Plaque shift and distal embolism in patients with acute myocardial infarction

BACKGROUNDS: Vessel expansion and axial plaque redistribution or distal plaque embolization contribute to the increase in lumen dimensions after stent implantation. METHODS AND RESULTS: Preintervention and postintervention grayscale volumetric intravascular ultrasound was used to study 43 de novo native coronary lesions treated with TAXUS or Express bare metal stents in the HORIZONS-AMI Trial. There was a decrease in lesion segment plaque + media (P + M) volume (-19.5 ± 22.2 mm(3) ) that was associated with a decrease in overall analysis segment (lesion plus 5 mm long proximal and distal reference segments) P + M volume (-17.5 ± 21.0 mm(3) ) that was greater than the shift of plaque from the lesion to the proximal and distal reference segments (1.9 ± 4.5 mm(3) , P < 0.0001). Overall analysis segment P + M volume decreased more in the angiographic thrombus (+) versus the thrombus (-) group (27.4 ± 23.4 vs. -8.9 ± 14.3 mm(3) , P = 0.003), whereas plaque shift to the reference segments showed no significant difference between the two groups (1.5 ± 5.2 vs. 2.3 ± 3.9 mm(3) , P = 0.590). Compared with the angiographic thrombus (-) group, patients in the thrombus (+) group more often developed no reflow (25% vs. 0%, P = 0.012) and had a higher preintervention CK-MB (P = 0.011), postintervention CK-MB (P < 0.001), and periprocedural (post-PCI minus pre-PCI) elevation of CK-MB (P = 0.001). CONCLUSIONS: In acute myocardial infarction lesions, there was a marked poststenting reduction in overall plaque volume that was significantly greater in patients with angiographic thrombus than without thrombus and may have explained a greater periprocedural rise in CK-MB.