Optical coherence tomography-guided percutaneous coronary intervention on a calcific protruding nodule. A) Angiography shows a mid-left anterior descending (LAD) nodular obstruction (arrowhead). B) Optical coherence tomography (OCT) imaging reveals a small minimal lumen area and (C) confirms the aetiology of the obstruction to be a calcific protruding nodule (arrowhead). Images and caption courtesy of EuroIntervention and Ziad A. Ali, MD, DPhil, et al. DOI: 10.4244/EIJ-D-21-00089