Relation of stent overexpansion to the angiographic no-reflow phenomenon in intravascular ultrasound-guided stent implantation for acute myocardial infarction.

The angiographic no-reflow phenomenon is observed in some patients during stent implantation for acute myocardial infarction (AMI). We attempted to clarify the influence of stent overexpansion and plaque morphology on the angiographic no-reflow phenomenon in AMI patients who underwent intravascular ultrasound (IVUS)-guided stent implantation. We assessed the thrombolysis in myocardial infarction (TIMI) flow grade in the coronary angiographic findings, and quantitative and qualitative IVUS findings, in a total of 90 patients who underwent IVUS-guided stenting for AMI. The patients were divided into two groups according to the stent-to-artery ratio: overexpansion group (ratio > or =1.2) and non-overexpansion group (ratio <1.2). Angiographic no-reflow (defined as TIMI flow grade <3) in stent implantation was observed in 15 patients (17%). Angiographic no-reflow was more frequently observed in the overexpansion group than in the non-overexpansion group (32% vs 11%, P = 0.0312). Patients with no-reflow had more lipid pool-like images or fissure/dissection than those without. In the overexpansion group, a lipid pool-like image and fissure/dissection were more frequently observed in patients with no-reflow. The rate of target lesion revascularization (TLR) in the overexpansion group was significantly lower than that in the non-overexpansion group during the follow-up period (10% vs 18%, P = 0.0476), but the incidence of pump failure in the overexpansion group was higher than that in the non-overexpansion group during the hospital course (28% vs 14%, P = 0.0358). Stent overexpansion in AMI patients is related to a higher incidence of angiographic no-reflow, especially if the lesion has a lipid pool-like image or fissure/dissection, although there is a tendency for lower TLR.