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A 45 year old man was admitted because of exertional angina. Coronary angiography revealed a 70% stenosis in the left circumflex artery (LCx). He was enrolled in the US SIRIUS study to evaluate the efficacy of sirolimus eluting stents in de novo native coronary lesions. A dramatic reduction of restenosis has previously been demonstrated using sirolimus eluting stents. A 3.0 × 18 mm sirolimus eluting stent (Cordis, Johnson & Johnson, Miami, Florida, USA) was deployed in the distal LCx lesion. Eight months later, angiography and intravascular ultrasound (IVUS) were performed according to the study protocol (see fig), although he had been asymptomatic. IVUS imaging demonstrated non-obstructive, eccentric echolucent tissue in the proximal part of the stent, which corresponded to the angiographic mild, eccentric luminal narrowing. No further procedure was performed.
Echolucent tissue, which is termed “black hole” and more appropriately “black wall”, has been reported after intracoronary brachytherapy. The tissue specimens obtained by atherectomy in a limited number of cases demonstrated that the echolucent findings appeared to be caused by a hypocellular matrix with areas of proteoglycan. Proteoglycan has a high water content that may explain the IVUS features. While we do not have histological data on this patient, the echolucent tissue in this patient may likewise be caused by hypocellular neointimal hyperplasia rich in proteoglycan.