Lipid-Rich Atherosclerosis of Coronary Artery

The goal of this clinical trial is to find out whether treating vulnerable plaques in the coronary arteries with a drug-coated balloon can make them less dangerous than using standard medication alone. The study includes adults with acute coronary syndrome (a type of heart problem caused by reduced blood flow in the coronary arteries). The main questions the study aims to answer are: * Does the drug-coated balloon reduce the amount of fat inside the plaque more than medication alone? * Is this treatment safe for patients? Participants will: * Undergo imaging of their coronary arteries during their planned heart procedure (PCI) * Be randomly assigned to receive either a drug-coated balloon treatment or no extra treatment * Undergo a heart scan (CT scan of the coronary arteries) within 2 weeks and again around 9 months after the procedure. * Undergo a second heart catherization 9 months later to examine changes in the plaque.

RESSURE-NIRS registry is designed to investigate clinical and pathophysiological characteristics of NIRS-derived lipid-rich plaque in patients with coronary artery disease. This is an on-going multi-center prospective registry in Japan.