Supervisors info:
Δωροθέα Τσεκούρα, Καρδιολόγος, ΕΔΙΠ
Θεόδωρος Ξάνθος, Καθηγητής, Ιατρική, Ευρωπαικό Πανεπιστήμιο Κύπρου
Ευαγγελία Κουσκούνη, Καθηγήτρια, Ιατρική, ΕΚΠΑ
Summary:
Significant left main coronary artery (LMCA) disease has been considered a determinant of increased cardiac mortality, approaching 50% at a 3 years follow up. Because of its clinical significance, the accurate assessment of the severity of the LMCA lesion and the appropriate treatment is of paramount importance. Coronary artery bypass grafting (CABG) has been traditionally the first choice of treatment. However recent evidence suggests comparable clinical outcomes between percutaneous coronary intervention (PCI) and CABG. On the other hand, a mistaken assessment of a stenosis as an important one leads to a wrong therapeutic approach with subsequent adverse consequences for the patient (unnecessary medication, premature distraction of the grafts).
Coronary angiography remains the gold standard diagnostic modality in the diagnosis of clinically significant LMCA lesions. There are however several important limitation which leads to a small but significant amount of false positive and false negative results. The novel intercoronary imaging modality of optical coherence tomography (OCT) provides unique details of intravascular structures, but to a limited depth within vascular wall (0,5-2mm). OCT allows a precise identification of vulnerable plaque, the identification of thrombus and according to the 2014 European Guidelines of Myocardial Revascularization, OCT should be considered to assess mechanisms of stent failure (Class IIA, Level B) and may be considered, in selected patients, to optimize stent implantation (Class IIB, Level C). The use of OCT method in the assessment of LMCA disease has begun to gain ground and recent studies support its ability to evaluate non ostial lesions of LMCA. However, the visualization of ostial lesions is considered not feasible. Additionally, an acceptable value of minimum lumen area or diameter of the vessel corresponding to a functionally significant stenosis of the LMCA has still not been found. Technically, OCT images of LMCA is acquired by continuous pull-backs from either the left anterior descending artery (LAD) or the left circumflex artery (LCX). Theoretically, both methods should be equivalent but to our knowledge this has never been investigated.
Our single centre study included 51 patients with LMCA disease (20-70% by angiographic,visual estimation). In all patients double pull-backs from both daughter vessels (LAD, LCX) were performed. The following parameters were measured: LMCA length, LMCA lesion length, Reference Lumen Area (RLA), Reference Lumen Diameter (RLD), Minimum Lumen Diameter (MLD), Minimum Lumen Area (MLA). The aim of our study was to investigate whether satisfactory reproducibility of LMCA measurement by OCT can be achived between two different pull-backs from LAD and LCX. The ICC showed excellent variability (ICC>0.8), between pull-back from the LAD and pull-back from the LCX , of RLA, RLD, LMCA length and lesion length measurements. And even though only intermediate ICCs (ICC=0.5-0.8) were found for the measurements of MLA and MLD overall differences for the mean values of the parameters were statistically not significant (p>0.005), without potential impact on clinical decision making. There were direct correlations and good agreement in OCT measurements with pullbacks from LAD and LCX : MLA ( r=0,691, p<0.01 ), MLD ( r=0,511, p<0,01 ) , RLA ( r=0,946, p<0,01 ), RLD (r=0,932, p<0,01 ), LMCA length (r=0,817, p<0.01 ) and lesion length (r0,933=, p<0,01). As a conclusion, there was excellent reliability between OCT based LMCA assessment using pull-backs from either daughter vessel. The limitation of this study is its relatively small sample size which precludes definitive conclusions. We recognise that this is a pilot exploratory study and further investigation is needed.
