Abstract
Background: Despite a high rate of in-stent restenosis (ISR) after stenting the right coronary artery (RCA) ostium, the mechanism of ostial RCA ISR is not well understood.
Aims: We aimed to clarify the cause of ostial RCA ISR using intravascular ultrasound (IVUS).
Methods: Overall, 139 ostial RCA ISR lesions were identified with IVUS, pre-revascularisation. Primary ISR mechanisms were classified as follows: 1) neointimal hyperplasia (NIH); 2) neoatherosclerosis; 3) ostium not covered by the stent; 4) stent fracture or deformation; 5) stent underexpansion (old minimum stent area <4.0 mm2 or stent expansion <50%); or 6) a protruding calcified nodule.
Results: The median duration from prior stenting was 1.2 (first quartile 0.6, third quartile 3.1) years. The primary mechanisms of ISR were NIH in 25% (n=35) of lesions, neoatherosclerosis in 22% (n=30), uncovered ostium in 6% (n=9) (biological cause 53%, n=74), stent fracture or deformation in 25% (n=35), underexpansion in 11% (n=15), and protruding calcified nodules in 11% (n=15) (mechanical cause 47%, n=65). Including secondary mechanisms, 51% (n=71) of ostial RCA ISRs had stent fractures that were associated with greater...
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