Serial Change and Clinical Impact of Irregular Protrusion in Lesions With Chronic Coronary Syndrome

BACKGROUND: The changes over time and effects on long-term clinical outcomes beyond 1 year of irregular protrusion (IP) in chronic coronary syndrome (CCS) remains unclear. AIMS: This study aimed to assess the time-dependent change and long-term clinical impact of IP in CCS lesions. METHODS: This study was a post hoc analysis of COLLABORATION study, which was a multicenter, prospective, observational study conducted from July 2018 to February 2020, assessing 1- and 12-month serial vessel responses after stent implantation using OCT and coronary angioscopy. Time-dependent change in the presence of IP was evaluated using the serial OCT examinations. The cumulative 3-year incidence of TLR was compared between the lesions with and without IP, as well as between those with and without residual IP at 1 month. RESULTS: Among 107 lesions, IP was detected in post-OCT pullbacks in 38 (35.5%) lesions. Out of the 38 lesions, IP remained in 9 (23.7%) lesions at 1 month and existed in 2 (5.3%) lesions at 12 months. The cumulative 3-year incidence of TLR was significantly higher in IP group than in non-IP group (13.6% vs. 3.0%, p = 0.04). Similarly, it was significantly higher in lesions with residual IP at 1 month than those without (33.3% vs. 4.3%, p < 0.01). All residual IP at 1 month were composed of angioscopic yellow plaques and red thrombi. CONCLUSIONS: The presence of IP decreased over time, but approximately one-fourth of IP remained at 1 month. IP and residual IP at 1 month were important post-stent OCT findings leading to long-term TLR in patients with CCS.