Clinical In-Stent Restenosis is related to stent length and diameter but not to diabetes in an unselected cohort

In-Stent Restenosis (ISR) is the main limitation of the long term success of PCI. The causes of ISR have not been clearly identified even though an association has been suggested with a number of factors, including diabetes. Method: During an 11 year period (1993–2003) a complete registry of all stent implantations was held in Iceland. The follow-up period was at least 1 year after PCI. Angiographic restenosis (N50% of luminal diameter) was studied in all patients who underwent a second diagnostic angiogram during the follow-up period. Results: 2811 PCI procedures with stent implantation were performed in 2495 patients. A second coronary angiogram was performed in 747 patients (30%) because of recurrent symptoms of angina. The ISR rate was 257 (34%). ISR was found in 51% of long stents (20 mm or longer) and 32% of short stents (b20 mm) (p=0.001). ISR was found in 39% of small stents (b3.5 mm), and 28% of large stents (3.5 mm or larger) (p=0.002). The ISR rate was 37% for male and 27% for female patients (p=0.03). There was no statistical difference in the frequency of ISR when patients were classified according to smoking status, hypertension or diabetes. Conclusion: In this unselected cohort, clinical ISR was related to stent length and diameter rather than to diabetes or other conventional risk factors.