Intravascular ultrasound-derived minimal lumen area criteria for functionally significant left main coronary artery stenosis.

Objective: This study sought to evaluate the intravascular ultrasound (IVUS) minimal lumen area (MLA) for functionally significant left main coronary artery (LMCA) stenosis using fractional flow reserve (FFR) as the standard.

Background: The evaluation of significant LMCA stenosis remains challenging.

Methods: We identified 112 patients with isolated ostial and shaft intermediate LMCA stenosis (angiographic diameter stenosis of 30% to 80%) who underwent IVUS and FFR measurement.

Results: The FFR was ≤0.80 in 66 LMCA lesions (59%); these exhibited smaller reference vessels, smaller minimal lumen diameter, greater diameter of stenosis, longer lesion length, smaller MLA, larger plaque burden, and more frequent plaque rupture. The independent factors of an FFR of ≤0.80 were plaque rupture (odds ratio [OR]: 4.47; 95% Confidence Interval (CI): 1.35 to 14.8; p = 0.014); body mass index (OR: 1.19; 95% CI: 1.00 to 1.41; p = 0.05), age (OR: 0.95; 95% CI: 0.90 to 1.00; p = 0.031), and IVUS MLA (OR: 0.37; 95% CI: 0.25 to 0.56; p < 0.001). The optimal IVUS MLA cutoff value for an FFR of ≤0.80 was 4.5 mm(2) (77% sensitivity, 82% specificity, 84% positive predictive value, 75% negative predictive value, area under the curve: 0.83, 95% CI: 0.76 to 0.96; p < 0.001) overall and 4.1 to 4.5 mm(2) in various subgroups. Adjustment for the body surface area, body mass index, and left ventricular mass did not improve the diagnostic accuracy of the IVUS MLA.

Conclusions: In patients with isolated ostial and shaft intermediate LMCA stenosis, an IVUS-derived MLA of ≤4.5 mm(2) is a useful index of an FFR of ≤0.80.