Repeated occurrence of slow flow phenomenon during and late after sirolimus-eluting stent implantation

A 78-year-old man with unstable angina showed 90% stenosis in the proximal left anterior descending artery. Pre-procedural intravascular ultrasound revealed ruptured plaque and attenuated plaque in the lesion. Under these conditions, two overlapping sirolimus-eluting stent (SES) implantation in this lesion resulted in slow flow which was recovered by intracoronary nitrates, nicorandil, and nitroprusside without further complications. When the patient showed up again 5 years later with recurrence of angina pectoris, angiography revealed a hazy ulcerated in-stent restenosis (ISR) at the site of the SES. Pre-procedural optical coherence tomography (OCT) imaging revealed multiple intimal ruptures, cavity formation behind the stent struts, a thin-cap fibroatheroma containing neointima surrounded by signal-poor, lipid-rich area in the proximal SES, suggesting the progression of neoatherosclerosis within SES. Importantly, there occurred slow flow again after balloon angioplasty for this lesion. We would suggest careful OCT examination is warranted to confirm development of neoatherosclerosis within the stent, and distal protection device should be considered to prevent slow flow phenomenon even in a patient with very late ISR.