CT Angiography: The test of the future-NOW. Harvey S. Hahn, MD, - - PowerPoint PPT Presentation

CT Angiography:

The test of the future-NOW.

Harvey S. Hahn, MD, FACC

Director, Cardiovascular Fellowship Training Program Director, Non-invasive Lab Kettering Medical Center Associate Professor of Medicine Wright State Univ & Loma Linda Univ Adjunct Professor of Medicine University of Cincinnati

A look into the future…

Old New

A look into the future…

Old NOW!

CTA

Computed tomography angiography. Multi-detector or MDCT (1,2,4,8,16,32,40,64, 128, & 320) Multi-slice or MSCT Dual source (128 x 2) 3-D

3-D CTA

It’s not just for the heart…

Coronary arteries Carotids Great vessels Aorta Renals Lower extremity run-offs.

What do you get with a CTA?

EF. Aortogram. Coronary anatomy. Soft plaque / amount of disease (plaque burden). Plus a look at nodes, lungs, upper GI tract.

Non-invasive coronary anatomy.

Left anterior descending (LAD)

3-D 360o views-Normal

3-D 360o views-CAD of LAD

Anomalous Coronary Artery-Cx

CTA and Prognosis

Andreini et al, JACC CV Imaging 2012

A&P… Anatomy versus Physiology

Physiology Looks for ischemia Echo Nuclear cMR Anatomy Looks at degree of stenosis / amount of coronary artery disease. CTA MRA Invasive cath

Cath

IVUS vs FFR

(Anatomy) v (Physiology)

For 2013 it’s $482.

Another ‘cost’-Radiation exposure

mSv CXR equivalents TSA backscatter scanner 0.001 1/20 Dental x-ray 0.005 0.25 CXR (PA) 0.02 1 Mammo 2 100 Head CT 2 100 Annual background radiation 3 150 Abd CT 10 500 64 slice CTA 9-15 450-750 MPI-sestamibi 9 450 MPI-Thallium 41 2050 Invasive diagnostic cath 3+ 150+ Next generation CTA ? ? Brenner, et al, NEJM 2007 Gerber et al, Circ 2009 Einstein, JACC 2012

< 1 mSv scans!

Submillisievert Median Radiation Dose for Coronary Angiography with a Second- Generation 320–Detector Row CT Scanner in 107 Consecutive Patients. Marcus Y. Chen, MD, Sujata M. Shanbhag, MD and Andrew E. Arai, MD. Radiology 2013

It’s FAST!

CTA-Summary

PROS: Fast. Get EF and wall motion. Get a ‘free’ aortogram. Triple rule out? CONS: Some radiation exposure. Contrast injection like other CTs so risk of renal dysfunction. Does not do well with rapid or irregular HR (yet).

Total radiation exposure 2.5 mSv

CT perfusion protocol

What about the radiation?

LIMA to LAD graft

Why do a cardiac test ?

• 1. Detect CAD
• 2. Evaluate

CP/assess ischemia.

• 3. Risk stratify

post MI

• 4. Prognosis
• 5. Asses for

viability aka “hibernating myocardium”

The MAIN question…

“Do I have any blocked up arteries?”

CTA in the ER

Observational trials and single center RCT

– ROMICAT 368 pts, 50% neg CT, no ACS – Hollander et. al, 568 pts, no MACE w/neg CT – Goldstein et. al, 197 pts, LOS & cost, no MACE

Multicenter RCT - CT-STAT

– 699 pts at 16 sites – CT vs. SPECT-MPI – 54% reduction in time to diagnosis – 38% cost savings – MACE after negative test

2/268 CT (0.75%, 95% CI 0.09-2.7%) 1/266 SPECT-MPI (0.38%, 95% CI 0.01-2.1%)

ACRIN PA 4005: Multicenter Randomized Controlled Study of a Rapid ‘Rule-out’ Strategy Using CT Coronary Angiogram Versus Traditional Care for Low-Risk ED Patients with Potential ACS Harold Litt MD-PhD University of Pennsylvania Philadelphia, PA

Results 1

1392 subjects July 2009 – Nov 2011

– 22 removed post-randomization (most CrCl) – 908 randomized to CCTA, 462 traditional care – Groups well matched, 60% black

Results 2 – Index visit testing

16% didn’t get CT

– 7-33% across sites – Elevated HR (27%)

