Despite advancements in stent design and polymer coatings over the past two decades, 1% to 2% of patients annually still experience instent restenosis (ISR). ISR reduces myocardial perfusion, may develop symptoms of myocardial ischemia, and thus leads to a high risk of myocardial infarction and cardiac death. Given that millions of drug-eluting stents (DES) are implanted globally every year, ISR remains a prevalent clinical issue with significant public health implications. Coronary intravascular imaging, includes intravascular ultrasound (IVUS) and optical coherence tomography (OCT), can help physicians gain deeper insights into the potential mechanisms of ISR. The preferred treatment strategy hinges on an accurate diagnosis and better understanding of etiology. The mechanism of ISR is multifaceted, and its treatment is challenging. Although the risk of ISR continues to decrease with advancements in DES application, further research is still needed to enrich the treatment options for ISR.

In-stent restenosis, Drug-eluting stent, Intravascular ultrasound, Optical coherence tomography, Percutaneous coronary intervention