Contractile reserve in segments with nontransmural infarction in chronic dysfunctional myocardium using low-dose dobutamine CMR.
OBJECTIVE
This study sought to quantify contractile reserve of chronic dysfunctional myocardium, in particular in segments with intermediate transmural extent of infarction (TEI), using low-dose dobutamine cardiac magnetic resonance (CMR) in patients with a chronic total coronary occlusion (CTO).


BACKGROUND
Recovery of dysfunctional segments with intermediate TEI after percutaneous coronary intervention is variable and difficult to predict, and may be related to contractility of the unenhanced rim.


METHODS
Fifty-one patients (mean age 60 +/- 9 years, 76% male) with a CTO underwent CMR at baseline and 35 patients underwent CMR at follow-up to quantify segmental wall thickening (SWT) at rest during 5 and 10 microg/kg/min dobutamine, and at follow-up. Delayed-enhancement CMR was performed to quantify TEI. Dysfunctional segments were stratified according to TEI, end-diastolic wall thickness (EDWT), or unenhanced rim thickness, and SWT was quantified. Segments with an intermediate TEI (25% to 75%) were further stratified according to baseline SWT of the unenhanced rim (SWT(UR)) (<45% and >45%), and SWT was quantified. For each parameter, odds ratio (OR) and diagnostic performance for the prediction of contractile reserve were calculated.


RESULTS
Significant contractile reserve was present in dysfunctional segments with EDWT >6 mm, unenhanced rim thickness >3 mm, or TEI of <25%; only TEI had significant relation with contractile reserve (OR: 0.98; 95% confidence interval [CI]: 0.96 to 0.99; p = 0.02). In segments with intermediate TEI (n = 58), mean SWT did not improve significantly. However, segments with SWT(UR) <45% showed contractile reserve and improved at follow-up, whereas segments with SWT(UR) >45% were unchanged. SWT(UR) had a significant relation with contractile reserve (OR: 0.98; 95% CI: 0.97 to 0.99; p = 0.02).


CONCLUSIONS
CMR quantification of transmurality of infarcted myocardium allows the assessment of the potential of dysfunctional segments to improve in function during dobutamine of most segments. However, in segments with intermediate TEI, measurement of baseline contractility of the epicardial rim better identifies which segments maintain contractile reserve.
Kirschbaum
Sharon W
SW
Department of Cardiology, Erasmus University Medical Center, Rotterdam, the Netherlands.
Rossi
Alexia
A
van Domburg
Ron T
RT
Gruszczynska
Katerina
K
Krestin
Gabriel P
GP
Serruys
Patrick W
PW
Duncker
Dirk J
DJ
de Feyter
Pim J
PJ
van Geuns
Robert-Jan M
RJ
D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D003287:Contrast Media; D054059:Coronary Occlusion / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D004280:Dobutamine / Q000008:administration & dosage; D005260:Female; D019786:Gadolinium DTPA; D006439:Hemodynamics; D006801:Humans; D007262:Infusions, Intravenous; D016015:Logistic Models; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D009206:Myocardium / Q000473:pathology*; D009426:Netherlands; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function; D013997:Time Factors; D016896:Treatment Outcome
D003287:Contrast Media; D004280:Dobutamine; D019786:Gadolinium DTPA