Abstract 19491: Left Atrial Blood Flow Velocity Distribution in Hypertrophic Cardiomyopathy: Association with Left Ventricular Diastolic Function and Interstitial Fibrosis
Introduction: New MRI techniques (T1-mapping, 4D flow) provide quantitative assessment of myocardial extracellular volume fraction (ECV) as a measure of fibrosis as well as the in-vivo assessment of 3-directional blood flow within the entire heart.
Hypothesis: To investigate if alterations in left ventricular (LV) diastolic function in hypertrophic cardiomyopathy (HCM) are associated with increases in LV ECV and alterations in left atrial (LA) blood flow dynamics.
Methods: 4D flow and T1-mapping were performed in 22 HCM patients (mean 53±14 years) and 15 age matched controls (mean 56±5 years). For all 4D flow data, the LA was 3D segmented and LA mean blood velocity was quantified. T1 values were acquired pre and post contrast and ECV was averaged to estimate whole heart ECV. Diastolic function was assessed by echo-Doppler in 16 of the 22 HCM patients prior to MRI.
Results: All HCM patients were in sinus rhythm without history of paroxysmal atrial fibrillation (AF); 6 patients had LV outflow tract obstruction. LA mean velocities in HCM patients (0.27±0.07 m/s) were significantly increased compared to controls (0.21±0.03 m/s, p=0.009) and more heterogeneously distributed (Figure A), but were not significantly different in patients with and without obstruction and with or without mild mitral regurgitation (MR) and moderate or severe MR. There were significant correlations between LA velocities and ECV (r=0.48; p=0.02) (Figure B), ECV and LA volume index (LAVI) (r=0.7; p<0.001), ECV and E/e’(r=0.5; p=0.04), LA velocities and LAVI (r=0.55; p=0.02) and LA velocities and E/e’(r=0.67; p=0.04).
Conclusion: HCM patients showed a significant difference in 3D LA flow compared to controls. The increased mean velocity may be an index of increased interstitial tissue and diastolic dysfunction. These novel functional measures may be useful in assessing severity of HCM and risk stratification, particularly the risk of future AF, and warrant further longitudinal investigation.
- Hypertrophic cardiomyopathy
- Magnetic resonance imaging
- Diastolic function
- Extracellular matrix
Author Disclosures: C. Contaldi: None. L. Choudhury: None. B. Allen: None. D. Lee: None. N. Furiasse: None. J. Puthumana: None. J. Carr: None. M. Markl: None. R. Bonow: None.
- © 2014 by American Heart Association, Inc.