Contribution of stent underexpansion to recurrence after sirolimus-eluting stent implantation for in-stent restenosis

Background - We used intravascular ultrasound (IVUS) to evaluate recurrence after sirolimus-eluting stent (SES) implantation treatment of in-stent restenosis (ISR). Methods and Results - Forty-eight ISR lesions ( 41 patients with objective evidence of ischemia) were treated with SES. Recurrent ISR was identified in 11 lesions ( all focal); repeat revascularization was performed in 10. These were compared with 16 patients ( 19 lesions) without recurrence as documented by angiography. Nine of 11 recurrent lesions had a minimum stent area (MSA) < 5.0 mm(2) versus 5 of 19 nonrecurrent lesions ( P = 0.003); 7 of 11 recurrent lesions had an MSA < 4.0 mm(2) versus 4 of 19 nonrecurrent lesions (P = 0.02); and 4 of 11 recurrent lesions had an MSA < 3.0 mm(2) versus 1 of 19 nonrecurrent lesions ( P = 0.03). A gap between SESs was identified in 3 of 11 recurrences versus 1 of 19 nonrecurrent lesions. Conclusions - Stent underexpansion is a significant cause of failure after SES implantation treatment of ISR.