Analysis of the long-term effects of drug-eluting stents on coronary arterial wall morphology as assessed by virtual histology intravascular ultrasound
Background: Animal models show impairment of arterial healing after drug-eluting stents (DES) compared with bare-metal stents (BMS). Virtual histology intravascular ultrasound (VH-IVUS) offers an opportunity to assess lesion morphology in vivo. Methods: We used VH-IVUS in 80 patients to assess long-term (median = 10 months) native artery vascular responses after 76 implantations of DES compared with 32 BMS. The presence of "necrotic core abutting the lumen" was evaluated at baseline and follow-up. Results: At baseline, necrotic core abutting the lumen through the stent struts was observed in 76% of DES and 75% of BMS. Although the percentage of necrotic core within the plaque behind the stents did not change during follow-up in DES (23% [18%, 28%] to 22% [17%, 27%], P = .57) or BMS (22% [19%, 27%] to 20% [12%, 26%], P = .29), necrotic core abutting the lumen through the stent struts decreased more in BMS (75% to 19%, P < .001) than DES (76% to 61%, P = .036) because of the lack of an overlying, protective neointima in DES-treated lesions. Furthermore, within the adjacent reference segments, the incidence of necrotic core abutting the lumen decreased in BMS-treated lesions (proximal 23% to 0%, P = .023; distal 21% to 0%, P = .023), but not in DES (proximal 22% to 17%, P = .48; distal 23% to 21%, P = .82). Conclusions: Serial VH-IVUS analysis of DES-treated lesions showed a greater frequency of unstable lesion morphometry at follow-up compared with BMS. The apparent mechanism was a suppression of the protective neointimal hyperplasia layer coupled with a lack of vulnerable plaque resolution at reference segments in DES compared with BMS.