Tagged MRI and PET in severe CAD: discrepancy between preoperative inotropic reserve and intramyocardial functional outcome after revascularization.
In severe coronary artery disease (CAD), it has been shown that intramyocardial inotropic reserve as assessed with tagged magnetic resonance imaging (MRI) is uniformly distributed among positron emission tomography (PET) patterns reflecting normal or concomitant reductions in perfusion and glucose metabolism. This preliminary study aimed to delineate the relationship between preoperative values of intramyocardial inotropic reserve (in different PET patterns of perfusion and glucose uptake) and intramyocardial functional outcome after surgical revascularization in severe CAD. Twelve patients underwent preoperative tagged MRI (baseline, 10 microg.kg(-1).min(-1) of dobutamine), H2 15O/[18F]fluorodeoxyglucose PET imaging, and postoperative resting tagged MRI. Regional midmyocardial circumferential shortening (Ecc, in %) and PET patterns (normal, match viable, mismatch viable, and infarcted) were assessed in three tagged MRI/PET short-axis slices. Ecc at baseline ranged from 12 +/- 6 to 8 +/- 5 and 4 +/- 4% in normal, match-viable, and infarcted regions, respectively (P <0.05) and was 8 +/- 5% in mismatch-viable regions. Of the 429 regions studied, 187 showed preoperative inotropic reserve with dobutamine, but 238 showed postoperative functional improvement. Postoperative functional improvement was less common in infarcted regions (41 vs. approximately 60% in the other PET patterns), but the extent of improvement was similar among PET patterns (approximately 6%). Postoperative functional improvement occurred in 53% of all (normal, match viable, and mismatch viable) regions without inotropic reserve. In severe CAD, revascularization affords greater intramyocardial functional benefit than expected from the evaluation of intramyocardial inotropic reserve with low-dose dobutamine. Postoperative functional improvement in PET-viable regions without inotropic reserve suggests that factors other than regionally enhanced perfusion contribute to such functional improvement.
Mazzadi
Alejandro N
AN
Centre de Recherche et d'Applications en Traitement de l'Image et du Signal, Unité Mixed de Recherche-Centre National de Recherche Scientifique 5515, Unité 630, Institut National de la Santé et de la Recherche Médicale, 69394 Lyon, France.
Janier
Marc F
MF
Brossier
Benjamin
B
André-Fouët
Xavier
X
Revel
Didier
D
Croisille
Pierre
P
D000328:Adult; D000368:Aged; D002316:Cardiotonic Agents; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D004280:Dobutamine; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009204:Myocardial Revascularization; D049268:Positron-Emission Tomography; D012720:Severity of Illness Index; D016896:Treatment Outcome
D002316:Cardiotonic Agents; D004280:Dobutamine