Similar cath rate

– CT higher pos rate

No testing

– 9% vs. 36%

Results 3 - Safety

No 30-day MACE in 640 pts with neg CTA

– 0% event rate, 95% CI 0–0.57%

Secondary aims - 30-day CCTA vs. trad One serious AE in each arm

– Bradycardia related to meds for HR control

Results 4 – Efficiency

CCTA more often discharged from ED

– 50% vs. 23% (95% CI 21.4-33.2)

• LOS shorter

– Overall CCTA vs. trad care: 18 vs. 25 hrs* – Negative testing: 12 vs. 25 hrs* – Per protocol (had CCTA or stress testing)

Overall 15 vs. 26 hrs* Negative CCTA or stress (trad care) 12 vs. 25 hrs* *p<0.001

More CCTA pts diagnosed with CAD

– 9.0 vs. 3.5% (95% CI 0-11.2)

Results 6 – Resource Utilization

No significant differences in 30-day resource utilization (CCTA vs. trad care) We are obtaining 1 year follow-up

Use of Resources CCTA-based (%) Traditional Care (%) 95% CI for Difference Catheterization 5.1 4.2

• 4.8 to 6.6

Revascularizatio n 2.7 1.3

• 4.3 to 7.0

Repeat ED visit 8.0 7.5

• 5.2 to 6.2

Re- hospitalization 3.1 2.4

• 4.9 to 6.4

Cardiologist visit 7.1 3.8

• 2.4 to 9.0

Time to diagnosis was shorter. 47% directly discharged from ER (vs 12%). No safety issues. Cheaper cost in the ER, but at 28 days costs caught up?

CTA vs MPI

So ~66% did NOT need to go to the cath lab!

Coronary Anatomy-best method?

CTA 85 cc of dye. 1-3 mSv of radiation. Just need a 18g IV. Home right after the test. Invasive cath 30 cc for coronaries 30 cc for LVgram 30 cc for aortogram TOTAL of 90 cc+. 3+ mSv of radation. Arterial access. Best case home in 2 hours.

Risks of invasive testing

Death Stroke / systemic embolism Renal injury (CIN-contrast induced nephropathy). Access complications

– Pseudoaneurysm – AV fistula – Retroperitoneal bleeds – Limb loss

cMR

PROS: No radiation exposure. EF and wall motion. Scar/viability evaluation with DCE with gad. No nephrogenic contrast injection. CONS: NFS due to gad. Takes a long time to acquire data. Loud. Claustrophobia. Patients with metallic devices are not candidates.

NSF

Nephrogenic systemic fibrosis Rare occurrence in renal failure patients exposed to gadolinium. FDA warning given. Avoiding contrast is the major reason to choose cMR over CTA.

Myocardial perfusion imaging (MPI)

PROS: Can be done with exercise treadmill or pharmacologic agents. Increases the sensitivity and specificity of a treadmill test. Get wall motion and EF. TID, h/l ratio are prognostic as well. CONS: Radiation exposure. 2 scans so about 4 hours total test time.

How diagnostic are nuclear scans?

~40% of MPI’s are equivocal!

Why not stress echo ?

Stress echo

PROS: No radiation. Get wall motion, EF. Get an echo – huge advantage. Can check for changes in E/E’, PAP, or MR. Test completed quickly (~1 hr vs 4). CONS: Body size a factor for image quality.

Plaque composition

Similar to IVUS. Ca2+-hard plaques are more stable. Dark-soft plaques with a lipid core. Can see remodeling (Glagov’s phenomena). Disease progression / regression.

CTA plaque analysis

CTA vs IVUS

Non-invasive. IVUS still requires dye and radiation and can physically disrupt plaques. Much more acceptable for serial measurements. Can follow both Ca2+ score as well as plaque volume. Both techniques poor for small vessels/branches so little loss

• f data.

CTA could replace IVUS as a major research tool.

What ‘Gold’ standard?

Noninvasive (physiologic) studies are measured against cath… Cath (anatomy) is the ‘gold’ standard Cath is not perfect- Glagov phenomena… FFR (physiology) now considered validation for cath. FFR validated by SPECT!

CTA and CHF

The typical question in the CHF patient is “is this ischemic or not?” CTA can tell you the answer. Perfusion CT will be able to detect viability, but at the cost of more radiation.

CTA and CHF

Treatment vs prevention…

#1 killer in the US? 1st sign of heart disease?

“Non-significant” plaques dominant.

