Impact of culprit plaque composition on the no-reflow phenomenon in patients with acute coronary syndrome - An intravascular ultrasound radiofrequency analysis

Background: The difference in the culprit plaque composition of acute coronary syndrome (ACS) patients with and without the no-reflow phenomenon has not been fully evaluated. Methods and Results: Intravascular ultrasound radiofrequency data of culprit plaques were obtained and analyzed in 49 ACS patients. The no-reflow phenomenon was defined as a decrease of at least 1 grade in 'Thrombolysis In Myocardial Infarction' flow immediately after mechanical dilatation compared with before mechanical dilatation, with no evidence of thrombus, spasm, or dissection. The no-reflow phenomenon was observed in 9 individuals. Culprit plaques with the no-reflow phenomenon contained a higher percentage of necrotic core component and a smaller percentage of fibrous component than plaques in the patients without the no-reflow phenomenon (necrotic core component, 22.1±9.3% vs 11.7±7.9%, p=0.0011; fibrous component, 59.6±11.2% vs 68.3±10.2%, p=0.027). Multivariate analysis identified the percentage of necrotic core component as an independent predictor of the no-reflow phenomenon after adjustment for plaque geometry and procedural factors (odds ratio, 1.7; 95%confidence interval, 1.1 to 2.5; p=0.015). Conclusion Culprit plaques of patients with the no-reflow phenomenon differ from those in patients without the no-reflow phenomenon.