Prospective Application of Pre-Defined Intravascular Ultrasound Criteria for Assessment of Intermediate Left Main Coronary Artery Lesions : Results From the Multicenter LITRO Study

ObjectivesThis study is a prospective validation of 6 mm2 as a minimum lumen area (MLA) cutoff value for revascularization of left main coronary artery (LMCA) lesions.BackgroundLesions involving the LMCA are prognostically relevant. Angiography has important limitations in the evaluation of LMCA lesions with intermediate severity. An MLA of 6 mm2 assessed by intravascular ultrasound has been proposed as a cutoff value to determine lesion severity, but there are no large studies evaluating the prospective application and safety of this approach.MethodsWe have designed a multicenter, prospective study. Consecutive patients with intermediate lesions in unprotected LMCA were evaluated with intravascular ultrasound. An MLA <6 mm2 was used as criterion for revascularization.ResultsA total of 354 patients were included in 22 centers. LMCA revascularization was performed in 90.5% (152 of 168) of patients with an MLA <6 mm2 and was deferred in 96% (179 of 186) of patients with an MLA of 6 mm2 or more. A large scatter was observed between both groups regarding angiographic parameters. In a 2-year follow-up period, cardiac death-free survival was 97.7% in the deferred group versus 94.5% in the revascularized group (p = 0.5), and event-free survival was 87.3% versus 80.6%, respectively (p = 0.3). In the 2-year period, only 8 (4.4%) patients in the deferred group required subsequent LMCA revascularization, none with an infarction.ConclusionsAngiographic measurements are not reliable in the assessment of intermediate LMCA lesions. An MLA of 6 mm2 or more is a safe value for deferring revascularization of the LMCA, given the application of the clinical and angiographic inclusion criteria used in this study.