Shimizu T, et al. - Researchers evaluated the characteristics of nonculprit left main coronary artery (LMCA) disease and its association with atherosclerosis in the rest of the coronary arteries, along with patient outcomes. They observed that atherosclerosis severity in LMCA predicted overall atherosclerotic plaque burden as well as the presence of high-risk plaques in the three major epicardial coronary arteries.

Methods

• The PROSPECT study involved 697 patients with acute coronary syndromes.
• Following percutaneous coronary intervention, the patients underwent three-vessel gray-scale and radiofrequency intravascular ultrasound.

Results

• Based on LMCA plaque burden, a total of 552 patients with adequate LMCA imaging were compared.
• Researchers observed the smallest LMCA minimum lumen area (17.4, 14.2, 10.5, lowest through highest tertiles, respectively, P < 0.0001) and the greatest percent necrotic core volume (2.8, 5.6, 9.5%, lowest through highest tertiles, respectively, P < 0.0001) in the tertile with the highest plaque burden in the LMCA.
• Furthermore, findings demonstrated that the tertile with the highest plaque burden was also significantly related to the highest overall non-LMCA percent atheroma volume within the major epicardial arteries (48.3, 49.2, 50.8%, lowest through highest tertiles, respectively, P < 0.0001).
• An independent association of the LMCA plaque burden with non-LMCA percent atheroma volume was also observed after adjusting for patient background (P=0.003).
• The tertile with the highest LMCA plaque burden had the highest number of patients with at least one of three PROSPECT predictors of future nonculprit major adverse cardiac events (MACE) (P=0.03); the predictors were minimum lumen area ≤ 4mm², plaque burden ≥ 70%, and virtual histology thin-cap fibroatheroma.
• In multivariable model, they found that total atheroma volume (per 1%) enabled an independent prediction of all MACE (hazard ratio [95% confidence interval]=1.06 [1.01–1.11], P=0.02) and strong trend for non-culprit-related MACE (hazard ratio [95% confidence interval]=1.06 [1.00–1.13], P=0.06), while plaque burden at LMCA failed to do so (all MACE, P=0.90, non-culprit-related MACE, P=0.85).