Intravascular ultrasound comparison of the self-expanding Sideguard stent in the side branch versus a balloon-expandable stent in the main vessel to assess mechanisms of acute lumen gain in bifurcation lesions.

Objectives: We compared the mechanisms of lumen gain after Cappella Sideguard (CS) side branch (SB) bifurcation stent deployment versus a balloon-expandable stent in the corresponding main vessel (MV).

Background: The novel CS SB bifurcation stent is a self-expanding, thin-strut, nitinol device with anatomic flaring at the SB ostium.

Methods: In 28 bifurcation lesions, intravascular ultrasound imaging of both the SB and the MV was performed both pre- and postintervention; vessel and lumen areas were measured every 1 mm over a 5 mm segment beginning at the carina.

Results: Although minimum lumen area (MLA) within the distal 5 mm segment beginning at the carina increased from 2.8 ± 1.3 mm(2) to 3.8 ± 1.1 mm(2), P < 0.001, in the SB and from 3.4 ± 1.4 mm(2) to 6.0 ± 1.1 mm(2), P < 0.001, in the MV, stent expansion (minimum stent area/distal reference lumen area) was significantly less in the SB compared with the MV (77.8 ± 21.3% vs. 91.6 ± 18.4%, P = 0.02). Post stenting, the MLA site was located at the carina more frequently in the SB (85.7%) than in the MV (60.7%), P = 0.04. Plaque volume in the 5 mm proximal to carina in the MV tended to decrease, whereas plaque volume in the SB increased slightly with no change in overall plaque volume in the 5-mm-long segment distal to the carina in the MV, suggesting plaque shift from the proximal MV to the SB.

Conclusions: Acute CS lumen gain is less than the lumen gain of a balloon-expandable stent in the MV because of less aggressive acute expansion and/or the plaque shift from the proximal MV to the SB.