Duration of development of symptomatic in-stent restenosis correlates with the stent-to-vessel-diameter ratio: an intravascular ultrasound study.

OBJECTIVE: Several predictors for in-stent restenosis (ISR) have been defined by intravascular ultrasound (IVUS) assessment; however, there is a lack of data correlating IVUS parameters with the speed of development of ISR. This study aims to investigate the relation between the duration of development of symptomatic ISR and the relative stent diameter. METHODS: A total of 46 lesions in 43 consecutive patients with symptomatic ISR were investigated by IVUS with the Endosonics system (Volcano Therapeutics Inc., Rancho Cardova, California, USA). Duration of development of symptomatic ISR was determined by the period of angiographic evidence for ISR. Early ISR was defined in case of occurrence before 6 months. Reference vessel diameter was assessed as mean diameter limited by the external elastic membrane. Relative stent diameter was defined by the stent-to-vessel-diameter ratio (SVDR). RESULTS: Mean duration of symptomatic ISR was 10.3+/-11.5 months for all 46 lesions. Early ISR was observed in 25 lesions (54%). Multivariate analysis revealed SVDR as the only independent predictor for early ISR (P=0.0242). Significant correlation was observed between the duration of development of symptomatic ISR and SVDR (r=0.634, P<0.001). On the basis of the receiver operating curve analysis, relative stent diameter was defined as small when SVDR< or =0.90. Symptomatic ISR within stents of small relative diameter occurred significantly earlier (5.3+/-3.0 versus 16.7+/-15.0 months, P<0.001) and more frequently before 6 months (73 versus 30%, P=0.003) than in stents with SVDR>0.90. CONCLUSIONS: This IVUS study revealed significant correlation between the duration of development of symptomatic ISR and SVDR, which was an independent predictor for early ISR. IVUS-guided stenting may avoid early ISR by adapting the stent diameter to the vessel diameter.