Coronary artery perforation is a rare, but well recognized, compli-cation of percutaneous coronary intervention (PCI), with a reportedincidence of 0.14–0.35%, but with a mortality as high as 10% [1].Optical coherence tomography (OCT) has emerged as a powerfultool for use in stent assessment, and, within a short time, it hasbecome the modality of choice for study of stent and vascularinteractions in vivo. However, in a first generation pullback Time-Domain OCT imaging wire system (TD-OCT; M2 OCT systems andImageWire, LightLab Imaging, Inc, Westford, MA), blood clearancewas achievedby proximal balloonocclusion andflushingof the vesselusing the distal end holes of the occlusion balloon (Helios OcclusionBalloon Catheter, Goodman-Avantec Vascular Corp, Sunnyvale, CA).We report on a case of coronary perforation during first generationTD-OCT imaging as routine follow-up angiography.A 64-year-old woman with a history of previous percutaneouscoronary intervention (PCI) was admitted for follow-up coronaryangiography and OCT imaging. She had undergone PCI at the leftanterior descending artery (LAD) 1 year ago and had no anginalsymptoms after PCI. Cardiac examination was unremarkable, with aheart rate of 72 bpm and blood pressure (BP) 130/80 mm Hg.Diagnostic coronary angiogram, which was performed via the righttransradial approach using 6 Fr equipment, revealed no in-stentrestenosis of previously implanted stents with moderate distal leftanterior descending(LAD)artery stenosis (Fig. 1). TD-OCT imaging wasperformedusingaroutineprocedure,suchasproximalballoonocclusionatproximalLADand flushingwithRinger'slactateat1 ml/s.DuringOCT,abrupt BP depression and loss of consciousness developed. Followingimmediate removal of the OCT device and occluding balloon, coronaryangiography showed a huge coronary perforation with extravasation atthe distal LAD-D2 bifurcated lesion. We reinserted a guidewire and aconventionalballoonwasinflated just proximal to thelesion in order tosealtheperforation.Resuscitationwithinotropesandpericardiocentesiswere performed.The contrast leakcontinued inspiteofalongperiodofballoon inflation; therefore, a 3.0×15 mm Coronary Stent Graft™ wasinserted,butfailedtosealtheperforationduetoasmallcoronaryarteryand bulky graft stent (Fig. 2). The patient was transferred to theoperating room for surgical repair. Following sternotomy, a hugeperforated artery measuring approximately 6 –7mm was observed.Leftinternalmammaryartery(LIMA)graftstoLADandasaphenousveingrafttodiagonalwereplaced.Followingsuturingofthepericardiumandsternum, the patient returned to the CCU. She expired due to suddencardiac arrest at 7 days after surgery.OCT is high resolution, and, combined with the blood-free environ-ment, provides a substantial advantage for the study of coronary stent,when compared with previous intravascular ultrasound (IVUS) [2].Thistool enables detailed evaluation of tissue coverage and stent malapposi-tion in follow-up analysis. This specific parameter has been used as a