Intramural hematoma extending from a dissection within an implanted stent: a case report treated with fenestration using a cutting balloon.

Background: Dissection after balloon dilation or stent implantation is a common complication of percutaneous coronary intervention. In general, coronary stent implantation for coronary artery dissection is safe when the dissection is completely covered by the stent, particularly when dissection occurs during pre-dilation. However, here, we report a case of severe restenosis caused by a pre-dilation hematoma that extended after stent implantation. Case summary: A 76-year-old man was diagnosed with angina on exertion and underwent percutaneous coronary intervention in the right coronary artery. After pre-dilation with a cutting balloon, non-flow-limiting dissection occurred. An everolimus-eluting stent was implanted, completely sealing the dissection, and intravascular ultrasound revealed adequate stent expansion without stent edge dissection. Two weeks after the procedure, confirmatory coronary angiography revealed severe restenosis extending from the distal stent edge to the distal right coronary artery. Intravascular ultrasound revealed a hematoma extending from the middle of the stent to the distal segment. Discussion: The patient had been on steroids for a long time. The cutting balloon used for pre-dilation may have created a deep dissection reaching the tunica media, already rendered vulnerable by steroids, potentially leading to injury to the vasa vasorum. The intramural hematoma from the bleeding vasa vasorum might have been the underlying cause of this phenomenon, as evidenced by its increase in size despite the entry of the dissection being completely sealed. Cardiologists should be aware of this possibility.