Bioresorbable Vascular Scaffolds for Heavily Calcified Lesions: How to Tackle the Rugged Passage?

Abstract: We present a case of a heavily calcified left anterior descending artery lesion successfully treated with bioresorbable vascular scaffold (BVS). Despite a 360° heavy calcification at the site of the culprit lesion and prior implantation of a proximal metal stent, meticulous lesion preparation with scoring balloon and use of a deep-seated child catheter facilitated the successful deployment of two BVSs. This case report demonstrates how optimal lesion preparation, adequate dedicated device support, and careful assessment with the use of intracoronary imaging device can facilitate implantation of BVS in complex lesions.

J INVASIVE CARDIOL 2015;27(8):E167-E168

Key words: bioresorbable vascular scaffolds, calcification

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Case Report

A 66-year-old man with previous percutaneous coronary intervention (PCI) to the left anterior descending (LAD) and circumflex (LCX) arteries presented with recurrent exertional angina. The initial angiogram showed a diffuse, calcified, asymmetric lesion in the mid-LAD, distal to the previously implanted tantalum Wiktor stent (Medtronic) and focal in-stent restenosis in the mid-LCX. After treating the LCX lesion successfully with a drug-eluting metal stent, the operators assessed the hemodynamic significance of the calcific LAD lesion using fractional flow reserve (FFR). In view of a positive result (FFR, 0.79), the lesion in the mid-vessel was initially tackled with predilatation with a 2.5 mm non-compliant (NC) balloon inflated to 24 atm. At that pressure, however, the balloon ruptured, likely secondary to the heavy calcification. Based on the intravascular ultrasound (IVUS) finding of a 360° superficial calcification with a minimal lumen area of 3.39 mm² in the mid-LAD (Figure 1), additional predilatation utilizing the 2.5 mm AngioSculpt scoring balloon (AngioScore) at high pressure (22 atm) was performed. Repeat IVUS confirmed: (1) the presence of cracks in the 360° layer of superficial calcification; and (2) an increase in the lumen area of 4.89 mm² (Figure 1). PCI strategy included implantation of bioresorbable scaffolds in order to avoid a LAD “full metal jacket” and allow future surgical revascularization with a mammary graft if required. The presence of a long, angulated, proximal LAD segment stented with Wiktor stents (strut thickness, 130 µm) in combination with the calcific nature of the lesions to be treated led the operators to consider utilizing a child catheter (GuideLiner; Vascular Solutions). However, the delivery of the Absorb bioresorbable vascular scaffold (BVS; Abbott Vascular) through a 6 Fr GuideLiner is a cumbersome task due to the friction caused by the simultaneous presence of the coronary wire and the bulky BVS struts within the GuideLiner lumen. Therefore, the BVS was preloaded to the distal tip of the GuideLiner outside the body and inserted to the mid-LAD en bloc with the GuideLiner. Final delivery of the two BVS devices to the culprit lesions was performed without any difficulty (Figure 2A). After high-pressure postdilatation (24 atm) with an NC balloon, an excellent final IVUS and angiographic result was achieved, demonstrating well-apposed, symmetric BVS struts with a scaffold area of 5.78 mm² (Figure 2B). 

Despite the well-known advantages of BVS devices, including scaffold resorption and conformability, and the similar rates of acute recoil as everolimus-eluting stents in simple lesions, their application to calcified lesions remains controversial.^1,2 The bulky BVS struts add extra difficulty to lesion crossing, whereas in cases of asymmetric, elliptical scaffold expansion (due to presence of calcification), scaffold disruption in the direction of the major axis is a matter of concern. The current case demonstrates how optimal lesion preparation (using scoring balloons when necessary) and adequate support (using child catheters) can overcome these difficulties and facilitate implantation of a symmetric, well-apposed BVS. Furthermore, this strategy does not require special equipment or skills, such as rotational atherectomy, and hence could be applicable in any institution, and may help expand the use of BVS devices in complex lesions. In the meantime, large studies assessing clinical outcomes of patients with complex lesions treated with BVS are eagerly awaited.

References

1. Bourantas CV, Onuma Y, Farooq V, Zhang Y, Garcia-Garcia HM, Serruys PW. Bioresorbable scaffolds: current knowledge, potentialities and limitations experienced during their first clinical applications. Int J Cardiol. 2013;167:11-21.
2. Onuma Y, Serruys PW, Gomez J, et al. Comparison of in vivo acute stent recoil between the bioresorbable everolimus-eluting coronary scaffolds (revision 1.0 and 1.1) and the metallic everolimus-eluting stent. Catheter Cardiovasc Interv. 2011;78:3-12.