The Role Of CT And MRI In The Management Of Ischemic Heart Disease,Patricia Nguyen, MD Division of Cardiovascular Medicine Stanford University,The Great Wall International Congress of Cardiology,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,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 Framingham Risk Score,CACS 400 = CHD Equivalent (10 year risk 20%),Greenland P, ACC/AHA Expert Consensus, JACC, 2007,Can We Do Better Than CACS?,CT exposes patients to radiation Calcification appears relatively lateVery late in women and young tend not to have Ca? Significance of progressionProgression more related to baseline CACSCa related to healed not vulnerable plaqueUnclear if statin improves Ca10% inter-scan variabilityFunctional defects appear years earlier andimprovement 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, 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 Events,Schachinger V, Circulation 2000,147 pts referred for XRA for chest pain or single vessel PCI43% had no angiographic evidence of CADAll significant after multivariate analysis (RF, atherosclerosis on XRA),More CVD Events With Impaired Vasodilation during 7 Year Follow-Up,Schachinger, Circulation 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 response 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 systemic 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 Vasodilation 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 analysisDecreased vasodilation in less active men and women but did not reachsignificance 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 dataCT images can be reformatted 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 heart 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)Overestimation and underestimation of plaque, especially on a per segmentanalysis,Sheth J, AJC, 2006,High Negative Predictive Value With 64 MDCT For In-Stent Restenosis,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-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 standardIndicated only if intermediate pretest probability and ifACS: enzymes and ECG must be negativeChest pain syndrome/Chronic ischemic dz (ECG un-interpretable, 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,