Abstract 17290: The Effect of Atrial Fibrillation at the Time of Imaging on Measurement of Myocardial T1 Time
INTRODUCTION: Atrial fibrillation (AF) is a common disease and is associated with cardiac fibrosis. Cardiac fibrosis can now be measured non-invasively using T1-mapping with cardiac magnetic resonance imaging (cMRI) and is a promising new tool for a wide range of clinical applications. We sought to investigate whether AF at the time of cMRI affects measurement of ventricular T1.
METHODS: Subjects with AF underwent cMRI prior to AF ablation. Look-Locker images were acquired in the short axis plane at the level of the mid-ventricular segment 10 minutes after Gadolinium contrast administration. MR Map version 1.3 was utilized to obtain a T1 map. The DICOM image was then analyzed in MatLab where six regions of interest were manually drawn corresponding to the anterior, anteroseptal, inferoseptal, inferior, inferolateral, and anterolateral walls in short-axis orientation. The myocardial T1 values for each voxel in each of the six regions were then exported for statistical analysis. Baseline demographic, clinical, and imaging characteristics were examined using univariate and multivariable linear regression modeling for an association with myocardial T1 time.
RESULTS: The final cohort consisted of 157 patients: 50 (32%) female, median age 61 years [IQR 55,67], 78 (50%)persistent AF, 16 (10%) lone AF, 12 (8%) with CHF, and median BMI 29 kg/m2 [26,34]. Forty seven (30%) subjects were in AF at the time of cMRI. Median global T1 time was 404 ms (IQR 381,428). In univariate analysis, shorter global T1 time was associated with female gender, higher BMI, persistent AF, and those in AF at time of cMRI (all P<0.05). In our final multivariable model, AF at the time of cMRI was associated with a 4.4% shorter T1 time (β-coefficient -18 [IQR -30,-5] P=0.000) compared to sinus rhythm when adjusted for age, gender, persistent AF, BMI, CHF, and renal dysfunction (eGFR<60).
CONCLUSIONS: Our data suggest that cardiac rhythm at the time of imaging affects myocardial T1 values in patients with AF. Further work is needed to confirm these findings and investigate whether they result from acute changes in myocardial tissue, a higher overall burden of AF in these subjects, or factors related to the image acquisition and measurement of T1 during AF.
Author Disclosures: J.A. Montgomery: None. W. Abdallah: None. Z.T. Yoneda: None. M.B. Shoemaker: None. D. Darbar: None. M. Lawson: None.
- © 2014 by American Heart Association, Inc.