Background

Bioprosthetic valve thrombosis may have implications for valve function and durability.

Objectives

Using a novel glycoprotein IIb/IIIa receptor radiotracer 18F-GP1, we investigated whether positron emission tomography (PET)-computed tomography (CT) could detect thrombus formation on bioprosthetic aortic valves.

Methods

Ex vivo experiments were performed on human platelets and explanted bioprosthetic aortic valves. In a prospective cross-sectional study, patients with either bioprosthetic or normal native aortic valves underwent echocardiography, CT angiography, and 18F-GP1 PET-CT.

Results

Flow cytometric analysis, histology, immunohistochemistry, and autoradiography demonstrated selective binding of 18F-GP1 to activated platelet glycoprotein IIb/IIIa receptors and thrombus adherent to prosthetic valves. In total, 75 participants were recruited: 53 with bioprosthetic valves (median time from implantation 37 months [IQR: 12-80 months]) and 22 with normal native aortic valves. Three participants had obstructive valve thrombosis, and a further 3 participants had asymptomatic hypoattenuated leaflet thickening on CT angiography. All bioprosthetic valves, but none of the native aortic valves, demonstrated focal 18F-GP1 uptake on the valve leaflets: median maximum target-to-background ratio 2.81 (IQR: 2.29-3.48) vs 1.43 (IQR: 1.28-1.53) (P < 0.001). Higher 18F-GP1 uptake was independently associated with duration of valve implantation and hypoattenuated leaflet thickening. All 3 participants with obstructive valve thrombosis were anticoagulated for 3 months, leading to resolution of their symptoms, improvement in mean valve gradients, and a reduction in 18F-GP1 uptake.

Conclusions

Adherence of activated platelets is a common and sustained finding on bioprosthetic aortic valves. 18F-GP1 uptake is higher in the presence of thrombus, regresses with anticoagulation, and has potential use as an adjunctive clinical tool. (18F-GP1 PET-CT to Detect Bioprosthetic Aortic Valve Thrombosis; NCT04073875)

中文翻译：

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18F-GP1 正电子发射断层扫描和生物主动脉瓣血栓

背景

生物瓣膜血栓形成可能会对瓣膜功能和耐用性产生影响。

目标

使用新型糖蛋白 IIb/IIIa 受体放射性示踪剂 18F-GP1，我们研究了正电子发射断层扫描 (PET)-计算机断层扫描 (CT) 是否可以检测生物主动脉瓣上的血栓形成。

方法

对人类血小板和外植生物主动脉瓣进行离体实验。在一项前瞻性横断面研究中，使用生物瓣膜或正常自体主动脉瓣的患者接受了超声心动图、CT 血管造影和 18F-GP1 PET-CT。

结果

流式细胞术分析、组织学、免疫组织化学和放射自显影证明 18F-GP1 选择性结合激活的血小板糖蛋白 IIb/IIIa 受体和粘附于人工瓣膜的血栓。总共招募了 75 名参与者：53 名使用生物瓣膜（植入后中位时间 37 个月 [IQR：12-80 个月]），22 名使用正常的天然主动脉瓣。3 名参与者患有阻塞性瓣膜血栓，另外 3 名参与者在 CT 血管造影中出现无症状的低衰减瓣叶增厚。所有生物瓣膜（但没有天然主动脉瓣）在瓣叶上表现出局灶性 18F-GP1 摄取：中位最大目标与背景比为 2.81（IQR：2.29-3.48）vs 1.43（IQR：1.28-1.53​​）（P < 0.001）。较高的 18F-GP1 摄取与瓣膜植入持续时间和低衰减的小叶增厚独立相关。所有 3 名患有阻塞性瓣膜血栓的参与者均接受了 3 个月的抗凝治疗，症状得到缓解，平均瓣膜压差得到改善，并且 18F-GP1 摄取减少。

结论

活化血小板的粘附是生物主动脉瓣上常见且持续的发现。存在血栓时 18F-GP1 的摄取较高，抗凝作用会消退，并且具有作为辅助临床工具的潜在用途。（18F-GP1 PET-CT 用于检测生物主动脉瓣血栓形成；NCT04073875）