Study Uses OCT and IVUS to Examine the In Vivo Mechanisms of Late DES Thrombosis

January 18, 2012—Giulio Guagliumi, MD, et al investigated the role of uncovered stent struts in late stent thrombosis after drug-eluting stent (DES) implantation with optical coherence tomography (OCT) and intravascular ultrasound (IVUS) and published their findings in the Journal of the American College of Cardiology: Cardiovascular Interventions (2012;5:12–20).

The investigators for this in vivo case-controlled study concluded that the presence of uncovered stent struts as assessed by OCT and positive vessel remodeling imaged by IVUS were associated with late stent thrombosis after DES. 

The background of this analysis is that autopsy studies have identified delayed healing and lack of endothelialization of DES struts as the hallmarks of late stent thrombosis but that DES strut coverage has not been examined in vivo in patients with late stent thrombosis.

As detailed by the investigators, they studied 54 patients, including 18 with DES late stent thrombosis (median, 615 days after implantation), undergoing emergent percutaneous coronary interventions and 36 matched DES control subjects undergoing routine repeat OCT and IVUS who did not experience late stent thrombosis for 3 years. Thrombus aspiration was performed during emergent percutaneous coronary intervention before OCT and IVUS assessment.

The investigators found that by OCT, patients with late stent thrombosis—compared with control subjects—had a higher percentage of uncovered (median [interquartile range], 12.27 [5.5–23.33] vs 4.14 [3–6.22]; P < .001) and malapposed (4.6 [1.85–7.19] vs 1.81 [0–2.99]; P < .001) struts. The mean neointimal thickness was similar in the two groups (0.23 ± 0.17 mm vs 0.17 ± 0.09 mm; P = .28). By IVUS, stent expansion was comparable in the two groups, although positive remodeling was increased in patients with late stent thrombosis (mean vessel cross-section area, 19.4 ± 5.8 mm² vs 15.1 ± 4.6 mm²; P = .003).

Thrombus aspiration demonstrated neutrophils and eosinophils in most cases. By multivariable analysis, the length of segment with uncovered stent struts by OCT and the remodeling index by IVUS were independent predictors of late stent thrombosis, reported the investigators in the Journal of the American College of Cardiology: Cardiovascular Interventions.