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Objectives: We examined the relation between angiographic, electrocardiographic, and gadolinium-enhanced cardiovascular magnetic resonance (CMR) characteristics of microvascular obstruction (MVO), and their predictive value on functional recovery after acute myocardial infarction (AMI)., Background: Microvascular obstruction on CMR has been shown to predict left ventricular (LV) remodeling, but it is not well known how it compares with commonly used criteria of microvascular injury, and earlier reports have produced conflicting results on the significance and extent of MVO., Methods: Thrombolysis In Myocardial Infarction (TIMI) flow grade, myocardial blush grade (MBG), and ST-segment resolution were assessed in 60 patients with AMI treated with primary stenting. Cardiovascular magnetic resonance was performed between 2 and 9 days after revascularization to determine early MVO on first-pass perfusion imaging, late MVO on late gadolinium-enhanced imaging, and infarct size and transmural extent. Cine imaging was used to determine LV volumes and global and regional function at baseline and 4-month follow-up., Results: Early and late MVO were both related to incomplete ST-segment resolution (p = 0.002 and p = 0.01, respectively), but not to TIMI flow grade and MBG. Of all angiographic, electrocardiographic, and CMR variables, late MVO was the strongest parameter to predict changes in end-diastolic volume (beta = 0.53; p = 0.001), end-systolic volume (beta = 8.67; p = 0.001), and ejection fraction (beta = 3.94; p = 0.006) at follow-up. Regional analysis showed that late MVO had incremental diagnostic value to transmural extent of infarction (odds ratio: 0.18; p < 0.0001)., Conclusions: In patients after revascularized AMI, late MVO proved a more powerful predictor of global and regional functional recovery than all of the other characteristics, including transmural extent of infarction.

Objectives: We studied the relation between presence and severity of microvascular obstruction (MO), measured by cardiovascular magnetic resonance (CMR) and intracoronary Doppler flow measurements, for assessment of myocardial reperfusion in patients with acute anterior myocardial infarction (MI) treated by primary percutaneous coronary intervention (PCI)., Background: Cardiovascular magnetic resonance has been used to detect and quantify MO in patients after acute MI but has never been compared with coronary blood flow velocity patterns., Methods: Twenty-seven patients with first anterior ST-segment elevation MI successfully treated with primary PCI were included. Coronary blood flow velocity was measured during recatheterization 4 to 8 days after primary PCI. These measurements were related to MO determined by late gadolinium-enhanced (LGE) CMR performed the day before recatheterization., Results: Early systolic retrograde flow was observed in 0 of 8 patients without MO on LGE CMR and in 10 (53%) of 19 patients with MO (p = 0.01). The extent of MO correlated with the diastolic-systolic velocity ratio (r = 0.44; p = 0.02), diastolic deceleration time (r = -0.61; p = 0.001), diastolic deceleration rate (r = 0.75; p < 0.0001), and coronary flow velocity reserve of the infarct-related artery (r = -0.44; p = 0.02). Furthermore, multivariate regression analyses, including extent of MO, infarct size, and transmural necrosis on LGE CMR, revealed that extent of MO was the only independent factor related to early systolic retrograde flow and diastolic deceleration rate., Conclusions: Assessment of microvascular injury by LGE CMR corresponds well to evaluation by intracoronary Doppler flow measurements. By means of CMR, quantification of myocardial function, infarct size, and microvascular injury can accurately be performed with a single noninvasive technique in patients with acute MI.

