Severe Endothelial Dysfunction After Sirolimus-Eluting Stent Implantation
A 40-year-old man with a recent anterior myocardial infarction but with no history of coronary spasm and no risk factors for endothelial dysfunction such as diabetes mellitus, hypertension, smoking, or hypercholesterolemia was admitted to our hospital. Coronary angiography showed diffuse 90% proximal left anterior descending artery stenosis (Figure 1A). He received a sirolimus-eluting stent (Cypher, Cordis Corporation, Miami Lakes, Fla) to treat diffuse long left anterior descending stenosis on January 20, 2005 (Figure 1B). After predilation, 3 Cypher stents (2.5×28 mm, 2.5×28 mm, and 3.0×23 mm) were deployed, overlapping 3 mm at nominal pressure. Overlapped segments were postdilated at 18 atm. Finally, complete expansion was obtained, and the lesion was fully covered. The patient remained asymptomatic after stenting. Follow-up angiography at 6 months on June 9, 2005, showed 0% stenosis (Figure 2A). To evaluate endothelium-dependent vasomotor response, we performed intracoronary infusion of acetylcholine at 0.14 μg/min over a period of 2 minutes, yielding estimated intracoronary concentrations of 10−8 mol/L. Angiography repeated immediately after acetylcholine infusion showed total occlusion at the middle portion of the stents (Figure 2B) associated with chest pain and ST elevation. No vasoconstrictive response was observed in any other coronary artery. Intracoronary nitroglycerin (250 μg, bolus) quickly and completely resolved this angiographic obstruction (Figure 2C). In this case, severe vasoconstrictive response was produced by small-dose intracoronary acetylcholine infusion. This phenomenon indicated severe endothelial dysfunction in the sirolimus-eluting stent at 6 months after stenting, suggesting delayed reendothelialization with inadequate endothelial coverage in the long sirolimus-eluting stents.