Impact of statins therapy on morphological changes in lipid-rich plaques stratified by 10-Year framingham risk score: A serial optical coherence tomography study

Abstract

The aim of the study was to investigate the impact of statins therapy on morphological changes of lipid-rich plaques by OCT (optical coherence tomography) in patients with known CHD (coronary heart disease), stratified by FRS. Ninety-seven lipid-rich plaques from sixty-nine patients who received statins therapy and underwent serial OCT images (baseline, 6-month and 12-month) were divided into 2 groups according to the FRS (framingham risk score): low risk group A (FRS<10%, N=35, n=45), moderate to high risk group B (FRS≥10%, N=34, n=52). Fibrous cap thickness (FCT) was measured at its thinnest part 3 times. Baseline characteristics were not different between the 2 groups. FCT sustained increased from baseline to 6-month and 12-month follow up in both group A (59.8±20.4μm, 118.3±62.5μm, and 158.8±83.4μm respectively, P<0.001) and group B (62.2±16.8μm, 125.1±78.7μm, 163.8±75.5μm respectively, P<0.001). Lipid index was significantly decreased in both group A (1862.1±1164.5, 1530.3±1108.7, 1322.9±1080.4, P<0.001) and group B (1646.6±958.5, 1535.1±1049.1, 1258.6±1045, P=0.016). The incidence of TCFA was decreased statistically in both group A (P <0.001) and group B (P <0.001). The patients with known CHD can equivalently benefit from statins therapy by stabilizing the lipid-rich plaques. Patients with moderate to high FRS might benefit more within the first year from event time.

Keywords: framingham risk score; lipid-rich plaques; morphological changes; optical coherence tomography; statins therapy.

Figure 1. The angiographic distribution of plaques between the 2 groups

Figure A showed the distribution of plaques in the 3 coronary arteries (LAD, LCX and RCA ). It was 24.4%, 20.0%, 55.6% for low risk group A ( white bar) and 38.5%, 17.3%, 44.2% for moderate to high group B (black bar). And figure B showed the distribution of plaques on the 3 lesion segments (proximal, middle and distal). It was 17.8%, 31.1%, 51.1% for low risk group A ( white bar) and 19.2%, 38.5%, 42.3% for moderate to high group B (black bar).

Figure 2. Dynamic changes in the LDL-C and hs-CRP of the 2 groups among the 3 time points

A. LDL-C was significantly decreased in the first 6-month, and was maintained at about 70mg/dL until 1 year in both 2 groups. B. Serum hs-CRP was significantly reduced from baseline to 6-month (<2.0mg/L) and kept stable from 6-month to 12-month in both 2 groups.

Figure 3. Dynamic changes in the FCT and the incidence of TCFA of the 2 groups among the 3 time points

A. Fibrous-cap thickness was sustained increased from baseline to 12-month in both 2 groups. B. The incidence of TCFA was sustained decreased in both 2 groups under the lipid lowering therapy.

Figure 4. Representative OCT images

A. Lipid core (white arc) was defined as a diffusely bordered, signal-poor region. B. TCFA (white arrow) was defined as a lipid-rich plaque with fibrous cap thickness≤65μm. C. Micro-channel (white arrow) was defined as a black hole within a plaque with a diameter of 50-300μm and can be observed on at least 3 consecutive frames. D. Macrophages accumulation (white arrow) was a region with signal-rich, distinct or confluent punctuate heterogeneous backward shadows. E. Cholesterol crystal (white arrow) was defined as linear and highly backscattering structures within the lipid-rich plaques.