Diagnostic accuracy of optical coherence tomography parameters in predicting in-stent hemodynamic severe coronary lesions: validation against fractional flow reserve.

BACKGROUND: By means of optical coherence tomography (OCT), coronary dimensions can be assessed accurately. However, whether OCT can identify hemodynamic significant coronary lesions as determined by fractional flow reserve (FFR) in patients with an in-stent lesion is not known. Therefore, we tried to assess the predictive value of OCT parameters in this setting as compared to FFR. METHODS AND RESULTS: In patients who underwent a percutaneous coronary intervention for an in-stent restenotic lesion, pre-, post-procedural and 6-month follow-up OCT and FFR acquisitions were performed. In case of an FFR ≤ 0.80, a lesion was classified as hemodynamically severe. Diagnostic efficiency of several OCT parameters were assessed with receiver operating characteristic curves. In 27 patients, 66 coupled OCT and FFR segments were analyzed and compared. The diagnostic efficiencies of OCT-based minimal luminal diameter (MLD) and minimal luminal area (MLA) are good, with an area under the curve (AUC) of 0.83 (95% confidence interval: 0.74-0.93) and 0.83 (0.73-0.93), and a best cutoff value of 1.77 mm (sensitivity 74% and specificity 78%) and 2.54 mm(2) (sensitivity 71% and specificity 84%), respectively. The diagnostic efficiency of OCT-based maximum neointimal area is moderate [AUC 0.73 (0.61-0.85)], and regarding maximum neointimal area stenosis, it is poor [0.39 (0.25-0.53)]. The corresponding best cutoff values are 5.01 mm(2) (sensitivity 66% and specificity 72%) and 49% (sensitivity 40% and specificity 66%), respectively. CONCLUSIONS: With OCT, a good diagnostic efficiency can be achieved in identifying coronary severity in in-stent lesions in a per-group analysis. This hallmark provides an extra dimension, next to morphological information, when acquiring OCT images in scientific studies. However, OCT seems limited in a per-patient clinical decision making process due to reasonable but limited sensitivity and specificity in predicting coronary severity.