Author + information
- Damiano Regazzoli, MD,
- Azeem Latib, MD∗ (, )
- Akihito Tanaka, MD,
- Daniela Di Marco, MD,
- Manuela Giglio, MD,
- Richard Jabbour, MD,
- Marco Bruno Ancona, MD,
- Pier Pasquale Leone, MD,
- Antonio Mangieri, MD,
- Matteo Montorfano, MD,
- Francesco Giannini, MD and
- Antonio Colombo, MD
- ↵∗San Raffaele University Hospital and EMO-GVM Centro Cuore Columbus, Via Olgettina 60, Milan 20132, Italy
Over the past 5 years bioresorbable vascular scaffolds (BVS) have become an attractive option for percutaneous coronary intervention because of the complete reabsorption process that occurs post-implantation (1), but the ideal follow-up technique after BVS implantation remains a challenge.
In fact, in recent years, multislice computed tomography (MSCT) has emerged both as a possible intermediate test to better select patients referred for coronary angiography and as an alternative or complementary test for monitoring revascularized patients, with the limitation of blooming artifacts that originate from metallic stents (2).
The use of this technique after BVS implantation has been evaluated in a cohort of the ABSORB trial (3). The study showed that MSCT could be an alternative to invasive imaging, ensuring good visualization of the treated segment and allowing a functional assessment of the vessel. It must be stressed, however, that the cited study enrolled patients with simple lesions, treated with a single short scaffold. A slightly more clinically complex population was enrolled in the PRAGUE-19 (Primary Angioplasty in Patients Transferred From General Community Hospitals to Specialized PTCA Units With or Without Emergency Thrombolysis) study (4), which evaluated the usefulness of MSCT after BVS implantation in patients with ST-segment elevation myocardial infarction.
We therefore decided to evaluate the feasibility of a detailed multislice computed tomographic analysis of BVS (not limited to assessment of scaffold patency but extended to evaluation of scaffold luminal area and quantification of percentage of restenosis) in an anatomically complex population treated with the Absorb BVS (Abbott Vascular, Santa Clara, California) at 2 high-volume centers in Milan, Italy, between May 2012 and October 2015. In fact, from the very beginning of our experience with BVS, we implanted this device in long and complex lesions using a specific technique (5), in the belief that this setting might maximize the potential advantages of complete reabsorption of the scaffold, as shown in Figure 1.
Among 279 treated patients, 41 (15%) underwent MSCT as part of clinical follow-up, usually 1 year after the procedure (procedure-to-MSCT interval 390 days; interquartile range: 302 to 588 days).
A 64-slice computed tomographic scanner (LightSpeed VCT XTE, GE Healthcare, Milwaukee, Wisconsin) was used for all patients, and the images were post-processed and analyzed on an external workstation (AW 4.5, GE Healthcare) by 2 expert radiologists. Computed tomographic images were visually graded according to a 3-point scale: 1 (poor), the coronary vessel was not well visualized; 2 (good), the vessel was adequately visualized; and 3 (excellent), the vessel was very well visualized.
All images were transferred to an external workstation (AW 4.5) for post-processing analysis. A center lumen line was semiautomatically created through the coronary artery. Cross-sectional views of the vessel were then analyzed; the radiopaque platinum indicators of the scaffolds were used as landmarks.
The outer vessel borders were manually traced to approximate the total vessel size; the reference vessel luminal area was calculated as the average of the mean proximal and mean distal vessel areas; luminal area stenosis was calculated as a percentage of the reference luminal area. The same analysis was carried out using diameters. Restenosis was defined as more than 50% of diameter stenosis and/or more than 75% of area stenosis.
Population characteristics and procedural data are summarized in Table 1. The majority of lesions (77.4%) were type B2 or C according to American College of Cardiology and American Heart Association classification, higher than in the largest randomized trial (ABSORB III) (6) and the largest real-world registry (GHOST-EU [Gauging Coronary Healing With Bioresorbable Scaffolding Platforms in Europe]) (7), in which the rates of types B2 and C lesions were 68.7% and 53.5%, respectively. Notably, bifurcation lesions were excluded from ABSORB III and present in only 23.1% of lesions in GHOST-EU, in contrast to 58.5% in our cohort. Total scaffold length per lesion was 35.7 ± 17.2 mm.
Interestingly, despite the great complexity of coronary artery disease (including almost 25% of severely calcified lesions), excellent evaluation of the lesions treated with BVS was possible in almost 95% of cases (Table 2). This permitted a reliable evaluation of mean reference area (6.6 ± 1.7 mm2) and diameter (2.9 ± 1.4 mm), as well as minimal scaffold area (4.9 ± 1.4 mm2) and diameter (2.5 ± 1.4 mm). However, a limitation is the lack of angiographic and intravascular imaging validation of these findings.
These preliminary data suggest that MSCT may have a key role in the follow-up of patients treated with BVS, thanks to the unique composition of BVS: radiolucent materials allowed lumen visualization in the scaffold segment of the same quality as in other segments. From a clinical point of view, our experience suggests that MSCT may have a major role in the noninvasive follow-up of patients with bioresorbable scaffolds. Furthermore, in the future, the use of computed tomography may also extend to the analysis, in this selected population, of plaque remodeling or even lesion-specific fractional flow reserve, thus combining the prognostic strength of a provocative test with the reassuring certainty of a reliable anatomic test.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. Regazzoli and Latib are joint first authors.
- American College of Cardiology Foundation
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