Assessment of myocardial ischemia by strain dobutamine stress echocardiography and cardiac magnetic resonance perfusion imaging before and after coronary artery bypass grafting.
BACKGROUND
Following coronary artery bypass grafting (CABG), testing for myocardial ischemia by noninvasive imaging is often hampered by false-positive results. The aim of this study was to find test parameters with the best potential to identify myocardial ischemia in post-CABG patients.


METHODS
Fifty-two consecutive patients scheduled for CABG, underwent both dobutamine stress echocardiography (DSE) and cardiac magnetic resonance first-pass perfusion imaging (CMR-FPPI) with adenosine vasodilation, before and 8-10 months after the surgical revascularization. A pathologic biphasic stress response (PBR) expresses the presence of contractile reserve during low-dose dobutamine that decreases to hypo- or akinesia provoked by high-dose dobutamine. During DSE, potential PBR, segmental wall-motion score (WMS) as well as peak-systolic longitudinal strain (PLS) at peak-dose dobutamine were assessed.


RESULTS
Post-CABG, there was still a relatively high prevalence of ischemia-positive segments evaluated by deformation imaging, but the number of such segments was significantly lower by PBR (20% and 22%) compared with peak-dose strain and WMS (62% and 77%, respectively; P<.05). The use of PBR instead of peak-dose WMS and strain could reduce the number of false-positive test results post-CABG.


CONCLUSIONS
Among all imaging modalities tested, PBR by WMS and strain may be useful parameters for identifying patients with the need for new revascularization. We furthermore found that DSE may be interpreted as positive when revealing at least three ischemia-positive segments. The sensitivity of these test modalities for detecting coronary restenosis needs to be determined in further studies on a cohort of symptomatic post-CABG patients.
University Hospital North Norway, Tromsø, Norway.
Assami
http://orcid.org/0000-0001-9084-5805
A
Rösner
University Hospital North Norway, Tromsø, Norway.|Department of Clinical Medicine, University of Tromsø, The Arctic University, Tromsø, Norway.
Henrik
H
Schirmer
University Hospital North Norway, Tromsø, Norway.
Amjid
A
Iqbal
ICREA-Universitat Pompeu Fabra, Barcelona, Spain.|K.U. Leuven, Leuven, Belgium.
Bart
B
Bijnens
University Hospital North Norway, Tromsø, Norway.
Derk
D
Avenarius
University Hospital North Norway, Tromsø, Norway.
Siri
S
Malm
D015331:Cohort Studies; D003287:Contrast Media; D001026:Coronary Artery Bypass; D004280:Dobutamine; D025401:Echocardiography, Stress / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging*; D009942:Organometallic Compounds; D055420:Perfusion Imaging; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results
D003287:Contrast Media; D009942:Organometallic Compounds; D004280:Dobutamine; D019786:Gadolinium DTPA; C112666:gadoversetamide
coronary artery bypass grafting; dobutamine stress echocardiography; inducible ischemia; magnetic resonance first-pass perfusion imaging; strain-rate imaging