Impact of Low-Density Lipoprotein Cholesterol Levels on Atherosclerotic Vascular Changes: Analysis of Korean Treat Stroke to Target Trial

The treat stroke to target (TST) trial demonstrated that achieving a lower low-density lipoprotein cholesterol (LDL-C) target (<70 mg/dL, low target [LT]) significantly reduced the risk of major cardio-cerebrovascular events compared with a higher target (90-110 mg/dL, high target [HT]). 1A subsequent analysis of the Korean TST cohort showed that the LT strategy was particularly effective in preventing recurrent strokes among patients with symptomatic extracranial atherosclerosis (ECAS), but not in those with intracranial atherosclerosis (ICAS). 2 However, whether LT and HT strategies differ in terms of the imaging outcome (progression or regression) of ICAS and ECAS remains unknown.We performed an additional analysis using vascular imaging data from Korean patients who underwent TST to address this.Between May 2015 and February 2021, 712 patients were recruited, 220 of whom underwent follow-up magnetic resonance angiography (MRA) at the physician's discretion.This is partly because this was a multicenter study and partly because this aspect was excluded from the initial design of the main TST; the characteristics of magnetic resonance imaging (MRI) used were heterogeneous: 1.5 T or 3.0 T scanners, including Siemens, GE, and Philips systems.Although specific acquisition parameters (such as repetition time, echo time, and flip angle) varied among institutions, each center followed standardized clinical protocols.The same modality, either time-of-flight MRA or contrastenhanced MRA (CE-MRA), was used for both the baseline and follow-up scans.The most recent scan was used as the second dataset in patients who underwent multiple scans.The median follow-up interval was 2 years.Details of the TST have been described in a previous study, 1 and the ethics committees of all participating centers approved the protocol.Investigators from each center who were blinded to the clinical information independently classified the degree of arterial