Intramyocardial fat deposition in patients with previous myocardial infarction assessed using advanced CMR imaging – feature tracking, fat water separation and parametric mapping

Abstract

Background: Intramyocardial fat deposition predisposes an individual to ventricular arrhythmias and increased risk of sudden cardiac death. This study aimed to detect fat infiltration in patients with previous myocardial infarction (MI) using advanced cardiac magnetic resonance (CMR) imaging techniques – feature tracking, fat water separation and parametric mapping. Methods: Twenty patients with chronic MI underwent advanced CMR imaging. The study protocol included conventional cine and late gadolinium enhancement (LGE) imaging. Additionally, fat water separation (2-point mDixon) and parametric mapping were performed in every patient. Left ventricular (LV) circumferential (EccLV) and radial (ErrLV) strain were calculated using dedicated software (CMR42, Circle Cardiovascular Imaging Inc., Calgary, Canada). The extent of global scar tissue was calculated in LGE and fat water separation images to compare advanced and conventional imaging techniques. The native and post-contrast T1 relaxation values of the remote myocardium, global LGE, intramyocardial fat, fibrosis and extracardiac adipose tissue were measured. Results: The infarct size as derived from conventional LGE and fat water separation images was similar. However, detection of intramyocardial fat was only possible with fat water separation imaging. Subjects with intramyocardial fat deposition demonstrated significantly smaller percentage of fibrosis than those without fat deposition (10.68 ± 5.07 % vs. 13.83 ± 6.30 %; p = 0.005). There was no difference between the groups with respect of mean native T1 values. The mean post-contrast T1 values of global LGE in patients with intramyocardial fat were significantly higher than in patients without (372.26 ± 39.01 ms vs. 312.70 ± 33.02 ms; p = 0.017). There was no significant difference in LV circumferential (EccLV) and radial (ErrLV) strain between myocardial segments containing fibrosis only and fibros [...].