Quantification of left atrial strain and strain rate using cardiovascular magnetic resonance myocardial feature tracking

Abstract Left-atrial (LA) strain is the result of complex hemodynamics, increasingly assessed by feature-tracking cardiovascular magnetic resonance (CMR). We investigate the value of multi-parametric regression (MPR) analyses and the influence of the heart rate on LA-strain. As LA-strain data remains limited, CMR-quantified sex- and age-dependent normal values were derived. After following a health assessment questionnaire, 183 healthy volunteers (11-70 years, 97 females, median 32.9±28.3 years) were recruited for LA-strain assessment. LA volumetric data, left ventricular strain, transmitral and pulmonary venous blood flow parameters were utilized to create clusters for MPR analyses for all subjects and heart rate-specific subgroups (range: 60–75 beats-per-minute, N=106). In comparison to the total cohort, subgroups showed no gender differences (p>0.05) for LA reservoir, conduit and booster strains (all: 47.3±12.7%; 29.0±15.5%; 17.6±5.4%) and strain rates (all: 2.1±1.0 s−1; -2.9 ± 1.5 s−1; -2.3 ± 1.0 s−1). MPR analyses identified parameter clusters with large effect size (|R²|≥0.26) for reservoir-, conduit- and booster strain and corresponding active and passive cardiac functional parameters. Increased correlations for the subgroup were found. In contrast to previous studies, heart rate selected subgroups showed no gender differences in LA-strain. MPR analyses improve characterization of LA-strain at selected heart rates.

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Abstract 5664: Left Atrial Strain In Patients With Atrial Fibrillation: Relationship To Fibrosis By Delayed Enhancement-MRI

Circulation ◽

10.1161/circ.118.suppl_18.s_980-a ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Suman S Kuppahally ◽

Robert S Oakes ◽

Eric N Fish ◽

Eugene Kholmovski ◽

Sathya Vijayakumar ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Strain Rate ◽

Left Atrial ◽

Delayed Enhancement ◽

Left Atrial Strain ◽

Chamber View ◽

Strain And Strain Rate ◽

Procedural Success ◽

Atrial Strain

Introduction: The extent of left atrial (LA) wall fibrosis detected by delayed enhancement (DE)-cardiac MRI prior to catheter ablation of atrial fibrillation (AF) appears to predict procedural success. However, it is currently unknown how the degree of fibrosis affects atrial mechanical function. Methods: Prior to catheter ablation of AF, 31 patients underwent DE-CMRI and 2-dimensional transthoracic echocardiography. 3D segmentation of LA was performed and the degree of fibrosis was determined using a semi-automated quantification algorithm. Longitudinal mid-septal and mid-lateral LA wall velocity, strain and strain rate were measured during ventricular systole from the apical 4-chamber view by velocity vector imaging. Results : There was greater percent of fibrosis as LA maximum (R = 0.4, p = 0.05) and minimum (R=0.52, p = 0.008) volumes increased. Figure shows examples of DE-CMRI and strain curves (C) for two patients: Patient 1(A) with mild fibrosis and patient 2 (B) with extensive fibrosis. Patient 1 shows much larger strain than patient 2. Larger LA volumes correlated inversely with maximal LA mid-lateral systolic wall strain (p < 0.005). The percent fibrosis also correlated inversely with maximal LA mid-lateral systolic wall strain (R=0.56, p < 0.005) and the systolic strain rate (R = 0.58, p = 0.002). Conclusion: LA strain and strain rate can be assessed using standard echocardiographic gray scale images. LA strain is related to both atrial volumes and fibrosis, which are markers of atrial disease progression. This relationship may represent changes in the properties of LA substrate. These novel imaging approaches may be helpful in predicting outcomes in patients with AF.

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