Background: After treatment with intracoronary brachytherapy, enlargement of lumen (negative late loss) at follow-up has been demonstrated. The aim of the study is to analyze the sensitivity and specificity of quantitative coronary angiography (QCA) parameters to detect a positive vessel remodeling after intracoronary -radiation as compared to intravascular ultrasound (IVUS).
Methods: Twenty-seven patients (27 vessels) treated with balloon angioplasty followed by catheter-based intracoronary -radiation with a (90)Strontium/(90)Yttrium source were assessed by both QCA and three-dimensional IVUS with electrocardiogram-gated pullback. Irradiated segments were analyzed over the total treatment length and in subsegment lengths of 5 mm.
Results: Change in minimum luminal diameter (MLD) was not a predictor for the positive remodeling in either total irradiated segments or 5 mm subsegments, with a 54.3% ROC curve area [95% confidence interval (CI), 30-79%], sensitivity of 39% and specificity of 44% (p = not significant) in the total irradiated segments and a 55.9% ROC curve area (95% CI, 46-66%), sensitivity of 55% and specificity of 54% (p = not significant) in the 5 mm subsegments. Changes in mean and maximal lumen diameter were not significant parameters to detect positive vessel remodeling. When only central subsegments were analyzed, change in MLD was a significant predictor, with a 63.3% ROC curve area (95% CI, 52-75%), sensitivity of 55% and specificity of 64% (p = 0.029).
Conclusion: Lumen enlargement detected by QCA does not reliably indicate a positive vessel remodeling after intracoronary radiation. IVUS analysis may be necessary to investigate the mechanism of restenosis after balloon angioplasty followed by catheter-based radiation.