European Society of Cardiology Annual meeting, 2010, Stockholm, Sweden Stress only Perfusion Imaging Oliver Gaemperli, MD Cardiovascular Center, University Hospital Zurich, Switzerland
Male patient, 48 yo Intermittent chest pain (non-anginal) Mild hypertension (controlled with amlodipine) No other cardiovascular risk factors, negative FHx Exercise test: 105% of max. predicted workload. No chest pain, 1.0 mm horizontal ST depression in inferior leads What next?
Myocardial perfusion study Can the study be stopped after the normal stress images? What additional information will be gained from the rest study? Is his prognosis the same than with a normal stress/rest study? Instead of a rest study, should we rather test for subclinical atherosclerosis?
Reasons for acquiring two sets (i.e. stress and rest) of images in MPI Identify reversibility of defects Increasing confidence to identify artifacts Assessment of nonperfusion variables (TID) Assessment of LVEF (if gating problem with 1 of the 2 studies) 4 decades of tradition! Logistic reasons (image reading at the end of the day)
Prognosis of patients with stress only perfusion studies Overall cardiac event rate: 0.6% No cardiac deaths 1 MI 3 UA N=729 Gibson et al. JACC 2002;39:999
Normal Stress-only vs. Standard stress/rest MPI Stress-only: N=8,034 pts Criteria for normal stress perfusion study: 1999 2007: 27,540 consecutive SPECT studies 16,854 patients with normal perfusion studies N.B. 1/3 of all referred patients between 1999 and 2007 -homogenous tracer distribution over LV -normal LV cavity size -LVEF 50% Standard stress/rest: N=8,820 pts Follow-up 4.5 y The Methodist Hospital, Houston, Texas Chang et al. JACC 2010;55:221
Normal Stress-only vs. Standard stress/rest MPI The Methodist Hospital, Houston, Texas Chang et al. JACC 2010;55:221
Stress-only imaging is safe in higher-risk populations Chang et al. JACC 2010;55:221
Impact of stress only protocols on radiopharmaceutical dosage Chang et al. JACC 2010;55:221
Normal Stress-only vs. Standard stress/rest MPI Annualized death rates were comparable (after correction for baseline factors) in patients with stressonly and stress/rest studies. In the stress-only group, there was no difference in mortality on the basis of whether patients received a low or high dose of radiopharmaceutical (unadjusted p=0.12, adjusted p=0.34) The Methodist Hospital, Houston, Texas Chang et al. JACC 2010;55:221
Prognosis of stress-only MPI Duwall et al. J Nucl Cardiol. 2010;7:370
Value of attenuation correction in stress-only SPECT imaging Interpretation of stress-only Tc-99m sestamibi SPECT imaging based on reader confidence N=90 Perceived need for rest study: 77% 76% 43% Heller GV et al. JNC 2004;11:273
Added value of stress gated SPECT over perfusion alone 101 pts with angiographically proven LM disease Berman DS et al. JNC 2007;14:521
Added value of stress gated SPECT over perfusion alone 101 pts with angiographically proven LM disease Berman DS et al. JNC 2007;14:521
Requirements for Stress-only Imaging Good quality images Experienced reader The stress study is done as the initial study The tracer dose is selected per accepted guidelines, and a large dose is used only if the patient would otherwise have qualified for a 2-day study Interpretation soon after acquisition and processing Unequivocally normal perfusion and function, by visual and quantitative analysis. The interpretation should equally be unequivocal Attenuation correction increases reader s confidence but is not a necessity for stress-only imaging paradigm This paradigm of stress only imaging could be applicable to exercise and pahrmacological stress testing and to patients with known or unknown coronary artery disease Iskandrian JACC 2010;55:231
ASNC 2009
Complementary role of CT angiography and MPI N=114 patients undergoing CT angiography and myocardial perfusion SPECT Relation between MSCT and MPI results MPI abnormal MPI normal 11% 48% CTCA abnormal 52% CTA normal 89% Schuijf et al. JACC 2006;48:2508 14
Survival free of death or MI Incremental prognostic value of MSCT and MPI 1 MSCT <50% and MPI normal MSCT <50% and MPI abnormal* MSCT 50% and MPI normal 0.5 Log-rank test: p<0.005 MSCT 50% and MPI abnormal* * MPI abnormal = SSS 4 0 0 125 250 375 500 625 Follow-up (days) Patients at risk 439 423 386 354 299 243 van Werkhoven JM, et al. JACC 2009;53:623
Stress only perfusion imaging combined with CTCA In 200 patients with low-to-intermediate pretest probability stress-only MPI combined with CTCA was compared with stress/rest MPI 24% of patients had abnormal perfusion by MPI Agreement between both techniques (normal/abnormal) was 100% In 47% of patients the CTCA added information on intermediate coronary lesions, nonstenotic plaques and/or coronary anomalies Mean radiation exposure of stress MPI/CTCA was 5.4 msv, examination time was shorter (130 vs. 245 min) Husmann et al. Eur Heart J 2009;30:600
Male patient, 58y Atypical chest pain CvRF: dyslipidemia, hypertension, obesity Unable to exercise: knee arthritis Unremarkable cardiopulmonary physical examination Normal baseline ECG
1-day adenosine stress / rest SPECT No significant ECG changes
CTCA with calcifications and plaques on LAD
Individualized stepwise fast-track algorithm including CTCA and stress-only SPECT *CTCA using prospective ECG-triggering SPECT using half-dose 150/450 MBq 1-day (Evolution) Individualized Nonselective CTCA* N=40 Stress MPI N=20 Rest MPI N=40 STOP N=20 1.9±0.8 msv STOP N=4 4.6±0.8 msv STOP N=16 8.6±1.4 msv CTCA Stress/Rest MPI N=40 Total population 193.1 min 325.7 min Mean per patient 4.8±3.4 msv 8.1±1.5 msv Pazhenkottil AP et al. EJNM 2010;37:522
Stress only myocardial perfusion imaging In patients with low-to-intermediate pretest probability the prevalence of normal perfusion scans is high The main purpose in these patients is to exclude CAD rather than to establish reversibility of defects In these patients it is safe to discontinue the test after a normal stress perfusion study The paradigm of stress only perfusion imaging can also be applied to higher risk patients Advantages are: reduced radiation dose, Reduced costs and time expenditure, improved patient throughput, savings in Tc use The addition of a different complementary test (e.g. CTCA) may be preferred to a rest study in certain patients with normal stress-only MPI
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Thank you Cardiovascular Center, University Hospital Zurich, Switzerland Email: oliver.gaemperli@usz.ch