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116 Cardio Diabetes Medicine 2017

Regression of Atherosclerosis

- In Diabetics

Dr Joy M Thomas, MD, DM ( Cardiology), FRCP (G), FACC, FHRS, FCSI
Chief Cardiologist ( Adult Cardiology) & Chief Electrophysiologist

Dr H. Nagaraja Rao, DCH, DNB (Pediatrics),
Senior registrar, Cardiology

INTRODUCTION: Plaque burden in a two-dimensional IVUS frame is
Atherosclerosis is a chronic disease of the vessel expressed by the ratio of plaque plus media area
wall that progresses over time by accumulation of divided by vessel area. Volumetric (three-dimension-
atheromatous plaque. This follows a course of arte- al) measures of disease burden include total ather-
rial injury associated with coexistent systemic risk oma volume (TAV), i.e., the sum of atheroma area
factors. Understanding the complex pathophysiology measured in sequential cross-sectional frames and
of atherosclerosis led to the development of inter- percent atheroma volume (PAV), i.e., the percent of
ventions that effectively reduce the clinical manifes- the vessel volume occupied by atheroma.PAV is con-
tations of coronary atherosclerotic disease including sidered the primary endpoint in the majority of serial
angina or acute coronary thrombosis [1,2]. Introduc- IVUS studies [5-6].
tion of medications including lipid-lowering drugs [3-
4], antihypertensive medications and investigational Intracoronary imaging technologies for in
anti-inflammatory agents have shown to favorably vivo assessment of plaque morphology and
affect the development and progression of coronary composition
plaque including reduction of plaque size and favor- Imaging modalities to characterize composition of
able changes in plaque morphology and composi- coronary atheroma in vivo
tion.Novel in vivo intracoronary imaging modalities
help in providing knowledge of the natural history of • IVUS-virtual histology (VH),
coronary atherosclerosis and assessment of plaque • Optical coherence tomography (OCT)
stabilization and regression in response to potent
anti-atherosclerotic medications. • Near-infrared spectroscopy (NIRS).
IVUS-VH : This investigatory modality uses radiof-
Coronary imaging for in vivo plaque requency range ultrasound signals to derive plaque
quantification and characterization: components, which are defined as necrotic core, fi-
brofatty tissue, fibrous tissue, or dense calcium. Le-
Intravascular ultrasound for quantification sions are classified as pathologic intimal thickening,
of coronary atheroma: fibrotic plaques, fibrocalcific plaques, thin- or thick-
cap fibroatheromas [7]. Studies have reported good
Intravascular ultrasound (IVUS) is based on acous-
tic sound wave backscattering. Reflected ultrasound correlation of IVUS-VH against human plaque his-
wave creates a gray-scale image resulting in a axi- tology. However, it is an imperfect surrogate of true
al resolution of 80–120 μm and a penetration depth histology and is limited by inter-observer variability
of 4–8 mm.IVUS Enables acquisition of tomographic and differences in definitions .
images of the entire coronary vessel wall and allows OCT: This imaging technique has an axial resolution
for accurate, reproducible quantification of athero- 10-fold higher compared with IVUS with limited axial
ma burden.This imaging modality, when performed penetration depth (1–4 mm). So, the assessment of
serially at consecutive time points,helps for assess- plaque burden is nearly impossible in the presence
ment of plaque progression or regression over time. of a lipid-rich plaque. OCT is well validated in the

GCDC 2017