Stent-induced hypersensitivity leading to refractory in-stent restenosis: a case report

Even in the era of new-generation drug-eluting stents, in-stent restenosis remains a common and challenging problem of percutaneous coronary intervention. Among the many factors that contribute to in-stent restenosis, stent-related hypersensitivity is relatively rare, but may be a significant trigger of chronic refractory in-stent restenosis. Nevertheless, it is difficult to diagnose and assess the stent-related hypersensitivity, and there is no standardized treatment strategy.

We present the case of a 63-year-old Chinese female who experienced refractory in-stent restenosis following the successful implantation of platinum chromium everolimus-eluting stents in the left main, left anterior descending and left circumflex artery. Although the cardiovascular risk factors were well-controlled, the patient developed four episodes of acute myocardial infarction with in-stent restenosis within 1 year. Intravascular ultrasound revealed diffuse neointimal hyperplasia in the in-stent restenosis lesion, and the blood tests showed no sign of systemic inflammation or infection. Thus, we speculated that the cause of refractory in-stent restenosis was stent-mediated hypersensitivity. Initially, the in-stent restenosis was treated with paclitaxel-coated balloon angioplasty, and only mild neointimal hyperplasia was observed on intravascular ultrasound 3 months after paclitaxel-coated balloon angioplasty. However, the paclitaxel-coated balloon could not prevent in-stent restenosis recurrence, and she eventually underwent coronary artery bypass grafting. After over 2 years of follow-up, her cardiac function had significantly improved, and the bridging vessels remained patent, as confirmed by computed tomography angiography.

When encountering refractory in-stent restenosis, physicians should consider the potential for stent-associated hypersensitivity. Since there may be difficulty in obtaining histopathological examination of restenotic vessels, intravascular imaging can be instrumental in detecting neointimal hyperplasia and diagnosing stent allergy. Coronary artery bypass grafting may be a reasonable treatment for patients with stent allergy; further clinical research is required to explore the optimal treatments.