Increased myocardial extracellular volume assessed by cardiovascular magnetic resonance T1 mapping and its determinants in type 2 diabetes mellitus patients with normal myocardial systolic strain

Background: Cardiac magnetic resonance (CMR) T1 mapping and tissue-tracking strain analysis are useful quantitative techniques that can characterize myocardial tissue and mechanical alterations, respectively, in patients with early diabetic cardiomyopathy. The purpose of this study was to assess the left ventricular myocardial T1 value, extracellular volume fraction (ECV), and systolic strain in asymptomatic patients with type 2 diabetes mellitus (T2DM) and their underlying relationships with clinical parameters. Methods: We recruited 50 T2DM patients (mean age: 55 +/- 7 years; 28 males) and 32 sex-, age-and BMI-matched healthy volunteers to undergo contrast-enhanced CMR examinations. The myocardial native T1, post-contrast T1 and ECV values of the left ventricle were measured from T1 and ECV maps acquired using the modified Look-Locker inversion recovery technique. The left ventricular global systolic strain and the strain rates were evaluated using routine cine images and tissue-tracking analysis software. The baseline clinical and biochemical indices were collected before the CMR examination. Results: The myocardial ECV and native T1 values were significantly higher in the diabetic patients than in the controls. (ECV: 27.4 +/- 2.5% vs. 24.6 +/- 2.2%, p < 0.001; native T1: 1026.9 +/- 30.0 ms vs. 1011.8 +/- 26.0 ms, p = 0.022). However, the left ventricular global systolic strain, strain rate, volume, myocardial mass, ejection fraction, and left atrial volume were similar between the diabetic patients and the healthy controls. In the diabetic patients, the native T1 values were independently correlated with the hemoglobin A1c levels (standardized beta = 0.368, p = 0.008). The ECVs were independently associated with the hemoglobin A1c levels (standardized beta = 0.389, p = 0.002), angiotensin-converting enzyme inhibitor (ACEI) treatment (standardized beta = - 0.271, p = 0.025) and HCT values (standardized beta = - 0.397, p = 0.001). Conclusions: Type 2 diabetes mellitus patients with normal myocardial systolic strain exhibit increased native T1 values and ECVs indicative of myocardial extracellular interstitial expansion, which might be related to poor glycemic control. The amelioration of myocardial interstitial matrix expansion might be associated with ACEI treatment. A valid assessment of the association of glucose control and ACEI treatment with myocardial fibrosis requires notably larger trials.