Background: An obesity paradox exists in which the overweight and obese patients seem to have a more favorable prognosis than in leaner patients with cardiovascular
diseases. We evaluated the relationship between Body mass index (BMI) and Left Main Coronary Artery (LMCA) by Virtual Histology Intravascular Ultrasound (VH-IVUS).
Methods: We analyzed data from 195 patients with coronary artery disease who were enrolled in the Heart Center. We measured the vascular structure of LMCA with VH-IVUS undergoing intervention.
Results: Mean age of healthy weight group (BMI < 23.0 mg/m2), overweight group (BMI, 23.0-24.9 mg/m2) and obese group (BMI ≥ 25.0 mg/m2) were 64.88 ± 10.73, 59.63 ± 14.22, 59.07 ± 10.66 years old, respectively. The mean age of healthy weight group was significantly older (P= 0.009). Mean values of lesion length, minimal lumen diameter, % diameter stenosis were not significant (P >
0.05). Mean values of EEM (External Elastic Membrane) area of obese group was statistically larger than that of the healthy weight group (26.26 ± 4.82 mm2, 24.16 ± 4.77mm2, respectively)(P = 0.030). However, lumen area, plaque area, plaque burden, etc. were similar (P > 0.05). EEM area
had a positive correlation with BMI (R = 0.149; P = 0.038). According to the multiple linear models, weight was the best predictor of LMCA EEM area (β = 0.067; P = 0.047).
Conclusion: LMCA of obese group was larger than that of healthy weight group. The clinical impact of larger LMCA deserve further study.

Keywords: Obesity paradox, Body mass index (BMI), Left main coronary artery, Virtual Histology Intravascular ultrasound (VH-IVUS), Coronary artery diseases

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