Biggest bang for the buck…

Yusuf and Pitt, Circ 2002

Napoli JCI 1997 Palinski FASEB 2002

Only 2 things lower CRP-ASA and statins. What should you do if your pt is on both and still has a high hsCRP? If nothing, and your pt is already on or will be on these meds, then why order the test in the first place?

PET Versus SPECT

PET

SPECT

Higher resolution images Lower resolution images 95% Sensitivity/Specificity 80% Sensitivity/Specificity Rest + Stress = 30 min Rest + Stress = 240 min 7 mSv dose (PET only) 13 mSv dose (SPECT) Reimbursed Reimbursed Cardiac Function at Rest & Exercise Cardiac Function only at Stress

PET is better and faster than SPECT period.

The regions only combo PET/CTA

PET/CTA

Average radiation exposure from CTA only 8.56 mSv. Total time for the test ~45 min instead of 4 hours. Average contrast load ~85 cc. Increased confidence and decreased downstream testing.

Why get a PET/CTA?

Table 3. Proposed PET/CTA results clinical pathway CTA Findings PET Findings Probable Pathology Clinical Decision Normal Normal No epicardial CAD Risk factor modification Abnormal Normal Non-flow limiting CAD Medial therapy Normal Abnormal Small branch disease or pre- clinical decrease in flow reserve Medical therapy or cath if severe symptoms Abnormal Abnormal Flow limiting CAD Cath or medical therapy

Diagnostic strategies

Hx is still critical first step for choosing strategy. Typical vs atypical CP. Degree of symptoms. Level of activity. Good CABG candidate

• r not.

EF / viability.

The options are…

1-Straight exercise treadmill. 2-Treadmill+echo (stress echo) 3-Stress-SPECT 6-Lexiscan-SPECT 7-Dipyridamole-PET 8-CTA

• r

9-PET / CTA

• r

10-Cath 4-Dobutamine echo 5-Dobutamine-SPECT

PET

PROS: More energy so better pictures, esp in obese pt. Attenuation correction. Increases the sensitivity and specificity beyond that of a SPECT scan. Get wall motion and EF at rest and stress. Faster than SPECT. Less radiation. We have a generator so doses not at the mercy of

• utside facilities.

CONS: Coverage. Cannot do with exercise (yet).

Testing flow diagram

Intermediate CP

Can exercise

EKG Normal

YES Plain exercise Stress test

1.Stress Echo 2.Stress- nuc

• 3. CTA

NO or female CanNOT exercise

• 1. CTA
• 2. SPECT
• 3. PET
• 4. PET/CTA

Did this clarify things? Probably not. What question are you trying to answer? What are you going to do with the info / test results?

Money slide…

Atypical CP-want to try and provoke symptoms- treadmill stress. Want to know if the pt has CAD or not. Don’t care about symptoms or ischemia-CTA. Low risk, don’t want to do anything unless you have to-want high specificity-stress echo. Want to avoid all radiation-stress echo. Don’t want to miss major problem-want high sensitivity-nuclear perfusion scan. Don’t want to miss anything-PET/CTA.

Summary

No test is perfect, not even cath. Treadmill is always the best if

• possible. Especially for atypical

CP. Echo and SPECT are similar as imaging modalities except in people with poor echo images. PET is the best. To rule out or rule in CAD, regardless of symptoms think CTA.

Stress Echo-dobutamine and exercise.

Extremely safe. Thousands of pt studied. ~1/2000 adverse events. Safe within 2-3 days of MI. More specific, but not as sensitive for CAD as nuclear.

Bax et al, JACC 1997

What else can you do to increase the yield of your tests ?

Add an imaging modality on top of the treadmill. Nuc scans and echo both increase the Sens/spec/predictive values to ~85%. Additional imaging is especially helpful in females and pt with abnl EKGs.

A picture is worth 1000 words !

RESEARCH

Intro to Stats

Sensitivity - Screen for disease. Specificity - Rule in for disease. Both Sens / Spec are inherent to the test itself. PPV - % results that are a true +. NPV - % results that are a true -. PPV / NPV depends on the population being tested.

The Rev. Bayes’ Theorem

HIV in a nun…

HIV ELIZA is 95% sensitive and specific. How confident are you of a + test in a nun assuming a 10% dz prevalence? What is the likelihood

• f this being a true+?

Disease + - Test +

• total

95 tp 90 fp 5 fn 810 tn 100 900

Sens=tp/(tp+fn) Spec=tn/(fp+tn) PPV=tp/(all positives) NPV=tn/(all neg)

51%!

DXV 301

Mitral valve replacement