Coronary Aneurysm Formation in a Patient Early after Everolimus-Eluting Stent Implantation

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J INVASIVE CARDIOL 2008;20:E174-E175

Coronary aneurysm formation after drug-eluting stent (DES) implantation is a rare complication. It has been documented with sirolimus-eluting stents (SES) and paclitaxeleluting stents (PES). The mechanism leading to aneurysm formation after DES implantation is not clear. Hypersensitivity reactions to the polymer and/or to the drug with a local inflammatory response are likely.1 Late stent thrombosis is a potentially fatal complication of aneurysm formation with DES implantation. However, coronary aneurysm formation has never been shown with second-generation DES like the everolimus-eluting stent (EES; Xience ^®Abbott Vascular, Redwood City, California).


Case Report. We report the case of a patient who was admitted because of chest pain and inferolateral ST-elevation. The diagnosis of an infero-postero-lateral ST-elevation myocardial infarction (STEMI) was made and the patient was taken to the catheterization laboratory. Coronary angiography showed a subtotal stenosis in the first and second obtuse marginal branches (OM) and a significant stenosis in the distal posterolateral artery (PLA) (Figure 1). All 3 lesions were predilated and 3 EES (Xience V^®, Abbott Vascular) were implanted (OM: Xience V^® 2.5 x 8 mm; OM: 3.0 x 15 mm distal; and PLA: 3.0 x 28 mm). He was scheduled for a restudy 3 months after the index procedure.
On readmission, the patient was asymptomatic. Angiography 3 months after the inferolateral STEMI revealed a large aneurysm around the stent in the second OM (Figures 2A and B). There were some aneurysmal changes around the stents in the first OM and the distal PLA as well (not shown). The aneurysm in the first OM was clearly visible on intravascular ultrasound (IVUS) (Figures 2A–D). The stent in the first OM was redilated using a 4.0 x 9 mm Maverick balloon (Figure 3A) with a good final result. After postdilatation, the stent was nicely apposed to the vessel wall on IVUS (Figure 3B). Lifelong aspirin 100 mg/day and clopidogrel 75 mg/day were recommended.

Discussion. Coronary aneurysm formation is a rare complication after DES implantation. Late-acquired stent malaposition (LASMA) is a recently-described pathological process that is associated with very late stent thrombosis in patients with DES, and it is a potential cause for the aneurysm formation in our patient. Virmani et al described a local hypersensitivity reaction with extensive vasculitis of the intima, media and adventitia, consisting predominantly of lymphocytes and eosinophils in a patient suffering from aneurysmal dilatation of the vessel wall (i.e., LASMA) within the stented segment and very late stent thrombosis 18 months after DES implantation. Chronic inflammation with outward remodeling of the arterial wall in response to DES implantation has been confirmed as one of the mechanisms of stent thrombosis in a larger pathological series from the same laboratory. In a recent study of our group,4 we found LASMA in more than three-quarters of the patients (77%) with DES and very late stent thrombosis, compared to only 12% in the DES control group without stent thrombosis. In addition, the extent of LASMA, in terms of both length and depth, was more pronounced in very late stent thrombosis patients than in the control group patients.
The EES is a DES based on the former Multilink Vision^® Stent (Abbott Vascular), and with its thin struts and fluoropolymer, it is thought to be highly biocompatible and inert.
This case illustrates that even with second-generation DES with a highly biocompatible polymer, there can be adverse reactions to the polymer and/or to the drug, leading to aneurysmal formation with possible late stent thrombosis as a serious sequela.
Definite treatment of these aneurysms is controversial. We decided to postdilate the stent within the aneurysm and treat the patient with aspirin and clopidogrel on a lifelong basis.

References

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