The prevalence and clinical consequences of intimal flaps detected by optical frequency domain imaging in the proximal segments of coronary arteries

Purpose: The prevalence and clinical consequences of intimal flaps due to vessel trauma or plaque rupture in the proximal segments of native coronary arteries has not been sufficiently described. Methods: OFDI investigation was performed following stent implantation for the treatment of ST-segment elevation myocardial infarction (STEMI). We defined the flap-like structure (FS) as a disruption of endoluminal vessel surface, and classified as flaps or artefacts under the consensus from 3 observers. We assessed the prevalence of FS in the sub-segment between the guide catheter tip and distal left main stem, or maximally 20-mm distal to the guide catheter tip in proximal right coronary artery, beyond 5-mm proximal to the stented segment. All FSs were left untreated since operators per protocol were blinded to the OFDI images. Results: A total of 8,931 frames in 97 STEMI patients were analyzed in a frame-by-frame fashion. OFDI identified 8 FSs in 7 patients, none of which were evident angiographically. Five FSs in 5 patients (5.1%) appeared to be flaps where only intima was involved, whereas the remaining 3 FSs in 3 patients were caused by artefacts, namely residual blood and interface light reflectivity. The mean distance from the guide catheter tip to the most proximal frame with flap was 4.8±2.7 mm. The mean length, root thickness, and maximum flap area were 0.9 mm, 0.3 mm, and 0.1 mm2, respectively. There were no adverse cardiac events observed during hospitalization and in the following 6 months. A case example of OFDI-detected flap A case example of OFDI-detected flap Conclusions: Post-procedural OFDI identified intimal flaps in the proximal coronary arteries, even angiographically silent, in 5.1% of STEMI patients. The detectable FS had no clinical consequences. A precise interpretation of FS may help the decision making to avoid unnecessary stent implantation.