Prospect Trial Baseline Data identify High-risk Lesions

　　Gregg W. Stone 医生在2007TCT公布的PROSPECT试验入选人群基线结果表明：血管内超声虚拟组织学重建VH IVUS）提供了一种优于标准的冠脉造影术识别易损斑块的方法。

　　根据试验结果，在所有入选的患者中，28％的病变通过造影认为是非罪犯病变，但是通过VH IVUS检查发现是潜在的高危的薄纤维帽斑块。PROSPECT研究入选通过肉眼判断造影显示为临界病变患者，其中大约27％的病变最小管腔面积为4mm2。

　　PROSPECT试验入选了697例急性冠脉综合征患者，这些患者将进行2年的随访，目的是发现将来发生不良心脏事件的危险因素。在入选的患者中，28.4%的患者至少有一个VH－薄纤维帽粥样硬化斑块（VH-TCFAS）（平均0.42个病变;变化范围： 0－5个病变/每个患者）。Stone 说道：“与以前的报道相比，该试验病变累及到的血管较多并且病变更弥漫。”

　　Stone说：“我们已经掌握了入选患者中完成三支冠状动脉VH IVUS检查的病变特征，VH－TCFA发生率比我们去年报道的低，那是因为我们给VH-TCFA一个更为严格的定义。”

　　PROSPECT病变主要分为5个类型，这些分型基于用VH分析的斑块组成成分即纤维斑块，纤维钙化斑块，病理性内膜增厚，厚纤维帽粥样硬化斑块和VH-TCFA。

　　VH-TCFA被认为是高危病变，其定义为病变没有厚纤维帽的证据（纤维帽厚度为200μm）、至少占病变周径的33％、而且在3个连续性图像中坏死核所占百分比超过10％。

　　成功完成定量冠状动脉造影分析（QCA）2086支血管中，1481例（71％）有可供分析的VH IVUS资料，造影下显示为非罪犯病变特征的，经IVUS发现每位患者平均有0.74个病变，并且其最小管腔面积（MLA）为4.0mm2（612例患者共有453个病变）。

　　IVUS检测的病变（n＝2318）分为纤维斑块（厚帽和VH-TCFA）以及根据MLA进行再次分类。

　　基线情况统计

　　入选697例患者，持续超过24小时的STEMI患者占30.3%，NSTEMI占65.4%，伴有ST段改变的不稳定心绞痛占4.3％。平均年龄为58岁，其中23.9％为女性。其他基线特点包括糖尿病占16.8％，高脂血症占40.1％，高血压占45.2％，既往心肌梗死占10.6％，72％的患者一支血管置入过支架，28％患者有两支血管置入支架。

　　值得期待的结果

　　Stone又指出“PROSPECT试验真正令人感兴趣的资料现在还不能提供。现处在随访阶段，我们希望用这些基线资料包括人口基线、生物标记物、冠脉造影、IVUS、虚拟组织学重建或联合这些数据进行准确识别患者和病变能够对将来的心脏事件进行预测。”

  　　（阜外心血管病医院　高立建　编译）

　　（医心网为独家授权网站，转载请标明转自医心网）

PROSPECT Trial Baseline Data Identify High-risk Lesions

Virtual histology IVUS may provide a valuable method of identifying vulnerable plaque over and above standard angiography, according to baseline results of the PROSPECT trial presented by Gregg W. Stone, MD, chairman of the Cardiovascular Research Foundation.

According to the trial results, VH IVUS identified potentially high-risk thin-cap fibroatheromas in 28% of lesions that were considered non-culprit by angiography. And approximately 27% of angiographically mild lesions imaged in the PROSPECT study had a minimum luminal area (MLA) of less than 4 mm2.

The PROSPECT trial has completed enrollment of 697 patients with acute coronary syndrome who will be followed for 2 years in an attempt to identify risk factors for future adverse cardiovascular events.

At least one virtual histology thin-cap fibroatheroma (VH TCFAs) was identified in the coronary trees of 28.4% of patients (mean, 0.42; range, 0-5 per patient). They were more widespread and diffuse than previously reported, Stone said.

“We believe we have completely characterized the coronary tree in these patients,” Stone said. “The VH-TCFA incidence of 28% was lower than what we reported last year, and that is because we used a more stringent definition for what we would call a VH-TCFA.”

In the trial, lesions were classified into five main types, Stone noted in a subsequent discussion period. These types, based on virtual histology composition, are fibrotic, fibrocalcific, pathologic intimal thickening, thick-cap fibroatheroma, and VH-TCFA.

VH-TCFA, presumed to be high-risk lesions, were defined in the study as lesions with no evidence of a thick cap (ie, a cap less than 200 mm) for at least 33% of the circumference of the lesion, with a confluent necrotic core of more than 10% in three or more consecutive image frames.

Of 2,086 vessels successfully imaged with quantitative coronary angiography, 1,481 (71%) had usable VH IVUS data. Looking specifically at angiographically nonculprit lesions, IVUS identified a mean of 0.74 lesions per patient with an MLA of less than 4.0 mm2 (a total of 453 lesions in 612 patients).

IVUS lesions (n = 2,381) were classified as fibroatheromas (thick-cap and VH-TCFA) and subclassified according to MLA (Figure).

Baseline demographics

Of the 697 patients enrolled, 30.3% had STEMI lasting more than 24 hours, 65.4% had non-STEMI, and 4.3 had unstable angina with ST changes. Mean age of patients was 58 years, and 23.9% were women. Other baseline characteristics included diabetes in 16.8% of patients, hyperlipidemia in 40.1%, hypertension in 45.2%, and previous MI in 10.6%. PCI was performed in one artery in 72% of patients and two arteries in 28%.

Yet to come

Stone said the “really interesting stuff” from the PROSPECT trial is yet to come.

“We’re now in the follow-up phase. We hope to identify the right mix of baseline demographics, biomarkers, angiography, IVUS, virtual histology, or combination thereof to identify patients and lesions at risk for future cardiac events,” he said.

“The VH-TCFA incidence of 28% was lower than what we reported last year.”
                                                                                                    — Gregg W. Stone, MD