title: Dobutamine-tagged MRI for inotropic reserve assessment in severe CAD: relationship with PET findings.
abstract: The impact of blood flow reductions on the intramyocardial inotropic reserve has not yet been established in coronary artery disease (CAD). We therefore evaluated in severe CAD the relationship between positron emission tomography (PET) patterns of perfusion and glucose uptake and the corresponding tagged magnetic resonance imaging (tagged MRI) values of midmyocardial strains under low-dose dobutamine. Eighteen patients underwent tagged MRI (at rest, with dobutamine) and H2(15)O/18F-fluorodeoxyglucose PET. Regional midmyocardial circumferential shortening (Ecc) and PET patterns (normal, match viable, mismatch viable, and infarcted) were assessed in three tagged MRI/PET short-axis slices. Regional Ecc at rest correlated with both perfusion (r = 0.49) and glucose uptake (r = 0.58). The presence of the inotropic reserve was similar in normal, match viable, and infarcted (approximately 40% of regions vs. 52% in mismatch viable, P < 0.05), but the extent of the increase after dobutamine was lower in infarcted regions (P = 0.06). Within each PET pattern, regions were grouped according to their Ecc values at rest into three categories (high, intermediate, and low contractile performance). In mismatch viable (hibernation), the inotropic reserve was similar among the three categories, but in the other PET patterns the presence and extent of the inotropic reserve was higher in those regions with lowest Ecc (without significant differences in perfusion). In severe CAD, the presence of the inotropic reserve assessed by midmyocardial changes under dobutamine does not relate to resting perfusion. At a similar level of perfusion, the presence of the inotropic reserve is inversely related to contractile performance at rest, but our results suggest that it may not be true for hibernating myocardium.
authors.affiliation: Unité Mixte de Recherche-Centre National de la Recherche Scientifique 5515, Centre de Recherche et d'Applications en Traitement de l'Image et du Signal, Lyon, France.
authors.forename: Alejandro N
authors.initials: AN
authors.lastname: Mazzadi
authors.forename: Marc F
authors.initials: MF
authors.lastname: Janier
authors.forename: Benjamin
authors.initials: B
authors.lastname: Brossier
authors.forename: Xavier
authors.initials: X
authors.lastname: André-Fouët
authors.forename: Eugene
authors.initials: E
authors.lastname: McFadden
authors.forename: Didier
authors.initials: D
authors.lastname: Revel
authors.forename: Pierre
authors.initials: P
authors.lastname: Croisille
mesh_terms: D000328:Adult; D000368:Aged; D002316:Cardiotonic Agents / Q000008:administration & dosage; D003327:Coronary Disease / Q000175:diagnosis* / Q000503:physiopathology*; D004280:Dobutamine / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D012720:Severity of Illness Index; D014055:Tomography, Emission-Computed
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine