**4. Clinical application of multimodality imaging in detecting vulnerable plaque**

#### **4.1. Assessment of the effect of pharmacotherapy on plaque modulation**

OCT has been used to evaluate the plaque stability by statin therapy, and an increase in fibrous cap thickness in coronary plaques was observed after the treatment [70, 71]. Recently, IVUS has been used to evaluate the effect of proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors on the progression of coronary atherosclerosis in statin-treated patients. PCSK9 inhibition with evolocumab was associated with a reduction in percent atheroma volume for evolocumab (−0.95%) but not placebo (+0.05%) and a greater percentage of patients demonstrating plaque regression (64.3 vs. 47.3%) [72].

#### **4.2. Assessment of the effect of local therapy on vulnerable plaque**

Previously, bioresorbable scaffold (BRS) has been investigated for the capability of sealing superficial plaque [73–75]. The neointima on top of the BRS struts altered the plaque phenotype by covering the calcific spots and TCFA, thus transforming the TCFA to thick-cap fibroatheromas that associate with the plaque stability without compromising the luminal dimensions [73]. It has been speculated that BRS may prevent the cardiac adverse event by invasive sealing of the high risk to rupture plaques. The ongoing PROSPECT ABSORB (NCT02171065) trial will examine the treatment of vulnerable plaques with the ABSORB bioresorbable vascular scaffold (BVS) plus guideline-directed medical therapy (GDMT) in comparison with GDMT alone [76]. All randomized patients will undergo 2-year followup angiography with three-vessel repeat NIRS-IVUS imaging, thus enabling evaluation of plaque regression/progression in intervening vessels and nonintervening vessels [77]. The SECRITT-II study will investigate the ability of BVS to expedite the process of de novo fibrous cap formation in comparison with high-dose statin therapy [77].
