Case report

A 65-year-old female patient presented in January 2013 with unstable angina. Coronary angiography showed a severely calcified long lesion of the proximal and mid segments of the left anterior descending coronary artery [Video S1 (please see enhanced content link on title page)]. In view of the angiographic findings, a decision was taken to do a planned rotational atherectomy (RA), which was performed with the Rotablator™ (Boston Scientific) using 1.5 then 1.75 mm burr sizes, followed by implantation of two overlapping 3.0 × 28 mm bioresorbable scaffolds (BRS) (Absorb™, Abbott). Post-dilatation was done using a 3.0 mm non-compliant balloon at 20 atm. Intravascular ultrasound (IVUS) showed a good result with a minimal overlapping zone (Fig. 1). A coronary angiography done 10 months later due to recurrent angina revealed a significant restenosis of the implanted BRS. Optical coherence tomography (OCT) showed a diffuse homogeneous intra-scaffold neointimal tissue with a minimum luminal area of 1.59 mm2 at the distal BRS and 1.98 mm2 at the proximal one (Fig. 2). A scoring balloon angioplasty using a 3.0 × 10 mm AngioSculpt™ scoring balloon (AngioScore) was performed followed by 3.5 × 20 and 3.0 × 20 mm Pantera Lux™ (Biotronik) paclitaxel eluting balloons (DEB) in the proximal and distal scaffolds, respectively. OCT clearly showed the neointimal cuts achieved by the scoring elements (white arrowheads, Fig. 3), neointimal disruption with some intraluminal material (yellow arrowheads, Fig. 3) and lumen expansion. At 2 years after balloon angioplasty (almost 3 years after BRS implantation), the patient remained asymptomatic and a scheduled angiographic control showed a patent vessel with no significant lesions. OCT showed favorable evolution of the neointimal damage caused by the scoring balloon and maintenance of the initial lumen expansion, with partial resorption of the scaffold struts for which footprints were still visible (Fig. 4).

Fig. 1
figure 1

Baseline angiogram and procedure. A Baseline angiogram showing a calcified stenosis of the proximal and mid LAD. B Lesion preparation with rotational atherecomy using the 1.75 burr. C Shows final result after implantation of two 3 × 28 mm bioresorbable scaffolds, with a good result in the final intravascular ultrasound (D)

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Fig. 2
figure 2

In-scaffold restenosis. In A, B, the angiogram shows diffuse in-scaffold restenosis in the proximal and distal scaffolds. B is the final angiographic appearance after scoring balloon/drug-eluting balloon treatment. Optical coherence tomography (OCT) images (a) and (c) show homogeneous intra-scaffold tissue. The b represents OCT cross section of the overlapping zone

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Fig. 3
figure 3

Final result after scoring balloon/drug-eluting balloon treatment. In A, B, the final angiographic appearance after balloon-only treatment of the restenosis. d–f Lumen expansion is clearly visible via optical coherence tomography (OCT). The white arrowheads show the lumen-surface marks achieved by the scoring elements. Intraluminal material caused by neointimal dissection is also observed (yellow arrowhead)

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Fig. 4
figure 4

Follow-up angiogram and optical coherence tomography (OCT) 2 years after treatment of the in-scaffold restenosis. a is done in a zone of muscular bridging showing the absence of significant stenosis in that area. The red arrowhead shows the metallic marker of the distal implanted scaffold. The favorable evolution with disappearance of the neointimal damages caused by the scoring balloon is clear in the OCT images b–f, which also show partial resorption of the scaffold struts

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Compliance with Ethics Guidelines

Informed consent was obtained from the patient for being included in the study.

Discussion

The most important proposed advantage of BRS over the current metallic stent technology is to restore the natural physiologic vasomotor function and to hinder late thrombotic events. In our case, the initial treatment strategy was using RA in disrupting the continuity of intravascular calcium rings facilitating BRS implantation and potentially achieving a stent-free vessel in the long-term.

RA is a safe and effective method for lesion preparation before stent implantation [1] and its use could be extrapolated before BRS implantation, where lesion preparation is of utmost importance. However, additional vessel injury with RA has been previously suggested to be associated with increased late lumen loss [2]. In our case, this mechanism appears very likely because the in-scaffold restenosis was diffuse and affected both implanted BRSs.

The rate of target-lesion revascularization ranges from 1 % to 3.3 % after BRS implantation [3, 4]. The most often used method for the treatment of in-scaffold restenosis is a drug-eluting stent (DES) [5], but there is no sufficient data supporting this approach, and the optimal treatment strategy is still uncertain. Drug-eluting balloons have demonstrated their efficacy in treatment of restenosis following metallic stent implantation [6]. Additionally, scoring balloon predilatation prevents balloon slippage and enhances local plaque disruption, and its use in combination with DEB angioplasty improved angiographic results in the ISAR-DESIRE 4 Study [7]. In this reported case, by adopting the scoring/paclitaxel-coated balloon strategy, we tried avoiding a metallic stent implantation targeting to maintain the long-term benefits of BRS. The entire resorption process of BRS takes approximately 3 years to complete. However, between 3 and 6 months and as a consequence of hydrolysis of ester bonds, the device loses its structural continuity, and the radial strength decreases considerably until it is lost [8]. This loss of radial force is suspected to be source of recoil when balloon dilatation is performed alone after 6 months. In this patient, the vessel wall 10 months after BRS implantation opposed minimal recoil to the scoring/DEB treatment, which achieved sufficient stable lumen size and remained effective until 2 years of follow-up.

In our case we tried to highlight the possibility of a balloon-only treatment of a restenosed bioresorbable scaffold. With an adequate initial lesion preparation, this strategy can be even applied in severely calcified coronary lesions. Finally, given the limited data, there is a need for further examination of the place of RA before BRS implantation and the optimal treatment strategy for in-scaffold restenosis from future RCTs.