Statin-induced cholesterol lowering and plaque regression after 6 months of magnetic resonance imaging-monitored therapy

Background - Statin therapy reduces adverse outcomes, with a minimal decrease in vessel stenosis. Magnetic resonance imaging (MRI) noninvasively detects atherosclerotic plaque (AP) reduction. We hypothesized that statin-induced AP regression can be monitored by MRI and detected earlier than previously reported and is significantly associated with its lipid-lowering effect. Methods and Results - APs in thoracic aorta were measured by combined surface/transesophageal MRI in 27 patients (treated with simvastatin 20 to 80 mg daily) before and after 6 months of therapy. AP volume and luminal dimensions were measured from 6 cross sections used to construct a 2.4-cm 3D volume of the aorta that included plaque and lumen. Method reproducibility was studied in 10 patients imaged twice, 1 week apart. AP volume was reduced from 3.3±1.4 to 2.9±1.4 cm³ at 6 months (P<0.02), whereas luminal volume increase was less accentuated (from 12.0±3.9 to 12.2±3.7 cm ³, P]<0.06). LDL cholesterol decreased by 23% (from 125±32 to 97±27 mg/dL, P<0.05) in 6 months. AP regression (plaque volume/area reduction) was significantly related to LDL cholesterol reduction (P<0.02 and P<0.005, respectively), and luminal volume increase was inversely related to LDL cholesterol reduction (P<0.04). Plaque volume measurement was highly reproducible (intraclass correlation R=0.98 and variability =4.8%). Intraobserver (0.91) and interobserver (0.81) concordances were documented for plaque volume assessment. Conclusions - AP regression and reverse remodeling can be detected accurately by MRI 6 months after statin therapy initiation, and it is strongly associated with LDL cholesterol reduction.