Abstract 899: Distribution of Thin-Cap Fibroatheroma and Necrotic Core after Stenting in Patients With Acute Coronary Syndrome: A Virtual Histology Intravascular Ultrasound Study
Thin-cap fibroatheromas (TCFAs) are prone to plaque rupture & thrombosis. Histopathologically, stent penetration into and/or abutment against necrotic core (NC) are thought to impair reendothelialization and lead to stent thrombosis.
Methods: We used virtual histology intravascular ultrasound (VH-IVUS) in 115 randomly selected pts with acute coronary syndrome (ACS) to analyze how frequently stent struts
abut the NC,
end within an adjacent NC, or
do not fully cover an adjacent TCFA.
Results: Implanted stents were 3.0±0.7mm in diameter, 25.5±15.6mm in length, and 6.1±1.6mm2 in minimum area. VH-IVUS demonstrated intrastent struts (grey arrows, left panel) in contact with a NC (single arrow, left panel) in 54/115 ACS culprit lesions (47%); 28/54 (52%) involved multiple NCs, and protrusion of NC through the struts was observed in 5/54 lesions (9%). In 24/115 pts, there were “missed” TCFAs within the adjacent reference segment (double arrow, right panel) - 63% proximal, 25% distal, and 13% both proximal and distal; in 9/24 of these pts stent edges ended in the middle of a NC. 17/40 pts with intrastent strut-NC contact also had an uncovered or penetrated adjacent reference segment TCFA vs 7/51 without intrastent strut-NC contact (P=0.02).
Conclusion: Intrastent strut-NC contact was seen in approximately 50% of pts with ACS. Stent edges did not fully cover or ended within an adjacent reference segment TCFA in 20%. 15% of pts had both intrastent strut-NC contact and an adjacent NC or TCFA not covered by the stent edge. Post-stent implantation VH-IVUS can identify high-risk lesions that may benefit from either additional stent implantation or prolonged dual antiplatelet therapy.