OCT Guided vs COmplete Pci in patieNts With sT Segment Elevation myocArdial infarCtion and mulTivessel Disease

In patients with ST segment elevation myocardial infarction (STEMI), percutaneous coronary intervention (PCI) of the culprit lesion significally reduces the risk of cardiovascular death. How to manage in this setting non-culprit lesion in patients with multivessel disease still remain a matter of debate. Recently, the COMPLETE trial showed that complete PCI of every coronary stenosis > 70% (or 50-69% lesions with FFR < 0.8) reduces risk of myocardial infarction (MI) and unstable angina (UA) at 3 years compared with culprit-lesion PCI [1]. Whether this findings are related to revascularization of every obstructive lesions rather than lesions with vulnerable-plaque characteristics, still remain unclear.

In high risk patients such as STEMI patients, physiopathology of coronary plaque deeply differs from stable angina, mainly due to peculiar features of plaque. STEMI lesions, when evaluated at autopsy or at intracoronary imaging, showed a pro-thrombotic pattern, with high prevalence of thin cap fibro-atheroma, plaque rupture or thrombus, and a larger amount of lipids and macrophage [2-6]. In this setting, angiography, even when combined with fractional flow reserve evaluation (which can describe more accurately the functional impact of the plaque), has intrinsic limitations because of lack of information about plaque characteristics [7,8].

Optical coherence tomography (OCT) is the latest development in intravascular coronary imaging. Similarly to intravascular ultrasound (IVUS), OCT provides cross-sectional images of the vessel. However, instead of sound, OCT employs light for tissue analysis that enables visualization of the coronary lesions with almost microscopic precision [9,10].

This tool can find high risk vulnerable plaque without angiographic or functional signs of severity, helping from misdiagnosing and under-treating these lesions, that could benefit from PCI even more than obstructive lesions without vulnerable plaque characteristics.

In an OCT substudy of the COMPLETE trial, researchers determined that half of patients had obstructive nonculprit lesions with vulnerable plaque, which could explain why complete revascularization conferred better outcomes than culprit lesion-only revascularization in the main trial. This substudy pointed out also a 20% of non-obstructive non-culprit lesions with vulnerable plaque caracteristics and up to 30% of obstructive non-culprit lesions without high risk morphology [11]. It suggest that a morphological approach to PCI in high risk patients can provide a more specific treatment compared with standard angiographic/functional approach. A correct identification of coronary plaque instability in a setting of STEMI patients could deeply impact in these patients risk of cardiovascular events, angina and re- hospitalization.