The 2011 multicentre, prospective LITRO study by de la Torre Hernandez et al aimed to apply pre-defined IVUS criteria to the assessment of LM stenosis. At the time of this study, an MLA of 6 mm2 as assessed by IVUS was generally considered to be a useful cutoff value to determine lesion severity, but this has not been validated in a prospective clinical trial. Patients with intermediate lesions in unprotected LM were evaluated with IVUS, using 6-mm2 MLA as a cutoff value to determine whether LM lesions should be revascularized or if the procedure could be deferred.
Results showed that of the 354 patients evaluated, 186 had an IVUS-derived MLA of 6 mm2 or more. Of these, 179 (96.2%) did not receive any revascularization procedures (deferred group). Eight patients required revascularization, 7 because of stable angina and 1 after unstable angina. Of the 168 patients with an MLA of <6 mm2, 152 (90.5%) underwent LM revascularization (revascularized group). No significant differences in clinical characteristics were reported between the two groups, however there was a wide scatter within the group in terms of angiographic parameters: namely stenosis and minimal lumen diameter (MLD). At 2-year follow-up, in the deferred group, survival free of cardiac death was 97.7% compared with 94.5% in the revascularized group. Survival free from cardiac death, MI, and any revascularization was 87.3% versus 80.6%, in deferred and revascularization groups, respectively (p =0.3). Among the patients with an MLA of <6 mm2, 16 patients did not undergo any revascularization procedures. Reasons included lesion complexity (heavily calcified or bifurcations), problems taking dual antiplatelet therapy, patient preference and high surgical risk (because of age or comorbidities.
The main limitation of the study was that it was not randomized, and population differences between the two groups may have confounded the findings. In addition, the follow-up was only two years. However, the study was valuable in determining a single criterion to guide revascularization decisions. The authors concluded that, in a patient population similar to that used in this study, an MLA of 6 mm2 or more is a safe and useful criterion for deferring revascularization of the LMCA.
- de la Torre Hernandez JM, Hernandez Hernandez F, Alfonso F, et al., Prospective application of pre-defined intravascular ultrasound criteria for assessment of intermediate left main coronary artery lesions results from the multicenter LITRO study, J Am Coll Cardiol, 2011;58:351-8.