Intimal flaps detected by optical frequency domain imaging in the proximal segments of native coronary arteries: An innocent bystander? insights from the TROFI trial

Background: The prevalence and clinical sequelae of optical frequency domain imaging (OFDI)-detected intimal flaps caused by vessel trauma or plaque rupture in the proximal native coronary arteries have not been described. Methods and Results: OFDI investigation was performed following stent implantation in patients with ST-segment elevation myocardial infarction (STEMI). We defined a flap-like structure (FS) as a disruption or discontinuation of the endoluminal vessel surface, and classified as actual flap or artifact. FS in the left main stem, or maximally 20 mm distal to the guiding catheter in the proximal right coronary artery were assessed. A total of 8,931 frames in 97 patients were analyzed in a frame-by-frame fashion (0.125-mm interval). OFDI identified 8 FS in 7 patients, none of which was evident angiographically. All FS were left untreated because the operators per protocol were blinded to the OFDI images. A total of 5 FS in 5 patients (5.1%) appeared to be actual flaps in which only the intima was involved (mean distance from guiding catheter: 4.8±2.7 mm). The remaining 3 FS in 3 patients were artifacts; namely, residual blood and interface light reflectivity. There were no adverse cardiac events during 6-months follow-up. Conclusions: In 5.1% of STEMI patients, post-procedural OFDI identified flaps with minimal involvement of the intima in the proximal coronary arteries. A precise interpretation of FS may help decision making to avoid unnecessary procedures.