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1、Diagnosis Of Subclinical Atherosclerosis: The Asymptomatic Patient,Subclinical Atherosclerosis And Early Abnormalities Of Structure And Function,Subclinical Atherosclerosis (Higher Risk),Functional Abnormalities Structural Abnormalities,Coronary Artery Calcium Score Is Predictive Of Death And MI,Gre
2、enland, 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 Framingham Risk Score,CACS 400 = CHD Equivalent (10 year risk 20%),Greenland P, ACC/AHA Expert Consensus, JACC, 2007,Can We Do Better
3、Than CACS?,CT exposes patients to radiation Calcification appears relatively late Very late in women and young tend not to have Ca ? Significance of progression Progression more related to baseline CACS Ca related to healed not vulnerable plaque Unclear if statin improves Ca 10% inter-scan variabili
4、ty Functional defects appear years earlier and improvement can occur as early as 2 weeks post Rx,Vascular Function Testing,Assessment of arterial response to chemical or physical stimuli known to cause vasoreactivity Endothelial-dependent: Ach, shear stress, cold pressor Endothelial-independent: NTG
5、, adenosine Measurement in diameter, CSA, velocity, or resistance Normal: Dilation Abnormal: Impaired Dilation, No Response, Constriction Coronary and peripheral arteries XRA, MRI, U/S (brachial artery),Impaired Vasoreactivity To Endothelial Dependent And Independent Stimuli Is Associated With CV Ev
6、ents,Schachinger V, Circulation 2000,147 pts referred for XRA for chest pain or single vessel PCI 43% had no angiographic evidence of CAD All significant after multivariate analysis (RF, atherosclerosis on XRA),More CVD Events With Impaired Vasodilation during 7 Year Follow-Up,Schachinger, Circulati
7、on 2000,MRI Assessment Of Vascular Function,Acquire long and short axis images at baseline Choose most linear segment of artery for short axis images to yield most circular cross section Give stimulus then reacquire high resolution images at “peak” effect of stimulus Measure % change in CSA in respo
8、nse to the stimulus,CSA Post-Stimulus CSA BL - CSA BL,% Vasodilation =,Pre Nitro,Post Nitro,Feasibility Study Of MRI Assessment,To determine if MRI can quantify changes in epicardial size in response to NTG 12 pts undergoing XRA (6 CAD, 6 Tx) and 20 healthy controls 0.4 mg sl NTG with minimal system
9、ic effects Excellent correlation of lumen area w/ XRA: r = 0.98,Terashima, JACC, 2005,Tx,Intra-observer variability 3 2% (r=0.99) Inter-observer variability 5 5% (r=0.96),Nl,MRI NTG Vasodilation Impaired In DM And ESRD,Pre Nitro,Post Nitro,Nl,ESRD,25.6%,17.8%,19.8%,14.8%,Nguyen P, JCMR 2008,MRI Vaso
10、dilation Decreased In Patients With High CAC (ADVANCE),Terashima M, JACC Img, 2008,Association significant after adjustment for RF,MRI NTG Decreased In Physically Inactive,18.9% (5.7%, 33.4%) for 35 vs. 27.6% (12.6%, 38.7%) for 35 (p=0.03) Positive correlation even after multivariate analysis Decrea
11、sed vasodilation in less active men and women but did not reach significance in women % vasodilation related to intensity,Nguyen, P, in prep. AJP,Diagnosis Of CAD And Anatomical Imaging: The Symptomatic Patient,CT Coronary Angiography,Axial images contain true data CT images can be reformatted in mu
12、ltiple 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 segments Improved sensitivity and specificity Similar NPV,Step Artifacts,Beta blockers given to reduce heart rate Shou
13、ld not be performed in patients with significant arrhythmias Improved temporal resolution with dual source system,Blooming Artifact Impairs Evaluation Of Calcified Segments,29 patients with 65 lesions, 45% complex lesions 25% of lesions non-evaluable (15% motion/image noise, 10% severe Ca) Overestim
