Abstract 2467: Is Left Main Angiographic Lesion Location Predictive of a Significant Stenosis by Intravascular Ultrasound and the Need for Revascularization? Observations from The Left Main IVUS Registry
Introduction: The Left Main IVUS Registry is a multicenter study to determine the value of diagnostic intravascular ultrasound (IVUS) for the evaluation of an inconclusive left main angiogram.
Hypothesis: We tested the hypothesis that primary location of an inconclusive angiographic lesion by core lab analysis may be predictive of a significant stenosis by IVUS assessment and the need for revascularization.
Methods: Symptomatic patients underwent clinically indicated IVUS of the left main at the discretion of the treating physician. IVUS criteria for a significant left main stenosis requiring CABG were: >60% relative cross-sectional area (CSA) lumen stenosis or an absolute lumen CSA of ≤5.0 mm2 when no distal reference vessel could be identified. Angiographic (QCA) and IVUS images were analyzed by an independent core laboratory.
Results: A total of 252 subjects were enrolled at 17 centers after an inconclusive left main angiogram. A discrete angiographic lesion location was identified in 169 patients (67%). Primary lesion location was proximal (including ostial) in 75 patients, mid in 25, and distal in 69. Angiographic lesion minimum lumen diameter was 2.39±0.66 mm in the proximal lesion group, 2.70±0.69 mm in the mid-lesion group, and 2.47±0.60 mm in the distal lesion group (p=.15). Mean lesion lumen diameter by IVUS was 3.15±0.67 mm in the proximal lesion group, 2.76±0.59 mm in the mid-lesion group, and 2.64±0.48 mm in the distal lesion group (p<.001). Mean lesion lumen area by IVUS was 7.80±3,21 mm2 in the proximal lesion group, 6.01±2.63 mm2 in the mid-lesion group, and 5.44±2.07 mm2 in the distal lesion group (p<.001). The number of calcified quadrants identified by IVUS was 0.63±0.85 in the proximal lesion group, 0.64±0.90 in the mid-lesion group, and 1.46±1.39 in the distal lesion group (p<.001). When an inconclusive lesion was identified by angiography in the proximal portion of the left main, 14.7% of patients met IVUS criteria for CABG, in the mid vessel 40.0%, and in the distal vessel 56.5% (p<.001).
Conclusions: In patients with an inconclusive left main angiogram, distal lesion location by angiography is associated with a significantly smaller lumen diameter and area by IVUS, higher calcium content, and greater need for revascularization.