Frequency of in-stent restenosis (ISR), according to post-percutaneous coronary intervention (PCI) minimal luminal diameter (MLD) and stent expansion ratio (SER).

Lesions with smaller post-PCI MLDs and SERs had significantly higher risks of ISR. Lesions with post-PCI MLDs ≤2.4 mm and SERs ≤70% were at the highest risk of ISR, with an odds ratio of 23.3 (95% confidence interval, 2.74–198.08) compared with lesions with larger MLDs and SERs. There was a significant interaction between post-PCI MLD and SER (p = 0.038) on ISR.