Objectives: The aim of this study was to evaluate myocardial infarction induced by percutaneous transluminal septal myocardial ablation (PTSMA) in symptomatic patients with hypertrophic obstructive cardiomyopathy using contrast-enhanced (CE) magnetic resonance imaging (MRI)., Background: Contrast-enhanced MRI delineates the extent of myocardial infarction in coronary artery disease, but its role in ethanol-induced infarction has not been established., Methods: Cine and CE MRI were performed before and one month after PTSMA in 24 patients. Size and location of the induced infarction were related to left ventricular (LV) mass reduction, enzyme release, volume of ethanol administered, LV outflow tract gradient reduction, and coronary ablation site., Results: One month after PTSMA, regional hyperenhancement was visualized in the basal interventricular septum in all patients. Mean infarction size was 20 +/- 9 g, corresponding to 10 +/- 5% and 31 +/- 16% of total LV and septal mass, respectively. Total LV mass decreased from 219 +/- 64 to 205 +/- 64 g (p < 0.01), and septal mass from 76 +/- 25 to 68 +/- 22 g (p < 0.01). Total LV mass reduction exceeded septal mass reduction (p < 0.01). Infarction size correlated with peak creatine phosphokinase-MB (beta = 0.67, p < 0.01), volume of ethanol administered (beta = 0.47, p = 0.02), total LV and septal mass reduction (beta = 0.50, p = 0.02; beta = 0.73, p < 0.01), and gradient reduction (beta = 0.63, p < 0.01). Seven patients with exclusively right-sided septal infarction had smaller infarction size and less gradient reduction than remaining patients with left-sided or transmural infarction (p < 0.01). In five of these, PTSMA was performed distal in the target artery., Conclusions: Contrast-enhanced MRI allowed detailed evaluation of size and location of septal myocardial infarction induced by PTSMA. Infarction size correlated well with clinical indexes of infarct size.

Objectives: We evaluated whether delayed contrast-enhanced magnetic resonance imaging (DCE-MRI) using an extracellular contrast agent could predict improvement of dysfunctional but viable myocardium after acute reperfused myocardial infarction (MI)., Background: The transmural extent of hyperenhancement at DCE-MRI has been related to improvement of function in reperfused MI. However, evidence is still limited, and earlier reports have produced conflicting results regarding the significance of contrast patterns after infarction., Methods: Thirty patients (mean age 59 +/- 11 years, 27 males) underwent cine MRI and DCE-MRI 7 +/- 3 days after a first reperfused acute MI and follow-up cine MRI at 13 +/- 3 weeks. Segmental wall thickening and segmental extent of hyperenhancement were scored in 1,689 segments., Results: Of 500 dysfunctional segments, 273 (55%) improved at follow-up. There was no difference in likelihood of improvement or complete functional recovery between segments with 0% and 1% to 25% hyperenhancement. The likelihood of improvement of segments without hyperenhancement was 2.9, 14.3, and 20 times higher than that of segments with 26% to 50%, 51% to 75%, and >75% hyperenhancement, respectively (p < 0.001). The likelihood of complete functional recovery of segments without hyperenhancement was 3.8, 11.1, and 50 times higher than that of segments with 26% to 50%, 51% to 75%, and >75% hyperenhancement, respectively (p < 0.001)., Conclusions: In patients with recent reperfused MI, functional improvement of stunned myocardium is predicted by DCE-MRI.

Objectives: We sought to compare contrast-enhanced magnetic resonance imaging (ceMRI) with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic ischemic heart disease and left ventricular (LV) dysfunction., Background: Contrast-enhanced MRI has been shown to identify scar tissue in ischemically damaged myocardium., Methods: Twenty-six patients with chronic coronary artery disease and LV dysfunction (mean ejection fraction 31 +/- 11%) underwent (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET), technetium-99m tetrofosmin single-photon emission computed tomography (SPECT), and ceMRI. In a 17-segment model, the segmental extent of hyperenhancement (SEH) by ceMRI, defined as the relative amount of contrast-enhanced tissue per myocardial segment, was compared with segmental FDG and tetrofosmin uptake by PET and SPECT., Results: In severely dysfunctional segments (n = 165), SEH was 9 +/- 14%, 33 +/- 25% (p < 0.05), and 80 +/- 23% (p < 0.05) in segments with normal metabolism/perfusion, metabolism/perfusion mismatch, and matched defects, respectively. Segmental glucose uptake by PET was inversely correlated to SEH (r = -0.86, p < 0.001). By receiver operator characteristic curve analysis, the area under the curve was 0.95 for the differentiation between viable and non-viable segments. At a cutoff value of 37%, SEH optimally differentiated viable from non-viable segments defined by PET. Using this threshold, the sensitivity and specificity of ceMRI to detect non-viable myocardium as defined by PET were 96% and 84%, respectively., Conclusions: Contrast-enhanced MRI allows assessment of myocardial viability with a high accuracy, compared with FDG-PET, in patients with chronic ischemic heart disease and LV dysfunction.