Myocardial fat deposition after left ventricular myocardial infarction: assessment by using MR water-fat separation imaging.

PURPOSE: To prospectively investigate the prevalence of fat deposition in chronic myocardial infarction (MI) by using magnetic resonance (MR) fat-water separation imaging with sampling of the entire left ventricular (LV) myocardium. A subsidiary aim was to determine the relationship between LV fat deposition and scar characteristics, as well as regional and global cardiac functional parameters.
MATERIALS AND METHODS: Twenty-five patients with LV MI were evaluated in this prospective institutional review board-approved, Health Insurance Portability and Accountability Act-compliant study after they provided written informed consent. A 1.5-T MR system was used to perform volumetric cine, fat-sensitive, and late gadolinium-enhanced (LGE) infarct imaging. Water-fat separation was performed by using a three-point Dixon reconstruction from in- and opposed-phase black-blood gradient-echo images. Fat deposition location was compared with LGE infarct imaging by using a 17-segment model. Global and regional functional variables, LGE volumes, and fat deposition were compared by using the Pearson correlation, Student t test, and multiple regression.
RESULTS: A fat deposition prevalence of 68% was found in areas of chronic MI. The patients with fat deposition had larger infarctions (30.0 mL +/- 15.1 [standard deviation] vs 14.8 mL +/- 6.1; P = .002), decreased wall thickening (2.3% +/- 20.0 vs 37.8% +/- 34.4; P = .003), and impaired endocardial wall motion (2.9 mm +/- 2.0 vs 5.8 mm +/- 2.6; P = .007). The volume of fat deposition was correlated with infarct volume, LV ejection fraction, LV end-diastolic volume index, and LV end-systolic volume index.
CONCLUSION: There is a high prevalence of fat deposition in healed MI. It is associated with post-infarction characteristics including infarct volume, LV mass, wall thickness, wall thickening, and wall motion.