Angioscopic Evaluation of Atrial Septal Defect Closure Device Neo-Endothelialization

Abstract

Background Current guidelines recommend at least 6 months of antithrombotic therapy and antibiotic prophylaxis after septal-occluding device deployment in transcatheter closure of atrial septal defect. It has been estimated that it takes ≈6 months for complete neo-endothelialization; however, neo-endothelialization has not previously been assessed in vivo in humans. Methods and Results The neointimal coverage of septal occluder devices was evaluated 6 months after implantation in 15 patients by angioscopy from the right atrium. Each occluder surface was divided into 9 areas; the levels of endothelialization in each area were semiquantitatively assessed by 4-point grades. Device neo-endothelialization was sufficient in two thirds of patients, but insufficient in one third. In the comparison between patients with sufficiently endothelialized devices of average grade score ≥2 (good endothelialization group, n=10) and those with poorly endothelialized devices of average grade score <2 (poor endothelialization group, n=5), those in the poor endothelialization group had larger devices deployed (27.0 mm [25.0-31.5 mm] versus 17.0 mm [15.6-22.5 mm], respectively) and progressive right heart dilatation. The endothelialization was poorer around the central areas. Moreover, the prevalence of thrombus formation on the devices was higher in the poorly endothelialized areas than in the sufficiently endothelialized areas (Grade 0, 94.1%; Grade 1, 63.2%; Grade 2, 0%; Grade 3, 1.6%). Conclusions Neo-endothelialization on the closure devices varied 6 months after implantation. Notably, poor endothelialization and thrombus attachment were observed around the central areas and on the larger devices.

Keywords: angioscopy; atrial septal defect; device neo‐endothelialization.

Figure 1. Definition of the endothelialization score.

A, Grade 0, complete exposure of device struts. Thrombus attached to the exposed struts (Video S1). B, Around the central hub, the surface of the device is exposed, defined as Grade 0 (Video S2). *Central hub. **Guidewire. C, Grade 1, sparse endothelialization (Video S3). D, Grade 2, moderate endothelialization with visible device struts (Video S4). E, Grade 3, complete endothelialization with nonvisible device struts (Video S5).

Figure 2. Neo‐endothelialization and thrombus attachment 6 months after implantation.

Neo‐endothelialization and thrombus attachment in each area of all patients are shown. Thrombus attachment as in Figure 1A is seen in the area marked “Th.” Neo‐endothelialization of the devices differs among the patients. ASO indicates Amplatzer Septal Occluder; FFX, Figulla Flex II; and Th, thrombus.

Figure 3. Relationship between device size and neo‐endothelialization.

The average endothelialization grade score is lower for the large devices with diameter ≥24 mm (n=7; 1.7 [1.3–2.1]) than for the small devices with diameter ≤22 mm (n=8; 2.3 [2.2–2.6]).

Figure 4. Relationship between the location of the device and neo‐endothelialization.

The rate of insufficient endothelialization with Grade 0 or 1 of each area is shown. Neo‐endothelialization around central areas, especially near the hub, is insufficient in all cases.

Figure 5. Relationship between thrombus formation and neo‐endothelialization.

The relationship between neo‐endothelialization and thrombus formation is shown. Thrombus attachment is found more frequently in the poorly endothelialized areas with Grades 0 (94.4%) and 1 (57.1%) than in the well‐endothelialized areas with Grades 2 (0%) and 3 (1.6%).