Forml med studien:

PROTOCOL
Diagnosing ischemia with stress echocardiography in comparison to and combination
with perfusion imaging.
ISCHEMIDIAGNOSTIKK MED STRESSEKKOKARDIOGRAFI I KOMBINASJON
MED SCINTIGRAFISK MYOCARDPERFUSJONS-AVBILDING
BACKGROUND:
Coronary angiography is the present”Gold standard” for the diagnosis of Coronary heart disease, although it is a measure of anatomical stenoses rather than ischemic function in terms of coronary reserve. As it is also invasive, non invasive methods are important. Myocardial perfusion by SPECT scintigraphy is evaluated during peak stress by injection of a radioactive tracer. It is an established method, and has a diagnostic sensitivity for Coronary heart disease of 80 - 90%, and a specificity of ca 80% (1). Stress echocardiography with exercise- or pharmacological stress, shows regional wall motion abnormalities in the presence of local ischemia during stress. The present method for interpretation is by visual evaluation of regional myocardial wall thickening and -function in gray scale images (Wall motion score, WMS). In clinical studies stress echocardiography has shown sensitivity for coronary heart disease of 80-90 %, and specificity of approximate 90% (2,3). The method is subjective, and demands expertise (4,5,6). Tissue Doppler measures wall motion velocities, and local deformation (strain) and strain rate can be derived from this (7). By this method, regional dysfunction can be quantitated (8, 9). This has been shown to give incremental information in stress echocardiography (10, 11). The increased sensitivity may also serve to reduce he stress level necessary for diagnosis of ischemia. Speckle tracking is a newer and less well studied method, where motion can be tracked by the speckle interference pattern in B-mode images (12). By this tracking, both regional strain and strain rate can be measured. Tissue Doppler has higher temporal resolution, and is less dependent on spatial smoothing, while speckle tracking has higher spatial resolution. It is unclear, however, whether the method tracks as well in high frame rate. The temporal smoothing I may also be of concern regarding sensitivity of this method in stress echo. OBJECTIVE:
- Evaluate the performance of speckle tracking during high heart rate - Evaluate diagnostic sensitivity and specificity of strain rate imaging in stress echo - Evaluate the diagnostic performance of speckle tracking during stress echo, compared - Compare the diagnostic sensitivity and specificity of strain rate imaging stress echocardiography to myocardial perfusion imaging by SPECT, and assess the eventual incremental information by combining both methods. - Coronary angiography is the external reference. Even though this is no physiological gold standard for ischemia, it will serve as an independent external reference for the comparison of the non invasive methods. STUDY DESIGN
Diagnostic study, sensitivity and specificity versus external reference. 60 – 90 patients, with stable angina / chest pain and no previous infarction, who are referred for a diagnostic coronary angiography will be examined. The stress modality will be dobutamine stress, up to 40 μg with eventual additional atropine. Echo acquisitions will be done at baseline, at 10 μg, 20 μg and peak stress. At peak stress 99Technetium tetrofosmine will be given, and perfusion images acquired afterwards. Resting stress will be acquired separately. Data are post processed, blinded to angiography results. Both stress echo and SPECT will be analysed according to the ASE 16 segments model of the left ventricle (21). Segments will be analysed by Wall motion score, peak systolic strain rate and strain, and perfusion by SPECT. Inter- and inter observer variability will also be assessed. Diagnostic sensitivity of WMS, SRI by both tissue Doppler at 20 μg and peak stress, as well as SPECT will be evaluated against coronary angiography as external reference. In addition, the incremental value of adding methods will be assessed. STUDY SIZE
60 – 90 patients who have been referred to coronary angiography. The number is based on
previous studies in stress echocardiography, where this study size has been sufficient to
demonstrate incremental value of strain rate imaging in stress echocardiography.
ETHICS:
The study is approved by the regional ethics committee and the data supervisory body for
Norway.
REFERENCES
1. Azzarelli S, Galassi AR, Foti R, Mammana C, Musumeci S, Giuffrida G, Tamburino C. Accuracy of 99mTc-tetrofosmin myocardial tomography in the evaluation of coronary artery disease. J Nucl Cardiol 1999 Mar-Apr;6(2):183-9 2. Quinn RR, Pflugfelder PW, Kostuk WJ, Boughner DR. Intracoronary ultrasound imaging: methods and clinical applications. Can J Cardiol 2000 Jul;16(7):911-7 3. Bjornstad K, Aakhus S, Hatle L. Comparison of digital dipyridamole stress echocardiography and upright bicycle stress echocardiography for identification of coronary artery stenosis. Cardiology 1995;86(6):514-20 4. Picano E, Lattanzi F, Orlandini A, Marini C, L'Abbate A. Stress echocardiography and the human factor: the importance of being expert. J Am Coll Cardiol 1991 Mar 1;17(3):666-9 5. Popp R et al. Recommendations for Training in Performance and Interpretation of Stress Echocardiography. J Am Soc Echocardiogr 1998;11:95-6.) 6. Fathi R, Cain P, Nakatani S, Yu HC, Marwick TH. Effect of tissue Doppler on the accuracy of novice and expert interpreters of dobutamine echocardiography. Am J Cardiol 2001 Aug 15;88(4):400-5 7. Heimdal A, Stoylen A, Torp H, Skjaerpe T. Real-time strain rate imaging of the left ventricle by ultrasound. J Am Soc Echocardiogr 1998 Nov;11(11):1013-9 8. Stoylen A, Heimdal A, Bjornstad K, Torp H, Skjaerpe T. Strain Rate Imaging in the diagnosis of regional dysfunction of the left ventricle. Echocardiography 1999; 16(4): 321-9 9. Støylen A, Heimdal A Bjørnstad K, Wiseth R, Vik-Mo H, Torp H, Angelsen B, Skjærpe T. Strain Rate Imaging by Ultrasound in the Diagnosis of Coronary Artery Disease. J Am Soc Echocardiogr 2000;13(12):1053-64 10. Ingul CB, Stoylen A, Slordahl SA, Wiseth R, Burgess M, Marwick TH. Automated analysis of myocardial deformation at dobutamine stress echocardiography: an angiographic validation. J Am Coll Cardiol. 2007 Apr 17;49(15):1651-9. 11. Bjork Ingul C, Rozis E, Slordahl SA, Marwick TH. Incremental value of strain rate imaging to wall motion analysis for prediction of outcome in patients undergoing dobutamine stress echocardiography. Circulation. 2007 Mar 13;115(10):1252-9. 12. Amundsen BH, Crosby J, Steen PA, Torp H, Slørdahl SA, Støylen A. Regional myocardial long-axis strain and strain rate measured by different tissue Doppler and speckle tracking echocardiography methods: a comparison with tagged magnetic resonance imaging. Eur J Echocardiogr. 2008 Jul 23. [Epub ahead of print] PMID: 18650220

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