The Usefulness of Intracoronary Imaging in Patients with ST-Segment Elevation Myocardial Infarction

Abstract

Intracoronary imaging (ICI) modalities, namely intravascular ultrasound (IVUS) and optical coherence tomography (OCT), have shown to be able to reduce major adverse cardiovascular events in patients undergoing percutaneous coronary intervention (PCI). Nevertheless, patients with ST-segment elevation myocardial infarction (STEMI) have been practically excluded from contemporary large randomized controlled trials. The available data are limited and derive mostly from observational studies. Nevertheless, contemporary studies are in favor of ICI utilization in patients who undergo primary PCI. Regarding technical aspects of PCI, ICI has been associated with the implantation of larger stent diameters, higher balloon inflations and lower residual in-stent stenosis post-PCI. OCT, although used significantly less often than IVUS, is a useful tool in the context of myocardial infarction without obstructive coronary artery disease since, due to its high spatial resolution, it can identify the underlying mechanism of STEMI, and, thus, guide therapy. Stent thrombosis (ST) is a rare, albeit a potential lethal, complication that is expressed clinically as STEMI in the vast majority of cases. Use of ICI is encouraged with current guidelines in order to discriminate the mechanism of ST among stent malapposition, underexpansion, uncovered stent struts, edge dissections, ruptured neoatherosclerotic lesions and coronary evaginations. Finally, ICI has been proposed as a tool to facilitate stent deferring during primary PCI based on culprit lesion characteristics.

Keywords: ACS; IVUS; OCT; STEMI; intracoronary imaging.

Figure 1

A sixty-year-old patient was referred for primary PCI due to inferior STEMI. He had a stent implanted in the right coronary artery (RCA) 11 years earlier. The initial coronary angiography showed no significant stenosis in the coronary arteries. A careful review of the angiogram revealed an area of “haziness” in the mid-RCA (arrow, A). OCT illustrated the presence of a non-obstructive red thrombus in the corresponding RCA segment (arrow, B) within the previously implanted stent, which appeared to be underexpanded and malapposed (arrow, C). Dilation with a non-compliant 3.5 mm balloon and a drug-coated 3.5 mm Agent balloon followed (D). Repeat OCT showed a significantly better stent expansion and apposition (E) with an excellent final angiographic result (F).

Figure 2

A fifty-three-year-old patient presented with substernal chest pain and ST-segment elevation in leads V2 through V6. He had a history significant for anterior STEMI with a DES placement in the LAD 3 years prior. The patient was led to the catheterization laboratory where he was diagnosed with in-stent thrombosis (A). After predilations with a 2.5 mm non-compliant balloon, intravascular ultrasound (IVUS) was performed showing stent underexpansion and neoatherosclerosis. (B) A new DES, a 3.0 mm × 12 mm DES, was delivered inside the previously implanted stent (C) followed by postdilations with a 3.5 mm non-compliant balloon (D) with a good final result (E).