Pathology of drug-eluting versus bare-metal stents in saphenous vein bypass graft lesions.
OBJECTIVE
The purpose of this study was to assess the pathological responses of atherosclerotic saphenous vein bypass grafts (SVBGs) to drug-eluting stents (DES) versus bare-metal stents (BMS).


BACKGROUND
Repeat bypass surgery is typically associated with a high rate of morbidity and mortality. Percutaneous coronary interventions have emerged as the preferred treatment; however, only limited data are available on SVBGs pathological responses to DES and BMS.


METHODS
Formalin-fixed SVBG of >2 years duration (n = 31) were collected to histologically characterize advanced atherosclerotic lesions in native SVBG. In a separate group, SVBGs treated with DES (n = 9) and BMS (n = 9) for >30 days duration were assessed for morphological and morphometric changes.


RESULTS
Necrotic core lesions were identified in 25% of SVBG sections, and plaque rupture with luminal thrombosis was observed in 6.3% of histological sections (32% [10 of 31] vein grafts examined). Morphometry of DES demonstrated reduction in neointimal thickening versus BMS (0.13 mm [interquartile range: 0.06 to 0.16 mm] vs. 0.30 mm [interquartile range: 0.20 to 0.48 mm], p = 0.004). DES lesions also showed greater delayed healing characterized by increased peristrut fibrin deposition, higher percentage of uncovered struts, and less endothelialization compared with BMS. Stent fractures (DES 56% vs. BMS 11%, p = 0.045) and late stent thrombosis (DES 44% vs. BMS 0%, p = 0.023) were more common in DES versus BMS.


CONCLUSIONS
Advanced SVBG atherosclerotic lesions are characterized by large hemorrhagic necrotic cores. Stenting of such lesions is associated with delayed vascular healing and late thrombosis particularly following DES implantation, which may help explain the higher rates of cardiovascular events observed in SVBG stenting as compared with native coronary arteries.
CVPath Institute Inc, Gaithersburg, Maryland 20878, USA.
Saami K
SK
Yazdani
Andrew
A
Farb
Masataka
M
Nakano
Marc
M
Vorpahl
Elena
E
Ladich
Aloke V
AV
Finn
Frank D
FD
Kolodgie
Renu
R
Virmani
D000368:Aged; D000369:Aged, 80 and over; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects / Q000295:instrumentation* / Q000401:mortality; D050197:Atherosclerosis / Q000209:etiology / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D001344:Autopsy; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000401:mortality; D003328:Coronary Thrombosis / Q000209:etiology / Q000473:pathology; D054855:Drug-Eluting Stents; D005260:Female; D005404:Fixatives; D005557:Formaldehyde; D006083:Graft Occlusion, Vascular / Q000209:etiology / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D009336:Necrosis; D058426:Neointima; D058226:Plaque, Atherosclerotic; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D012501:Saphenous Vein / Q000473:pathology / Q000637:transplantation*; D015607:Stents; D013997:Time Factors; D016707:Tissue Fixation; D016896:Treatment Outcome
D005404:Fixatives; D008670:Metals; D005557:Formaldehyde