Intravascular imaging and coronary calcification

Intravascular ultrasound (IVUS) and optical coherence tomography are more sensitive in detecting coronary calcification compared with coronary angiography. The key to predicting successful stent expansion in a calcified lesion is the total amount of calcium (calcium thickness, angle, and length). The main mechanism of atherectomy is to remove a small amount of superficial calcium (calcium modification) to facilitate calcium fracture, and the mechanism of other devices (cutting or scoring balloon, excimer laser, or lithotripsy) is not removal of calcium, but calcium fracture. Causes of in-stent restenosis in the drug-eluting stent era include stent underexpansion, often from peri-stent calcium, and neoatherosclerotic calcification. Although understanding the mechanism of each case of in-stent restenosis is important, avoiding stent underexpansion from underlying calcium at the time of first stent implantation is far more important.