Coronary calcification as a mechanism of plaque/media shrinkage in vessels treated with bioresorbable vascular scaffold: A multimodality intracoronary imaging study

Background and aims Whether coronary calcification is correlated with plaque/media shrinkage (PS) remains unclear. The aim of this study was to assess the relationship between the calcification process and PS, combining serial optical coherence tomography (OCT) and intravascular ultrasound (IVUS) in vessels treated with bioresorbable vascular scaffolds (BVS). Methods In 15 patients (16 vessels), OCT and IVUS images were matched using anatomic landmarks at post-procedure and five years. PS was defined as relative decrease in plaque/media area >5%. The association between the calcification process and PS was investigated. Mixed effect models were used to assess correlations and changes over time. Results Seventy-two OCT and IVUS paired cross sections in- and out-scaffolded segments were matched at baseline and follow-up (432 images). In total, 35 out of the 72 cross sections showed PS, and 37 cross sections showed no PS (non-PS) at 5-year follow-up. Delta (Δ) plaque/media area showed negative correlation with Δ OCT calcium area (r = −0.29, p = 0.004), Δ OCT calcium arc (r = −0.42, p < 0.001), Δ OCT calcium length (r = −0.5, p < 0.001), and Δ IVUS calcium arc (r = −0.31, p = 0.024), respectively. On echogenicity analysis, Δ plaque/media area was positively associated with Δ hypoechogenic area (r = 0.47, p = 0.002). An increase in calcium area was negatively correlated to Δ hypoechogenicity (r = −0.29, p < 0.016). The increase in calcium area was positively correlated with Δ lumen area (r = 0.24, p = 0.044). Conclusions In segments treated with BVS, the calcification process was associated with PS, decrease in the hypoechogenic tissue and late luminal enlargement. Combining IVUS and OCT provides a unique method to assess the correlation between the calcification process and plaque/media shrinkage.