Assessment of microvascular obstruction and prediction of short-term remodeling after acute mycoardial infarction: Cardiac MR imaging study

Purpose: 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 (Ml). Materials and Methods: This study had local ethics committee approval; all patients gave written informed consent. Sixtv-three patients with first acute Ml. treated wilh primarv stent placement and optimal medical therapv. underwent cine MR imaging at 4-7 days and al 4 months after Ml. 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 contrasl material administration; (b) a three-dimensional segmented saturation-recoverv gradient-echo sequence (intermediate hypoenhancement), mean time, 2.17 minutes ± 0.26; and (c) a two-dimensional segmented inversion-recoverv gradient-ecdo 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. Univariadle linear regression analysis was used to identifv the predictive value of each MR imaging technique. Results: Early hypoenhancement was detected in 44 (70%) of 63 patients; intermediate hypoendancement, in 39 (62%); and late hvpoenhancement, in 37 (59%). Late hypoenhancement was the strongest predictor of change in LA end-diastolic and end-systolic volumes over time (β = 14.3,r = 0.40, P = .00I and β = 11.3.,r= 0.44, P < .001,. respectively), whereas intermediate and lale hypoenhancement had comparable predictive values of change in LV ejection fraction (β = -3.1. r = -0.29. P = .02 and (β = -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). Conclusion: 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