Intravascular imaging and vulnerable plaque detection

Ron Waksman MD, FACC, FSCAIProfessor of Medicine (Cardiology), Georgetown

University Associate Chief of Cardiology Washington Hospital Center

Washington DC

Need for intervention in original non-culprit lesion correlates to underlying extent of coronary artery disease

0%

2%

4%

6%

8%

10%

0 60 120 180 240 300 360

Days from study entry

New

Les

ion

PCI

Single Vessel (n=1479) Double Vessel (n=1091) Triple Vessel (n=777)

Glaser et al Circulation 2006

Female sex

Minimal lumen irregularities

Prior coronary intervention

NO REPEAT PCI

REPEAT PCI0.1 1.0 10.0

New lesion PCI in subgroups

OR=0.77

Double vessel disease

Triple vessel disease (vs. single)

Age ≥65 years

Hx hypertension

Diabetes mellitus

OR=1.70

OR=3.61

OR=0.66

OR=1.47

OR=1.01

OR=1.41

OR=2.03

Glaser R et al Circulation 2005.111:143

Glaser R et al Circulation 2005.111:143

Glaser R et al Circulation 2005.111:143

Braunwald, J Am Coll Cardiol 2006;47:C101

Proposed algorithm for the detection of plaques likely to result in acute coronary syndromes

Invasive approaches to vulnerable plaque diagnosis

• Intravascular thermography• IVUS based: Palpography and

virtual histology• Near infrared spectroscopy• Optical coherence tomography-optical

analog of ultrasound imaging measuring the back-scattered light (optical echoes) returning from an arterial sample as a function of delay.

Individual temperature wall differences by in-vivo thermography

Circulation 1999;99:1965S1-S5: proximal to distal sites

IBIS study

Van Mieghem et al J Am Coll Cardiol 2006;47:1134

High strain spots on palpography• pre- 4.8 ± 4.5• post- 3.6 ± 4.4• Significant decrease inSTEMI patients

MSCT

VH

Palp

Use of VH to predict distal embolization after PCI for STEMI

Kanaguchi et al. J Am Coll Cardiol 2007;50:1641

Serruys PW et al. Circulation 2008;118:1172

IBIS 2. Darapladib reduces necrotic core area in patients with an acute coronary syndrome: Representative examples

Change in individual plaque components

Necrotic core

Dense calcium

Fibro-fatty

Fibrous

Darapladib Placebo

Serial assessment of bioabsorbable stent with IVUS and VH

Serruys PW et al Lancet 2009;373:897

Before stenting After stenting 6 months 2 years

Use of NIR spectroscopy to distinguish cholesterol from collagen

1100 1200 1300 1400 1500 1600 1700 1800 1900

wavelength

1.0

0.8

0.6

0.4

0.2

Abs

orba

nce

Chemogram of a RCA in a DM/HC pig that died of sudden cardiac death 3 months later.

Acute sudden cardiac death in a DM/HC pig.

Additional information from intra-coronary NIR

Spectroscopy

RCA

Ring oflipid core plaque

No stenosis, however, a lipid core plaque

Mild narrowing but no LCP

Courtesy of Dr. Simon DixonBeaumont Hospital, Royal Oak, MI

Dilation of the lipid core plaque

No flow in artery after angioplasty

Complete Heart Block,BP 30 mm Hg

Balloon angioplasty

Plaque contents passed downstream

Courtesy of Dr. Simon DixonBeaumont Hospital, Royal Oak, MI

Stenosis

Chemogramof RCA withring LCP at stenosisin 62 yo male

Distalembolizationfollowing dilationleading to MIand CPR

Similar chemogramwith ring LCPfrom autopsyspecimen of48 yo male

Suddencoronary death

Massive LCPand remnantof fatalthrombus Thrombus

remnant

Assessment of AMI culprit lesion morphology with OCT, angioscopy, IVUS

Kubo et al J Am Coll Cardiol 2007;50:933

Assessment of AMI culprit lesion morphology with OCT, IVUS, angioscopy

Kubo et al J Am Coll Cardiol 2007;50:933

Measurement of fibrouscap thickness

Serruys PW et al Lancet 2009;373:897

Serial assessment of stent struts with optical coherence tomography

Plaque ErosionPlaque Erosion

Plaque rupturePlaque rupture

Plaque erosionPlaque erosion

(Kubo et al. J Am Coll Cardiol 2007;50:933(Kubo et al. J Am Coll Cardiol 2007;50:933--9)9)(Kubo et al. J Am Coll Cardiol 2007;50:933(Kubo et al. J Am Coll Cardiol 2007;50:933--9)9)

Incidence=73%Incidence=73% Incidence=47%Incidence=47% Incidence=40%Incidence=40%

Incidence=23%Incidence=23% Incidence=3%Incidence=3% Incidence=0%Incidence=0%

RTRT

1m1mmmIncidence=Incidence=

100%100%RTRTIncidence=100%Incidence=100%

Incidence=33%Incidence=33%

WTWT

RTRT

Incidence=100%Incidence=100%

Incidence=100%Incidence=100%

Thro

mbu

s Fo

rmat

ion

Thro

mbu

s Fo

rmat

ion

Proximal Distal

s

Lipid fraction index (LFI):

High Intermediate Low Void

D

P

•• 48 year old female with stable angina

• Previous revascularization

• Risk factors: hypertension, hyperlipidemia and family history

• Three vessel disease

• Proximal LAD, 20% stenosis

Intravascular magnetic resonance imaging

LFI Distribution in 99 patients sorted by max LFIEach column represents a single patient

0102030405060708090

100

0 10 20 30 40 50 60 70 80 90 100

Patients

LFI

66% of patients had > 1 lipid-rich measurement19% of patients had > 2 lipid-rich measurements33% of patients had no lipid-rich measurements

66% of patients had > 1 lipid-rich measurement19% of patients had > 2 lipid-rich measurements33% of patients had no lipid-rich measurements

TOPIMAGE – LFI Results

LFI ≥35 = lipid rich

Summary• New non-invasive techniques are being

developed which may show the presence of lesions with an increased propensity to instability.

• However, invasive approaches, may be necessary to demonstrate those specific lesions at increased risk of causing clinical instability.

• No one device demonstrates all the information needed to assess vulnerable plaques and so a combination may be necessary.