Association between diffuse myocardial fibrosis by cardiac magnetic resonance contrast-enhanced T₁ mapping and subclinical myocardial dysfunction in diabetic patients: a pilot study.

BACKGROUND Diabetic patients have increased interstitial myocardial fibrosis on histological examination. Magnetic resonance imaging (MRI) T(1) mapping is a previously validated imaging technique that can quantify the burden of global and regional interstitial fibrosis. However, the association between MRI T(1) mapping and subtle left ventricular (LV) dysfunction in diabetic patients is unknown. METHODS AND RESULTS Fifty diabetic patients with normal LV ejection fraction (EF) and no underlying coronary artery disease or regional macroscopic scar on MRI delayed enhancement were prospectively recruited. Diabetic patients were compared with 19 healthy controls who were frequency matched in age, sex and body mass index. There were no significant differences in mean LV end-diastolic volume index, end-systolic volume index and LVEF between diabetic patients and healthy controls. Diabetic patients had significantly shorter global contrast-enhanced myocardial T(1) time (425±72 ms vs. 504±34 ms, P<0.001). There was no correlation between global contrast-enhanced myocardial T(1) time and LVEF (r=0.14, P=0.32) in the diabetic patients. However, there was good correlation between global contrast-enhanced myocardial T(1) time and global longitudinal strain (r=-0.73, P<0.001). Global contrast-enhanced myocardial T(1) time was the strongest independent determinant of global longitudinal strain on multivariate analysis (standardized β=-0.626, P<0.001). Similarly, there was good correlation between global contrast-enhanced myocardial T(1) time and septal E' (r=0.54, P<0.001). Global contrast-enhanced myocardial T(1) time was also the strongest independent determinant of septal E' (standardized β=0.432, P<0.001). CONCLUSIONS A shorter global contrast-enhanced myocardial T(1) time was associated with more impaired longitudinal myocardial systolic and diastolic function in diabetic patients.