14、ation and underestimation of plaque, especially on a per segment analysis,Sheth J, AJC, 2006,High Negative Predictive Value With 64 MDCT For In-Stent Restenosis,XRA vs. CTA (64 slice MDCT) in 81 patients Sensitivity 91%, Specificity 93% PPV 77%, NPV 98%, Predictive Accuracy 93% 12% segments not asse
15、ssable,Grade 1: none Grade 2: mild w/ 75% stenosis occlusion,Lewis B, JACC 2007,In-Stent Restenosis,Neointimal hyperplasia without significant stenosis,Complete stent occlusion,Oncel D, Am. J. Roentgenol 2008,Dx Of High Grade Lesions: CT Angiography,XRA remains the gold standard Indicated only if in
16、termediate pretest probability and if ACS: enzymes and ECG must be negative Chest pain syndrome/Chronic ischemic dz (ECG un- interpretable, cannot exercise or equivocal stress test) Evaluation of new onset heart failure Not recommended for in stent restenosis Radiation dose is 5 to 13 mSv (1 yr back
17、ground radiation) and 100 cc of contrast required,MR Coronary Angiography Promising But Complex Acquisition With Lower Spatial Resolution,Diagnosis And Risk Assessment In The Symptomatic Patient : Functional Imaging by MRI,MRI Assessment Of Resting Function Is “Gold Standard”,MRI Stress Perfusion: A
18、reas With Significant Stenosis Enhance Less And More Slowly,Stress,Rest,Sensitivity, Specificity And Accuracy,MRI 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
19、 echo is preferred If image quality impaired in echo, MRI perfusion is a good alternative,Abnormal Microvascular Function In Syndrome X,Painting, NEJM, 2002,Guiding Revascularization Post MI And Prognosis: Myocardial Viability,MRI Assessment Of Viability,Infarct (Gd),Normal,Imaging Sequence (SE, FSE
20、, GRE) Normal myocardium signal is null (dark) Infarct has partially recovered (bright),TI,Gd is injected. Wait 10 - 15min. Gd accumulates in infarcted tissue A 180 RF pulse inverts all the spins. Tissues return to nl at different rates. At time TI, imaging sequence begins.,180 Inversion Pulse,Low C
21、hance Of Recovery If Delayed Enhancement 75%,Kim, R et al, NEJM 2000,No hyperenhancement =78% segments improved Only 1 out of 58 segments improved if hyperenhancement 75% Less certain outcome for segments between 25-50% Same relationship in segments with most dysfunction Recent studies have also sho
22、wn increased areas of DE indicates worse prognosis,Delayed Enhancement Compared To Available Techniques,Comparable sensitivity to DBA echo but slightly lower specificity MRI preferred in patients with severe baseline hypokinesis Comparable sensitivity and specificity to PET and SPECT Ability to dete
23、ct small, subendocardial infarcts better than PET or SPECT,MRI Detects Small Infarcts Better Than SPECT,Ibrahim T, JACC 2007,Microvascular Obstruction After AMI Is Marker Of Poor Prognosis,Wu KC, Circulation 1998,Comprehensive Evaluation Of Patient With Ischemic Cardiomyopathy,MRI Delayed Enhancemen
24、t As Alternative to DBA Echo On A Case By Case Basis,Comparable sensitivity and specificity for DBA echo and MRI delayed enhancement Due to cost and patient comfort, DBA echo is preferred Exceptions: Patients with baseline severe hypokinesis to akinesis Image quality impaired in echo,Conclusion,MRI
25、can provide earlier detection of subclinical disease than coronary calcium but further study needed CTA for subset of patients with negative or equivocal evaluations or requiring coronary anatomy evaluation but with low probability of CAD MRI can provide comprehensive evaluation of patient with ischemic cardiomyopathy Resting function Detection of ischemia Viability,