Background: The impact of cardiovascular risk factors on subclinical but measurable left main coronary artery (LMCA) atherosclerosis is not well known.
Methods: We analyzed 150 consecutive patients with first-time coronary artery disease presentation undergoing intervention of a left anterior descending coronary artery or left circumflex lesion with motorized intravascular ultrasound transducer pullback that included a nonstenotic LMCA. Framingham, PROCAM, and European SCORE risk assessments were determined in 107 patients <65 years of age (because the Framingham, PROCAM, and European SCORE studies excluded patients >65 years old). Intravascular ultrasound measurements were compared in patients with <10% vs 10% to 20% risk of events.
Results: Plaque volumes were greater in patients with higher risk scores: P = .007 in patients with 10% to 20% PROCAM risk, P = .063 in patients with 10% to 20% Framingham risk, and P = .059 in patients with 10% to 20% SCORE risk (P = .059). The mean arc of LMCA calcium (12 degrees +/- 25 degrees overall) correlated with plaque volume (51 +/- 28 mm3, r = 0.30, P = .0001) and with the number of coronary risk factors (P = .048) and ranged from 0.28 degrees +/- 0.74 degrees in patients with 0 to 1 risk factors to 9.95 degrees +/- 21.55 degrees in patients with 2 to 4 risk factors to 19.38 degrees +/- 32.51 degrees in patients with 5 to 7 risk factors. Regression analysis showed obesity and age were the most important factors contributing to LMCA calcium.
Conclusion: Intravascular ultrasound measurable atherosclerosis in nonstenotic LMCA correlates with conventional primary coronary risk scores. Left main coronary artery calcium correlates both with LMCA plaque volume and risk factors. Thus, subclinical LMCA atherosclerosis may be a marker for events that are predicted by commonly used primary risk-assessment algorithms.