Myocardial contractile response to increasing doses of dobutamine in patients with reperfused acute myocardial infarction by cardiac magnetic resonance imaging.
BACKGROUND
Cardiac magnetic resonance imaging uses contractile response to dobutamine (DCMR) and delayed contrast enhancement (DE) to assess myocardial viability. However, early after acute myocardial infarction (AMI) the optimal dose of dobutamine is unclear.


METHODS
In patients early after reperfused AMI, DCMR at 5, 10 and 20 microg*kg(-1)*min(-1) and measurement of DE was performed. On three short-axis slices 18 segments were graded as no DE, DE <50% and DE >or=50%. Thickening (systolic-diastolic wall thickness) and contractile reserve (max. thickening - rest) were determined. Segments were classified dysfunctional if thickening was >2 SD below normal or <2 mm.


RESULTS
Forty-nine patients participated. In segments with no DE, thickening increased continuously but contractile reserve was low (0.9 +/- 3.2 mm) and dysfunctional segments were unchanged (rest: 13.1% vs. 20 microg: 14.8%). In segments with DE, contractile reserve was high (1.4 +/- 3.0 mm and 1.5 +/- 3.0 mm) and dysfunctional segments decreased from rest to 20 microg (50 vs. 24.8% and 79.9 vs. 43.2%). Between 5 and 10 microg no change of thickening and of dysfunctional segments occurred.


CONCLUSIONS
Early after AMI, DCMR demonstrated no diagnostic benefit in segments with no DE. In segments with DE, higher dose of dobutamine can provide additional information on contractile reserve and dysfunctional segments.
Clinic of Cardiology/Angiology, Heart-Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany. barmeyer@uke.uni-hamburg.de
Achim A
AA
Barmeyer
Alexander
A
Stork
Martin
M
Bansmann
Kai
K
Muellerleile
Marcus
M
Bavastro
Mirko
M
Heuer
Gerhard
G
Adam
Thomas
T
Meinertz
Gunnar K
GK
Lund
D001794:Blood Pressure / Q000187:drug effects; D002316:Cardiotonic Agents / Q000008:administration & dosage* / Q000494:pharmacology; D003287:Contrast Media; D017023:Coronary Angiography; D003326:Coronary Circulation; D004280:Dobutamine / Q000008:administration & dosage* / Q000494:pharmacology; D004562:Electrocardiography; D005260:Female; D019786:Gadolinium DTPA; D006321:Heart; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008279:Magnetic Resonance Imaging; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D009203:Myocardial Infarction / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D015588:Observer Variation; D020127:Recovery of Function
D002316:Cardiotonic Agents; D003287:Contrast Media; D004280:Dobutamine; D019786:Gadolinium DTPA