Late Coronary Stent Infection: A Unique Complication afterDrug-Eluting Stent Implantation

Coronary stent infection is a rare but previously reported complication of coronary artery stenting procedures (CAS).^1–13 In the few cases reported in the literature, patients have presented within days to weeks of stent implantation with fever, and the infection presumably was related to periprocedural bacteremia or direct septic stent implantation.^14–18

Case Report. A 75-year-old male was seen for stable angina pectoris in June 2005. His past medical history included hypertension, type II diabetes mellitus, hypercholesterolemia and renal insufficiency, with a baseline creatine of 1.8 mg/dL. Cardiac catheterization revealed a subtotal stenosis proximally in the right coronary artery (RCA), which was successfully treated with a 3 x 12 mm Taxus drug-eluting stent (DES) (Boston Scientific Corp., Natick, Massachusetts) during the same procedure. The procedure was uneventful, and the patient was discharged the next day with an unchanged creatine level.

The patient was subsequently followed by his primary physician, and there was no report of fever or angina. He was treated in August 2005 and again in February 2006 with iron dextran infusions for anemia secondary to worsening renal insufficiency. The patient underwent several dental procedures during this period without prophylactic antibiotics. In March 2006 the patient complained of fatigue, yet was afebrile and denied chest pain. His creatine was 3 mg/dL. Coumadin therapy for chronic atrial fibrillation was initiated.

In June 2006, 11 months after the index procedure, the patient presented with a non-Q wave myocardial infarction. He also complained of fever, lethargy, and weight loss over the previous several weeks. Blood cultures were positive for methicillin-resistant Staphylococcus aureus (MRSA). Echocardiography was negative for valvular vegetations. The patient was treated with intravenous (IV) gentamicin 267 mg daily for 10 days, rifampin 600 mg twice daily and IV vancomycin 1 gm daily for 6 weeks.

The patient was readmitted 1 month later with a skin rash and increasing renal insufficiency (his plasma creatine was 6 mg/dL). Blood cultures again were positive for MRSA. Extensive evaluation, including transesophageal echocardiography and chest computed tomography, failed to reveal the source of infection. The initial antibiotic program was discontinued and was replaced with linezoloid 600 mg twice daily for 28 days and IV daptamycin 500 mg every 48 hours for 6 weeks. Subsequent repeat blood cultures remained positive for MRSA. Cardiac magnetic resonance angiography (MRA) revealed a nonenhancing fluid collection surrounding the right coronary stent, suggesting the presence of an abscess (Figure 1). Coronary arteriography revealed severe narrowing of the RCA at the stent site with aneurysmal dilatation (Figure 2).

The patient underwent coronary bypass surgery using the femoral artery and vein for cardiopulmonary bypass. A 2.5 cm² abscess was found at the stent site in the RCA (Figure 3). After establishing an adequate distal vein graft anastomosis, the right coronary abscess was opened and the purulence removed. The capsule, stent and excess fibrous tissue were removed after oversewing the proximal and distal vessel. A monofilament absorbable suture was utilized. The patient was rewarmed and separated from cardiopulmonary bypass without difficulty.

A prolonged postoperative course was complicated by renal and respiratory insufficiency. The patient subsequently recovered and resides in an assisted-living facility.

Discussion

The present case report describes the late development of an infection of a coronary DES. The patient presented several months after stent deployment, and the diagnosis was made with cardiac MRA during evaluation of bacteremia refractory to antibiotic therapy. The patient was managed with surgery and survived after a prolonged, complicated hospital course.

Infection is a rare complication of CAS.^1–13 All of the reported cases presented with fever occurring days to a few weeks after percutaneous intervention. The etiology was likely bacteremia, with secondary seeding of an unendothelialized foreign body or stent contamination at the time of deployment.^14–18 In the cases of DES involvement, impairment of local defense mechanisms may also be a factor.^10–13,17 Staphylococcus aureus was the most common organism isolated. Despite intravenous antibiotics and surgery, the mortality rate in these reported cases was near 50%.

The unique feature of the present case is its late development several months after the index procedure. Recent angioscopy and autopsy studies have demonstrated the lack of endothelial coverage of DES months after deployment.^19,20 Thus, there is a small but definite risk of late stent thrombosis in these patients.²¹ It is conceivable that the persistently exposed stent struts provided a nidus for infection during an episode of bacteremia.

Late infection of a DES has not previously been reported in the literature, and lack of awareness of this stent complication may have delayed diagnosis in the present case.

In summary, a case of late DES infection presented months after the initial procedure. Persistently exposed struts due to delayed endothelialization of DES could provide a source for infection during an episode of bacteremia. Given the large number of DES that are currently implanted worldwide, this problem may be more common than is currently evident, thus, clinicians should be cognizant of this potential complication.

Acknowledgment. The authors gratefully acknowledge the assistance and expertise of Dr. Richard Daw of Wake Heart and Vascular Associates.

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