A Case of Giant Coronary Artery Aneurysm after Placement of a Heparin-Coated Stent

From the Division of Cardiology, Department of Medicine, Beth Israel Medical Center, New York, New York. The authors report no conflicts of interest regarding the content herein. Manuscript submitted June 12, 2008, provisional acceptance given August 11, 2008 and final version accepted November 3, 2008. Address for correspondence: Jyoti Sharma, MD, Division of Cardiology, Department of Medicine, Beth Israel Medical Center, Department of Cardiology, 1st Avenue and 16th Street, New York, NY 10003. E-mail: jsharma@chpnet.org

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ABSTRACT: The formation of coronary aneurysms and pseudoaneurysms are a rare but previously described complication after percutaneous coronary intervention (PCI). We present a unique case of the development of a giant coronary aneurysm after placement of a heparin-coated stent. A 79-year-old female who had PCI to the left anterior descending coronary artery (LAD) using a heparin-coated stent three years previously underwent cardiac catheterization. Coronary angiography revealed a giant aneurysm measuring 19 x 18 mm immediately distal to the previously implanted stent in the LAD. The patient refused any further intervention and was treated with aggressive medical management. Eighteen months have now passed, and the patient has been stable without further cardiac events or complaints.

J INVASIVE CARDIOL 2009;21:E22–E23

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The formation of coronary aneurysms and pseudoaneurysms are a rare but previously described complication following percutaneous coronary intervention (PCI). Though there have been a number of case reports of this condition in patients after placement of drug-eluting stents (DES), it is a less common finding after placement of bare-metal stents (BMS). The clinical course of coronary aneurysm following stent placement varies markedly, and its pathophysiology is still unclear. We present a unique case of the development of a giant coronary aneurysm following PCI with a heparin-coated stent. Case Report. A 79-year-old female with a history of diabetes mellitus, coronary artery disease and cervical cancer returned three years after her last visit because of an abnormal computed tomographic (CT) finding. She denied chest pain, shortness of breath or any other complaints. Three years earlier, the patient underwent PCI to the left anterior descending coronary artery (LAD) with a heparin-coated stent (Hepacoat™ Bx Velocity, Cordis Corp., Miami Lakes, Florida). The recent CT of the chest, performed for routine evaluation, incidentally revealed an aneurysm of the LAD. She had no evidence of coronary artery ectasia or aneurysm on her previous coronary angiograms (Figure 1A). Coronary angiography was performed, which revealed significant in-stent restenosis with a giant aneurysm of the LAD immediately distal to the previously implanted stent. The aneurysm measured 19 x 18 mm (Figure 1B). The patient was referred for coronary artery bypass grafting, but she declined the surgery. She also declined to undergo another PCI and was treated with aggressive medical management. Twenty months have now passed, and the patient has been stable without further cardiac events or complaints. Discussion. The clinical course of coronary artery aneurysms after DES stent placement is variable and the true incidence is still unknown. A meta-analysis of randomized trials showed that the incidence of coronary aneurysms was similar overall between DES and BMS (1.1% for DES and 0.8% for BMS [odds ratio 1.326, 95% confidence interval 0.571–3.078; p = 0.512]).¹ In these randomized trials, an aneurysm was defined as a vessel diameter 20% greater than the reference vessel diameter. This is in contrast to the conventional definition of a coronary aneurysm, defined as an area that exceeds the diameter of the largest coronary artery by 50% or more.² In addition, the results of these trials were derived from early angiographic follow up, and it is unclear what the incidence of aneurysm formation is with long-term follow up. The exact mechanism of how a stent disrupts the vessel wall and causes coronary aneurysm or pseudoaneurym is still unclear. In addition to mechanical injury, it has been hypothesized that an altered pattern of vascular healing post stent implantation may be the etiology of aneurysm formation after DES implantation. Histological studies focusing primarily on DES have shown an extensive inflammatory reaction involving eosinophils and T lymphocytes. Virmani et al presented an autopsy case with aneurysm formation around the stented segment of the coronary artery with a severe localized hypersensitivity reaction invading through all vessel wall layers,³ suggesting that late stent thrombosis and coronary aneurysm formation may share the same pathogenesis of localized hypersensitivity to DES.⁴ This type of hypersensitivity reaction, along with delayed endothelialization, have rarely been observed with the use of BMS. Aoki et al categorized coronary aneurysms based on the rate of growth and associated clinical symptoms.¹ Our patient’s aneurysm falls into the Type II class, where aneurysms tend to be subacute-to-chronic in their presentation and are often detected incidentally during repeat angiography.¹ While the prognostic indication of these classes is yet to be determined, they may be helpful in deciding the management of patients in the future. It is also important to make the distinction between pseudoaneurysms and aneurysms. True coronary aneurysms have an intact vessel wall, while pseudoaneurysms have a loss of vessel wall integrity. Such loss of vessel wall integrity is due to damage of the two inner layers of the vessel (intima and media) and damage to the adventitia or perivascular tissue. Changes to the vessel wall can be evaluated using intravascular ultrasound (IVUS). In one series of IVUS in patients with an angiographic aneurysm, 27% had a true aneurysm, 4% had a pseudoaneurysm, 16% had complex atheromatous plaques and 53% had normal arterial segments.5 IVUS has become the “gold standard” to differentiate coronary aneurysms and pseudoaneurysms.⁶ In the literature, bypass surgery, coiling and placement of a graft stent⁷ have all proven to be reasonable strategies to treat these types of vessel abnormalities. There are limited data regarding the natural history and efficacy of therapy for coronary aneurysms. Overall therapy decisions should be individualized based on aneurysm size, pathophysiology and patient symptoms. Several case reports suggest that even if patients are medically managed, their course may be benign.^7–9 Our patient, whose aneurysm was larger than most of the reported cases, did well without any further intervention. In addition, there have been case reports of aneurysms and pseudoaneurysms healing spontaneously.^7,10 We present a case exhibiting the natural history of a coronary aneurysm following heparin-coated stent placement treated medically, with a good result. As far as we know, this is the first case report of a coronary aneurysm following heparin-coated stent placement. The fact that our patient developed an aneurysm following heparin-coated stenting suggests mechanical injury to the vessel as an important etiology of coronary aneurysm, rather than the hypersensitivity reaction, inflammatory response and delayed endothelialization that are usually seen with DES.

References

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