1、The Role Of Echo/CT/MR In The Management Of Ischemic Heart Disease,Patricia Nguyen, MD Stanford University Division of Cardiovascular Medicine,Coronary Artery Disease,Screening,Guide Revascularization,Risk Assessment,70% stenosis,Mechanical Complications,Ischemia,Function,Echo and MRI,CT,CAC,Viabili
2、ty,Diagnosis,Coronary Artery Calcium Score Is Predictive Of Death And MI,Greenland, P. et al. ACC/AHA Expert Consensus, JACC, 2007,Higher CACS, higher event rates,*f/u 3-5 years,Coronary Artery Calcium Score Improves Risk Stratification Over FRS,CACS 400 = CHD Equivalent (10 year risk 20%),Greenland
3、, P. , ACC/AHA Expert Consensus, JACC, 2007,If patients have 2 RF then perform FRSOlder age (M 45 years; F 55 years).For men age 70, older age counts as 2 risk factorsCigarette smokingHypertensionLow HDL cholesterol Family history of premature coronary heart disease,If patients high risk, do not per
4、form,CAC Algorithm,Which Patient Should Be Referred For CACS?,80 yo man with DM, HTN (SBP 180) 50 yo woman with untreated HTN (SBP 160) 65 yo man with untreated HTN (SBP 150), and dyslipidemia (Tchol 180, HDL 35),Calculate Risk Score,80 yo man with DM, HTN (SBP 180) 50 yo woman with hypertension (SB
5、P 160) 65 yo man with untreated hypertension (SBP 150), dyslipidemia (Tchol 180, HDL 35): 17%Intermediate risk patients benefit from further risk stratification with CACs,Screening With Coronary Calcium,Provides independent prognostic value over traditional cardiac risk factors Asymptomatic patients
6、 with intermediate Framingham risk scores (age, gender, smoking, Tchol, HDL, SBP) No role in patients with established CAD If CAC 400 then treat as high risk High risk patients with CAC = 0 still derive benefit from prevention,CT Coronary Angiography,Axial images contain true dataCT images can be re
7、formatted inmultiple 2D views and with 3D reconstruction,High Grade LAD Lesion,Mhlenbruc G, Eur Radio 2006,Sensitivity And Specificity: 64 MDCT,From 4 to 64 MDCT Decrease in number of unevaluable segmentsImproved sensitivity and specificitySimilar NPV,Step Artifacts,Beta blockers given to reduce hea
8、rt rateShould not be performed in patients with significant arrhythmiasImproved temporal resolution with dual source system,Blooming Artifact Impairs Evaluation Of Calcified Segments,29 patients with 65 lesions, 45% complex lesions25% of lesions non-evaluable (15% motion/image noise, 10% severe Ca),
9、Sheth J, AJC, 2006,Underestimation And Overestimation Of Segmental Stenosis In Over Half Of Lesions,Herzog C, Radiology 2007,Blurring Impairs Evaluation Of In-Stent Restenosis,Use thinner slices (0.75 mm) for reconstructionUse smoother reconstruction filters (lower number)Improves contrast detailDec
10、reases noisePoorer edge detection,High Negative Predictive Value With 64 MDCT,XRA vs. CTA (64 slice MDCT) in 81 patientsSensitivity 91%, Specificity 93%PPV 77%, NPV 98%, Predictive Accuracy 93%12% segments not assessable,Grade 1: none Grade 2: mild w/ 75% stenosis occlusion,Lewis B, JACC 2007,In-Ste
11、nt Restenosis,Neointimal hyperplasia without significant stenosis,Complete stent occlusion,Oncel D, Am. J. Roentgenol 2008,Dx of High Grade Lesions: CT Angiography,Indicated only if intermediate pretest probabilityACS: enzymes and ECG must be negativeChest pain syndrome/Chronic ischemic dz (ECG un-i
12、nterpretable, cannot exercise or equivocal stress test) Evaluation of new onset heart failureNot recommended for in stent restenosisRadiation dose is 5 to 13 mSv (1 yr background radiation) and 100 cc of contrast required,MR Angiography: Spiral High Resolution Imaging,Coronary Artery Disease,Screeni
13、ng,Guide Revascularization,Risk Assessment,70% stenosis,Mechanical Complications,Ischemia,Function,Echo and MRI,CT,CAC,Viability,Diagnosis,Diagnosis By Echo Or MRI: Ischemic Cascade,Wall Motion And Resting Function,Dx of CAD in pts with ACS only if clinical hx and ECG inconclusive Resting wall motio
14、n abnormalities AMI High negative predictive value Risk assessment LV function: MR indicated only if Echo insufficient RV function best assessed by MRI,LV Dysfunction Is Predictive of Mortality Early and Late after MI,Fleischmann KE. Am J Cardiol 1997,Larose , JACC 2007,RV Dysfunction Is Predictive
15、Of Mortality,140 pts 30 days after MI, underwent cine MRI17 month follow - up 26 deaths,Function Assessment: Steady State Free Precession,Principle of Stress Imaging,Induce stress by exercise or pharmacologic (DBA or vasodilator transient ischemia) Echocardiography stress testing Compare wall motion
16、 at stress and rest MRI stress perfusion Compare perfusion at stress and rest,MRI Approach To Perfusion,Rest study compared to stress study (during adenosine infusion) Single bolus, equilibrium period, double bolus of Gd-DTPA Low doses (0.025-0.05 mmol/kg) maintain linear relationship btwn Gd conc.
