Introduction: Diagnosis and management of signifi-cant left main coronary artery disease (LMCAD) con-tinues to be a source of clinical apprehension and un-certainty. Once solely in the surgical realm, the mana-gement of LMCA has migrated progressively towards interventional cardiology with each advance in percu-taneous technique and device therapy. Current clinical practice guidelines recommend revascularization for all patients with ≥50% stenosis of the left main coro-nary artery (LM), regardless of symptomatic status or associated ischemic burden.

Methods: We present a case of acute myocardial in-farction with LMCA disease to the 48 year-old female patient without cardiovascular or familial history and without significant risk factors, with the use of intra-vascular imaging for the revascularization decision by a complex procedure of percutaneous coronary an-gioplasty. She is emergency admitted for severe chest pain, the first episode of this type in life. It is diagnosed with anterior acute myocardial infarction without ST segment elevation and it is decided to perform urgent coronary angiography.

Results: T he coronarography indicates a stenosis of approximately 40-50% of the left main coronary ar-tery in the medio-distal segment with the interest of the anterior descending artery ostium and the left cir-cumflex artery, apparently at the limit of angiographic significance. Because the native vessel diameter could not be accurately assessed, intravascular ultrasonography (IVUS) is used, which reveals the 60-70% stenosis plaque of distal LMC and >50% interest in LCX and LAD. Of note, significant vasospasm in catheter canu-lation, with partial response to nitrate administration. It is decided to perform percutaneous coronary angio-plasty with the implantation of biolimus-eluting stents in the LMCA, LAD and LCX by Cullotte technique and post-dilation in Kissing-Balloons with optimal results. The patient is monitored for several days with favorable progression, being subsequently discharged with opti-mized home treatment.

Conclusions: In particular, visual estimates of inter-mediate LM stenoses (30–70%) from coronary angi-ography have significant interobserver variability. The use of IVUS is particularly helpful in the determination of plaque extent and characteristics within the LM, as well as in determining ostial involvement of daughter branches. IVUS can provide an estimate of the ische-mic burden of the LM lesion, and its use following LM PCI improves clinical outcomes