Two cases of very late thrombosis of sirolimus-eluting stents implanted in diseased saphenous vein grafts

Following are 2 cases of angiographically documented very late stent thromboses that occurred in patients enrolled in the Reduction of Restenosis in Saphenous Vein Grafts with Cypher Stent (RRISC) trial.

Case 1

A 69-year-old man with a history of hypercholesterolemia and hypertension who had undergone coronary artery bypass graft (CABG) surgery 20 years earlier was admitted to our institution for unstable angina. Coronary angiography showed a severe stenosis of the saphenous vein graft on a big circumflex artery (Figure 1, top left). The patient was successfully treated with implantation of a sirolimus-eluting stent (3.5 x 33 mm inflated at 22 atm) under distal embolization protection with the Medtronic GuardWire device (Figure 1, top right). He received double antiplatelet therapy with clopidogrel (Plavix) and aspirin. At the 6-month follow-up, the control angiogram showed a widely patent stent almost without any hyperplasia (Figure 1, bottom left). The patient remained on double antiplatelet therapy for another 7 months; 13 months after the baseline procedure, both aspirin and clopidogrel were discontinued because of a planned orthopedic surgical procedure on the knee. One week after suspension of the 2 drugs, the patient was admitted to our hospital with a serious anterolateral myocardial infarction due to very late occlusive stent thrombosis (Figure 1, bottom right). All attempts to reopen the saphenous vein graft failed, and the patient died 1 month later due to progressive heart failure.

Figure 1. Severe stenosis of the saphenous vein graft is shown on coronary angiography (top

left). A sirolimus-eluting stent was implanted (top right). At the 6-month follow-up, angiography

showed a widely patent stent (bottom left). One week after discontinuation of aspirin and

clopidogrel, the patient had an anterolateral myocardial infarction due to very late occlusive stent

thrombosis (bottom right).

Case 2

An 80-year-old man with hypercholesterolemia who had undergone CABG surgery 13 years earlier presented to our hospital with unstable angina. At coronary angiography, a severe eccentric focal lesion of the saphenous vein graft on the right coronary artery was detected (Figure 2, top left). The stenosis was treated percutaneously with implantation of a sirolimus-eluting stent (3.0 x 33 mm inflated at 18 atm). The procedure was performed after placement of the Medtronic GuardWire device, and the result was optimal (Figure 2, top right). The patient received clopidogrel and aspirin for 6 months. He then underwent the planned control angiogram, which showed a patent stent without evidence of intimal hyperplasia. Clopidogrel was discontinued, and the patient continued taking aspirin only. At 16 months, the patient underwent angiography, which confirmed the optimal result of the stent in the saphenous vein graft (Figure 2, bottom left). However, 30 months after the index procedure, the patient experienced an acute coronary syndrome with transient inferior ST-segment elevation shown on electrocardiogram. Tirofiban (Aggrastat) and low-molecular-weight heparin were started in the hospital where the patient was admitted. He was then transferred to our catheterization laboratory. An angiogram showed a subocclusive very late stent thrombosis of the sirolimus-eluting stent implanted 30 months earlier (Figure 2, bottom right). In this case, the new lesion was successfully treated with implantation of 2 bare-metal stents, and the patient was discharged without complications several days later.

Figure 2. An eccentric focal lesion of the saphenous vein graft is shown on coronary angiography

(top left). A sirolimus-eluting stent was implanted (top right). At 16 months, the saphenous vein

graft was patent (bottom left). Thirty months after the initial procedure, a subocclusive very late

stenosis of the saphenous vein graft was shown on coronary angiography (bottom right).