Assessment of microvascular obstruction and prediction of short-term remodeling after acute myocardial infarction: cardiac MR imaging study.
OBJECTIVE
To evaluate which cardiac magnetic resonance (MR) imaging technique for detection of microvascular obstruction (MVO) best predicts left ventricular (LV) remodeling after acute myocardial infarction (MI).


METHODS
This study had local ethics committee approval; all patients gave written informed consent. Sixty-three patients with first acute MI, treated with primary stent placement and optimal medical therapy, underwent cine MR imaging at 4-7 days and at 4 months after MI. Presence of MVO was qualitatively evaluated at baseline by using three techniques: (a) a single-shot saturation-recovery gradient-echo first-pass perfusion sequence (early hypoenhancement), mean time, 1.09 minutes +/- 0.07 (standard deviation) after contrast material administration; (b) a three-dimensional segmented saturation-recovery gradient-echo sequence (intermediate hypoenhancement), mean time, 2.17 minutes +/- 0.26; and (c) a two-dimensional segmented inversion-recovery gradient-echo late gadolinium enhancement sequence (late hypoenhancement), mean time, 13.32 minutes +/- 1.26. Contrast-to-noise ratios (CNRs) were calculated from the signal-to-noise ratios of the infarcted myocardium and MVO areas. Univariable linear regression analysis was used to identify the predictive value of each MR imaging technique.


RESULTS
Early hypoenhancement was detected in 44 (70%) of 63 patients; intermediate hypoenhancement, in 39 (62%); and late hypoenhancement, in 37 (59%). Late hypoenhancement was the strongest predictor of change in LV end-diastolic and end-systolic volumes over time (beta = 14.3, r = 0.40, P = .001 and beta = 11.3, r = 0.44, P < .001, respectively), whereas intermediate and late hypoenhancement had comparable predictive values of change in LV ejection fraction (beta = -3.1, r = -0.29, P = .02 and beta = -2.8, r = -0.27, P = .04, respectively). CNR corrected for spatial resolution was significantly superior for late enhancement compared with the other sequences (P < .001).


CONCLUSIONS
By using cardiac MR imaging, late hypoenhancement is the best prognostic marker of LV remodeling, with highest CNR between the infarcted myocardium and MVO regions.
Nijveldt
Robin
R
Departments of Cardiology and Physics and Medical Technology, VU University Medical Center, Amsterdam, the Netherlands.
Hofman
Mark B M
MB
Hirsch
Alexander
A
Beek
Aernout M
AM
Umans
Victor A W M
VA
Algra
Paul R
PR
Piek
Jan J
JJ
van Rossum
Albert C
AC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015906:Angioplasty, Balloon, Coronary; D003287:Contrast Media / Q000008:administration & dosage; D054059:Coronary Occlusion / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology* / Q000628:therapy; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015607:Stents; D020257:Ventricular Remodeling / Q000502:physiology*
D003287:Contrast Media; D019786:Gadolinium DTPA