Objective: We aimed to assess and compare the morphological characteristics of ostial and non-ostial left main coronary artery (LMCA) lesion without heavy calcification using intravascular ultrasound (IVUS) imaging.
Methods: Between Oct. 2004 and Oct. 2007, 153 patients with confirmed or suspected coronary artery narrowing in coronary angiography with satisfactory IVUS images and non-heavy calcification were included in the study (ostial lesions, n = 47; non-ostial lesion, n = 106). IVUS analysis included plaque composition, external elastic membrane (EEM), lumen, plaque cross-sectional area (CSA), plaque burden (plaque CSA/EEM CSA) at the lesion, proximal and/or distal reference site, and remodeling index (RI, lesion EEM CSA/reference EEM CSA). Negative remodeling was defined as RI < 0.95.
Results: LMCA mean reference lumen and vessel diameter was 4.1 +/- 0.8 mm and 5.3 +/- 0.8 mm respectively. Incidence of patients with minimum lumen area (MLA < 6.0 mm(2)) was similar between the two groups (29.5% for ostial lesions and 31.9% for non-ostial lesions, P = 0.87). There were significantly more fibrous (70.2% vs. 35.8%) and soft (8.5% vs. 3.8%) plaques while significantly less calcified plaque (19.2% vs. 43.4%) in patients with hostile lesions compared those with non-ostial lesions (all P < 0.05). Compared to non-ostial lesions, ostial lesion had significant smaller plaque area [(10.8 +/- 4.5) mm(2) vs. (13.3 +/- 5.4) mm(2), P = 0.007], less plaque burden (54.8% +/- 15.9% vs. 61.9% +/- 14.5%, P = 0.020), smaller RI (0.9 +/- 0.2 vs. 1.0 +/- 0.2, P = 0.000) and higher incidence of negative remodeling (74.5% vs. 34.9%, P = 0.000). Multivariant Logistic regression analysis showed that the site of lesion (ostial or non-ostial lesion, OR = 4.9, P = 0.004), plaque area (OR = 1.2, P = 0.01) and plaque burden (OR = 0.003, P = 0.000) were the independent predictors of LMCA remodeling.
Conclusion: Negative remodeling might be responsible for the development of LMCA ostial narrowing.