1 Carotid plaque lipid reduction, determined by T2 mapping, occurs early after high-intensity statin initiation in patients presented with acute myocardial infarction

Introduction A recently-validated, highly sensitive T2 mapping magnetic resonance (MRI) technique accurately quantifies carotid atherosclerotic plaque lipid. The aims of this study were to test the hypothesis that intensive LDL-c reduction translates into rapid depletion of plaque lipids and whether plaque lipid content is related to standard or ‘functional’ blood lipid measurements, including PCSK9 level and cholesterol efflux capacity. Methods Statin naive subjects presenting with acute coronary syndrome underwent carotid artery MRI at 3 Tesla scanner to quantify plaque lipid. Patients were subsequently commenced on high dose statin as part of clinical care and underwent a second MRI after three months. Plaque composition was measured using objective semi-automated techniques implemented in Matlab and statistical analysis was performed using SPSS 22.0. Results 23 out of 24 patients had measurable lipid. Three months after statin initiation there was a significant reduction in carotid lipid percentage [from 10.3% (7.2–14.2) to 7.4% (5.4–10.0), p=0.002] and a significant increase in fibrous percentage [from 83.3%±6.6 to 85.5%±4.8, p=0.039]. None of the studied functional blood biomarkers were related to either baseline carotid plaque lipid content or its propensity to change with statin treatment. Conclusion T2-mapping demonstrated depleted carotid plaque lipid following the initiation of high-intensity statin treatment. Standard or functional blood biomarkers did not predict changes in plaque lipid content with treatment. These findings support the use of plaque imaging as a potential tool to identify patients who may be suitable for intensive lipid modification.