Aims The aim of our study was to establish normal ranges for left atrial (LA) strain and strain rate using cardiac magnetic resonance feature tracking (CMR-FT), LA sphericity index, and to compare LA strain using CMR-FT with 2D-speckle tracking echocardiography (STE) in a healthy population. Methods and results A total of 112 volunteers (45 male, 67 female) had adequate tracking for analysis on CMR-FT (Circle Cardiovascular Imaging, Calgary, Canada). The median age was 42 years (range 19–79 years, interquartile range 30–53 years). LA reservoir, conduit, booster strain, strain rate using CMR-FT, and sphericity index were evaluated. Of the 112 volunteers, 91 patients had adequate tracking on 2D-STE using three commonly applied zero-baseline time reference methods: R-R gating, P-P gating, and volume gating (defining end-systole at the LA maximum and end-diastole at the LA minimum). The LA strain, strain rate using CMR-FT, and sphericity index were reported and comparable between both genders (P > 0.05 for all). The LA booster function including strain and strain rate increased significantly with age (P < 0.001 for all), while the LA conduit function gradually decreased. In comparison with STE, the LA reservoir strain was comparable between CMR and volume-gating methods (38.48 ± 9.31 vs. 36.77 ± 6.46; P = 0.13) but not with R-R and P-P gating methods (P < 0.001 for all). LA strain, strain rate, and sphericity index using CMR-FT had good intraobserver and interobserver reproducibility. Conclusion LA strain, strain rate using CMR-FT, and sphericity index can be quickly assessed with good intraobserver and interobserver reproducibility.

Speckle tracking echocardiography (STE), and more recently, cardiovascular magnetic resonance myocardial feature tracking (cMR-ft) provides insight into all phases of atrial function. the aim of our study was to compare all phases of RA strain using cMR-ft and Ste and also assess the relationship between RA and LA strain. A total of 61 healthy volunteers with mean age of 45 ± 13 years had adequate tracking for analysis on CMR-FT and 2D-STE. Females had larger RA reservoir strain (39 ± 15% vs. 32 ± 13%, p = 0.046) and conduit strain (26 ± 12% vs. 20 ± 9%, p = 0.03) when compared to males, but was not the case with booster strain (14 ± 7% vs. 12 ± 6%, p = 0.45). In comparison with STE derived strain, the RA reservoir and conduit strain were not significantly different between CMR-FT and the three echocardiography gating methods (p > 0.05 for all). Noticeably, there were no significant differences in strain and strain rate between RA and LA function using CMR-FT (p > 0.05 for all). RA strain and strain rate using cMR-ft had fair and good intra-and inter-observer reproducibility and had superior reproducibility compared to Ste derived strain. Right atrial (RA) strain is emerging as a promising technique for robust assessment of RA function 1,2. For decades, the right heart has been underplayed in its contribution to overall cardiac function and has been affectionately coined the "forgotten heart". While the right heart is no longer forgotten, it remains poorly understood and to date calls for further investigation. Speckle tracking echocardiography (STE), and more recently, cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) provides insight into all phases of atrial function including reservoir, conduit, and booster 3-5. Recently, RA dyssynchrony can be analysed by determining the time to peak strain in the reservoir phase or during atrial contractile phase 6. RA function can be challenging by STE given the anatomic location of the RA, thin atrial wall, RA appendage, and the presence of superior and inferior vena cava 7,8. On the contrary, given its higher spatial resolution and ability to define endocardial borders, CMR has long been accepted as the gold standard modality for assessment of the heart 9. CMR-derived myocardial feature tracking (FT) is a technique analogous to echocardiography speckle tracking, deriving quantitative deformation parameters from routinely available steady state free precession (SSFP) cine sequence, and therefore does not require additional tagging sequence acquisitions 10. While there are obvious advantages of CMR, RA strain using CMR compared with those using STE is currently lacking. The aim of our study was (1) compare all phases of RA strain using CMR-FT and STE, and (2) assess the relationship between RA and LA strain.

To determine the differences in left atrial (LA) function and geometry assessed by cardiac magnetic resonance (CMR) between transthyretin (ATTR) and immunoglobulin light chain (AL) cardiac amyloidosis (CA). We performed a retrospective analysis of 54 consecutive patients (68.5% male, mean age 67 ± 11 years) with confirmed CA (24 ATTR, 30 AL) who underwent comprehensive CMR examinations. LA structural and functional assessment including LA volume, LA sphericity index, and LA strain parameters were compared between both subtypes. In addition, 15 age-matched controls were compared to all groups. Patients with ATTR-CA were older (73 ± 9 vs. 62 ± 10 years, p < 0.001) and more likely to be male (83.3% vs. 56.7%, p = 0.036) when compared to AL-CA. No significant difference existed in LA maximum volume and LA sphericity index between ATTR-CA and AL-CA. LA minimum volumes were larger in ATTR-CA when compared with AL-CA. There was a significant difference in LA function with worse strain values in ATTR vs AL: left atrial reservoir [7.4 (6.3–12.8) in ATTR vs. 13.8 (6.90–24.8) in AL, p = 0.017] and booster strains [3.6 (2.6–5.5) in ATTR vs. 5.2 (3.6–12.1) in AL, p = 0.039]. After adjusting for age, LA reservoir remained significantly lower in ATTR-CA compared to AL-CA (p = 0.03), but not LA booster (p = 0.16). We demonstrate novel differences in LA function between ATTR-CA and AL-CA despite similar LA geometry. Our findings of more impaired LA function in ATTR may offer insight into higher AF burden in these patients.

BackgroundAtrial function has a close interdependence with ventricular function and plays a central role in maintaining optimal cardiac function. There are two well‐defined timing methods used to determine the start point. The aim of this prospective study was to objectively assess the influence of gating method selection on reported left and right strain values within the same group of healthy subjects.Methods101 volunteers (44 male, 57 female) had adequate tracking for analysis on TomTec Imaging Systems (Unterschleissheim, Germany). The median age was 41 years (range 19‐79 years, interquartile range 30‐52 years). Atrial strain by 2D‐speckle tracking echocardiography was evaluated using two commonly applied zero baseline time reference methods: R‐R gating and P‐P gating, in addition to volume gating (defining end‐systole at the atrial maximum and end‐diastole at the atrial minimum).ResultsTrue atrial minimum occurred prior to the onset of the QRS in most healthy volunteers. There was a significant difference for LA and RA reservoir strain between volume gating and R‐R gating (mean difference, 4.63%; P < .001 for LA; mean difference, 4.23%; P < .001 for RA), as well as volume gating and P‐P gating (mean difference, 5.26%; P < .001 for LA; mean difference, 6.24%; P < .001 for RA). Noticeably, reservoir strain was comparable between R‐R gating and P‐P gating (mean difference, 0.58%, P = .06) in LA, but not on RA (mean difference, 2.02%, P < .001).ConclusionsThere was variability in atrial strain values depending on the zero baseline time reference method used.

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