Prediction of distal embolization during percutaneous coronary intervention for unstable plaques with grayscale and integrated backscatter intravascular ultrasound

Objectives We performed microscopic examination of the debris collected by a distal protection device and investigated the usefulness of grayscale and integrated backscatter intravascular ultrasound (IB‐IVUS) for the prediction of distal embolization during percutaneous coronary intervention (PCI) in cases of unstable angina. Background The prediction of distal embolization during PCI has not been studied in depth because assessment of distal embolization is difficult. Methods We prospectively studied 39 consecutive patients with unstable angina who underwent PCI with a filter distal protection device. The preprocedural plaque volume at target lesions was measured with grayscale IVUS and plaque characteristics were assessed with IB‐IVUS. We performed microscopic examination of the particles collected by the distal protection device. Results There was a significant correlation between the plaque volume and the number of the collected particles >100 μm in diameter ( r = 0.48, P = 0.0034). Filter no‐reflow (FNR) phenomenon was found in nine patients. The plaque volume was significantly greater (355 ± 133 mm 3 vs. 199 ± 90 mm 3 , P = 0.0004), and the lipid ratio was significantly higher (29.3 ± 4.3% vs. 26.1 ± 4.3 P = 0.045) in the FNR group compared with the non‐FNR group. Multivariate logistic regression analysis showed that the plaque volume was an independent predictor of FNR phenomenon. Conclusions Although tissue characterization of IB‐IVUS may provide additional information for distal embolization, plaque volume is the only significant predictor of distal embolization during PCI.