PITFALLS IN USING INTRAVASCULAR IMAGING DURING PCI: SIZING THE STENT ACCORDING TO MEAN ARTERIAL LUMEN DIAMETER MAY RESULT IN STENT UNDEREXPANSION

Highlights Contemporary algorithms for optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) are easy to learn and understand, however, these algorithms are mostly declarative, and not substantiated in practice. In particular, using the mean reference lumen diameter may result in underestimation of the optimal stent size in relation to the degree of stenosis, i.e., the difference between the minimum and maximum diameters (lumen asymmetry), whereas choosing a stent based on the mean lumen diameter leads to stent underexpansion. Aim. To assess whether choosing a stent size based on the mean lumen diameter of the reference segment of the artery may result in its underexpansion. Methods. The prospective cohort study included patients with chronic coronary artery disease and complex lesion anatomy who underwent high-risk OCT-guided PCI. Based on the OCT results, the distal and proximal reference segments were determined, in which the minimum and maximum diameters were measured, followed by calculating the mean lumen diameter, which was further used for stent selection. Based on the results of repeated OCT after stent implantation, the degree of stent expansion was assessed. The expected relationship between the degree of stent expansion and the baseline lumen asymmetry was assessed by correlation analysis. Linear regression was used to determine the asymmetry threshold corresponding to clinically relevant stent expansion of 80%. Results. Overall, 24 patients were enrolled, 3 of them were excluded because of inability to perform OCT without lesion predilatation. On average, the maximum and minimum diameters of the reference lumen according to OCT were 2.87 ± 0.66 mm and 1.85 ± 0.44 mm, respectively. The ratio between minimum and maximum diameter was 0.35 ± 0.09. The mean diameter was 2.30 ± 0.51 mm, the difference between the maximum and mean diameters was 0.61 ± 0.28 mm. The criterion of stent expansion ≥ 80% was achieved in 6 cases (28.6%). The correlation analysis has shown a statistically significant inversely proportional dependence of the relative stent expansion on the baseline lumen asymmetry (the difference between the maximum and minimum diameters (r = –0.41, p = 0.032), while clinically relevant stent expansion ≥ 80% was observed with a relative difference in diameters of less than 30% Conclusion. In case of significant lumen asymmetry choosing a stent diameter based on the mean lumen diameter is associated with stent uderexpansion.