Neurology, Radcliffe Infirmary, Woodstock Road, Oxford, UK.
Stroke. 2008 Jun;39(6):1722-9. doi: 10.1161/STROKEAHA.107.507988. Epub 2008 Apr 10.
Advances in carotid plaque imaging could allow quantification of fibrous cap thickness in vivo. While a cap thickness <65 microm is the accepted definition of rupture-prone plaque in the coronary circulation, the threshold value for carotid plaques is unknown.
We made detailed histological assessments of 526 carotid plaques from consecutive patients undergoing endarterectomy for symptomatic carotid stenosis. The thickness of the fibrous cap at the thinnest and most representative part was measured.
Cap thickness could be measured reliably in 428 (81%) plaques. In the ruptured plaques (n=257), the median representative cap thickness was 300 microm (IQR 200 to 500 microm) and the median minimum cap thickness was 150 microm (80 to 210 microm; mean=181 microm), which is much greater than the mean cap thickness of 23 microm at the point of rupture that has been reported for coronary plaques. For nonruptured plaques, the median cap thickness values were 500 microm (300 to 700 microm) and 250 microm (180 to 400 microm), respectively. The optimum cut-offs for discriminating between ruptured and nonruptured plaques were a minimum cap thickness <200 microm (OR 5.00, 3.26 to 7.65, P<0.001), a representative cap thickness <500 microm (OR 3.38, 2.25 to 5.08, P<0.001), or a combination of both (OR 5.11, 3.19 to 8.19, P<0.001). Minimum and representative cap thickness were only modestly correlated (r(2)=0.30) and were both independently associated with cap rupture.
Critical cap thickness is greater in carotid plaques than coronary plaques. Minimum and representative cap thicknesses were both independently associated with cap rupture. A combination of minimum cap thickness <200 microm and a representative cap thickness <500 microm identified ruptured plaques most reliably. Prospective imaging studies are required to establish whether these cut points predict clinical events in patients with asymptomatic carotid stenosis.
颈动脉斑块成像技术的进步使得在体定量纤维帽厚度成为可能。虽然冠状动脉循环中易于破裂的斑块纤维帽厚度公认小于65微米，但颈动脉斑块的阈值尚不清楚。
我们对526例因有症状颈动脉狭窄接受动脉内膜切除术的连续患者的颈动脉斑块进行了详细的组织学评估。测量了纤维帽最薄且最具代表性部位的厚度。
428个（81%）斑块的纤维帽厚度能够可靠测量。在破裂斑块（n = 257）中，代表性纤维帽厚度中位数为300微米（四分位间距200至500微米），最小纤维帽厚度中位数为150微米（80至210微米；均值 = 181微米），这远大于报道的冠状动脉斑块破裂处平均23微米的纤维帽厚度。对于未破裂斑块，纤维帽厚度中位数分别为500微米（300至700微米）和250微米（180至400微米）。区分破裂与未破裂斑块的最佳截断值为最小纤维帽厚度小于200微米（比值比5.00，3.26至7.65，P < 0.001）、代表性纤维帽厚度小于500微米（比值比3.38，2.25至5.08，P < 0.001）或两者结合（比值比5.11，3.19至8.19，P < 0.001）。最小和代表性纤维帽厚度仅呈中度相关（r² = 0.30），且均与纤维帽破裂独立相关。
颈动脉斑块的临界纤维帽厚度大于冠状动脉斑块。最小和代表性纤维帽厚度均与纤维帽破裂独立相关。最小纤维帽厚度小于200微米且代表性纤维帽厚度小于500微米的组合最可靠地识别出破裂斑块。需要进行前瞻性成像研究以确定这些切点是否能预测无症状颈动脉狭窄患者的临床事件。
