Factors Determining Left Main Coronary Artery Luminal Area

A certain minimal luminal cross-sectional area has been traditionally used in clinical practice as a cut-off value to determine severity of left main coronary artery (LMCA) stenosis. The severity of stenosis, however, depends on the baseline luminal area (ie, area prior to stenosis), which may vary among individuals. The present study was undertaken to define normal LMCA luminal area using current technology in vivo.

LMCA luminal area was determined using multislice computed tomography coronary angiography. Eighty-six subjects with normal coronary arteries and calcium score of zero were included in this study. Left ventricular (LV) mass and LV volumes (systolic, diastolic) were also measured.

A wide distribution was found in LMCA luminal area, with median value 17.3 mm² and range 8.1-33.9 mm². A relationship was found between log(LMCA luminal area) and log(LV mass) (r=.515; P<.001) and with body surface area (r=.273; P=.01). Significant relationships were also found between LMCA luminal area and LV volumes (systolic, diastolic). In multiple regression analysis, however, the LV mass was the only independent predictor of LMCA luminal area.

LMCA luminal area varies substantially among individuals with normal coronary arteries and is related to many other factors. The data suggest that the current practice of using a minimal luminal area cut-off when assessing LMCA stenosis may be misleading, and thus available information should be individualized.