Membranous diaphragm formation after simultaneous kissing stenting with sirolimus-eluting stents for the left main bifurcation: insight from optical coherence tomography findings.

Two patients who underwent simultaneous kissing stenting with sirolimus-eluting stents in the left main coronary artery were investigated with optical coherence tomography (OCT) at just more than 1 year postoperatively. In both cases, follow-up angiogram indicated complete coverage of the new metal carina with a membranous diaphragm, yet OCT showed varying tissue-coverage patterns transitioning from stent inflow to stent outflow. These patterns included single-strut coverage, bridge-like membrane formation between more than 1 strut, and end-to-end coverage of the carina; no uncovered stent struts were detected. OCT also demonstrated mixed patterns of tissue characteristics on the metal carina, ranging from poor endothelialization to modest neointima formation. These varying tissue characteristics suggest that the process of tissue coverage in the metal carina is different from that occurring on the vessel wall; this may indicate delayed healing in the carina.