Thrombus Contribution to Very Late Restenosis of Bare-Metal Stent Treated by Excimer Laser Angioplasty: In Vivo Assessment with Optical Coherence Tomography
- Volume 23 - Issue 5 - May 2011
- Posted on: 4/29/11
- 0 Comments
- 3922 reads
A 75-year-old, male ex-smoker with hypertension and family history of ischemic heart disease, previous anterior myocardial infarction, and angioplasty with bare-metal stent implantation to the left anterior descending artery 4 years earlier, developed effort angina. A nuclear myocardial scan documented a stress-inducible perfusion defect in the left ventricular anterior wall. The patient was taking 100 mg aspirin daily and a 300 mg loading dose of clopidogrel was administered the day before coronary angiography.
Coronary angiography showed focal proximal in-stent restenosis (Figure 1, Panel A). Optical coherence tomography (OCT) (ImageWire and Imaging System M2, LightLab Imaging, Westford, Massachusetts) was performed using a non-occlusive technique with automated pump injection of iso-osmolar contrast (Visipaque, GE Healthcare, Cork, Ireland) with a pullback speed of 2 mm/second, after intracoronary administration of 400 µg nitroglycerin and intravenous injection of 5,000 IU heparin. The stent was imaged for its entire length. OCT showed restenotic tissue with asymmetric thickness and heterogenous backscattering signal: low on the abluminal site close to the stent struts, and high toward the lumen, at 7 to 12 o’clock, from mid to proximal stent segment, with a minimal luminal area of 2.6 mm2 (Figure 1, Panels IA and IB). At 1 to 6 o’clock, the restenotic tissue showed a uniform lower thickness with homogenous high backscattering signal, typical of neointimal hyperplasia (Figure 1, Panels IA and IB). At the proximal stent edge, an intraluminal protruding thrombotic mass was detected (Figure 1, Panel C). The decision to perform laser angioplasty was made, and an additional bolus of 4,000 IU of intravenous heparin were administered. After excimer laser ablation with a 1.7 mm catheter (Vitesse 1.7, Spectranetics, Colorado Springs, Colorado), the heterogeneous restenotic tissue fragmented into irregular masses protruding into the lumen, highly suggestive of thrombotic material (Panels IIA and IIB). After laser ablation with a 2.0 mm catheter, the thrombotic masses detached from the vessel wall, causing further lumen narrowing (Figure 1, Panels IIIA and IIIB). Post-dilatation of the stent with a 2.5 x 10 mm Maverick balloon (Boston Scientific, Natick, Massachusetts) and implantation of a sirolimus-eluting Cypher stent (Cordis Corporation, Miami, Florida) 3.5 x 23 mm were performed, with optimal angiographic result (Figure 1, Panel B). The patient was discharged home with the indication to continue life-long aspirin at a dosage of 100 mg daily and clopidogrel for 12 months at a dosage of 75 mg daily.