MRI-Induced Stent Dislodgment Soon After Left Main Coronary Artery Stenting

Abstract

e58S everal studies have shown the safety of MRI after coronary stenting; however, few of them included patients soon after stenting. In this report, we describe a case of MRIinduced stent dislodgment from left main coronary artery (LMCA) 2 weeks after stenting. Case ReportA 56-year-old woman underwent coronary angiography for recurrence of angina 12 months after coronary artery bypass graft surgery. Coronary artery bypass graft surgery had been performed with left internal mammary artery grafted to left anterior descending artery and a saphenous vein graft to obtuse marginal branch for LMCA stenosis (Figure 1). The comorbidities of patient included hypertension, dyslipidemia, diabetes mellitus, and prior neurosurgery for a pituitary adenoma. The repeat angiogram showed known stenosis in LMCA, nonobstructive disease of left anterior descending artery and right coronary artery, patent saphenous vein graft to obtuse marginal branch, and an occluded left internal mammary artery (Figure 2). After discussion, stenting of the LMCA with a 3.5×8 mm drug-eluting stent (Cypher; Cordis Corp, Markham, Ontario) was deployed after predilatation under intravascular ultrasound guidance ( Figure 3).The patient underwent MRI of the head in a 1.5-Tesla scanner for surveillance of pituitary pathology 2 weeks after stenting. Follow-up angiography ( Figure 4) was performed to investigate the symptoms of chest pain and assess stent patency. The implanted stent could not be visualized in the LMCA on angiography, and an intermediate residual stenosis was observed. A whole-body screening computed tomography was performed to locate the missing stent that was successfully identified in the proximal branch of the left iliac artery ( Figure 5). In the absence of symptoms for arterial insufficiency, no attempt was made to retrieve the embolized stent. Normal perfusion on repeat nuclear imaging confirmed that residual LMCA stenosis was not hemodynamically significant, and patient was continued on medical therapy with no clinical events occurring during long-term clinical follow-up. DiscussionTo our knowledge, this is the first report of coronary stent dislodgment related to an MRI procedure. Although the clinical implications of stent dislodgment can be serious, fortunately no adverse consequences were observed in this case as the stent migrated to a peripheral vessel in pelvis, an area with significant collateral circulation. Safety of MRI After Coronary StentingCareful screening of patients undergoing MRI is mandated in patients with metallic objects and implants.1 To improve safety, all implant devices are classified as MR safe, MR conditional, or MR unsafe based on the hazard posed in strong magnetic fields. The stents are composed of metal alloys, such as stainless steel, tantalum, nitinol, cobalt, titanium, chromium, and nickel, which are weak ferromagnetic metals and classified as MR conditional, which means that there is no known hazard in a specified MR environment within standard use. The currently available stents are predominantly ...

2020 MR Safety for Cardiac Devices: An Update for Radiologists

“…56 -58 To our knowledge, there has only been one unusual case report from Ontario, where a drug-eluting coronary stent (Cypher; Cordis Corp) in the left main coronary artery was dislodged when a 56-year-old patient underwent an MRI of the head in a 1.5 T scanner 2 weeks after stent implantation. 59…”

“…[56][57][58] To our knowledge, there has only been one unusual case report from Ontario, where a drug-eluting coronary stent (Cypher; Cordis Corp) in the left main coronary artery was dislodged when a 56-year-old patient underwent an MRI of the head in a 1.5 T scanner 2 weeks after stent implantation. 59 Bioprosthetic and mechanical valves, as well as annuloplasty rings, are labeled MR safe or MR conditional at 3 T or less, including the Starr-Edwards ball-and-cage mechanical heart valve that was once an absolute contraindication to MRI, but now considered MR conditional at 1.5 T. 60,61 Percutaneous transcatheter aortic valves are considered MR conditional at 1.5 and 3 T, when limiting SAR to <2 W/kg and imaging time to <15 minutes per pulse sequence. It has been shown that 3 T produces smaller forces on mechanical valves than a beating heart.…”

Do Patients with Implants Experience Strong Sensations That Lead to Early Termination of MRI Examinations?

“…The interaction may result in induced currents, device heating, and vibration of the device. Summing up, the different interactions between MRI and metallic implants are so strong that even MRI-induced stent dislodgment may be possible [10].…”

Letter by Lederman et al Regarding Article, “MRI-Induced Stent Dislodgment Soon After Left Main Coronary Artery Stenting”

“…It is important to dispute that MRI caused coronary stent dislodgement in the patient described by Parthasarathy and colleagues 1 . The BX Velocity stent used in the Cypher device in their report is composed of 316L stainless steel 2 , which is weakly ferromagnetic.…”