Discrepancies in vessel sizing between angiography and intravascular ultrasound varies according to the vessel evaluated.

Background/objectives: Quantitative coronary analysis (QCA) of the coronary artery and stent size may be influenced by anatomical location in relation to both calibration point and the X-ray tube. The impact of this phenomenon on lesion assessment is undetermined.

Methods: In total, 427 consecutive patients who underwent PCI with intravascular ultrasound (IVUS)-guidance were enrolled. The minimum stent diameter (MSD) was measured using QCA (MSDQCA) and IVUS (MSDIVUS) analysis. We used reference objects positioned at a different height from the X-ray source to validate our approach.

Results: A statistically positive moderate correlation was observed between MSDQCA and MSDIVUS (r=0.649, p=0.001). The mean MSDQCA and MSDIVUS were 3.04±0.49 mm and 2.68±0.47 mm respectively. The difference between MSDQCA and MSDIVUS of >0.75 mm was more frequently observed in the LCx rather than in the LAD (7.4% in the LAD vs. 24.3% in the LCx, p=0.001). The discrepancy between the MSDQCA and MSDIVUS for the LCx was larger than for the LAD, and tended to be larger than for the RCA (13.3% vs. 18.5%, p=0.05 and 18.5% vs. 14.5%, p=0.17). A discrepancy >20% was more frequently observed in the small (≤2.5 mm) than in the large MSDIVUS group (52.7% vs. 25.1%, p=0.001). This discrepancy was more common in the LCx than in the LAD or RCA (48.6% vs. 30.9% vs. 31.2%, p=0.03).

Conclusions: Assessment of the MSDQCA is more likely to overestimate in the LCx than in the LAD, particularly when the MSDIVUS is <2.5 mm. Therefore, we should be less aggressive in oversizing balloons and stents based on QCA for the LCx or small vessel intervention.