Clinical differences among types of in-stent calcifications in coronary arteries: how can this be better managed?

Introduction: In-stent calcification is recognized as a significant contributor to unfavorable clinical outcomes. Understanding the various types and underlying mechanisms of in-stent calcification can help interventional operators to make decisions.

Areas covered: This review will describe the distinct types of in-stent calcification, which are categorized into in-stent smooth calcification and in-stent calcified nodule. The mechanisms and characteristics of in-stent smooth calcification and calcified nodule will be summarized. Given the differences between these two types, treatment approaches will be discussed. This review will focus on histopathology and intracoronary imaging. For the purpose of this review, evidence was gathered from electronic literature searches via PubMed, with a particular focus on primary evidence published in the last 5 years.

Expert opinion: Several treatment devices are available such as conventional balloon, modified balloon, atherectomy device, and intravascular lithotripsy. In-stent smooth calcification and calcified nodule might result in different clinical courses after repeated target lesion revascularization. Understanding the mechanisms with the various types of in-stent calcification may assist operators in selecting appropriate treatment strategies.