Abstract
BACKGROUND: Percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) is indicated in selected patients with symptoms or significant ischemic burden, balancing clinical benefit against procedural risk. CASE SUMMARY: A 66-year-old man with inferolateral ST-segment elevation myocardial infarction was found to have a calcified ostial left anterior descending artery CTO. During staged antegrade CTO PCI, high-pressure balloon inflation at the proximal cap resulted in an unintentional balloon rupture, creating a focal microdissection without perforation. This event enabled true-lumen wiring, lesion preparation, and successful stent implantation with optimal angiographic and intravascular ultrasound results. DISCUSSION: The mechanism was consistent with balloon-assisted microdissection rather than hydrodynamic contrast recanalization. Although unintentional, the rupture facilitated plaque modification and re-entry. TAKE-HOME MESSAGE: Unintentional balloon rupture may rarely act as a bailout mechanism during complex CTO PCI but should never be considered a routine strategy.