Abstract 2826: Deep Ultrasound Attenuation and Plaque Rupture Detected by Intravascular Ultrasound Impacts Quantitative Coronary Flow during Percutaneous Coronary Intervention in Acute Myocardial Infarction
Background: Despite its theoretical advantage, several randomized trials failed to show positive effect of routine distal protection on clinical outcomes during percutaneous coronary intervention (PCI) in patients (pts) with acute myocardial infarction (AMI). Thus, reliable and feasible intravascular imaging techniques are needed to identify pts subgroups that would maximally benefit from embolic protection during the acute phase of AMI. The aim of this intravascular ultrasound (IVUS) study was to elucidate whether deep ultrasound attenuation (UA) and plaque rupture affects coronary flow after PCI in pts with AMI.
Methods and Results: 214 consecutive pts with AMI who underwent IVUS interrogation before PCI were included. UA was defined as IVUS images with backward signal attenuation ≥180° behind plaque without dense calcium. Plaque rupture was determined by the presence of fissure/dissection on the lumen surface, which was confirmed by the injection of saline or contrast medium. The corrected Thrombolysis In Myocardial Infarction frame count (CTFC) was used to evaluate coronary flow after PCI. Inadequate reflow was defined as CTFC ≥40 without mechanical obstruction after PCI. Inadequate reflow after PCI occurred in 33 (15%) pts. Multivariate analysis disclosed that UA was the most powerful predictor of inadequate reflow (OR 10.0, p<0.001). Among pts with UA (n=76), pts with inadequate reflow (n=26) had longer UA (6.7 vs 3.9mm, p<0.001) and higher proportion of plaque rupture (81 vs 58%, p<0.05) than those with good reflow (n=50). According to the optimal cutoff of the length of UA from the analysis of receiver operating characteristic curve and the presence of plaque rupture, pts with UA were divided into 3 groups. Pts with longer UA (≥5mm) with plaque rupture (n=23) had higher rate of inadequate reflow compared with those who had either longer UA (≥5mm) or plaque rupture (n=38) and those with shorter UA (<5mm) without plaque rupture (n=15) (65 vs 24 vs 13%, p<0.001).
Conclusions: The presence of both longer deep ultrasound attenuation and plaque rupture is related to higher incidence of inadequate reflow following PCI, indicating that this subset of pts is at high risk for atheroembolism. Distal protection may be clinically beneficial in this subset of pts.