Attenuated Plaque Detected by Intravascular Ultrasound : Clinical, Angiographic, and Morphologic Features and Post-Percutaneous Coronary Intervention Complications in Patients With Acute Coronary Syndromes

ObjectivesWe evaluated the clinical significance of attenuated plaque (hypoechoic plaque with deep ultrasound attenuation).BackgroundAttenuated plaques are unusual intravascular ultrasound (IVUS) findings in patients with acute coronary syndrome (ACS).MethodsWe reviewed clinical presentations and angiographic and pre-intervention IVUS findings in 293 ACS patients undergoing percutaneous coronary intervention (PCI) without a distal protection device: 187 with non–ST-segment elevation myocardial infarction (NSTEMI) and 106 with ST-segment elevation myocardial infarction (STEMI).ResultsAttenuated plaque was observed in 75 patients (25.6%): 39.6% of STEMI versus 17.6% of NSTEMI (p < 0.001). (We also reviewed 100 randomly selected patients with stable angina and pre-intervention IVUS; none had attenuated plaque.) Overall, in ACS patients with attenuated plaques: 1) the level of C-reactive protein was higher; 2) angiographic thrombus and initial coronary flow Thrombolysis In Myocardial Infarction flow grade <2 were more common; and 3) IVUS lesion site plaque burden and remodeling index were significantly greater, lesion site luminal dimensions significantly smaller, and thrombus, positive remodeling, and plaque rupture were more common. No-reflow (26.7% vs. 4.6%, p < 0.001) and deteriorated post-PCI coronary blood flow (8.0% vs. 2.8%, p = 0.001) were higher. In ACS patients with normal coronary blood flow at baseline, deterioration in the coronary blood flow post-PCI was more common in lesions with attenuated plaque.ConclusionsAttenuated plaque was more common in ACS patients with STEMI than NSTEMI. Attenuated plaque in ACS patients was associated with a higher C-reactive protein level, more severe and complex lesion morphology, reduced coronary blood flow before PCI, and especially no-reflow after PCI.