Objectives: We compared intravascular ultrasound findings of drug-eluting stent (DES)-treated lesions that developed thrombosis versus in-stent restenosis (ISR).
Background: Stent underexpansion is a predictor of both DES thrombosis and ISR. However, all underexpanded DES may not be equal.
Methods: Intravascular ultrasound findings from 20 definite DES thrombosis patients (representing all definite thromboses from 1,407 consecutive DES patients undergoing intravascular ultrasound imaging) were compared with 50 risk-factor-balanced ISR patients with no evidence of stent thrombosis and 50 risk-factor-balanced "no-event" patients with neither thrombosis nor ISR.
Results: Minimum stent area (3.9 +/- 1.0 mm(2) vs. 5.0 +/- 1.7 mm(2), p = 0.008), mean stent area (5.3 +/- 1.0 mm(2) vs. 7.2 +/- 2.0 mm(2), p = 0.001), and both focal (55.4 +/- 13.2% vs. 74.9 +/- 19.9%, p < 0.001) and diffuse stent expansion (77.4 +/- 19.3% vs. 109.5 +/- 23.1%, p < 0.001) were significantly smaller in the stent thrombosis group versus ISR and in both groups versus the "no-event" group. Minimum stent area <4.0 mm(2) (65% vs. 32%, p = 0.01) or <5.0 mm(2) (85% vs. 52%, p = 0.01) was more common in the stent thrombosis versus the ISR group and in both groups vs. "no-event" patients; and the relative length of the stent area <5 mm(2) was greatest in the stent thrombosis group (36.6 +/- 37.7%), intermediate in the ISR group (22.8 +/- 35.6%), and least in the "no-event" group (10.9 +/- 26.4%), p = 0.04. In the stent thrombosis group, the minimum stent area site occurred in the proximal stent segment in 50% versus 24% in the ISR group (p = 0.03). There were no differences in edge dissection, stent fracture, or stent-vessel-wall malapposition among the groups.
Conclusions: The DES-treated lesions that develop thrombosis or restenosis are often underexpanded, but underexpansion associated with thrombosis is more severe, diffuse, and proximal in location.