Relation of Atherothrombosis Burden and Volume Detected by Intravascular Ultrasound to Angiographic No-Reflow Phenomenon During Stent Implantation in Patients With Acute Myocardial Infarction

This study investigated the mechanism of occurrence of the no-reflow phenomenon during stent implantation in patients with acute myocardial infarction (AMI) using intravascular ultrasound (IVUS) with volumetric analysis. Of 70 patients with AMI who underwent IVUS-guided stent implantation within 24 hours of symptom onset, 12 developed decreased Thrombolysis In Myocardial Infarction flow grade during stent implantation and without subsequent restoration to Thrombolysis In Myocardial Infarction flow grade before stenting. External elastic membrane cross-sectional area and maximum diameter at the culprit lesion as measured by IVUS before stent implantation were significantly larger in the no-reflow group (n = 12) than in the normal reflow group (n = 58; 20.1 ± 6.5 vs 16.4 ± 4.3 mm 2, p = 0.015 for cross-sectional area and 5.2 ± 0.9 vs 4.8 ± 0.6 mm, p = 0.049 for maximum diameter). Plaque volume, volumetric plaque burden (plaque volume/external elastic membrane volume), and change in plaque volume during stent implantation (plaque volume after vs before) were significantly greater in the no-reflow group than in the normal reflow group (239 ± 142 vs 178 ± 72 mm 3, p = 0.030; 0.76 ± 0.07 vs 0.71 ± 0.06, p = 0.010; and −46 ± 63 vs −11 ± 37 mm 3, p = 0.013, respectively). In conclusion, high atherothrombotic burden and decreased plaque volume as detected by IVUS may be risk factors for development of the no-reflow phenomenon during stent implantation in patients with AMI.