4/27/2018

1

Subha V. Raman, MD, MSEE, FACC, FAHAProfessor and Medical Director, CMR/CCT 

Contemporary Approaches to Myocardial Ischemia

OSU Cardiovascular MR/CT UpdateApril 27, 2018

Disclosures

Institutional research support from Siemens

Co-inventor, MR-compatible treadmill

4/27/2018

2

Outline

Motivation for stress testing in IHD; typical scenarios

Exercise and pharmacologic stress methods

Guidelines

Myocardial Ischemia:inadequate oxygen supply to meet demand

4/27/2018

3

What Are Looking For? Appropriate Test

Detection of myocardial ischemia Stress ECG / dynamic ECG changes

Stress cardiac imaging tests – nuclear, echo, CMR

Detection of CAD Coronary artery calcium (CAC)

CT coronary angiography (CCT)

X-ray coronary angiography

Scenarios for Stress Testing:detection / diagnosis

Typical or atypical symptoms – are they due to IHD?

Ventricular arrhythmias – is substrate ischemia?

Substernal chest discomfort

Provoked by exertion

Relieved with rest or nitroglycerin

Infarct scar

Reentry loop

4/27/2018

4

Exercise Stress

Increase demand and assess supply evaluate ECG, coronary blood flow, contractility,

regional wall motion, myocardial perfusion, oxygenation, etc.

Reproduce exertional symptoms

Arrhythmias with physical activity suppression vs. augmentation of PVCs

Peak Exercise Recovery

Right ventricular outflow tract PVCs ablation

Exercise-induced ST depression = Ischemia

CAVEATS

x No LBBB, V-paced rhythm, repolarization abnormalities

x Ischemia not localized by ST

STRENGTHS

V. strong prognostic value

Correlate symptoms & results with typical exertion

ACC/AHA Guidelines 2002.

4/27/2018

5

Pharmacologic stress imagingNo

Exercise stress imagingNoResting ECG

interpretable?

Yes

Yes

Exercise stress ECG

ACC/AHA Guidelines 2002.

Can patient exercise?

Choosing between Exercise & Pharmacologic Stress for Ischemia Testing

preoperative evaluation – often can’t exercise

Estimated Perioperative Risk

Poor orunknown functional capacity

Pharmacologic Stress Testing

2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management

4/27/2018

6

Pharmacologic Stress: Dobutamine

Synthetic catecholamine

Plasma half-life ~2 min

Up to 10 g/kg/min: Inotropic effects (via 1 and 1)

High dose (20-40 g/kg/min): HR progressively ↑ (1) Blood pressure increases (though SVR↓ via 2 >> 1)

Hemodynamic changes ↑ O2 demand Territories supplied by critical stenosis WMA

Dobutamine Stress Imaging Tests

Echo Wall motion at each stage

Acoustic window may be limited by body habitus, lung disease

Cardiac MRI Wall motion + perfusion + scar

MRI contraindications

Hundley WG et al. Circ 1999.

4/27/2018

7

DSE DCMR

Sensitivity 74% 86%

Specificity 70% 86%

PPV 81% 91%

NPV 61% 78%

Accuracy 73% 86%

Nagel E et al. Circ 1999.

Dobutamine Stress Echo vs. CMR

Dobutamine CMR: Prognostic Value and Cost-Effective

Wallace EL et al. JACC Im 2009.

HR for MI/cardiac death:4.1 [95% CI 2.2 – 9.4]

similar survival with ~12500 € savings per life year

Petrov G, Kelle S et al. Clin Res Cardiol 2013.

Costs Survival

4/27/2018

8

Vasodilator ‘Stress’

REST VASODILATOR

Vasodilator Stress Imaging Tests

Inject radioisotope at rest and during vasodilator infusion

SPECT (nuclear) Extraction of isotope where there is

myocardial blood flow

Breast & gut attenuation artifacts

Cardiac MRI First-pass imaging during infusion of T1

shortening (gadolinium-based) contrast agent

Usual MRI contraindications

Breastartifactvs. anteriorischemia

ST

RE

SS

RE

ST

SPECT

4/27/2018

9

SPECT vs. Vasodilator Stress CMR

Greenwood JP et al. Lancet 2012.

