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- Jun-Jack Cheng1
Coronary artery aneurysm (CAA) is a rare complication of bare metal and drug-eluting stent implantation. Although previous reports implicated etiologic factors such as inflammation, allergic reaction, hypersensitivity, deep vessel wall injury, and residual dissection, the mechanisms underlying CAA development remain unclear. Bioresorbable scaffolds have ushered in a new era in interventional cardiology. The everolimus-eluting bioresorbable vascular scaffold (BVS; absorb, Abbott vascular, CA) is widely used in clinical practice because of its efficacy and safety. However, many questions remain to be answered, as CAA and late strut malapposition are theoretically possible after BVS implantation. We report a case of CAA after BVS implantation in a 55-year-old man with angina. In addition, we describe the findings of a literature review of eleven patients who developed an intra-scaffold aneurysm.
A 55-year-old man with hypertension and hyperlipidemia presented with effort angina for 1 year. CAG showed significant stenosis in the proximal LAD and middle LCX. He underwent IVUS guided PCI for the LAD and LCX with 3.0 × 18 mm and 3.5 × 28 mm BVSs that were postdilated with 3.5 mm and 3.75 mm noncompliant balloons at 16 atm, respectively (Fig. A-C). The final IVUS pullback confirmed optimal expansion and good apposition of these two scaffolds without edge dissection. Eighteen months later, follow-up CTA showed lumen dilatation in the scaffold segment at the middle LCX (Fig. D, E). CAG confirmed the presence of ectatic change with aneurysm formation in the LCX scaffold segment (Fig. F, G). A longitudinal OCT image confirmed the increase in vessel area and lumen area. (Fig. H), and a cross-sectional OCT revealed focal cleavage of the scaffold rings and a vessel bulge in the segment free from the scaffold struts (Fig. I). In addition, OCT revealed the absence of strut malapposition and well-covered strut remnants in the vessel wall, but there was no structural continuity at the aneurysm site. To avoid scaffold deformation, further intervention for the LCX aneurysm was not performed. Dual antiplatelet therapy was prescribed to prevent thrombus formation. The patient has not reported chest discomfort during more than 1 year of follow-up.
CAA is defined as an in-scaffold diameter >1.5 times the reference vessel diameter. The true incidence of CAA after BVS implantation is unknown, although the incidence of CAA after drug-eluting stent (DES) implantation is around 0.2% to 2.3%.
Development of CAA after BVS implantation was reported in 11 patients recently, including the present case (Table); most were male, four patients underwent PCI for CTO. The CAAs in this series were detected within 2 to 32 months, and all CAAs developed in the scaffold segment. OCT and IVUS studies showed that some of the scaffolds were incorporated into the vessel wall and that completely endothelialized strut was present in the positively remodeled vessel wall. However, some patients exhibited gradual scaffold degradation, which resulted in disrupted strut continuity, thus facilitating outward strut displacement along with CAA.
Management of CAA after BVS is challenging and should be tailored to the anatomic setting of the CAA. Because of the loss of integrity of BVS struts, which is ongoing at 12 months postoperatively, most previously reported patients did not receive further intervention for CAA. Instead, long-term dual antiplatelet therapy and early follow-up were adopted. However, Manna et al reported a patient with in-scaffold restenosis in the middle portion of an aneurysm and subsequent implantation of a drug-eluting self-expandable stent. That can adapt to the vessel diameter and provides optimal strut apposition even in CAA. Varghese et al reported covered stent implantation, to exclude an aneurysm, in a patient with a CAA that had significantly increased in size at a 1-year follow-up examination.
BVS are emerging materials in percutaneous coronary intervention recently. Eleven patients of bioresorbable vascular scaffold malapposition with an aneurysm had been reviewed. Ten were male and four patients underwent PCI for CTO. Except two receiving subsequent intervention treatment, long-term DAPT and early follow-up were adopted for all others. Further studies are desired to comprehensively study the incidence and understand the underlying pathogenesis of CAAs after BVS implantation. Then we possibly could find out optimal strategy to handle this new challenging issues.