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 360 o views-normal
3-D 360 o views-cad of LAD
Anomalous Coronary Artery-Cx
CTA and Prognosis Andreini et al, JACC CV Imaging 2012
A&P Anatomy versus Physiology Anatomy Looks at degree of stenosis / amount of coronary artery disease. CTA MRA Invasive cath Physiology Looks for ischemia Echo Nuclear cmr Cath IVUS vs FFR (Anatomy) v (Physiology)
For 2013 it s $482.
Another cost -Radiation exposure msv 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?? CXR equivalents 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) Use of Resources CCTA-based (%) Traditional Care (%) We are obtaining 1 year follow-up 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 Rehospitalization 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?
PROS: No radiation. Get wall motion, EF. Stress echo 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 of data. CTA could replace IVUS as a major research tool.
What Gold standard? Noninvasive (physiologic) studies are measured against cath FFR (physiology) now considered validation for cath. FFR validated by SPECT! Cath (anatomy) is the gold standard Cath is not perfect- Glagov phenomena
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 preclinical decrease in flow reserve if severe symptoms Medical therapy or cath 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 or not. EF / viability.
The options are 1-Straight exercise treadmill. 2-Treadmill+echo (stress echo) 3-Stress-SPECT 4-Dobutamine echo 5-Dobutamine-SPECT 6-Lexiscan-SPECT 7-Dipyridamole-PET 8-CTA or 9-PET / CTA or 10-Cath
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 outside facilities. CONS: Coverage. Cannot do with exercise (yet).
Can exercise Testing flow diagram Intermediate CP CanNOT exercise YES Plain exercise Stress test EKG Normal NO or female 1.Stress Echo 2.Stressnuc 3. CTA 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 symptomstreadmill 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? A picture is worth 1000 words! 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.
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 Test + - total Disease + - 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) 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 of this being a true+? 51%!
DXV 301
Mitral valve replacement