SPECT CMR

Sensitivity 66% 86%

Specificity 83% 83%

PPV 71% 77%

NPV 79% 91%

Adenosine CMR:Similar Accuracy in Women and Men

Males vs. Females AUC:CMR – 0.89 vs. 0.90 (NS)

SPECT – 0.74 vs. 0.67 (p<0.001)

Greenwood J et al. Circ 2014.

4/27/2018

10

Adenosine CMR in Acute Chest Pain Intermediate risk patients randomized to –

obs unit + CMR

inpatient admission, care per admitting provider

Index visit cath in 19% (inpatient) vs. 2% (obs), p=0.01

Cath within 12 months in 33% (inpatient) vs. 15% (obs), p=0.04

Miller CD et al. JACC Im 2011, JACC Im 2013.

$2533

$842

Lower Cost

Time (Months)

Fewer Events

HR of event with usual care:3.4 (1.4 to 8.0), p = 0.006

CMR-IMPACT Trial Underway

Troponin up to 1.0 ng/mL

Aorta/proximal PAs, T1 & T2 mapping, adenosine, LGE

Randomize

CMR-guided careCMR determines need for invasive strategy

ControlGuideline-adherent, invasive strategy

Aim 1: Composite of death, nonfatal MI, and cardiac readmission

Aim 2: angiography, coronary revascularization, recurrent cardiac testing, and cardiac-related ED visits

Chadwick Miller, PI; NCT01931852

Intermediate/high risk chest pain patients with detectable to minimally elevated troponin

4/27/2018

11

Ischemic Heart Disease: Coronary Artery Disease and Beyond

Epicardial Coronary ArteryPlaque erosionPlaque composition

CapillariesSystemic inflammationBlood viscosityVessel density

modified from Gan LM et al. JCTR 2013.

Resistance ArteryVascular function; neurohumoral factors

EndotheliumSmooth muscle cells

Vascular remodeling

Perfusion CMR: Uniquely Able to Detect Coronary Microvascular Dysfunction

4/27/2018

12

Late Gadolinium Enhancement (LGE-CMR): “Bright is Dead”

Kim RJ et al. NEJM 2000.Transmurality of scar, %

Impr

ovem

ent

in c

ontr

actil

ity,

%

LV

Transmural enhancement (scar) of the lateral wall

LGE-negative, no MI history

MI by history

LGE, no MI history

NS

p=0.001

Kwong RY et al. Circ 2008.

Silent MIs in Diabetics

• Death• MI• New CHF or UA• Stroke• Ventricular arrhythmias

4/27/2018

13

Epicardial Enhancement of Myocarditis

Cardiac AmyloidosisMidwall Enhancement of NICM

Subendocardial Infarct Scar

Value Added: Other Causes of Symptoms

Distinct signatures to help diagnose myocardial disease

Cardiac MRI in DDx of Chest Pain

Ischemia Myocarditis Tako-tsubo

Cine

T2

LGE

69 ms >60 ms70-90ms

JACC Im 2011, Circ Im 2012

4/27/2018

14

Concluding Thoughts

Stress tests help in evaluation & management of IHD

Exercise preferred when feasible, esp. to diagnosis IHD correlate symptoms with test results

quantify functional capacity, ischemic burden

determine ischemic substrate for ventricular arrhythmia

Pharmacologic stress when needed

Physiologic effects differ by exercise/drug protocol

CMR gives you options

Thank You

Karolina Zareba, MDJason Craft, MD

Salman Bhatti, MDMatthew Tong, DO

Saurabh Rajpal, MBBSDaniel Addison, MD

Orlando Simonetti, PhDRizwan Ahmad, PhDJuliet Varghese, PhD

Ning Jin, PhDAndrea Cardona, MD

Beth McCarthy, RTSuzanne Smart, BS

Debbie Scandling, BSAaron O’Brien, MS

Mohamed Elamin, MDVidhya Kumar, PhD