Validation and application of OCT tissue attenuation index for the detection of neointimal foam cells.

Neointimal infiltration with foamy macrophages is recognized as an early and important sign of de-novo atherosclerosis after stent implantation (neoatherosclerosis). Recent histopathological studies have proven that automated quantification of signal attenuation using intravascular optical coherence tomography (OCT) imaging allows for sensitive identification of macrophages in native atherosclerotic disease. Whether this is true for neointimal foam cells in the setting of neoatherosclerosis remains unknown. Autopsy samples of stented coronary arteries (n = 13 cases) were evaluated by histology and OCT. After co-registration with histology, the attenuation rate of emitted laser light was measured in regions with and without neointimal foamy macrophages relative to its peak intensity at the blood-tissue interface. Attenuation index was subsequently determined as slope of a regression curve fitted to individual data points. Receiver operating curve (ROC) analysis was used to establish an optimal cut-off for detecting foamy macrophages in homogenous and non-homogenous neointima, respectively. Finally, the tissue attenuation index was applied to confirm or exclude the presence of neointimal foamy macrophages in symptomatic patients presenting with in-stent restenosis and undergoing intravascular OCT imaging (n = 29 cases). Tissue attenuation index derived from post-mortem samples differed significantly between histologically confirmed regions with and without neointimal foamy macrophages (- 1.23 ± 1.42 vs. - 0.52 ± 1.79, p < 0.05). ROC analysis was able to distinguish neointima with foamy macrophage infiltration from neointima without (93% sensitivity, 73% specificity, cut-off - 0.79, AUC 0.87 for homogenous neointima and 40% sensitivity, 95% specificity, cut-off - 1.93, AUC 0.69 for non-homogenous neointima). In symptomatic patients presenting with in-stent restenosis after stent implantation and undergoing intravascular imaging with OCT, neointimal foamy macrophages were detected in 34.2% of homogenous and 43.6% of non-homogenous neointimal ROI's evaluated. OCT-derived and histopathologically validated tissue attenuation index enables identification of neointimal foamy macrophages in stented coronary arteries. Such image-based post-processing software algorithm may help discern and triage subjects at increased risk for device-related events.

Prognostic role of restenosis in 10 004 patients undergoing routine control angiography after coronary stenting.

AIM: Routine control angiography is a valuable tool with high-sensitivity in detecting restenosis after coronary stenting. However, the prognostic role of restenosis is still controversial. We investigated the impact of restenosis on 4-year mortality in patients undergoing routine control angiography after coronary stenting. METHODS AND RESULTS: All the patients undergoing successful implantation of coronary stents for de novo lesions from 1998 to 2009 and routine control angiography after 6-8 months at two centres in Munich, Germany were studied. Restenosis was defined as diameter stenosis ≥50% in the in-segment area at follow-up angiography. The primary outcome was 4-year mortality. The study included 10 004 patients with 15 004 treated lesions. Restenosis was detected in 2643 (26.4%) patients. Overall, there were 702 deaths during the follow-up. Of these, 218 deaths occurred among patients with restenosis and 484 deaths occurred among patients without restenosis [unadjusted hazard ratio: HR: 1.19; (95% confidence interval CI: 1.02-1.40); P = 0.03]. The Cox proportional hazards model adjusting for other variables identified restenosis as an independent correlate of 4-year mortality [HR: 1.23; (95% CI: 1.03-1.46); P = 0.02]. Other independent correlates of 4-year mortality were age [for each 10-year increase, HR: 2.34; (95% CI: 2.12-2.60); P < 0.001], diabetes mellitus [HR: 1.68; (95% CI: 1.41-1.99); P < 0.001], current smoking habit [HR: 1.39; (95% CI: 1.09-1.76); P = 0.01], and left ventricular ejection fraction [for each 5% decrease, HR: 1.39; (95% CI: 1.31-1.48); P < 0.001]. CONCLUSIONS: In this large cohort of patients, the presence of restenosis at follow-up angiography after coronary stenting was predictive of 4-year mortality. Whether routine control angiography after coronary stenting is beneficial and influences outcomes should be evaluated by properly designed randomized trials.