17、and signal intensity Higher doses (0.075 to 0.1 mmol/kg) incr contrast 30 phases acquired, with breath-holding Short axis, multi-slice (i.e. 4 ) FGRET (hybrid echoplanar imaging and SPGR),Areas With Significant Stenosis Enhance Less And More Slowly,Stress,Rest,Sensitivity, Specificity And Accuracy,M
18、RI Perfusion Alternative To Stress Echo On A Case by Case Basis,Comparable sensitivity and specificity for stress echo and MRI perfusion Due to cost, versatility and patient comfort, stress echo is preferred If image quality impaired in echo, MRI perfusion is a good alternative,Abnormal Microvascula
19、r Function In Syndrome X,Painting, NEJM, 2002,Viability,Patients with ICM have a poor prognosis. Five year survival rates range from 50-60% Survival is worse as LVEF decreases Global ventricular dysfunction is not necessarily irreversible Inotropic stimulation improves LVF Previous observational stu
20、dy shows reversibility Patients with viable myocardium benefit most from revascularization LV function, Sxs,Viable Myocardium,Non-invasive Tests,DBA For Viability,Low dose DBA (5 to 20 ug/kg/min), coronary blood flow increases with recruitment of contractile reserve and improvement of wall motionIf
21、DB is increased further, wall motion worsens if a critical lesion is presentBiphasic response= hibernating myocardiumIf continued augmentation of systolic response, critical stenosis not presentSensitivity 84%, Specificity 81%, PPV 83%, NPV 81,Bax, JAAC 1997,Advantages And Limitations of DBA,Lower s
22、ensitivity and higher specificity compared to perfusion imaging (SPECT/PET and MRI) Specificity increases with biphasic response High inter-observer variability, operator dependent Incomplete visualization of wall thickening in up to 15-20% of pts False + Tethering of nonviable segments adjacent to
23、viable ones can give an illusion of recovery False - Inotropic response attenuated (ischemic at low doses) in pts receiving B blockers or with severely stenotic coronary or extensive damage,MRI Assessment Of Viability,Gd-DTPA = extracellular, interstitial contrast agent Increase Vd in infarcted tiss
24、ue (less cells, more space) Acute MI: Necrosis membrane rupture & edema Chronic MI: Myocytes replaced collagen (scar) Longer washout time in infarcted tissue due to decreased capillary density 37 fold increase in # capillaries w/ erythrocyte stasis More extracellular space Smaller capillary SA decre
25、ases rate of transport and increases diffusion distance Diffusion time = (travel distance)2 Infarcted tissue has more Gd that remains longer Gd shortens T1 in infarct relative to normal tissue Infarcted is bright and nl myocardium is black,Contrast-Enhanced MR,Infarct (Gd),Normal,Imaging Sequence (S
26、E, FSE, GRE) Normal myocardium signal is null (dark) Infarct has partially recovered (bright),TI,Gd is injected. Wait 10 - 15min.Gd accumulates in infarcted tissueA 180 RF pulse inverts all the spins.Tissues return to nl at different rates.At time TI, imaging sequence begins.,180 Inversion Pulse,Acc
27、uracy Of MRI-DE,Kim R, Circulation 1999,Canine Model (n=18)At day 0, surgeryAcute MI and Chronic MI (n=14)Reperfused MI (n=4)Ischemia (n=8)At day 3In vivo imaging performed with reversible occluder/Doppler flowAt day 1, 3, wk 8 In vivo and Ex vivo Imaging,Kim R, Circulation 1999,Delayed Enhancement
28、Only In Regions With Permanent Occlusion,Kim R, Circulation. 1999,Good correlation at D1, D2, 8 wksSpatial extent identical fornecrosis and scarDE only in areas of infarct,Spatial Extent Of Delayed Enhancement Correlated With Infarct,Volume of DE decreased 3.4xVolume of “nl” increased 1.2 x? Reversi
29、ble injury? Scar shrinkage w/ compensatory hypertrophy,Kim R, Circulation 1999,Volume Of Scar Decreased With Time,Clinical Utility Of MRI Delayed Enhancement,51 patients with LV dysfunction recruitedprior to PCI or CABGAreas without hyperenhancement recoverRange of transmural involvement,Kim, R et a
30、l, NEJM 2000,Low Chance of Recovery If Delayed Enhancement 75%,Kim, R et al, NEJM 2000,No hyperenhancement =78% segments improvedOnly 1 out of 58 segments improved if hyperenhancement 75%Less certain outcome for segments between 25-50%Same relationship in segments with most dysfunction,Delayed Enhan
31、cement Compared To Available Techniques,Comparable sensitivity and specificity to PET and SPECT Comparable sensitivity to DBA echo but slightly lower specificity Ability to detect small, subendocardial infarcts better than PET or SPECT,MRI Detects Small Infarcts Better Than SPECT,Ibrahim T, JACC 200
32、7,Microvascular Obstruction After AMI Is Marker Of Poor Prognosis,Wu KC, Circulation 1998,Comprehensive Evaluation Of Ischemic Patient,Coronary Artery Disease,Screening,Guide Revascularization,Risk Assessment,70% stenosis,Mechanical Complications,Ischemia,Function,Echo and MRI,CT,CAC,Viability,Diagn
33、osis,Echo Is The Modality Of Choice For Mechanical Complications,Accounts for 8% of in hospital mortality in AMIAcuteRuptureMitral regurgitationLV thrombusPericardial effusion/tamponadeChronic Infarct expansion (remodelling)Ventricular aneurysm (true vs pseudo)LV thrombus,Ruptured Papillary Muscle,P
34、seudoaneurysm,Conclusion,Screening: CACS used for intermediate patients Diagnosis (Anatomical evaluation): Most patients should be referred for XRA CTA for subset of patients with negative or equivocal evaluations or requiring coronary anatomy evaluation but with low probability of CAD Risk Stratification and Guidance for Revascularization: Echo first line for mechanical complications Echo first line for ischemia except in patients with high suspicion of microvascular disease MRI is preferred for assessment of viability in patients with severely decreased LV function,
