Stress Testing and You:A Guide for the Interventionalist

Matthew Schumaecker, MDCarilion Clinic

April 7, 2014

Disclosures

• I read stress tests for a living• The only reason I am not an interventionalist:

Trends in PCI

Trend in Nuclear Stress Test Results

Rozanski et al J Am Coll Cardiol. 2013;61(10):1054-1065

Part I:Why do We Perform Stress Tests?

• Diagnose coronary disease?• Avoid lawsuits?• Make money?

You Can’t Cath Everyone with Chest Pain!

Stress Testing for Detection of CAD

ETT Stress Echo Stress Nuclear0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

67%

85% 87%

77%

88%

73%

SensitivitySpecificity

Are we really trying to predict CAD?If not, what are we doing here?

Why Detecting (asymptomatic) CAD Might Not Matter

Why Detecting (Asymptomatic)CAD Might Not Matter

All-Cause Mortality — As Randomized

HR 0.86 (0.72, 1.04)

P = 0.123

0.460.41

Is there any role to stress testing asymptomatic individuals?

NOT USUALLY

“Special” Asymptomatic Indications

• Consideration for class Ic antiarrhythmic• Newly diagnosed cardiomyopathy• CT calcium score > 400 Agatston units• MAYBE – high risk (>20%/10 year) diabetics

Cumulative Event-Free Survivalby SPECT Degree of Normalcy

Hachamovitch R, Berman DS, Shaw LJ, et al. Circulation. 1998 Feb 17;97(6):535-43.

n=5534

Elhendy et al

Cumulative Event-Free Survivalby Stress Echo Degree of Normalcy

Cardiac Death Rate Stratified by Revascularization vs. Medical Therapy and by SPECT Degree of Normalcy

Hachamovitch R, Berman DS, Shaw LJ, et al. Circulation. 1998 Feb 17;97(6):535-43.

Black boxes – Medical TherapyWhite boxes – Revascularization

Incremental Prognostic Value of MPI

Hachamovich et al. Circulation. 2002 Feb 19;105(7):823-9

Incremental Prognostic Value of Echo

Marwick J Am Coll Cardiol. 1997 Jul;30(1):83-90.

Prognostic Value of an Equivocal Study

Berman DS, Hachamovitch R, Kiat H, et al. J Am Coll Cardiol. 1995 Sep;26(3):639-47.

Part II:Advances in Nuclear Cardiology

PET

• Advantages of PET over SPECT– Higher energy resolution – Mandatory attenuation correction– Quantification of coronary blood flow

• Disadvantages of PET over SPECT– Camera is MUCH more expensive– Radioisotopes are very short-lived

SPECT vs PET

Tc99m

140 keVɣray

F18

E=mc2

511keVphoton

511keVphoton

e-

β+

Cardiac PET

• Half life of currently utilized cardiac PET perfusion agents:

Agent T1/2

N-13 132 seconds

O-15 148 seconds

Rb-82 75 seconds

Cardiac PET

• 18F Fludeoxyglucose has t1/2 of 110 minutes

BUT

• This is a viability agent, not a perfusion agent

18F-Flurpiridaz PET

Jamshid Maddahi, M.D., FACC, FASNC, and René R. S. Packard, M.D.

123I-BMIPP

• 99mTc can be used to evalulate chest pain at rest but only if patient is having pain at the time.

Cardiac Memory

• Myocytes preferentially metabolize FFA• In ischemia millieu, switch to glycolysis

Cardiac Memory

• Substrate switch can last up to 24 hours• If injected with 123I-BMIPP, SPECT images will

show defect if patient has been ischemic within 24 hours

Dilsizian et al, Circ 2005;112:2169-2174

BMIPP Trial

J Am Coll Cardiol. 2010 Jul 20;56(4):290-9

D-SPECT

CZT

• Much more photosensitive than Na-I

Stress First/Only

• 60-70% nuclear studies normal• If stress images are normal, rest images are

not clinically valuable• In lower risk patients, we could do stress

imaging and only if abnormal bring back for rest

Radiation ExposureNormal BMI

Procedure Radiation Exposure

Dual Isotope Imaging traditional SPECT 24mSv

Same Isotope (Tc-Tc) Imaging/traditional SPECT

12mSV

Same Isotope (Tc-Tc) Imaging / D-SPECT 4 mSv

Stress Only (Tc) / D-SPECT 1 mSv

Part III:Discuss