Background-The extent of the peri-infarct zone by magnetic resonance imaging (MRI) has been related to all-cause mortality in patients with coronary artery disease. This relationship may result from arrhythmogenesis in the infarct border. However, the relationship between tissue heterogeneity in the infarct periphery and arrhythmic substrate has not been investigated. In the present study, we quantify myocardial infarct heterogeneity by contrast-enhanced MRI and relate it to an electrophysiological marker of arrhythmic substrate in patients with left ventricular (LV) systolic dysfunction undergoing prophylactic implantable cardioverter defibrillator placement. Methods and Results-Before implantable cardioverter defibrillator implantation for primary prevention of sudden cardiac death, 47 patients underwent cine and contrast-enhanced MRI to measure LV function, volumes, mass, and infarct size. A method for quantifying the heterogeneous infarct periphery and the denser infarct core is described. MRI indices were related to inducibility of sustained monomorphic ventricular tachycardia during electrophysiological or device testing. For the noninducible versus inducible patients, LV ejection fraction (30Ϯ10% versus 29Ϯ7%, Pϭ0.79), LV end-diastolic volume (220Ϯ70 versus 228Ϯ57 mL, Pϭ0.68), and infarct size by standard contrast-enhanced MRI definitions (PϭNS) were similar. Quantification of tissue heterogeneity at the infarct periphery was strongly associated with inducibility for monomorphic ventricular tachycardia (noninducible versus inducible: 13Ϯ9 versus 19Ϯ8 g, Pϭ0.015) and was the single significant factor in a stepwise logistic regression. Conclusions-Tissue heterogeneity is present and quantifiable within human infarcts. More extensive tissue heterogeneity correlates with increased ventricular irritability by programmed electrical stimulation. These findings support the hypothesis that anatomic tissue heterogeneity increases susceptibility to ventricular arrhythmias in patients with prior myocardial infarction and LV dysfunction.

Background-Accurate risk stratification is crucial for effective treatment planning after myocardial infarction (MI).Previous studies suggest that the peri-infarct border zone may be an important arrhythmogenic substrate. In this pilot study, we tested the hypothesis that the extent of the peri-infarct zone quantified by contrast-enhanced cardiac magnetic resonance (CMR) is an independent predictor of post-MI mortality. Methods and Results-We studied 144 patients with documented coronary artery disease and abnormal myocardial delayed enhancement (MDE) consistent with MI. A computer-assisted, semiautomatic algorithm quantified the total infarct size and divided it into the core and peri-infarct regions based on signal-intensity thresholds (Ͼ3 SDs and 2 to 3 SDs above remote normal myocardium, respectively). The peri-infarct zone was normalized as a percentage of the total infarct size (%MDE periphery ). After a median follow-up of 2.

When an objective technique is used to define MI size by CE-MRI, accurate infarct size measurements can be obtained from images obtained up to 30 min after contrast administration.

Contrast-enhanced CMRI T(1) mapping identifies changes in myocardial T(1) times in heart failure, which appear to reflect diffuse fibrosis.

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