In this episode, we delve into the CALIPSO (Calcified Lesion Intervention Planning Steered by OCT) trial, a pivotal study evaluating the efficacy of optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) compared to traditional angiography-guided PCI in patients with moderate to severe calcified coronary lesions. Conducted across 12 centers in France, the trial demonstrated that OCT-guided PCI, utilizing a predefined lesion preparation algorithm, resulted in significantly larger minimal stent areas and improved stent expansion without increasing procedural risks. We explore the trial's design, key findings, and discuss the potential implications for interventional cardiology practice.